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'5') (Obsoleted by RFC 8126) -- Obsolete informational reference (is this intentional?): RFC 4601 (ref. '7') (Obsoleted by RFC 7761) Summary: 2 errors (**), 0 flaws (~~), 18 warnings (==), 19 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 1 PIM working group S. Sami 2 Internet Draft 3 Intended status: Proposed standard May 25, 2017 4 Expires: November 2017 6 Protocol independent multicast- Next Generation (PIM-NG): 7 Protocol Specifications 9 draft-sami-pim-ng-11.txt 11 Status of this Memo 13 This Internet-Draft is submitted in full conformance with the 14 provisions of BCP 78 and BCP 79. 16 Internet-Drafts are working documents of the Internet Engineering 17 Task Force (IETF), its areas, and its working groups. Note that 18 other groups may also distribute working documents as Internet- 19 Drafts. 21 Internet-Drafts are draft documents valid for a maximum of six months 22 and may be updated, replaced, or obsoleted by other documents at any 23 time. It is inappropriate to use Internet-Drafts as reference 24 material or to cite them other than as "work in progress." 26 The list of current Internet-Drafts can be accessed at 27 http://www.ietf.org/ietf/1id-abstracts.txt 29 The list of Internet-Draft Shadow Directories can be accessed at 30 http://www.ietf.org/shadow.html 32 This Internet-Draft will expire on November 25, 2017. 34 Copyright Notice 36 Copyright (c) 2017 IETF Trust and the persons identified as the 37 document authors. All rights reserved. 39 This document is subject to BCP 78 and the IETF Trust's Legal 40 Provisions Relating to IETF Documents 41 (http://trustee.ietf.org/license-info) in effect on the date of 42 publication of this document. Please review these documents 43 carefully, as they describe your rights and restrictions with respect 44 to this document. Code Components extracted from this document must 45 include Simplified BSD License text as described in Section 4.e of 46 the Trust Legal Provisions and are provided without warranty as 47 described in the Simplified BSD License. 49 This document is subject to BCP 78 and the IETF Trust's Legal 50 Provisions Relating to IETF Documents 51 (http://trustee.ietf.org/license-info) in effect on the date of 52 publication of this document. Please review these documents 53 carefully, as they describe your rights and restrictions with respect 54 to this document. 56 Abstract 58 This document specifies protocol independent multicast- Next 59 generation or simply called PIM-NG. PIM-NG uses the underlying 60 unicast routing information, but unlike PIM-SM it doesn't necessarily 61 need to build unidirectional shared trees rooted at a Rendezvous 62 Point (RP) per group, due to the fact that the processes through 63 which a source registers with the Rendezvous Point and a host finds 64 the source of the multicast destination groups it needs are done in a 65 whole new way and hence, the source of multicast group (G) is 66 discovered faster. So at some points PIM-NG works faster than its 67 predecessor. Also the new Domain concept, unique to PIM-NG, along the 68 RPF check method used in PIM-NG specifications provides many features 69 along a robust and flexible control and administration over multicast 70 networks. 72 Table of Contents 74 1. Introduction...................................................9 75 2. Terminology....................................................9 76 2.1. Definitions..............................................10 77 3. IP Address considerations.....................................14 78 4. PIM-NG processes..............................................15 79 4.1. New packet Header........................................15 80 4.2. Source Discovery.........................................16 81 4.2.1. Source register process with RP.....................17 82 4.2.2. Communication between client and the source.........21 83 4.2.3. Source specific multicast...........................31 84 4.2.4. Source Discovery Delay Prevention...................33 85 4.2.4.1. Delay prevention in Default-Mode...............34 86 4.2.4.2. Delay prevention in Admin-Mode.................36 87 4.3. Communication between PIM-NG routers.....................39 88 4.4. RP discovery.............................................44 89 4.4.1. Static RP discovery.................................45 90 4.4.2. Dynamic RP discovery................................46 91 4.4.2.1. Multicast IP addresses used....................47 92 4.4.2.2. Dynamic RP discovery TYPE-1....................47 93 4.4.2.2.1. RP introduction process...................49 94 4.4.2.2.2. Back up C-RP considerations...............51 95 4.4.2.2.3. PIM-NG clients processes in Dynamic-RP....58 96 4.4.2.2.3.1. New PIM-NG router/client.............60 97 4.4.2.3. Dynamic RP discovery type 2....................61 98 4.4.2.3.1. Client related concepts...................63 99 4.4.2.3.2. C-MAPPER concepts.........................64 100 4.4.2.3.2.1. Value of the A-BIT...................67 101 4.4.2.3.2.2. C-MAPPER preparation.................67 102 4.4.2.3.3. C-RP concepts.............................69 103 4.4.2.3.3.1. C-RP redundancy......................70 104 4.4.2.3.3.2. C-RP processes.......................72 105 4.4.2.3.3.3. Redundant C-RPs......................73 106 4.4.2.3.3.4. PIM-NG Anycast RP....................79 107 4.4.2.3.3.5. PIM-NG C-RP Mesh-Group...............80 108 4.4.2.3.3.6. Backup C-RP considerations...........82 109 4.5. C-MAPPER Redundancy in PIM-NG............................82 110 4.5.1. SC-MAPPER considerations............................91 111 4.5.2. C-MAPPER Mesh-Group.................................92 112 4.5.2.1. Active C-MAPPER Election.......................94 113 4.5.3. ANYCAST RP rules....................................95 114 4.5.4. Configuration process of Redundant C-MAPPERs........95 115 4.5.5. C-RP and Redundant C-MAPPERs........................97 116 4.6. Multiple multicast domains...............................98 117 4.6.1. Definitions and concepts...........................100 118 4.6.1.1. Domain........................................100 119 4.6.1.2. PIM-EDGE-ROUTER (PER/PPER)....................107 120 4.6.1.3. Tree Root (TR)................................114 121 4.6.1.4. Domain-set and RPF check......................117 122 4.6.2. Inter-domain connectivity concepts.................121 123 4.6.2.1. Public Domains................................121 124 4.6.2.1.1. Intra-domain concepts....................122 125 4.6.2.1.2. Inter-domain concepts....................124 126 4.6.2.2. Private domains...............................128 127 4.6.2.2.1. Intra-Domain processes...................129 128 4.6.2.2.2. Inter-domain concepts....................135 129 4.6.3. Core-Domain implementation.........................138 130 4.6.4. Multiple multicast domains scenario................143 131 4.6.5. PIM-NG Sub-Domain..................................149 132 4.6.6. PIM-NG Stub-Domain.................................161 133 4.7. PIM-NG Bidirectional logic..............................164 134 4.7.1. Requirements.......................................164 135 4.7.2. Bidirectional Multicast Group Discovery............165 136 4.7.2.1. Manual Mode...................................165 137 4.7.2.2. Autosense mechanism...........................167 138 4.7.3. Redundant TRs......................................170 139 4.7.3.1. ANYCAST Approach..............................170 140 4.7.3.2. TR Grouping...................................171 141 4.7.4. Bidirectional Tree formation.......................173 142 4.7.4.1. Tree formation between TRs....................174 143 4.7.4.2. Completing the Tree formation.................175 144 4.7.5. Inter-Domain Bidirectional connectivity rules......177 145 4.8. PIM-SM compatibility....................................181 146 4.8.1. PIM-SM compatibility and SA messages...............181 147 4.8.2. PIM-SM compatibility and join/prune messages.......184 148 4.9. Loop prevention.........................................186 149 4.10. DR election and PIM Assert Message.....................187 150 5. Security Considerations......................................187 151 5.1. Attacks based on forged messages........................188 152 5.1.1. Unicast forged messages............................188 153 5.1.2. Forged link local messages.........................188 154 5.1.3. Forged multicast messages..........................189 155 5.2. Non-cryptographic authentication mechanisms.............190 156 5.3. Authentication..........................................191 157 5.3.1. Protecting Multicast Introduction Message..........192 158 5.4. Denial-Of-Service attacks...............................192 159 6. IANA Considerations..........................................193 160 6.1. PIM-NG multicast destination group addresses............193 161 6.2. PIM-NG packets and values of type field.................193 162 6.3. PIM-NG Domain numbers...................................193 163 7. Conclusions..................................................194 164 8. References...................................................194 165 8.1. Normative References....................................194 166 8.2. Informative References..................................195 167 9. Acknowledgments..............................................196 168 Table of figures 170 Figure 1 the new packet Header.......................................15 172 Figure 2 source register request packet..............................18 174 Figure 3 multicast mapping table.....................................18 176 Figure 4 C-RP acknowledge message....................................19 178 Figure 5 source communication with the RP............................20 180 Figure 6 Request for source packet................................23 182 Figure 7 Request for Source packet format..........................24 184 Figure 8 C-RP Acknowledge packet format..............................25 186 Figure 9 C-RP answer to the host in case that source doesn't exist...26 188 Figure 10 Join/prune message format..................................29 190 Figure 11 Encoded Source Address Format..............................30 192 Figure 12 Communication between Host and Source......................32 194 Figure 13 Client Request Table (CRT).................................38 196 Figure 14 New-Activated-Source-Notification message format...........38 198 Figure 15 original PIM-SM hello packet compared with the new hello 199 packet format........................................................40 201 Figure 16 PIM domain topology table (PDTT)...........................42 203 Figure 17 C-MAPPER-INTRODUCTION massage sent to 239.0.1.190..........50 205 Figure 18 SC-MAPPER/RP answers to a host REQUEST-FOR-C-MAPPER message53 207 Figure 19 SC-MAPPER/RP multicast introductions to all PIM-NG-CLIENTS.54 209 Figure 20 PIM-NG network with backup RP (SC-RP)......................55 211 Figure 21 RP introduction message format.............................56 213 Figure 22 C-MAPPER/RP unicast HELLO/KEEP-ALIVE message to back up RPs58 214 Figure 23 request- for-C-MAPPER packet sent to the SC-MAPPER.........59 216 Figure 24 New client added...........................................61 218 Figure 25 network design with one multicast domain...................63 220 Figure 26 C-MAPPER introduction message formats......................66 222 Figure 27 multicast domain with one C-MAPPER.........................69 224 Figure 28 network designs with one multicast domain..................70 226 Figure 29 C-RP introduction message format...........................71 228 Figure 30 PEER-MAPPING table and PEER-LIST table.....................75 230 Figure 31 AMMT compared with MMT.....................................76 232 Figure 32 AMMT Format................................................77 234 Figure 33 network with single multicast domain and redundant C-MAPPERs83 236 Figure 34 PEER-MAPPING Table.........................................84 238 Figure 35 introduction message format sent to ALL PIM-NG MAPPERS 239 239.0.1.188..........................................................86 241 Figure 36 A- Multicast MAPPING TABLE.................................87 243 Figure 37 sample illustration of the above process...................90 245 Figure 38 network with 2 PIM-NG multicast domains....................99 247 Figure 39 PER introduction message..................................113 249 Figure 40 Internal Multicast Source Table...........................113 251 Figure 41 TR introduction message...................................116 253 Figure 42 Joined-Groups table used by both TR'(s) and Clients.......117 255 Figure 43 Inter-domain connectivity and RPF check...................119 257 Figure 44 Intra-Domain connectivity and RPF check...................120 259 Figure 45 network with 2 multicast domains..........................125 260 Figure 46 Multicast network with private PIM-NG domains.............129 262 Figure 47 core domain implementation................................141 264 Figure 48 join/prune message being sent towards the source..........143 266 Figure 49 network with multiple multicast domains...................144 268 Figure 50 multicast network and multicast advertisements............146 270 Figure 51 Mesh-Groups and C-MAPPER peering..........................157 272 Figure 52 PPER and PER communication with C-MAPPER..................159 274 Figure 53 Sample PIM-NG domain Divided to Sub-Domains...............160 276 Figure 54 Stub-Domain as the transitory multicast domain............163 278 Figure 55 Bidirectional Groups Table (BGT)..........................165 280 Figure 56 Bidirectional Tree formation with ANYCAST TR Address......176 282 Figure 57 Bidirectional Tree formation with TR grouping.............177 283 1. Introduction 285 This document specifies a protocol for efficiently routing multicast 286 groups that may span wide-area (and inter-domain) internets. This 287 protocol is called protocol independent multicast-Next Generation or 288 simply put PIM-NG. The name is chosen duo to the fact that this new 289 protocol has some behaviors similar to PIM-SM, in parts related to 290 using the underlying unicast routing information base to find the 291 best path to reach a source and not being limited to any specific 292 routing protocol. 294 But as the overall process of Multicast source discovery is a whole 295 new story it is called PIM-NG or the next generation of PIM-SM[7]. 297 PIM-NG provides many new features and concepts related to multicast 298 routing which together open new doors and possibilities such as 299 removing the need for Shared path trees to form, being able to easily 300 consider transit multicast domains, use as much as 254*255 RPs within 301 a single multicast domain and using redundant Tree Roots per 302 bidirectional tree and eventually redundant Bidirectional Trees per 303 Bidirectional Group. Also it provides the possibility of considering 304 transit multicast domains easily. In addition to the above this 305 protocol is a lot more secure than current implementations because of 306 its unique multicast domain concept introduced for the first time. 308 2. Terminology 310 In this document, the key words "MUST", "MUST NOT", "REQUIRED", 311 "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", 312 "MAY","ONLY" and "OPTIONAL" are to be interpreted as described in RFC 313 2119 [1] and indicate requirement levels for compliant PIM-NG 314 implementations. 316 Commands used in this document, MUST NOT be interpreted as the solid 317 commands, and are only used as an example to simplify the explanation 318 of the processes used by PIM-NG. 320 2.1. Definitions 322 The following terms have special significance for PIM-NG: 324 Candidate Rendezvous Point (C-RP): 326 C-RP is a router that has been configured to take the role of a 327 multicast information station in a PIM-NG domain. Unlike PIM-SM 328 specifications in RFC4601 [7], it is not used as the root of the non- 329 source-specific distribution tree for a multicast group. Any 330 multicast source will inform the RP about its existence by sending a 331 register message (S,G) to the RP , and RP will save the unicast 332 address of the source for further use in an special table. And any 333 host looking for the source of any desired multicast group will send 334 a request of (*,G) or (S,G) to the RP to receive the unicast address 335 of the desired multicast source. 337 Candidate MAPPER (C-MAPPER): 339 C-MAPPER is a router in charge of introducing the existing components 340 of a PIM-NG multicast domain to all PIM-NG population within a 341 multicast domain and also is responsible for the exchange of A- 342 Multicast Mapping Table between different PIM-NG multicast domains. 343 It acts like a BSR [9] in parts related to introducing the C-RPs to 344 all PIM-NG routers. The difference between a C-MAPPER and a BSR is 345 that the C-MAPPER doesn't do the group to RP mapping. It will only 346 introduce the existing components such as C-RP'(s), 348 Client: 350 Client is a router that either wants to register a source, or is 351 looking for a source. To be more specific any none C-RP or C-MAPPER 352 router can be called a client. And each C-RP and C-MAPPER can act as 353 a client too, which is not recommended. 355 Tree Root (TR): 357 A PIM-NG-AWARE router that after being configured, MUST be introduced 358 to the multicast domain to become the root of each (S,G) tree. Any 359 client in need of receiving multicast traffic from a source will send 360 its join/prune messages towards the existing TR in the domain, or if 361 no TR is considered in the domain, directly to the existing TRs in 362 the core-domain. 364 EDGE-Client: 366 It is a PIM-NG client within a PIM-NG multicast domain that can act 367 as a boundary between downstream clients and upstream clients, to 368 limit the propagation of multicast introduction messages sent by C- 369 MAPPER'(s) or C-RP'(s). an EDGE-CLIENT can be placed at the edge of 370 multi-access network'(s), which are part of one unified PIM-NG 371 multicast domain. 373 PIM-EDGE-ROUTER (PER): 375 It is a PIM-NG aware router that connects 2 or more separate PIM-NG 376 multicast domains and Sub-Domains by using the underlying IGP 377 protocol used inside the network or a routing protocol capable of 378 transferring multicast traffic like MBGP. 380 PRIVATE-PIM-EDGE-ROUTER (PPER): 382 It is PIM-NG PER that is placed at the edge of a private PIM-NG 383 multicast domain. A PPER is also in charge of NAT operations in the 384 domain. As soon as the PPER is configured it MUST introduce itself to 385 the closest C-MAPPER in the domain. 387 BORDER-PIM-ROUTER (BPR): 389 It is a PER or PPER which is placed between a PIM-NG multicast Domain 390 and a PIM-SM multicast domain, and has one or more internal 391 interfaces connected to the PIM-NG multicast domain and one or more 392 interfaces connected to the PIM-SM multicast domain. In case of using 393 PER as the BPR, the PER MUST introduce itself to the closest C- 394 MAPPER. 396 Second candidate Rendezvous Point (SC-RP): 398 SC-RP is a router configured or elected to act as the backup C-RP if 399 needed. And if C-RP goes offline will immediately take its place. 401 Second Candidate MAPPER (SC-MAPPER): 403 SC-MAPPER is a router configured or chosen to act as the backup C- 404 MAPPER if needed. And if C-MAPPER goes offline will immediately take 405 its place 407 Internal interface (II): 409 All interfaces of a PIM-NG router are internal interfaces by default, 410 and are assumed to be connected to either internal domain from a PIM- 411 NG-PER/PPER or PIM-NG-BPR point of view or a multi-access-network 412 from a PIM-NG-CLIENT point of view. 414 External interface (EI): 416 It is an interface configured as an external interface. External 417 interface is assumed to be connected to an external domain from a 418 PIM-NG-PER point of view or connected to the domain a PIM-NG-CLIENT 419 is a member of and thus, multicast introductions received on an 420 external interface won't be forwarded to internal interfaces. Also a 421 PIM-NG-BPR can have an external interface which is by default the 422 interface connected to a PIM-SM domain. 424 PIM-NG DOMAIN: 426 A domain is actually a public or private PIM-NG multicast network 427 including its own set of C-MAPPERs, C-RPs and clients isolated from 428 other domains. Clients and C-RPs inside one domain do not react to C- 429 MAPPER introduction messages that might be received from other 430 Domains. The only points of connection between 2 different domains 431 are the C-MAPPERs and if used PIM-EDGE-ROUTERs. Each DOMAIN can be 432 connected to either one or more PIM-NG-DOMAIN and if needed PIM-SM 433 domains or a single PIM-NG-CORE-DOMAIN. 435 PIM-NG CORE-DOMAIN: 437 A special domain implementation of PIM-NG, which if applied gives a 438 hierarchical design approach, alongside a good and sound multicast 439 traffic flow control to the administrators of different CORE-DOMAINs. 440 A CORE-DOMAIN can be connected to one or more CORE-DOMAINs and one or 441 more PIM-NG-DOMAINs. PIM-NG-DOMAINs MUST BE connected to the outside 442 world or World Wide Web through a CORE-DOMAIN if they need to 443 advertise their multicast sources globally. 445 Multicast mapping table (MMT): 447 After a router is configured as a C-RP, a table called multicast- 448 mapping table is created on it. This table will then hold the 449 information needed to be used by clients to find a source. After a C- 450 RP receives a register message from a source it will put an entry for 451 that source in this table which indicates the unicast address of the 452 source plus the multicast destination group it is representing in the 453 format (S,G) alongside the unicast address of the client which is 454 sending the register message. It is done to bring compatibility with 455 the needs of SSM. 457 Abbreviated multicast mapping table (A-multicast mapping table) 458 (AMMT): 460 Is an abbreviated form of Multicast mapping table which only holds 461 the information regarding each source which exists in the domain and 462 the unicast address of that source. This table is created on C- 463 MAPPERs and C-RPs and is used in related processes. 465 PIM domain topology table (PDTT): 467 This table is used to store the information needed to find C-RP/RPs, 468 C-MAPPER, TRs and other components that may exist in a PIM-NG 469 multicast Domain. It holds the unicast address of such components 470 alongside other information needed. 472 Core topology table (CTT): 474 It is created on C-MAPPERS inside the core-domain. It only holds the 475 address of any existing TR'(s) inside the core domain. And is the 476 only PIM-NG topology table that CAN be exchanged between the PIM-NG- 477 CORE-DOMAIN and any existing PIM-NG-DOMAIN connected to the core 478 domain. Also this table is the ONLY PIM-NG topology table that CAN be 479 exchanged between peer C-MAPPERs in different PIM-NG-DOMAINs so that 480 all PIM-NG-DOMAINs will know about the TR'(s) inside the core domain. 481 This table MUST NOT be exchanged between PIM-NG-CORE-DOMAINs. 483 Peer mapping table: 485 It is created on C-RPs and C-MAPPERs as soon as a C-RP or C-MAPPER 486 becomes peer with new C-RP or C-MAPPER. 488 Internal multicast source table (IMST): 490 This table is created on PPER'(s) and in case of private network'(s) 491 within a unified PIM-NG multicast domain connected to other parts of 492 the Network using NAT, on EDGE-CLIENTS, and helps the PPER or EDGE- 493 CLIENT to act on behalf of a host in search of a source by putting an 494 entry inside the table to keep track of the behavior of the domain. 495 It holds the address of the requesting client and the multicast group 496 requested. 498 Client request table (CRT): 500 This table is created on C-RP'(s) and holds the unicast address of 501 clients to which the C-RP sends a NULL-ACK in response to the clients 502 request to find the source for multicast group(G)along the multicast 503 group (G)which the client needs to find the generating source. 505 Bidirectional Groups Table (BGT): 507 This table is created on C-MAPPERs and C-RPs and hold the information 508 of active or to be active Bidirectional multicast groups. 510 Bidirectional Translator TR (TTR): 512 A TR part of all available TR groups which is used to communicate 513 with TRs in other multicast domains with regards to exchanging the 514 information of active Bidirectional multicast groups. 516 3. IP Address considerations 518 PIM-NG processes need to use 3 new multicast destination addresses 519 from Internetwork Control Block [2]. These addresses are going to be 520 used in PIM-NG processes and are needed to be assigned. For the 521 simplicity of explanations in this document, multicast address 522 239.0.1.188, 239.0.1.189 and 239.0.1.190 from the Scoped Multicast 523 Ranges are used as advised by IANA. But PIM-NG needs the use of 524 addresses from the "internetwork control block" and the use of the 3 525 addresses from the scoped multicast range is only for the sake of 526 simplicity in the process of explanation. 528 Also it MUST BE noted that any IP addresses, whether multicast or 529 unicast, used in this document from this point forward ARE ONLY used 530 as an example to simplify the explanation process. For example 531 addresses 228.8.8.8 and 229.9.9.9 are used only to simplify the 532 explanation process. 534 4. PIM-NG processes 536 PIM-NG processes are related tightly to the new packet formats 537 defined for it. So in each section related packet formats are going 538 to be explained or shown. 540 4.1. New packet Header 542 The new packet'(s) format is designed and defined in the way, so it 543 can support the needs of PIM-NG. 545 The new packet header format specification for PIM-NG is as follows: 547 0 1 2 3 548 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 549 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 550 |PIM Ver| Type | Reserved | Checksum | 551 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 552 Figure 1 the new packet Header 554 PIM-ver : is 3 556 As the new packet format will be used in different situations, the 557 new type field definitions must be explained. The new definitions are 558 as follows: 560 5 bit TYPE field to support up to 32 different functions: 562 Message type destination 564 --------------------------------------------------------------------- 566 0- Hello Multicast to All-PIM routers 567 1- Register Unicast to RP and EDGE-CLIENT 568 2- Keep alive to RP Unicast from source to RP 569 3- Join/prune Multicast to ALL-PIM-ROUTERs 570 4- Request For Source Unicast to RP 571 5- Ack to Client/source Unicast from RP or EDGE-Client 572 To source 573 6- Assert Multicast to ALL-PIM routers 574 7- Host request to C-MAPPER Unicast to C-MAPPER 575 8- RP introduction Multicast to ALL-RPs 576 9- RP introduction Unicast to C-MAPPER 577 10- C-MAPPER introduction1 Multicast to ALL-PIM-NG routers 578 11- C-MAPPER introduction2 Multicast to ALL-MAPPERs 579 12- Request-for-C-MAPPER Unicast to SC-MAPPER 580 13- C-MAPPER ack Unicast to Client 581 14- Edge Unicast to C-MAPPER 582 15- BPR Unicast to C-MAPPER 583 16- TR Unicast to C-MAPPER and 584 Peer-TR 585 17- NASN Unicast from C-RP to C-MAPPER 586 And Multicast from C-MAPPER to 587 ALL-PIM-NG routers 589 The above definitions will be explained, as we proceed through out 590 different sections of PIM-NG specifications. 592 4.2. Source Discovery 594 In the original PIM-SM specifications of the communication between a 595 SOURCE and RP we see that the source sends Register messages to the 596 RP and the RP will only accept the Register message, if any host or 597 hosts asked for that particular multicast group. Otherwise the RP 598 will send a register-stop message back to the source and the source 599 starts a register-suppression timer of 60 seconds. And 5 seconds 600 before the suppression timer expires the source sends a register- 601 message with its null-register bit set. Now if the RP doesn't know 602 any hosts asking for that specific group it will send another 603 register-stop. The process goes on until a host asks the RP about 604 that group. 606 Now what happens if right after the suppression timer starts by the 607 source a host comes up and asks for that specific source? As it is 608 explained in the original PIM-SM specifications, the host will have 609 to send its join messages to the RP until the RP hears again from the 610 source and this time, due to the fact that there is a host asking for 611 the group the RP won't send a register stop and will forward the 612 packet down the RPT .This process didn't seem so efficient, so some 613 changes has been made to the way a SOURCE communicates with the RP 614 alongside the new packet definitions 616 4.2.1. Source register process with RP 618 In PIM-NG the process to initially deliver the multicast traffic to a 619 host asking for it, is somehow different from that of PIM-SM. It 620 initially starts by: 622 1- Source introducing itself to a router called RP(rendezvous 623 point) 625 2- RP keeps and enters the information related to the source in to 626 a table for further use. 628 3- Host asks the RP about the source of an specific group 630 4- Host sends a join request to the source directly 632 For the sake of simplicity let's consider that all the routers know 633 the address of C-RP. The source of the multicast traffic starts its 634 process by introducing itself to the C-RP, by sending Unicast- 635 Encapsulated register messages to it. The source does the 636 introduction process completely different from the original PIM-SM 637 specifications. In PIM-SM source introduces itself by sending a 638 packet containing the multicast data to be sent. But the introduction 639 process in PIM-NG is done through sending a register-request packet 640 containing only the address of the source along the multicast group 641 address the source represents (Figure 2). The C-RP receives the 642 message and by looking in its type field, it knows that it is a 643 Source register request message sent from a source. From here the C- 644 RP will act differently from what is defined in the PIM-SM 645 specifications. 647 0 1 2 3 648 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 649 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 650 |PIM Ver| Type | Reserved | Checksum | 651 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 652 |B| RESERVED | 653 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 654 | D O M A I N | 655 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 656 | Source unicast address | 657 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 658 | Multicast destination group 1(G) | 659 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 660 | Source Host (server) address | 661 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 662 | . | 663 | . | 664 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 665 | Multicast destination group n (G) | 666 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 667 | Source Host (server) address | 668 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 669 Figure 2 source register request packet 671 o Type: register 673 o Source Unicast Address: Holds the unicast address of the PIM- 674 NG-CLIENT sending the register message to the C-RP. 676 o Source HOST Address: holds the unicast address of the, server 677 or host in the connected LAN which is the actual generator of 678 the multicast data. 680 The C-RP looks in to the source unicast address and the Multicast 681 group destination address fields and puts an entry into its multicast 682 mapping table. The multicast mapping table consists of the multicast 683 group represented by a source and that source's unicast address, 684 along 2 timers. Figure 3 shows the multicast mapping table(MMT) 685 created by C-RP'(S): 687 +-------------------------------------------------------------------+ 688 |Source addr(S)|Dest group (G)|Source HOST| keep alive |expiry time | 689 +-------------------------------------------------------------------+ 690 | | | | | | 691 +-------------------------------------------------------------------+ 692 | | | | | | 693 +-------------------------------------------------------------------+ 694 Figure 3 multicast mapping table 696 o Source keep alive timer : the time in which RP should receive 697 keep alive from the source 699 o Source expiry time : time in which , if no keep-alive received 700 the entry will be deleted 702 Each C-RP will create another table besides the multicast-mapping 703 table called A-MULTICAST MAPPING TABLE (AMMT) which will be explained 704 later. Each new multicast destination address it enters in its MMT 705 will be put in the AMMT too. 707 Inside the register-message, each source sends a keep-alive timer 708 value defaulting to 30sec to the C-RP, which later will be used by 709 the C-RP in the process. 711 Then the C-RP sends a unicast acknowledge-message(Figure 5) back to 712 the source, using the unicast address of the source .after receiving 713 the acknowledge the source proceeds with sending periodic keep-alive 714 messages to C-RP , to tell the C-RP that it is alive and so the C-RP 715 wont delete the entry related to the source from its multicast- 716 mapping table. For each keep-alive C-RP receives it will send an 717 acknowledgement. If the C-RP doesn't hear the first keep alive, it 718 will start to count down the expiry timer for the source which is by 719 default 3*keep-alive timer .if the C-RP doesn't hear from the source 720 in the expiry time duration it will delete the entry for that source. 722 0 1 2 3 723 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 724 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 725 |PIM Ver| Type | Reserved | Checksum | 726 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 727 | D O M A I N | 728 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 729 | RP's unicast address | 730 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 731 | Multicast Destination Group 1 | 732 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 733 | . | 734 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 735 | Multicast Destination Group n | 736 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 737 Figure 4 C-RP acknowledge message 739 o Type : RP acknowledge to source 741 [Figure is presented in PDF version] 743 Figure 5 source communication with the RP 745 Now let's start by explaining the process related to the 746 communication of the source and RP as shown in Figure 5: 748 1- The server behind R1 (called S1), starts sending multicast to 749 228.8.8.8 and R1 receives those multicasts on its connected LAN 750 interface. 752 2- R1 will try to contact the C-RP and introduce itself and the 753 multicast group it represents, by sending the Unicast-Encapsulated 754 register-request message to the address of the C-RP. C-RP receives 755 a PIM packet and looks at the TYPE-FIELD. 757 3- After looking at the TYPE_FIELD C-RP finds out that it is a 758 register-request which is sent from a source. So the C-RP looks in 759 to the source unicast address and the Multicast group destination 760 address fields and writes the unicast address of the source 761 alongside the multicast group address it represents alongside the 762 keep-alive timer and the expiry timer as a new entry in its MMT. 764 4- RP sends acknowledge back to the SOURCE. 766 5- After receiving the acknowledge the source starts its keep-alive 767 timer ,and will send periodic keep-alive messages as long as it 768 wants to send traffic for the multicast group address it 769 represents. These keep-alive messages can be simply a register 770 message. 772 So this was the process related to the communication between a source 773 and the C-RP. In the next section the process related to the 774 communication between a host and a source, or how a host sends join 775 request for a multicast group address to the source will be 776 explained. 778 4.2.2. Communication between client and the source 780 The process through which, a host finds the source and communicates 781 with it in order to receive the multicast traffic, is in parts 782 different from that of the original PIM-SM specifications. So let's 783 have a flash back at the process of the original PIM-SM: 785 1. Host sends a join message of (*, G) to the RP, and joins the RPT 786 for the (*, G). 788 2. RP sends the join request to the source with (S,G), indicating 789 that a host is asking for the traffic or the RP simply forwards the 790 multicast packets received from the source down RPT towards the 791 host. 793 3. Source sends the multicast packet to the RP ,and RP forwards it to 794 the host 796 4. After receiving the first couple of packets , the host sends a 797 join request directly to the source 799 5. So the host leaves the RPT and switches to SPT for (S,G) 801 6. Host sends a prune to the upstream router, so the RP will stop 802 forwarding that traffic. 804 This process works fine, but not as efficient and as fast as 805 possible. Waiting for the first couple of packets or even first 806 packet to be received and then switch to SPT for the (S,G) and after 807 that sending a prune to the upstream router ,doesn't seem so 808 efficient. What happens when a host sends a join for a particular 809 group (*, G) or (S, G) right after the RP sent a register-stop to the 810 source? The process seems to waste some valuable time. 812 So PIM-NG uses a new process to reach the source, alongside new 813 messages. We are going to consider that the host/hosts know about the 814 C-RP for now. 816 Let's start by assuming that a HOST behind R4(Figure 5), asks for 817 228.8.8.8 traffic using IGMPV2-3 .the request arrives at R4, and now 818 it is up to R4 to find the source and send Join message to the 819 source. But in order to find the source R4 knows that it will have to 820 ask C-RP as the information station of the Multicast domain about the 821 address of the source. 823 So R4 sends a unicast-encapsulated PIM-NG request message to the C- 824 RP. R4 sets the TYPE-FIELD to " Request For Source" and puts its own 825 unicast IP address in the "SOURCE UNICAST ADDRESS" field and puts the 826 multicast group address 228.8.8.8 in the format of (* , 228.8.8.8) in 827 the " Multicast group destination address " field, And sends the 828 packet to the destination address of C-RP. 830 0 1 2 3 831 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 832 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 833 |PIM Ver| Type | Reserved | Checksum | 834 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 835 |B| reserved | 836 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 837 | D O M A I N | 838 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 839 | Client's unicast address(R4) | 840 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 841 | Multicast destination group 1(G) | 842 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 843 | source of multicast group 1(*) | 844 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 845 | . | 846 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 847 | Multicast destination group N (G) | 848 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 849 | source of multicast group N(*) | 850 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 851 Figure 6 Request for source packet 853 o Type: Request For Source 855 There might be a case that there are two source HOSTs sending traffic 856 for the 228.8.8.8 group and the host behind R4 , asks through IGMP to 857 receive the traffic generated by a specific source (i.e.10.1.1.10) 858 .then the format of the request packet it sends will be as shown in 859 Figure 7.this is different from SSM multicast. As it is considered 860 that the CLIENT/HOST knows the address of the server or host 861 originating the traffic destined for group (G), but not the address 862 of CLIENT who is responsible for forwarding the traffic on behalf of 863 the server and acting as the DR. 865 0 1 2 3 866 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 867 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 868 |PIM Ver| Type | Reserved | Checksum | 869 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 870 |B| reserved | 871 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 872 | D O M A I N | 873 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 874 | Client's unicast address(R4) | 875 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 876 | Multicast destination group1(G) | 877 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 878 | Source Host of Group 1(G)(S) | 879 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 880 | . | 881 | . | 882 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 883 | Multicast destination group n(G) | 884 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 885 | Source Host of Group n(G)(S) | 886 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 887 Figure 7 Request for Source packet format 889 o Type: Request For Source 891 C-RP receives the packet, and checks the type-field.the type-field 892 indicates that it is a host request to find the unicast address of a 893 source. So C-RP checks the Multicast group destination address field 894 and finds out that the host is either: 896 1- Looking for the unicast address of a source representing 897 228.8.8.8 multicast traffic (*, G). 899 2- Looking for the unicast address of a specific source representing 900 228.8.8.8 multicast traffic (*, S, G). Different from PIM-SSM. 902 Then the C-RP looks in to its MMT or AMMT if the network is consisted 903 of separate PIM-NG domains, and acts in two different ways: 905 1- C-RP finds an entry in its MMT which indicates that the source 906 exists: 908 In this case, instead of forwarding the traffic towards the source 909 and join the SPT for (S,G), C-RP sends back the address of the source 910 directly toward R4 using R4's unicast address found in the "source 911 unicast address " field with a packet shown in Figure 8 : 913 0 1 2 3 914 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 915 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 916 |PIM Ver| Type | Reserved | Checksum | 917 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 918 | D O M A I N | 919 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 920 | RP's unicast address(R4) | 921 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 922 | GDPT | 923 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 924 | Requested Multicast Group 1 (G) | 925 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 926 | Source of group 1(G),(S) | 927 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 928 | DOMAIN-set for Group 1 | 929 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 930 | . | 931 | . | 932 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 933 | Requested Multicast Group n (G) | 934 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 935 | Source of group n(G),(S) | 936 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 937 | DOMAIN-set for Group n | 938 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 939 Figure 8 C-RP Acknowledge packet format 941 o Type: RP acknowledge to host 943 o DOMAIN-SET: is part of the AMMT and its use will be explained 944 later. It shows the domain in which a source is registered. And 945 also the path towards the source, so that a client can decide on 946 generating the join/prune message better. 948 o GDPT Filed: Holds the global Delay prevention timer set on C-RP 949 and is used to automatically synchronize this timer on all the 950 clients receiving a Null-ACK from C-RP. 952 C-RP sets the type field to "RP acknowledge to host" and puts its own 953 unicast IP address in the source unicast address field and fills out 954 the "Multicast group destination address" field in the format of (S, 955 G). 957 One other thing that the C-RP sends back to the client is the Domain 958 set, which shows the domain in which the source is resided and also 959 the path through which the join/prune message can reach the source. 960 In case that the source resides in a separate domain and to be more 961 specific the PIM-NG network is consisted of different and separate 962 domains, clients will use the domain set to decide whether a 963 join/prune message MUST path a core domain first or MUST NOT which 964 the related concepts will be explained later. A Domain-Set with the 965 Null value in it indicates that a source is resided within a Multi- 966 Access Network which the related processes will be discussed in the 967 appropriate sections. 969 2- C-RP doesn't find an entry in its multicast-mapping table: 971 In this case C-RP answers to the host, with a packet which indicates 972 that the source doesn't exist now and the host must try again later. 973 Figure 9 shows the packet sent by RP to the host: 975 0 1 2 3 976 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 977 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 978 |PIM Ver| Type | Reserved | Checksum | 979 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 980 | D O M A I N | 981 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 982 | RP's unicast address(R4) | 983 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 984 | GDPT | 985 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 986 | Requested Multicast group 1 (G) | 987 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 988 | Source of group 1(*) | 989 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 990 | . | 991 | . | 992 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 993 | Requested Multicast group n (G) | 994 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 995 | Source of group n (*) | 996 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 997 Figure 9 C-RP answer to the host in case that source doesn't exist 998 o Type: RP acknowledge 1000 R4 receives a unicast-encapsulated PIM_NG packet, and looks into the 1001 TYPE-FIELD. The type field indicates that it is the C-RP answer to 1002 the host request for finding the unicast address of a source. So R4 1003 will check the source unicast address field and makes sure it was 1004 sent from the C-RP and then looks into the Multicast group 1005 destination address field. 1007 R4 will act in 2 different ways, depending which one of the 2 above 1008 conditions is meat: 1010 1- If the entry inside the " Source of group field" is in the format 1011 of (*, G), then R4 understands that the source doesn't exists for 1012 now and it has to try again later .the time of resending the 1013 request will be equal to the HELLO time or 30 seconds. 1015 2- If the entry inside the "Source of group field" is in the format 1016 of (S, G) then R4 will take S, and looks into its unicast routing 1017 table to find the best way for reaching to S which is in our 1018 example the unicast address of R1. After finding the best path to 1019 R1, R4 sends a join/prune message to the upstream neighbor in the 1020 best path towards the source so the join/prune messages goes hop- 1021 by-hop until it reaches the desired destination. And depending on 1022 whether a TR exists in the domain or not and whether any core- 1023 domain is considered in the PIM-NG overall network, client will : 1025 o Join the (S,G)tree in case there are no residing TRs inside the 1026 domain 1028 o Join the (S, G, RPT) which is assumed by PIM-NG specifications 1029 the shortest path tree rooted at TR in case a TR exists in the 1030 domain. Joining the (S,G,RPT) tree inside each single domain is 1031 strongly advised due to the fact that it will reduce the 1032 unnecessary join/prune messages being sent towards a source in 1033 case that new clients come up later which need to receive the 1034 same traffic. 1036 o Join the (S, G, RPT) which is considered by PIM-NG 1037 specifications the shortest path tree towards a source rooted 1038 at core-domain-TR. for this tree to be formed 2 conditions 1039 MUST exist : 1041 1. Core-domain MUST do exist, and any existing TR inside 1042 the core-domain MUST be known to the PIM-NG population. 1044 2. A source MUST be reachable by passing through the core- 1045 domain. Which the decision is up to the client 1046 generating the join/prune message, by checking the 1047 DOMAIN-SET associated with a source. 1049 This process MUST be done if the above conditions are meat, 1050 duo to the fact that, if a PIM-NG-Core-domain exists there 1051 will be one or more PIM-NG-DOMAINs connected to it and if one 1052 or more new clients in other domains come up later which are 1053 in need of receiving the same traffic, it will be waste of 1054 time and network resources to send the new join/prune messages 1055 towards the source. Related concepts will be explained later. 1057 R4 MUST save the state for the join message being sent. By saving the 1058 incoming interface for (*, G) or (S, G, TR) if it is a SSM join, and 1059 the outgoing interface for the (S, G) or (S, G, TR).and use this for 1060 RPF check later when receiving packets destined for (G). The related 1061 processes are done the way described in RFC4601 [7]. 1063 The packet that is being sent by R4 to R1 as a join/prune message is 1064 shown in Figure 10 along the new encoded source address format 1065 0 1 2 3 1066 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 1067 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1068 |PIM Ver| Type | Reserved | Checksum | 1069 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1070 | Upstream Neighbor Address (Encoded-Unicast format) | 1071 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1072 | Reserved | Num groups | Holdtime | 1073 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1074 | Multicast Group Address 1 (Encoded-Group format) | 1075 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1076 | Number of Joined Sources | Number of Pruned Sources | 1077 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1078 | Joined Source Address 1 (Encoded-Source format) | 1079 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1080 | Tree Root address | 1081 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1082 | Core Domain Tree Root Address | 1083 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1084 | . | 1085 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1086 | Joined Source Address n (Encoded-Source format) | 1087 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1088 | Tree Root address | 1089 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1090 | Core Domain Tree Root Address | 1091 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1092 | Pruned Source Address 1 (Encoded-Source format) | 1093 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1094 | . | 1095 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1096 | Pruned Source Address n (Encoded-Source format) | 1097 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1098 | . | 1099 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1100 | Multicast Group Address m (Encoded-Group format) | 1101 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1102 | Number of Joined Sources | Number of Pruned Sources | 1103 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1104 | Joined Source Address 1 (Encoded-Source format) | 1105 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1106 | . | 1107 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1108 | Joined Source Address n (Encoded-Source format) | 1109 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1110 | Pruned Source Address 1 (Encoded-Source format) | 1111 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1112 | . | 1113 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1114 | Pruned Source Address n (Encoded-Source format) | 1115 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1116 Figure 10 Join/prune message format 1118 o Type : join/prune 1119 o Tree-Root address: if any TR exists in the Domain, this field 1120 holds the address of the TR to towards which the message MUST be 1121 forwarded first, before being forwarded towards the source. The 1122 concepts will be discussed later. 1123 o Core Domain Tree-Root Address: holds the unicast address of the 1124 TR resided in the core domain, and is used only in topologies that 1125 contain Core-domain implementations, and incase the source is not 1126 an internal source and MUST be reached by passing a core domain. 1127 The related concepts will be discussed later. 1129 0 1 2 3 1130 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 1131 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1132 | Addr Family | Encoding Type | Rsrvd |S|C|R| Mask Len | 1133 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1134 | Source Address 1135 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-... 1136 Figure 11 Encoded Source Address Format 1138 o S-BIT: only for compatibility with PIM-V1. 1140 o R-BIT: Tree Root bit is set by the client who is sending the 1141 join/prune message for the first time for a source in a topology 1142 with one or more TR'(s) to join the (S, G, TR) tree. a value of 1 1143 is set by the creator of the join/prune message to tell upstream 1144 routers that the packet MUST be forwarded first towards the 1145 existing TR in the domain which the address of it can be found in 1146 the appropriate field .and a value of 0 can be set by the TR after 1147 receiving the join/prune message and before forwarding it towards 1148 the source. A value of 0 dictates to upstream routers that the 1149 join/prune had reached an existing TR In the domain and from now on 1150 MUST be forwarded towards either the source, if the source is an 1151 internal source or there are no core domain implementations, or the 1152 TR inside the core domain if the source is an external source that 1153 can be reached by core domain. This bit can also be set by a PER or 1154 by a PER/BPR in case a join/prune message is received from another 1155 PIM-NG domain or a PIM-SM domain and must be forwarded towards any 1156 existing TR in the domain to either reach a source inside the 1157 domain or towards a source in other domains. 1159 o C-BIT: Core-Domain-BIT can be set by either the client originating 1160 a join/prune message or the TR inside the core domain. If a client 1161 is originating a join/prune message for a source which is not an 1162 internal source and can be reached by passing through an existing 1163 core domain, it will set this bit to 1. A value of 1 means that the 1164 packet MUST be forwarded towards the TR inside the core domain 1165 first with the unicast address that can be found in the appropriate 1166 field. And a value of 0 can be set by the TR inside the core 1167 domain, which dictates to upstream routers that the join/prune 1168 message MUST be forwarded hop-by-hop towards the source from now 1169 on. This bit can also be set by a BPR in case it receives a 1170 join/prune message from a PIM-SM neighbor router. The related 1171 processes and concepts will be discussed later. 1173 Source (R1) receives the join/prune message. And joins the shortest 1174 path tree for (G) and starts sending the multicast data destined for 1175 (G) down the shortest path tree towards the receiver. 1177 In order to receive packets from R1, R4 will have to send periodic 1178 keep-alive or join messages every 30 seconds to R1. R1 receives the 1179 join-request and will know that R4 still needs the traffic. If R1 1180 (source) doesn't receive 2 keep-alive messages from the host (R4) it 1181 will assume that the host doesn't exist anymore and will 1182 automatically stop forwarding multicast traffic to the host (R4). 1184 If R4 no longer needs to receive the traffic from R1, it will inform 1185 R1 by sending a prune message to the upstream PIM-NG router 1186 forwarding the traffic .this is done due to the fact that there might 1187 be other hosts connected to the upstream routers in need of receiving 1188 the traffic. 1190 4.2.3. Source specific multicast 1192 Source specific multicast (SSM) [6] can be implemented under the 1193 following rules: 1195 o PIM-NG routers MUST NOT send the unicast-encapsulated Request 1196 for Source message for SSM addresses. 1198 o PIM-NG routers MUST NOT send a register message for any packet 1199 that is destined to an SSM address. 1201 o If any TR exists in a PIM-NG domain, a PIM-NG router MUST join 1202 the (S, G, RPT) rooted at the TR which is considered the 1203 shortest path tree towards a source by PIM-NG specifications. 1205 o ONLY incase that in a PIM-NG multicast Domain TR is implemented 1206 and the TR and C-RP are the same components, a Client is allowed 1207 to create the join/prune message for the SSM address and send it 1208 towards the existing C-RP, which is also the TR. 1210 [Figure is presented in PDF version] 1212 Figure 12 Communication between Host and Source 1214 4.2.4. Source Discovery Delay Prevention 1216 One of the important factors in a multicast domain is the time 1217 through which a client discovers or finds the source of a multicast 1218 group (G). 1220 Up to this point the processes through which a source registers with 1221 C-RP and finally a client discovers the (S) for (G) by sending a 1222 request for source message to the C-RP have been explained. 1223 Throughout the explanations we saw that if a source is registered 1224 ,since the information regarding the source is saved in an special 1225 table called MMT as soon as a client sends a request for source to C- 1226 RP the C-RP will be able to send back the unicast address of (S) for 1227 (G) in an acknowledge message to the client. 1229 Now what happens if a client sends its request for source message to 1230 find the (S) for (G) to the C-RP and the source (S) for (G) is not 1231 registered yet? 1233 As it has been explained by PIM-NG specifications, in such a case the 1234 C-RP will send a NULL-ACK for the requested (G) back to the client 1235 which is in the form of (*, G) and the client will have to start a 30 1236 second timer after receiving the NULL-ACK from C-RP and send 1237 periodical request for source messages until the source becomes 1238 active and the C-RP responds with an acknowledge containing (S) for 1239 (G). 1241 Now what will happen if the (S) for (G) becomes active right after 1242 the C-RP sends the NULL-ACK to the client? 1244 As explained the client will have to try again in 30 seconds and send 1245 its periodical request again to the C-RP. In this case and 1246 considering that the (S) for (G) becomes active 1 second after the C- 1247 RP responds to client with a NULL-ACK, the worst case scenario will 1248 be that an unwanted 30 second delay will occur until the client sends 1249 its request again and finds the (S) for (G). 1251 To eliminate this delay in source discovery, PIM-NG introduces a 1252 mechanism or process through which the C-RP will: 1254 o Save the state of the clients to which it sends a NULL-ACK for 1255 the requested (G). 1257 o As soon as the (S) for (G) becomes active and registers the C- 1258 RP will inform the clients who had been responded with a NULL- 1259 ACK for that specific source (S). 1261 Through the above the C-RP will be able to inform the client as soon 1262 as the source becomes active and the client will be able to find (S) 1263 for (G) as fast as possible. 1265 To do so PIM-NG specifications introduces its Source Discovery Delay 1266 Prevention method which is divided in to 2 modes: 1268 o Default-Mode. 1270 o Admin-Mode. 1272 4.2.4.1. Delay prevention in Default-Mode 1274 This mode is activated by default as soon as a PIM-NG-Aware Router is 1275 configured to become a C-RP and is suitable for all types of 1276 multicast network topologies form small sized networks to large sized 1277 networks. But it is strongly advised by PIM-NG specifications to use 1278 this mode in small sized networks in which the number of clients are 1279 low. 1281 Bellow rules and specifications apply to Default-Mode: 1283 o It is done automatically by existing C-RPs. 1285 o It is suitable for small sized network topologies but 1286 applicable to medium and large sized networks too. 1288 o In this mode C-RP will save the state of clients to which a 1289 NULL-ACK is sent in a special table called Client Request Table 1290 (CRT). And by state PIM-NG means the unicast address of the 1291 client alongside the multicast group (G) which the client needs 1292 to find the associated source(S) for it and finally a timer 1293 which defaults to 33sec (30+3). 1295 o C-RP MUST only put an entry in CRT for the clients to which it 1296 sends a NULL-ACK. 1298 o For each (G) that the C-RP sends a NULL-ACK an entry MUST be 1299 put in CRT. 1301 o The timer which defaults to 33sec(30sec for the default 1302 periodical client request + 3sec) is a countdown timer and 1303 resets to 33sec ONLY when both of the bellow conditions are 1304 true: 1306 1- The source is not active and registered within 33seconds. 1308 2- C-RP receives clients periodical Request For source within 1309 33sec which shows that the client is still interested in 1310 finding (S) for (G). 1312 o An entry is deleted from CRT when any of the bellow conditions 1313 is true: 1315 1- The source for (G) becomes active within the time period of 1316 25 seconds or since the timer in CRT is a countdown timer 33 1317 to 8 seconds which results in C-RP sending an Acknowledge 1318 containing (S) for (G) to the client. 1320 2- The source becomes active in the time period between 8 to 0 1321 seconds and C-RP receives the periodical Request for Source 1322 form the client and responds to client's request by an 1323 Acknowledge of (S, G). 1325 3- The source is not activated within the 33sec time interval 1326 and C-RP doesn't receive the periodical Request of client for 1327 that specific (G) in 33sec which indicates that the client is 1328 not interested anymore in finding (S) for (G). 1330 4- The source is activated and registered in the time interval 1331 between 8 to 0 seconds but the C-RP doesn't receive the 1332 periodical Request for Source from the Client which shows 1333 that there client is not interested anymore in finding (S) 1334 for (G). 1336 o As long as there is an entry in CRT, for each new source (S) 1337 that becomes active C-RP MUST check the contents of CRT and 1338 check the (G) represented by newly activated source(S) against 1339 the entries inside CRT and if there is a match then depending on 1340 the time that is shown by the timer C-RP MUST act in one of the 1341 bellow ways: 1343 1- If the timer shows a time between 33 to 8 seconds, the C-RP 1344 MUST immediately send its unicast-encapsulated Acknowledge 1345 containing (S) for (G) to the client and after the timer goes 1346 off and becomes equal to 0 delete that entry from the CRT. 1348 2- If the timer shows a time between 8 to 0 seconds, the C-RP 1349 MUST NOT send an Acknowledge back to the client and MUST wait 1350 to receive the client's periodical Request for Source and 1351 then send an Acknowledge in response to the Client's Request 1352 and delete the entry from CRT. Note that each 30 seconds the 1353 client who has received a NULL-ACK will send periodical 1354 Request to C-RP and since when the timer shows 8sec we will 1355 have 3 seconds to the next periodical Request it will help to 1356 reduce C-RP's work to wait for the next periodical Request, 1357 also in case that the client is not interested anymore in 1358 finding the (S) for (G) then at this point it will be a waste 1359 of C-RP resources to send an Acknowledge after the timer 1360 passes the 8sec. 1362 o For Default-Mode to work without problem the timers on all 1363 routers MUST be the same. Thus the C-RP sends the value of the 1364 Timer set on it in the Null-ACK packet in the GDPT field so that 1365 the synchronization is done automatically. 1367 o If the default timer is changed by an administrator, the time 1368 range in which the C-RP is to send a notification MUST be 1369 between the higher limit and the 8 seconds. so if for instance 1370 the time is set to 60 then C-RP MUST only send notifications 1371 between 60 to 8 seconds. 1373 The above being explained and since the involved processes will keep 1374 the C-RP a little busier it is suggested to use this mode in 1375 topologies with a low number of clients although this mode works 1376 perfectly under any topology. Also it must be noted and considered 1377 that due to the unique Domain concept(4.6.1.1. ) introduced by PIM-NG 1378 which allows implementing the Sub-Domain concept(section 4.6.5) it is 1379 possible to divide any large multicast domain to a number of smaller 1380 domains which then makes it possible to easily use the Default-Mode 1381 under any network topology. 1383 4.2.4.2. Delay prevention in Admin-Mode 1385 This mode is a suitable choice for large network topologies with many 1386 clients which will reduce the work overhead of C-RP'(s). and is 1387 suggested to be used in scenarios in which C-MAPPER'(s) are 1388 considered and also the Sub-Domain concept is not considered. 1390 Bellow rules and specifications apply to Admin-Mode: 1392 o The Admin-Mode as the name implies needs to be activated on all 1393 existing C-RPs by an administrator. 1395 o For each Client's Request for Source to find the (S) for (G) 1396 that the C-RP sends a NULL-ACK of (*, G) an entry MUST be put in 1397 CRT. 1399 o The entry in CRT is as explained in Default-Mode. 1401 o As long as there is an entry in CRT, for each new source (S) 1402 that becomes active C-RP MUST check the contents of CRT and 1403 check the (G) represented by newly activated source(S) against 1404 the entries inside CRT and if there is a match then depending on 1405 the time that is shown by the timer C-RP MUST act in one of the 1406 bellow ways: 1408 1- If the timer shows a time between 33 to 8 seconds and 1409 Dynamic RP discovery type 1(4.4.2.2. ) is in use, the C-RP 1410 which is also acting as the C-MAPPER MUST send a Multicast 1411 Notification called New-Activated-Source-Notification(NASN) 1412 to the entire population of PIM-NG-AWARE routers using the 1413 destination address 239.0.1.190 which is used by this draft 1414 for the simplicity in explaining the processes as the address 1415 used by C-MAPPER'(s) when sending multicast introductions or 1416 notification within the multicast domain. This notification 1417 contains either only all the (G) for which there is an entry 1418 in CRT or both the (G) and the unicast address of the source 1419 (S) representing (G). both methods can be used although the 1420 later is faster approach but less secure because it is not a 1421 good approach to let all the clients know about the unicast 1422 address of all the sources that are active in the domain. 1424 2- If the timer shows a time between 33 to 8 seconds and 1425 Dynamic RP discovery type 2(4.4.2.3. ) is in use, then the C- 1426 RP MUST send a unicast-encapsulated New-Activated-Source- 1427 Notification to the closest Active C-MAPPER the way it sends 1428 its introductions. This notification contains either only all 1429 the (G) for which there is an entry in CRT or both the (G) 1430 and the unicast address of the source (S) representing (G). 1431 both methods can be used although the later is faster 1432 approach but less secure because it is not a good approach to 1433 let all the clients know about the unicast address of all the 1434 sources that are active in the domain. After C-MAPPER 1435 receives the C-RP notification it will send out a multicast 1436 notification to the entire population of PIM-NG-AWARE routers 1437 within the domain using the destination address 239.0.1.190. 1439 3- If the timer shows a time between 8 to 0 seconds, the C-RP 1440 MUST NOT send the notification to the C-MAPPER and MUST wait 1441 to receive the client's periodical Request for Source and 1442 then send an Acknowledge in response to the Client's Request 1443 and delete the entry from CRT. Note that each 30 seconds the 1444 client who has received a NULL-ACK will send periodical 1445 Request to C-RP and since when the timer shows 8sec we will 1446 have 3 seconds to the next periodical Request it will help to 1447 reduce C-RP's work to wait for the next periodical Request, 1448 also in case that the client is not interested anymore in 1449 finding the (S) for (G) then at this point it will be a waste 1450 of C-RP resources to send an Acknowledge after the timer 1451 passes the 8sec. 1453 4- In all the above conditions, after the C-RP receives the 1454 client's request for source representing (G) for each (G) 1455 there is an entry in CRT, the C-RP MUST delete the entry for 1456 that (G) from the CRT after the timer goes off and is equal 1457 to 0. 1459 o All the clients receive the notification and those that have 1460 received a NULL-ACK for (G) will send their queries to C-RP 1461 again only if there is an entry for (G) they had received a 1462 NULL-ACK for. Since considering that if the clients send their 1463 queries immediately RP might get too busy, then each client MUST 1464 activate a 3 second timer and after the timer goes off will send 1465 its query. Or if the notification contains the unicast address 1466 of the source too then clients will be able to join the SPT for 1467 (S, G) immediately. it is possible to make modifications so that 1468 this special notification is only readable by clients that have 1469 received a NULL-ACK 1471 +-----------------------------------------------------+ 1472 |Client unicast addr| Requested Group (G) |Timer | 1473 +-----------------------------------------------------+ 1474 | | | | 1475 +-----------------------------------------------------+ 1476 Figure 13 Client Request Table (CRT) 1478 0 1 2 3 1479 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 1480 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1481 |PIM Ver| Type | Reserved | Checksum | 1482 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1483 | D O M A I N | 1484 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1485 | C-MAPPER's unicast address | 1486 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1487 | Activated Group 1 (G-1) | 1488 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1489 | . . . | 1490 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1491 | Activated Group N (G-N) | 1492 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1493 Figure 14 New-Activated-Source-Notification message format 1495 o Type: NASN (New-Activated-Source-Notification) 1497 4.3. Communication between PIM-NG routers 1499 It is important, that connected PIM-NG neighbor routers maintain a 1500 steady state of connection. In order to do this PIM-NG routers will 1501 send periodic HELLO messages or simply called Keep-Alive messages to 1502 their neighbors. 1504 This HELLO messages will be sent to the address 224.0.0.13, all PIM 1505 routers. 1507 What is changed is not the process of sending, rather the contents of 1508 the hello message. A new hello packet is defined and compared to the 1509 original PIM-SM specifications, Figure 15. 1511 Original PIM-SM HELLO packet 1513 0 1 2 3 1514 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 1515 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1516 |PIM Ver| Type | Reserved | Checksum | 1517 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1518 | OptionType | OptionLength | 1519 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1520 | OptionValue | 1521 | ... | 1522 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1523 | . | 1524 | . | 1525 | . | 1526 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1527 | OptionType | OptionLength | 1528 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1529 | OptionValue | 1530 | ... | 1531 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1533 PIM-NG hello packet 1535 0 1 2 3 1536 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 1537 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1538 |PIM Ver| Type | Reserved | Checksum | 1539 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1540 |R|E|Z| | 1541 |M|D|T| Reserved | 1542 |G|C| | | 1543 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1544 | D O M A I N | 1545 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1546 | PIM Domain topology table | 1547 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1548 | JOINED GROUPS TABLE | 1549 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1550 | OptionValue | 1551 | ... | 1552 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1553 | . | 1554 | . | 1555 | . | 1556 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1557 | OptionType | OptionLength | 1558 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1559 | OptionValue | 1560 | ... | 1561 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1562 Figure 15 original PIM-SM hello packet compared with the new hello 1563 packet format 1565 Type: HELLO 1567 New fields are added to the new packet which in later sections their 1568 usage will be covered: 1570 1- RM-BIT: can be set to 1 by the sending neighbor to inform the 1571 other neighbors about the existence of the C-MAPPER incase dynamic 1572 methods are being used. A value of 0 indicates that the neighbor 1573 doesn't know about any RP or C-MAPPER. 1575 2- EDG-BIT: if set indicates to all downstream CLIENTS that a PIM 1576 EDGE-Client exists in the network to limit the propagation of 1577 multicast introductions sent by C-MAPPERs and C-RPs. And to 1578 register a multicast source the clients MUST send the register 1579 message directly to the EDGE-CLIENT which is responsible of NAT 1580 operations. The EDGE-CLIENT can be considered as the DR of a Multi- 1581 Access Network which is part of one PIM-NG Multicast Domain. 1582 Downstream routers need to look into PIM DOMAIN TOPOLOGY TABLE to 1583 find the address of EDGE-CLIENT, if the EDGE-BIT is set. 1585 3- ZTC-BIT: if set indicates that there has been a change in the 1586 multicast groups the CLIENT has joined the SPT for. a PIM-NG-CLIENT 1587 will set this bit in case there has been a change in its JOINED 1588 GROUP TBALE and will send the table in the hello message. 1590 4- Domain field: a 32 bit field used to announce the Domain a PIM-NG- 1591 ROUTER is resided in to the neighbors. Only PIM-NG-ROUTERs with 1592 matching Domains can become neighbor. 1594 5- PIM Domain topology table: this table as described before in the 1595 definition section, holds the information related to the C-RP'(s), 1596 C-MAPPER'(s) and other components. What is included in this table 1597 is actually the unicast addresses of each of the components 1598 mentioned. 1600 6- JOINED GROUPS TABLE: holds the list of all the multicast groups a 1601 PIM-NG-CLIENT has joined the SPT for and is receiving the related 1602 traffic, in the format of (S, G) or (S, S, G) which the first S 1603 indicates the unicast address of the PIM-NG-CLIENT which is sending 1604 the traffic to the domain and the second S indicates the address of 1605 the host or server inside the LAN behind the client. this table 1606 will help clients in the process of sending join messages to the 1607 source of a multicast group in case their neighbors are already 1608 receiving that traffic : 1610 o the client in need of receiving multicast traffic for 1611 (*,G)or(S,G) first looks inside this table to see if the 1612 neighbor PIM-NG-CLIENTS has already joined the group and 1613 receiving the traffic ,before asking the C-RP for the unicast 1614 address of the source. 1616 o If there is an entry in this table for the multicast group it 1617 needs it will send a join/prune message to the neighbor for 1618 that group. 1620 o If there is no entry for the multicast group it needs in this 1621 table, it will then ask the C-RP. 1623 o A CLINET will send the table only incase that there has been a 1624 change in its internal JOINED GROUP TABLE , like joining the 1625 SPT for a new group or leaving/pruning from a group .in such 1626 cases client must inform the neighbors by setting the ZTC-BIT 1627 in its hello message. 1629 +-----------------------------------------------------+ 1630 |Source unicast addr| Role | priority |Domain|TR Group| 1631 +-----------------------------------------------------+ 1632 | | | | | | 1633 +-----------------------------------------------------+ 1634 | | | | | | 1635 +-----------------------------------------------------+ 1636 Figure 16 PIM domain topology table (PDTT) 1638 o Source unicast address field: holds the unicast address, related 1639 with either one of C-MAPPER, C-RP, SC-MAPPER, BPR or EDGE-CLIENT. 1641 o Role: indicates that the address entry inside the source unicast 1642 address field belongs to what component of the PIM-NG domain: 1644 1. C-MAPPER(C-M) and SC-MAPPER(SC-M)with binary codes 1 and 2 1646 2. C-RP and SC-RP with binary codes 3 and 4 1648 3. A ROLE of EDGE with binary code 9, can be seen in designs, that 1649 to reduce the propagation of multicast introduction messages, a 1650 Client is chosen to act as the EDGE-CLIENT and will not pass any 1651 multicast introductions received on external interfaces to 1652 internal interfaces. In such a design the EDGE-CLIENT IS 1653 responsible of introducing only the existing TR'(S) to its 1654 downstream clients by sending the PIM-DOMAIN TOPOLOGY TABLE to 1655 downstream neighbors. An EDGE-CLIENT MUST BE ONLY used in parts 1656 of a PIM-NG multicast network where no C-MAPPER, C-RP or TR 1657 exists. And the downstream routers MUST BE only clients. Also in 1658 such networks a multicast source can use private IP addresses, 1659 and such a source MUST send register messages to the existing 1660 EDGE-CLIENT'(s). Related concepts will be explained in the 1661 appropriate section'(S). 1663 4. A role of PPER (PRIVATE-PIM-EDGE-ROUTER) with binary code 8 can 1664 be seen when a private PIM-NG domain is connected to another 1665 domain through the use of PIM-EDGE-ROUTERs which are responsible 1666 for the process of NETWORK ADDRESS TRANSLATION (NAT). 1668 5. A role of BPR with binary code 10 can be seen in designs where 1669 a PIM-NG multicast domain is connected to a PIM-SM multicast 1670 domain. The information related to BPR is locally significant to 1671 C-MAPPER and won't be sent to all PIM-NG routers. 1673 6. A role of STC-MAPPER (STANDBY-C-MAPPER) with binary code 5 can 1674 be seen in network designs with PEER-C-MAPPERs inside the same 1675 Domain. In the case of existing Peer C-MAPPERs, C-RPs will use 1676 the closest C-MAPPER to propagate the information associated 1677 with existing sources inside the domain. 1679 7. A role of TR with binary code 6 can be seen in case any TR 1680 implementations are considered inside the domain. Please do note 1681 that a C-MAPPER or C-RP can take the role of TR too or the TR 1682 can be a separate and unique PIM-NG-AWARE-ROUTER inside the 1683 domain. 1685 8. A role of C-TR (core-TR) with binary code 7 can be seen in PIM- 1686 NG-DOMAINs. It indicates the existence of a core-domain and the 1687 unicast address of any existing TR inside the core domain for 1688 further use by clients inside each domain. 1690 o Priority: this field holds the priority related to an EDGE-CLIENT 1691 and is used only in hello packets sent to private networks by an 1692 edge-client. Related concepts will be discussed later. 1694 o DOMAIN: in case separate PIM-NG multicast domains are going to be 1695 connected to each other through the use of an EDGE router, the 1696 Domain to which a PIM-EDGE-ROUTER is connected will be informed 1697 inside this field. This field is usable by C-MAPPERs inside each 1698 domain and thus won't be sent to ALL-PIM-NG-CLIENTS by C-MAPPER 1699 when sending introductions to 239.0.1.190. 1701 o TR Group: this field indicates the TR group each TR belongs too 1702 and is set to 0 by default. It is ONLY set by C-MAPPER or the 1703 Active C-MAPPER and is used in Bidirectional PIM-NG processes. 1705 When a PIM-NG-CLIENT receives a join message from its neighbor for a 1706 multicast group, that it is joined to and is receiving the traffic 1707 for, it will then forward the traffic on the interface that the 1708 neighbor is connected to and towards that neighbor. 1710 The definitions given by the original PIM-SM [7] are applicable to the 1711 other fields. 1713 4.4. RP discovery 1715 RP discovery in general, points to the processes involved in, how a 1716 Client finds the C-RP in the first place to send a request to and 1717 reach the destination it wants. 1719 In PIM-NG RP discovery is done in 3 different conditions or better to 1720 say network topologies. Choosing the best solution depends on the 1721 specifications of the network and will be decided by network 1722 administrators. 1724 Bellow the 3 different RP discovery solutions are briefly defined, 1725 and will be explained later: 1727 1- Static RP discovery : 1729 The unicast address of C-RP is statically given to each PIM-NG 1730 router through special commands. 1732 2- Dynamic RP discovery type 1 : 1734 Type 1 is used in networks not so big to need redundant RPs. and 1735 also used in order to make the process of RP discovery easier and 1736 more scalable. This type uses its own set of commands for the sake 1737 of simplicity in explaining the processes .in this type of RP- 1738 DISCOVERY a router is given the role of both C-MAPPER and C-RP 1740 3- Dynamic RP discovery type 2 : 1742 Type 2 is used in large networks with many routers, which will need 1743 to have C-RP redundancy. Also this type is suitable for the future 1744 needs of World Wide Web (internet). This type uses its own set of 1745 commands for the sake of simplicity in explaining the processes. In 1746 this type C-MAPPER and C-RP'(s) are different routers. 1748 In the following sections the above three RP discovery methods will 1749 be discussed. 1751 Also please note that any command line written in this document from 1752 this point forward is just to provide a good sense of understanding, 1753 and to provide simplicity in explaining the processes involved and 1754 shall not be taken as the solid command line to be used. Also to make 1755 the explanation process and the understanding easier some of the 1756 processes and specifications are explained through scenarios and 1757 examples. 1759 4.4.1. Static RP discovery 1761 As the name indicates, the unicast address of the C-RP which is the 1762 IP address of a loop back interface created on RP, is set on each PIM 1763 router so the PIM routers will be able to communicate with RP. 1765 The process is as follows: 1767 1- A loopback interface, typically loopback0 is created on RP and an 1768 IP address is assigned to it. 1770 2- The candidate RP router will know that it is the RP and will have 1771 to use its loopback 0 by initiating the command : 1773 <# IP PIM-NG SET-RP SOURC-LO "x" INTERFACE X, INTERFACE Y, INTERFACE 1774 Z.> 1776 by initiating this command on the router, the router understands that 1777 it is the RP and it will have to use its loopback 0 unicast address 1778 to communicate, or better to say it will use its loopback 0 in the " 1779 source unicast address field " and also if it sees its loopback 0 1780 unicast IP address as the destination of a PIM-NG packet it will have 1781 to answer to that packet. And also it will have to bring its 1782 interface "X, Y, Z" in to the PIM game. 1784 3- On all the other PIM routers the bellow command is initiated : 1786 <# IP PIM-NG CLIENT RP-ADDRESS "X.Y.Z.W" INTERFACE "X", INTERFACE 1787 "Y"> 1789 This command tells the router that it is a client of the RP with 1790 address of "X.Y.Z.W" .and to find any source or to be able to send 1791 multicast traffic to any host looking for that traffic, it will have 1792 to contact the RP through the processes explained before. And also it 1793 will have to bring its interface "X, Y" in to the PIM game. 1795 Since the C-MAPPER plays a significant role when it comes to 1796 connecting different PIM-NG multicast domains and for exchanging the 1797 information related to existing multicast sources in each domain the 1798 C-RP takes the role of a C-MAPPER too in the static mode. But no C- 1799 MAPPER introduction messages will be generated by the C-RP within the 1800 multicast domain and the additional role of C-MAPPER is only used 1801 when exchanging information related to existing multicast sources 1802 with other domains. 1804 A PIM-NG specification advises that a mechanism be implemented 1805 through which any existing components such as PPER'(s) and BPR'(s) 1806 MUST learn about the C-MAPPER or better to say the existing C-RP 1807 through static configuration of the C-RP unicast address. 1809 In case any TR exists within the multicast domain or the domain is 1810 connected to a PIM-NG core domain, PIM-NG strongly advises that the 1811 unicast address of existing TR'(S) be introduced to each Client 1812 through static configuration since there will be no C-MAPPER 1813 introduction in the static RP discovery mode. 1815 At the end PIM-NG specifications strongly advises to implement the 1816 static RP discovery method in design plans where the multicast domain 1817 is of small size and the domain is not connected to other domains. 1818 And if the multicast domain whether big or small is supposed to be 1819 connected to another domain it is strongly advised by PIM-NG 1820 specifications to use one of the Dynamic RP discovery methods 1821 described in the following sections. 1823 Although in the final sections of PIM-NG specifications a new concept 1824 will be explained which is related to connection of a Multi-Access 1825 network which can also be considered a small sized multicast domain 1826 to another domain or a service provider multicast domain without the 1827 need for existing of any C-MAPPER, C-RP or TR in that Multi-Access 1828 network which is unique to PIM-NG. 1830 4.4.2. Dynamic RP discovery 1832 As stated before PIM-NG uses 2 types of dynamic RP discovery methods 1833 depending on the needs and the size of the network: 1835 1- Dynamic discovery type 1 1837 2- Dynamic discovery type 2 1839 4.4.2.1. Multicast IP addresses used 1841 Before explaining the processes involved in PIM-NG DYNAMIC-RP- 1842 DISCOVERY-TYPE1, there are some multicast destination group addresses 1843 that must be defined which are used in both DYNAMIC-RP-DISCOVERY 1844 methods: 1846 1- Multicast group address 239.0.1.190 : 1848 This address is reserved to be used by C-MAPPER at the time of 1849 introducing itself to other PIM-NG routers. PIM-GN routers/clients 1850 will listen to this multicast group address to find the C-MAPPER 1851 and the existing C-RPS. So a new PIM-NG C-MAPPER will send its 1852 introduction to this destination address. 1854 2- Multicast group address 239.0.1.189: this address is required to 1855 be used as the reserved range for the communication of RPs in order 1856 to hold an election between RPs incase backup RPs are needed. Also 1857 this address is used to find peers automatically in case redundant 1858 C-RP is needed in the network. 1860 3- Multicast group address 239.0.1.188 : this address is required to 1861 be used as the reserved range for the communication of MAPPERs in 1862 order to hold an election between MAPPERs incase backup MAPPERs are 1863 needed. The usage of this range will be covered later. 1865 Now that the addresses are defined, it is time to explain the process 1866 through which the PIM-NG dynamic RP discovery is done and 1867 implemented. 1869 4.4.2.2. Dynamic RP discovery TYPE-1 1871 There might be some network designs in which, the presence of only 1872 one dedicated router as the RP is adequate but for administration 1873 purposes, administrators prefer to use an automatic mechanism, so 1874 that every PIM router will know the RP. An example of such networks 1875 can be an enterprise or a company which uses multicast applications 1876 such as voice and video conference often and not always. In other 1877 words the network doesn't need to have multiple redundant RPs and 1878 also they don't use multicast applications all the time, but for the 1879 sake of easy administration and maintenance administrators prefer to 1880 use the automatic mechanism. 1882 In such a network a router will be used as the designated RP or 1883 candidate RP (C-RP), and will introduce itself to other PIM 1884 routers/clients as both C-MAPPER and C-RP .and as soon as all the 1885 clients understand about the presence of the C-MAPPER and C-RP the 1886 rest of the process is as before. 1888 The process is as follows: 1890 1- A router is chosen as the C-RP. Then like the specifications of 1891 the static RP a loopback interface is configured on it. The 1892 loopback is better to be the loopback 0 interface. 1894 2- The commands : 1896 <#IP PIM-NG DYNAMIC-RP1 SOURCE-LO "X" INTERFACE [TYPE] "X" , 1897 INTERFACE [TYPE] "Y"> and 1899 <#IP PIM-NG DOMAIN [X]> are initiated on the RP. 1901 Above commands tells the router that it is both C-MAPPER and C-RP 1902 in the network and the Dynamic discovery method used is type1 and 1903 it should use its interface loopback "X" as the C-MAPPER and C-RP 1904 unicast address in introductions. And it should bring its interface 1905 "x, y,.." into the PIM-Ng game. 1907 So router sees that it is the C-RP and the discovery protocol used 1908 is Dynamic and the discovery method is type1, and knows that: 1910 o It is the only RP in the network and also it must introduce 1911 itself as the C-MAPPER. 1913 o It is resided in domain X 1915 o It should Send multicast introduction messages to multicast 1916 address 239.0.1.190, out its interface "x, y" and any other 1917 interfaces configured to be in the PIM-NG game. 1919 o It should put the interfaces defined in the command in to 1920 forwarding for the multicast address destinations 239.0.1.188 1921 and 239.0.1.189. 1923 o It should Send periodic C-MAPPER-introduction messages every 60 1924 seconds. 1926 o If by any means it is reloaded as soon as it comes back up, it 1927 should send a multicast introduction to 239.0.1.190 ASAP. 1929 3- All the other none-RP PIM-NG routers are configured as the clients 1930 of C-MAPPER/RP. 1932 4- on PIM-NG none-RP routers(clients) commands : 1934 <#IP PIM-NG DYNAMIC-RP CLIENT INTERFACE [TYPE] "X", INTERFACE 1935 [TYPE] "Y"> 1937 <#IP PIM-NG DOMAIN [X]> are initiated. 1939 above commands tells the router that it is in a PIM-NG network and 1940 the protocol by which it can find the RP is Dynamic RP discovery 1941 .also it understands that it should bring its interface "x ,y" and 1942 any other interfaces dictated, in PIM-NG game. 1944 After entering the above commands in a none-RP or a client 1945 router'(s) the router knows that: 1947 o it is in PIM-NG domain X 1949 o It should use dynamic methods to find the RP .so it will wait 1950 to receive a C-MAPPER introduction message. 1952 o it should listen to multicast address 239.0.1.190 to hear the 1953 C-MAPPER-introduction message to learn about the C-RP/RPs 1955 o it should bring the interfaces mentioned in the command in PIM- 1956 NG game 1958 o It should put the interfaces mentioned in the command in 1959 forward for the address 239.0.1.190 so others will hear the C- 1960 MAPPER introduction message. Also it should put those interfaces 1961 in to forwarding state for group addresses 239.0.1.189 and 1962 239.0.1.188. 1964 o If it doesn't receive the address of the C-MAPPER in the first 1965 hello-acknowledge received from the neighbor, it should wait to 1966 hear from the C-MAPPER. 1968 Now that the overall process is covered, in the next section the way 1969 RP and clients communicate will be explained and the new packet 1970 formats will be shown. 1972 4.4.2.2.1. RP introduction process 1974 As soon as the router designated as the C-RP and C-MAPPER, is 1975 configured and knows that it is the only RP in the network, it will 1976 start the process of introducing itself as the C-MAPPER to the 1977 network by sending the C-MAPPER-INTRODUCTION massage to the multicast 1978 destination address 239.0.1.190 (Figure 17). 1980 0 1 2 3 1981 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 1982 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1983 |PIM Ver| Type | Reserved | Checksum | 1984 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1985 | D O M A I N | 1986 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1987 |R| | | |Z| | | 1988 |M|A| G R O U P |P R I O R I T Y|T|B| R E S E R V E D | 1989 | | | | | |C| | | 1990 | | | | |N| | | 1991 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1992 | HOLD TIME | R E S E R V E D | 1993 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1994 | C-MAPPER's unicast address | 1995 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1996 | SC-MAPPER'S unicast Address | 1997 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1998 | PIM domain topology table | 1999 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2000 Figure 17 C-MAPPER-INTRODUCTION massage sent to 239.0.1.190 2002 o Type: C-MAPPER-INTRODUCTION 2004 o RM-BIT field : if set to 1 in a C-MAPPER introduction message sent 2005 to 239.0.1.190 , tells to all PIM-NG CLIENTS that only 1 RP exists 2006 in the domain .so the address of the C-MAPPER is the unicast 2007 address of C-RP . If this bit is not set to 1 then indicates to all 2008 PIM-NG CLIENTS that in order to find existing C-RPs they should 2009 read the contents of PDTT. 2011 o A-BIT field: is set to 0 in this type. Its usage will be discussed 2012 later. 2014 o GROUP and PRIORITY fields: 8 bit fields, and are set to all zeros 2015 when sending introduction to 239.0.1.190 .and clients won't read 2016 the contents of these fields. 2018 o ZTCN-BIT field : if a C-MAPPER needs to inform ALL-PIM-NG-CLIENTS 2019 about a change it will set this bit, also if a C-MAPPER needs to 2020 inform a change in the domain to SC-MAPPER or PEER C-MAPPERs ,it 2021 will set this bit .use will be discussed later. 2023 o B-BIT: Bidirectional Bit. If set to 1 in such introduction message 2024 indicates that the domain uses the manual mode(4.7.2.1. ) and for 2025 any multicast group found in Bidirectional Groups Table sources and 2026 receivers MUST immediately join the SPT rooted at closest TR. 2028 o DOMAIN: indicates the domain in which a C-MAPPER resides. It can 2029 be used as either a security factor or as an scoping mechanism so 2030 that clients and C-RPs inside one domain wont react to the 2031 introductions sent from a C-MAPPER in another domain. 2033 o PIM Domain topology table (PDTT): when the RM-BIT is set the C- 2034 MAPPER won't send this table in its introductions sent to 2035 239.0.1.190, unless a TR is considered in the domain. 2037 The Type field is set to C-MAPPER-INTRODUCTION1 so the clients 2038 receiving the packet will know that it is an introduction message 2039 sent from the C-MAPPER and will look directly into the "SOURCE 2040 UNICAST ADDRESS" field. The address field contains the unicast 2041 address of the interface loopback "X" of the C-MAPPER.and the next 2042 field contains the address of the SC-MAPPER if any exists. 2044 After sending the first introduction message , C-MAPPER/RP sets a 2045 timer of 60 seconds and starts counting down to 0 ,and resends the 2046 introduction message so all the PIM-NG routers will know that the C- 2047 MAPPER still exists. 2049 4.4.2.2.2. Back up C-RP considerations 2051 If any backup C-RP is needed to be considered in such networks 2052 explained above for the sake of high availability a mechanism for the 2053 negotiation between the RPs and election of the candidate RP(C-RP) is 2054 needed. 2056 The process is as follows: 2058 1- The addition of to the command tells the router 2059 its group number and the PEER RP GROUP[X] tells the router that 2060 there is another RP which it must become peer with but since the 2061 group number of the peer is the same as its own value an 2062 election is needed to elect the C-RP and SC-RP. The values in 2063 front of the GROUP means that all the RPs belong to one unified 2064 group. The usage of the GROUP will later be more clarified. and 2065 the at the end of the command 2066 will define each C-RP's priority in the election process : 2068 <#IP PIM-NG DYNAMIC-RP1 SOURCE-LO "X" INTERFACE [TYPE] "X" , 2069 INTERFACE [TYPE] "Y"> 2071 <#IP PIM-NG GROUP [X] PRIORITY[VALUE]> 2072 <#IP PIM-NG PEER RP GROUP[X] ADDRESS> 2074 2- If the address of the peer is not used, RPs will send multicast 2075 introduction messages to the reserved address 239.0.1.189, so 2076 the other RP/RPS will find each other. 2078 3- An election based on the highest priority configured on each C- 2079 RP , or highest C-RP unicast address will be held between the C- 2080 RPs 2082 4- The candidate RP will take the responsibility of both C-MAPPER 2083 and C-RP as explained above 2085 5- RPs will send unicast keep-alive messages to each other every 2086 30 second. 2088 6- The candidate RP, C-RP, will send a copy of its multicast- 2089 mapping table only incase that any changes occur in the domain. 2090 And C-RP periodical introduction messages to SC-RP wont contain 2091 any MULTICAST MAPPING table. 2093 7- In case any changes occur C-RP will set the Z-BIT inside its 2094 introduction message to SC-RP which indicates that a change has 2095 occurred. 2097 8- If more than 2 RPs are considered in a network design, an 2098 election between none candidate RPS will be held to choose the 2099 second best choice (SC-RP) to be the RP if the candidate RP is 2100 dead. 2102 9- The candidate C-RP which has the role of C-MAPPER too, will 2103 send the unicast address of the second best candidate as SC- 2104 MAPPER in its introduction message sent to all PIM-NG routers 2105 every 60 second for further use by PIM-NG clients. 2107 10- PIM-NG clients will write the address of the C-MAPPER, SC- 2108 MAPPER and C-RP in a special table called PIM Domain Topology 2109 Table (PDTT) for further use. 2111 11- If SC-MAPPER/RP doesn't receive any INTRODUCTION/KEEPALIVE- 2112 MESSAGE from the C-MAPPER/RP in 2*INTRODUCTION/KEEPALIVE-MESSAGE 2113 plus 5 seconds timer (2*30+5) it will immediately take the place 2114 of the C-RP and send a multicast introduction to 239.0.1.190. 2116 12- If the SC-MAPPER/RP receives a REQUEST-FOR-C-MAPPER message 2117 from a client asking about the existence of the C-MAPPER in 70 2118 seconds it will react in 2 ways : 2120 o It will immediately query the C-MAPPER/RP by sending an 2121 introduction message and if it receives a KEEP-ALIVE message 2122 from the C-MAPPER/RP which means the C-MAPPER/RP is still 2123 alive then it assumes that the client which is looking for 2124 C-MAPPER/RP is having problems .so it will return the 2125 address of the current C-MAPPER/RP back to the host in a 2126 unicast C-MAPPER-INTRODUCTION (Figure 17) 2128 0 1 2 3 2129 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2130 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2131 |PIM Ver| Type | Reserved | Checksum | 2132 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2133 | D O M A I N | 2134 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2135 |R| | | |Z| | 2136 |M|A| G R O U P |P R I O R I T Y|T| R E S E R V E D | 2137 | | | | | |C| | 2138 | | | | |N| | 2139 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2140 | C-MAPPER's unicast address | 2141 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2142 | SC-MAPPER'S unicast Address | 2143 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2144 | PIM domain topology table | 2145 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2146 Figure 18 SC-MAPPER/RP answers to a host REQUEST-FOR-C-MAPPER message 2148 o Type: C-MAPPER acknowledge 2150 o If SC-MAPPER/RP hasn't received KEEP_ALIVE messages for the 2151 past 2*30 seconds , then it should not receive such a 2152 message, as by now SC-MAPPER/RP must had taken the place of 2153 C-MAPPER/RP and sent out a C-MAPPER introduction to 2154 introduce itself. (Figure 18). 2156 0 1 2 3 2157 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2158 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2159 |PIM Ver| Type | Reserved | Checksum | 2160 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2161 | D O M A I N | 2162 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2163 |R| | | |Z| | | 2164 |M|A| G R O U P |P R I O R I T Y|T|B| R E S E R V E D | 2165 | | | | |C| | | 2166 | | | | |N| | | 2167 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2168 | HOLD TIME | RESERVED | 2169 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2170 | C-MAPPER's unicast address | 2171 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2172 | SC-MAPPER'S unicast Address | 2173 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2174 | PIM domain topology table | 2175 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2176 Figure 19 SC-MAPPER/RP multicast introductions to all PIM-NG-CLIENTS 2178 Type: C-MAPPER INTRODUCTION1 2180 If clients see the address of the SC-MAPPER in the C-MAPPER unciast 2181 address field they will assume that the current C-MAPPER is dead and 2182 will update their tables with the new one. 2184 13- If the previous C-MAPPER/RP gets back again then another 2185 election will be held between RPS and the C-RP will introduce 2186 itself. 2188 14- All PIM-NG routers will put their interfaces inside the game 2189 of PIM-NG into forwarding for the group address 239.0.1.189 and 2190 239.0.1.188 and won't listen to these packets. Only will forward 2191 them. 2193 [Figure is presented in PDF version] 2195 Figure 20 PIM-NG network with backup RP (SC-RP) 2197 RP introduction packet formats are shown below: 2199 0 1 2 3 2200 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2201 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2202 |PIM Ver| Type | Addr length | Checksum | 2203 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2204 | D O M A I N | 2205 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2206 |P|Z| PRIORITY | GROUP | MESH-PRIORITY |R|reserved | 2207 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2208 | HOLD TIME | RESERVED | 2209 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2210 | RP'S unicast address | 2211 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2212 | Sc-RP unicast address | 2213 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2214 | PEER list | 2215 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2216 | Multicast MAPPING table | 2217 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2218 | A-Multicast mapping table | 2219 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2220 Figure 21 RP introduction message format 2222 o Type: RP introduction 2223 o P-BIT field (PEER): is used when a C-RP wants to become peer with 2224 another C-RP. C-RP sets this bit to 1 and sends an introduction to 2225 239.0.1.189. By seeing this bit set only C-RPs configured to become 2226 peer with another C-RP from a different Group will react to the 2227 message contents. Others will only forward. 2229 o Z-BIT field (ZONE TOPOLOGY CHANGE NOTIFICATION): this bit is set 2230 to 1 in case a C-RP needs to inform the SC-MAPPER C-MAPPER or 2231 peering C-RP about any changes occurred. when this bit is set ,the 2232 C-RP will then sends out one of the tables shown in Figure-34 2233 depending on the fact that to whom this introduction is being sent 2234 and in what type of domain it is resided. 2236 o Group field: 8 bit field containing the group that the C-RP is a 2237 member of. Helps the C-RPs to see if the packet is sent from a C-RP 2238 they are configured to become peer with or in cases that backup C- 2239 RP is needed. This field is set to all ZEROs when sending to a C- 2240 MAPPER. 2242 o Priority field: is only used when finding and communicating with 2243 SC-RP. Otherwise set to all ZEROs. 2245 o Mesh-priority: will be used in the process of electing the active 2246 C-RP in a MESH-Group. 2248 o R-BIT: if set to 1 by a C-RP, indicates to the C-MAPPER that the 2249 RP has the role of TR too. 2251 o SC-RP unicast address: will be sent only when introducing to PEER- 2252 C-RPs or C-MAPPER.and not to a back up RP. 2254 o DOMAIN: indicates the domain the C-RP is a member of. helps the C- 2255 RP to differ between the packets received from C-RPs inside other 2256 domain in an special design of multiple PIM-NG multicast domains. 2258 o Multicast MAPPING table (MMT): it is sent only when introducing to 2259 SC-RP.and is sent in case any changes occur. 2261 o A-Multicast MAPPING table (AMMT): this table is sent by a C-RP to 2262 C-MAPPER in case it realizes that the domain it is resided in is 2263 connected to another domain, or there are multiple C-MAPPERs 2264 resided in the domain. When the C-RP receives a C-MAPPER 2265 introduction with the A-BIT set, it starts to send this table to 2266 the C-MAPPER. Also this table is sent by C-RP to PEER-C-RPs if any 2267 PEER-C-RP exists. 2269 o Hold time: is used only when introducing to C-MAPPER and indicates 2270 the amount of time C-MAPPER will expect to hear C-RP keep-alive 2271 message. 2273 0 1 2 3 2274 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2275 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2276 |PIM Ver| Type | Addr length | Checksum | 2277 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2278 | D O M A I N | 2279 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2280 |P|Z| PRIORITY | GROUP | MESH-PRIORITY |R|reserved | 2281 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2282 | HOLD TIME | RESERVED | 2283 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2284 | RP'S unicast address | 2285 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2286 | PEER list | 2287 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2288 | Multicast MAPPING table | 2289 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2290 | A-Multicast mapping table | 2291 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2292 Figure 22 C-MAPPER/RP unicast HELLO/KEEP-ALIVE message to back up RPs 2294 o Type: RP introduction 2296 4.4.2.2.3. PIM-NG clients processes in Dynamic-RP 2298 PIM-NG router/client processes are related to the process of 2299 forwarding special multicast traffics by default out of the 2300 interfaces which are in the game of PIM-NG, and the processes of 2301 finding RP and maintain connectivity with RP and PIM-NG neighbors. 2303 The processes are as follows: 2305 1- Each PIM-NG router using DYNAMIC-RP-DISCOVERY will put its 2306 interfaces inside the game of PIM-NG, in to forward for the 2307 multicast address groups 239.0.1.189, 239.0.1.190 and 239.0.1.188. 2309 2- PIM-NG clients need to read the content of RM bit inside C-MAPPER 2310 introduction messages to interpret the topology of the network. If 2311 this bit is set to 1, it means that only one C-RP exists in the 2312 network and the unicast address of the C-MAPPER inside the 2313 introduction message is the real address of the C-RP. If this bit 2314 is not set then clients will assume that there are possibly more 2315 than 1 C-RP in the network and in order to find the unicast address 2316 of C-RP or C-RPs they will have to read the contents of PIM domain 2317 topology table, and update their local PDTT with the information 2318 provided in this table by C-MAPPER. 2320 3- Each PIM-NG router maintains connectivity with its neighbor PIM-NG 2321 router through the process of sending periodic HELLO/KEEP-ALIVE 2322 messages to its neighbor every 30 seconds. 2324 4- If no HELLO message is received from the neighbor router in 2325 2*HELLO time, the entry for that neighbor is erased. 2327 5- If a PIM-NG router doesn't hear from the C-MAPPER in 70 2328 seconds(periodic C-MAPPER introduction+10sec) it will act as 2329 follows : 2331 o It will send a unicast REQUEST-FOR-C-MAPPER message to the address 2332 of the SC-MAPPER if any SC-MAPPER does exist in the network and 2333 waits for the response from the SC-MAPPER/RP as described in the 2334 previous section (4.4.2.2.2. ) .Figure 22 shows the format of the 2335 packet. 2337 0 1 2 3 2338 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2339 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2340 |PIM Ver| Type | Reserved | Checksum | 2341 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2342 | D O M A I N | 2343 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2344 | Clients unicast address | 2345 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2346 | C-MAPPER's unicast address | 2347 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2348 Figure 23 request- for-C-MAPPER packet sent to the SC-MAPPER 2350 o Type: REQUEST-FOR-C-MAPPER 2352 o The Client (i.e. R4) puts its own address in the client unicast 2353 address field and the unicast address of the SC-MAPPER/RP in the 2354 C-MAPPER unicast address field. 2356 o If no SC-MAPPER/RP exists then it will query the neighboring PIM- 2357 NG routers by sending a HELLO packet with the RM-BIT set to 0, 2358 indicating that it doesn't know any C-MAPPER. 2360 o If it doesn't receive the C-MAPPER's unicast address from the 2361 neighbor in the first hello inside the Pim-domain-topology-table 2362 or if the C-MAPPER address received from the neighbor PIM-NG 2363 router is the same as its own current entry for the C-MAPPER then 2364 it should wait to hear from the C-MAPPER. 2366 4.4.2.2.3.1. New PIM-NG router/client 2368 In this section, actions taken by a new PIM-NG router added to the 2369 network using DYNAMIC-DISCOVERY without any knowledge about the C-RP 2370 is explained: 2372 1- Puts its interfaces defined by the related commands in to 2373 forwarding for the multicast address groups 239.0.1.189/40/188 2375 2- Sends HELLO message to all PIM routers address of 224.0.0.13 out 2376 of the interfaces in the game of PIM-NG, to introduce itself to the 2377 neighbor PIM-NG routers. 2379 3- If in the first received HELLO message from the neighbor it sees 2380 the unicast address of the C-MAPPER it will use it and updates its 2381 PMTT. 2383 4- If no C-MAPPER address is seen in the HELLO packet received from 2384 the upstream neighbor, it will wait to hear an introduction from 2385 the C-MAPPER or receive it inside the next hello messages sent from 2386 the neighbor. 2388 5- If in the Hello message received the EDGE-BIT is set, it assumes 2389 that it is inside a private network, and it may have to act 2390 differently in order to register a source with the C-RP. The 2391 related concepts will be discussed later in a separate section. 2393 [Figure is presented in PDF version] 2395 Figure 24 New client added 2397 4.4.2.3. Dynamic RP discovery type 2 2399 In previous sections the processes related to the dynamic RP 2400 discovery type 1 in which there are no needs for redundant RPs and 2401 networks seems to be of small to medium size has been described. Now 2402 let us consider larger networks. In larger networks (i.e. internet or 2403 enterprises) with many multicast actions and sessions in process, the 2404 high availability of the RPs and also load balance between RPs 2405 through using redundant RPs becomes an important factor. 2407 In fact hosts in different parts of a large network must be able to 2408 find the desired source as fast as possible, if the source exists. So 2409 as described by the original PIM-SM specifications, the network will 2410 need redundant RPs alongside a new feature called MAPPING-AGENT or 2411 simply PIM-NG-C-MAPPER. 2413 C-MAPPER is in charge of introducing C-RPs to all PIM-NG routers. And 2414 the process is in parts like the original PIM-SM RFC 4601[7], and in 2415 parts different. Bellow the steps involved in the process of PIM-NG 2416 is briefly described and later will be explained in details: 2418 1- C-MAPPER introduces itself to all PIM-NG routers, so that everyone 2419 knows about its address. 2421 2- C-RP'(s) introduce themselves to the C-MAPPER, by sending unicast 2422 RP introductions to the C-MAPPER's address. So they wait to receive 2423 a C-MAPPER introduction. 2425 3- If any TR exists in the multicast domain, it MUST introduce itself 2426 to the closest C-MAPPER. 2428 4- C-MAPPER will send discovery messages or introduction messages to 2429 PIM-NG routers to inform them about the existence of the RPs so 2430 sources can use the RP address to introduce themselves to the 2431 nearest RP. 2433 5- Clients or simply put all none PIM-NG C-MAPPER, RP and TR routers 2434 will use the C-MAPPER to find RP'(s) or TR'(s). 2436 6- Clients or simply put ALL none PIM-NG C-MAPPER, RP and TR routers 2437 will either only-forward specific multicast address groups or 2438 listen to them . 2440 Figure 25 will be used as the basic topology to explain the process 2441 related to an enterprise network with one multicast domain. 2443 [Figure is presented in PDF version] 2445 Figure 25 network design with one multicast domain 2447 In the following sections processes related to different components 2448 of a PIM-NG domain will be explained. 2450 4.4.2.3.1. Client related concepts 2452 The processes related to a client are as described in section 2453 4.4.2.2.3. . 2455 Clients will choose the closest C-RP or C-MAPPER according to their 2456 unicast routing information. And if there is a tie, they will choose 2457 based on the highest C-RP or C-MAPPER IP address that can be found 2458 inside the PMTT information received with the C-MAPPER introduction 2459 message. 2461 4.4.2.3.2. C-MAPPER concepts 2463 C-MAPPER is in charge of discovering C-RP'(s) and introducing them to 2464 the population of PIM-NG routers through sending INRODUCTION-MESSAGES 2465 to the destination address 239.0.1.190. Sending these periodic 2466 introductions causes any existing C-RP'(s) or TR'(s) and PIM-NG 2467 clients to learn the unicast address of the C-MAPPER and SC-MAPPER in 2468 case any BACKUP MAPPER is considered in the network. 2470 In the introduction message C-MAPPER will send its own unicast 2471 address alongside the unicast address of the C-RP/RPs inside the 2472 PMTT. 2474 The introduction messages are sent under these circumstances: 2476 1. Periodically as keep-alive messages so all the population knows 2477 about the existence of the C-MAPPPER, and new routers can learn 2478 about the C-MAPPER and the C-RP/RPs. sent to 239.0.1.190 2480 2. Whenever it receives an introduction from a new C-RP. Sent to 2481 239.0.1.190 2483 3. Whenever it receives an introduction from a C-RP indicating a 2484 change in the group addresses the C-RP represents. Sent to 2485 239.0.1.190 2487 4. Whenever it receives a request from a client, The C-MAPPER will 2488 send a unicast introduction or acknowledgment in this case to 2489 the address of the client. 2491 5. If other MAPPERs exist in the network as backup C-MAPPERs the 2492 MAPPERs will send introduction messages to the address group 2493 239.0.1.188 to find each other and hold elections to elect the 2494 C-MAPPER and SC-MAPPER (backup MAPPER) or to become PEERs. 2496 Message format sent to 239.0.1.190(ALL-PIM-NG-CLIENTS) 2498 0 1 2 3 2499 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2500 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2501 |PIM Ver| Type | Reserved | Checksum | 2502 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2503 | D O M A I N | 2504 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2505 |R| | | |Z| | | 2506 |M|A| G R O U P |P R I O R I T Y|T|B| R E S E R V E D | 2507 | | | | |C| | | 2508 | | | | |N| | | 2509 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2510 | HOLD TIME | RESERVED | 2511 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2512 | C-MAPPER's unicast address | 2513 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2514 | SC-MAPPER'S unicast Address | 2515 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2516 | PIM domain topology table | 2517 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2518 o Type: MAPPER introduction1 2519 o Group: is not used and will be set to all 0's. 2520 o Priority: is not used and will be set to all 0's. 2522 Message format sent to 239.0.1.188(ALL-PIM-NG-MAPPERs) and PEER-MAPPERS 2524 0 1 2 3 2525 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2526 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2527 |PIM Ver| Type | Reserved | Checksum | 2528 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2529 | D O M A I N | 2530 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2531 |R| |P| | |Z| | | 2532 |M|A|E| G R O U P |P R I O R I T Y|T| MESH-PRIORITY |RSRVD | 2533 | | |E| | |C| | | 2534 | | |R| | |N| | | 2535 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2536 | HOLD TIME | RESERVED | 2537 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2538 | C-MAPPER's unicast address | 2539 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2540 | SC-MAPPER'S unicast Address | 2541 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2542 | PIM domain topology table | 2543 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2544 | A-MULTICAST MAPPING TABLE | 2545 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2546 | Core topology table | 2547 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2548 Figure 26 C-MAPPER introduction message formats 2550 o PEER-BIT field: if set indicates that the introduction message 2551 is meant for a PEER C-MAPPER and not for SC-MAPPERS and will be 2552 discussed later. 2553 o A-BIT: won't be set in this message type. 2554 o Hold time: will be set to all 0's, when sending the 2555 introduction to 239.0.1.188. when sending to found peers this 2556 field holds the hold time timer that must be used for the peer. 2558 C-MAPPER will set the type field to MAPPER introduction 1 or 2 2559 depending on the destination group it is sending the message to. And 2560 will put its own unicast address in the C-MAPPER unicast address 2561 field. And also will use the SC-MAPPER unicast address field to 2562 introduce the SC-MAPPER if any exists. 2564 After introducing itself it will introduce any existing C-RP'(s) or 2565 TR'(s) in the domain, by sending PMTT. 2567 As this periodical introductions sent by C-MAPPER are used by all 2568 PIM-NG routers to confirm the existence of the C-MAPPER and also will 2569 be considered by all PIM-NG none-RP routers (clients) as C-RP'(s) or 2570 any existing TR KEEP-ALIVE message , the C-MAPPER sends periodical 2571 unicast introductions every 30 seconds to the C-RP/RPs and will 2572 expect to hear from C-RP/RPs every 30 seconds by receiving a unicat 2573 RP-introduction. 2575 C-MAPPER will set the A-BIT (4.4.2.3.2.1. ) as soon as it becomes 2576 PEER with another C-MAPPER with either different domain value or the 2577 same domain value and different group. 2579 4.4.2.3.2.1. Value of the A-BIT 2581 This bit is set by the C-MAPPER as soon as it becomes PEER with 2582 another C-MAPPER. It indicates to the C-RPs that: 2584 o They are in a network with more than 1 C-MAPPER which became 2585 peers or in a network with different and separate Multicast 2586 domains, with each domain connected to the other one through 2587 peer C-MAPPERs. 2589 o C-RP/RPs will have to send A-MULTICAST-MAPPING TABLE to the C- 2590 MAPPER. 2592 4.4.2.3.2.2. C-MAPPER preparation 2594 The process begins by choosing a router to act as the C-MAPPER in 2595 the PIM-NG network. For the sake of simplicity of understanding and 2596 explaining the processes , first the processes related to a single C- 2597 MAPPER is explained and later processes related to redundant C- 2598 MAPPERs will be explained(4.5. ). 2600 In a single multicast domain (Figure 25) with one C-MAPPER, the 2601 process starts by choosing one router to act as C-MAPPER .when it is 2602 chosen the rest is as follows: 2604 o commands : 2606 <#IP PIM-NG DYNAMIC-RP2> 2608 <#IP PIM-NG DOMAIN [X]> 2610 <#IP PIM-NG MAPPER> 2612 <#IP PIM-NG SOURCE-LO"X"> 2614 <#IP PIM-NG INTERFACE "X", INTERFACE"Y"> 2616 Are initiated on the router. This command tells the router that: 2618 1- It is in PIM-NG DOMAIN X that uses DYNAMIC-RP-DISCOVERY 2619 TYPE2 2621 2- It is the C-MAPPER in the network 2622 3- It should bring its interfaces "x, y" and any other 2623 interfaces configured as a PIM-NG interface in to the PIM-NG 2624 game. 2626 4- As no other commands are entered, it is the only MAPPER and 2627 it is in a single multicast domain. So it MUST NOT set the A- 2628 BIT when sending introduction messages out of its interfaces 2629 in the game of PIM-NG. 2631 5- It should send its introduction to multicast destination 2632 address of 239.0.1.190 as the C-MAPPER, so all PIM-NG routers 2633 and especially C-RP/RPs will learn its address. 2635 6- As a PIM-NG router it should maintain connectivity with its 2636 neighboring PIM-NG routers through sending HELLO messages out 2637 of the interfaces defined by the command. 2639 7- As a PIM-NG C-MAPPER it should send introduction/keep-alive 2640 messages every 60 seconds to 239.0.1.190, so every router in 2641 the PIM-NG network knows about its existence and the new ones 2642 will learn its address and the C-RP/RPs address. This 2643 periodic introduction/keep-alive messages will also act as 2644 the introduction/keep-alive on behalf of the C-RP/RPs. 2646 8- As soon as it receives a C-RP introduction, the C-MAPPER 2647 will check the DOMAIN value to see if it matches its own 2648 value and if it does the C-MAPPER will put an entry in its 2649 PMTT alongside the multicast groups and the associated 2650 unicast addresses it may receives from each C-RP inside the 2651 AMMT. 2653 9- The C-MAPPER will maintain connectivity with each C-RP by 2654 sending periodic unicast introduction messages to the address 2655 of each C-RP. And will expect to receive an introduction from 2656 each C-RP in return. 2658 10- If it doesn't receive an introduction from each C-RP for 2659 60+10sec it will delete the entry for the RP and announces 2660 the loss in its next introduction. 2662 11- In case any SC-RP exists , if C-MAPPER doesn't receive a 2663 keep alive from the C-RP for (60sec+10=70sec) , it will 2664 automatically send an intro to the address of Sc-MAPPER.and 2665 after receiving the first intro from Sc-MAPPER it will inform 2666 all PIM-NG clients in an introduction message. 2668 [Figure is presented in PDF version] 2670 Figure 27 multicast domain with one C-MAPPER 2672 4.4.2.3.3. C-RP concepts 2674 As explained before, the role of a C-RP in general is like an 2675 information registry station. Any client that needs to register a 2676 source will communicate with the C-RP and any client in need to find 2677 a source for a multicast group (G) will have to ask the C-RP. These 2678 parts had been covered in the first sections and we are not going to 2679 talk about the related processes again. 2681 What had been explained earlier about the C-RP, was mainly related to 2682 its processes in a domain with a small or medium size that the 2683 presence of only one C-RP and if needed, a backup C-RP (SC-RP) could 2684 support the needs of the network. But in larger networks beside the 2685 high availability factor, redundancy becomes vital. 2687 In this case there may be the need for presence of more than 1 C-RP 2688 all working together to bring both high availability and redundancy 2689 to the network. 2691 4.4.2.3.3.1. C-RP redundancy 2693 In a single domain (Figure 28) with redundant C-RPs, the main task is 2694 for the C-RPS to find each other and also introduce themselves to all 2695 PIM-NG clients. 2697 [Figure is presented in PDF version] 2699 Figure 28 network designs with one multicast domain 2701 After a PIM-NG router is configured to become a C-RP and is told that 2702 Dynamic-Discovery type 2 is in use. It needs to introduce itself to 2703 all PIM-NG clients. To do so a PIM-NG C-RP needs to wait to learn 2704 about the existence of a C-MAPPER in the domain. As explained in the 2705 previous sections this is done when a C-RP receives a C-MAPPER 2706 introduction sent to 239.0.1.190, containing the unicast address of 2707 the C-MAPPER. Then it will introduce itself as the C-RP to the C- 2708 MAPPER by sending a unicast C-RP introduction message to the address 2709 of C-MAPPER. Format of this introduction and related definitions can 2710 be seen bellow. 2712 0 1 2 3 2713 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2714 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2715 |PIM Ver| Type | Addr length | Checksum | 2716 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2717 | D O M A I N | 2718 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2719 |P|Z| PRIORITY | GROUP | MESH-PRIORITY |R|reserved | 2720 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2721 | HOLD TIME | RESERVED | 2722 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2723 | RP'S unicast address | 2724 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2725 | Sc-RP unicast address | 2726 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2727 | PEER list | 2728 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2729 | Multicast MAPPING table | 2730 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2731 | A-Multicast mapping table | 2732 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2733 Figure 29 C-RP introduction message format 2735 o Type : RP introduction dynamic 2736 o Priority : set to 0 2737 o Group : set to 0 2738 o Hold time: Hold time is the amount of time a receiver must keep 2739 the neighbor reachable, in seconds. If the Hold time is set to 2740 '0xffff', the receiver of this message never times out the 2741 neighbor. This may be used with dial-on-demand links, to avoid 2742 keeping the link up with periodic Hello messages. 2743 o P-BIT : set to 0 2744 o PEER-LIST : won't be sent 2745 o Multicast Mapping Table : won't be sent to C-MAPPER and only to 2746 Sc-RP 2747 o A- Multicast Mapping Table : will be sent to C-MAPPER ,SC-RP and 2748 peer C-RPs 2750 4.4.2.3.3.2. C-RP processes 2752 The processes involved are as follows: 2754 1- A router is chosen to become C-RP and also told that it is in a 2755 network that a C-MAPPER exists as a separate component by 2756 initiating a set of commands : 2758 <#IP PIM-NG DYNAMIC-RP2> 2760 <#IP PIM-NG DOMAIN [X]> 2762 <#IP PIM-NG RP> 2764 <#IP PIM-NG SOURCE-LO"X"> 2766 <#IP PIM-NG INTERFACE "X", INTERFACE"Y"> 2768 2- The above set of commands tells the router that it is a RP in 2769 PIM-NG-domain(X). And it should use its LOOP-BACK "X" interface 2770 as the RP source address when introducing itself. Also it has 2771 to bring the interfaces "X, Y" inside the PIM-NG game and put 2772 them into forward for 239.0.1.190, 239.0.1.189 and 239.0.1.188. 2774 3- Because the RP discovery method used is of type2, a PIM-NG RP 2775 waits until it hears the C-MAPPER introduction. 2777 4- After receiving C-MAPPER introduction message first it checks 2778 the Domain field inside the introduction message to see if the 2779 domain value matches its own domain value it puts the source 2780 address of the C-MAPPER into its local PIM domain topology 2781 table. 2783 5- The C-RP'(s) MUST check the A-BIT, to understand how should it 2784 contact with the C-MAPPER. 2786 6- RP sends a unicast introduction to the unicast address of C- 2787 MAPPER and waits to receive a unicast introduction from C- 2788 MAPPER which is interpreted as an acknowledgment from the C- 2789 MAPPER. 2791 7- After the acknowledgment from the C-MAPPER is received, RP 2792 starts to sending periodical unicast introductions as keep 2793 alive every 60 seconds to C-MAPPER in response to C-MAPPER 2794 periodical unicast introductions. 2796 8- If any SC-RP exists, the C-RP will also send the address of SC- 2797 RP for further use by C-MAPPER. 2799 9- If any changes occur in the domain, like the registration or 2800 deletion of a multicast group source (G) the RP will only 2801 update its own tables since the A-BIT is set to 0. 2803 4.4.2.3.3.3. Redundant C-RPs 2805 Now that the processes and concepts related to each C-RP are 2806 explained it is time to bring redundancy to the network and make C- 2807 RPs redundant. 2809 Considering the design shown in Figure 28, we have 2 C-RPs in our 2810 network ,one belongs to GROUP-A and the other GROUP-B.and each one of 2811 the C-RPs are configured up to this point to act as a C-RP and 2812 introduce itself to the C-MAPPER. Also it should be noted that both 2813 C-RPs MUST be inside the same DOMAIN. 2815 In order to bring redundancy in to the network, each C-RP must be 2816 told to become peer with a C-RP in another group, so they will be 2817 able to exchange their entire AMMT. This way we will cover both needs 2818 of the network which are high availability (backup C-RP) and 2819 redundancy at the same time. But it MUST be noted that a C-RP cannot 2820 and MUST NOT become peer with a C-RP in another domain. 2822 The processes involved are as follows: 2824 1- Each C-RP must be told that it belongs to a GROUP, and also 2825 that it is peer with a C-RP from another Group. This is done by 2826 initiating a set of commands on each RP .consider the following 2827 set of commands are initiated on both C-RPs (Figure 28) : 2829 <#IP PIM-NG GROUP [A]> 2831 <#IP PIM-NG PEER RP GROUP [B]|PEER ADDRESS> 2833 2- After the above commands are initiated on C-RP-GROUP-A (C-RP-A 2834 for simplicity) it starts a series of processes. 2836 3- First of all it puts an entry for the new peer in a table 2837 called PEER-LIST. 2839 4- Sends out a multicast C-RP introduction message to all PIM-NG 2840 C-RPs with the destination address of 239.0.1.189. 2842 5- In the introduction message, C-RP-A sets the P-BIT to 1 which 2843 tells to existing C-RPS that the introduction message is meant 2844 for a C-RP that is looking for its peer. This is done duo to the 2845 fact that there might be SC-RPs in the network, and this bit 2846 will make them to ignore the packet. 2848 6- Sets the value of GROUP field to its own GROUP value. 2850 7- Alongside its unicast address and any existing SC-RP, C-RP will 2851 send keep-alive timer value to C-RP-B. it shows the keep-alive 2852 timer value that C-RP-B has to set for C-RP-A. 2854 8- One other table that is sent in this initial introduction 2855 message is the entire AMMT of C-RP-A. 2857 9- After receiving an introduction message from the other C-RP 2858 which in our case is C-RP-B, C-RP-A will update its PEER MAPPING 2859 table with information needed. And starts sending periodic 2860 unicast introduction messages as keep-alive messages to the 2861 unicast address of C-RP-B every 60 seconds. These periodic 2862 introductions do not contain the MMT. 2864 10- After the initial phase of finding C-RP-B is done, C-RP-A will 2865 send the entire AMMT table just in case there is a change in the 2866 domain. This change can be the registration of a new source with 2867 C-RP-A or deletion of a source from the MMT. In such a case C- 2868 RP-A will set the Z-BIT in its unicast introduction message. 2870 11- In a case, that C-RP-A receives an introduction from its peer 2871 with the Z-BIT set and containing the AMMT, it will only update 2872 its own AMMT and won't inform the C-MAPPER about the change if 2873 the A-BIT inside the received C-MAPPER introduction messages is 2874 set to 1. This is duo to this fact that the change had been 2875 informed to the C-MAPPER before by C-RP-B, and if C-RP-A is 2876 going to inform again it will be a double introduction process 2877 and will waste bandwidth and C-MAPPERs resources and is not a 2878 necessary task nor recommended. 2880 12- If C-RP-A doesn't receive an intro from the C-RP-B for 60 sec 2881 it will send a final unicast intro to the unicast address of C- 2882 RP-B to see if it is alive or not. If after this last unicast 2883 introduction C-RP-A doesn't receive any introductions from C-RP- 2884 B and there is any SC-RP-B, C-RP-A will immediately send a 2885 unicast introduction to the address of SC-RP-B. 2887 13- If no SC-RP-B is considered in the domain, then C-RP-A will 2888 start sending periodic multicast introduction messages to the 2889 address 239.0.1.189 to find its peer every 60 seconds. Until it 2890 hears again from the C-RP-B or other C-RPs it might have became 2891 peer with. 2893 The same set of actions will be done by the other C-RP (C-RP-B). 2895 Now that the related processes are explained let's take a look at the 2896 format of PEER-MAPPING table and PEER-LIST table which is created on 2897 both C-MAPPER'(s) and C-RP'(s) in Figure 30. 2899 PEER-MAPPING table 2901 +--------------------------------------------------------------------+ 2902 |PEER ADDR|Domain|GROUP|Mesh-Group|Priority|status|keep-alive|expiry | 2903 +--------------------------------------------------------------------+ 2904 | | | | | | | | | 2905 +--------------------------------------------------------------------+ 2906 | | | | | | | | | 2907 +--------------------------------------------------------------------+ 2908 Figure 30 PEER-MAPPING table and PEER-LIST table 2910 o Peer unicast address: unicast address of the peer which will be 2911 found later. 2912 o Status: gets a value of either A (active) or S (standby) and is 2913 used by C-MAPPERs in case more than one C-MAPPER exists. 2915 Multicast mapping table 2917 +-------------------------------------------------------------------+ 2918 |Source addr(S)|Dest group (G)|Source HOST| keep alive |expiry time | 2919 +-------------------------------------------------------------------+ 2920 | | | | | | 2921 +-------------------------------------------------------------------+ 2922 | | | | | | 2923 +-------------------------------------------------------------------+ 2924 A-Multicast mapping table 2926 +------------------------------------------------------------------+ 2927 |Source addr|Dest group (G)|Sorce Host|Originator|DOMAIN-set|status| 2928 +------------------------------------------------------------------+ 2929 | | | | | | | 2930 +------------------------------------------------------------------+ 2931 | | | | | | | 2932 +------------------------------------------------------------------+ 2933 o Status field: takes the values equal to suspend or active. If an 2934 entry inside the AMMT has the status of suspend, it means that it 2935 cannot be used until either it is removed or activated again but 2936 its usage is not meant for this process and will be discussed 2937 later. So if any entry inside this table has the status of suspend 2938 C-RPs won't give the source address to any clients that may be 2939 looking for the source address of a group (G) which matches that 2940 entry. 2942 o Domain-set: shows the domain in which a source is generated and 2943 registered. It is called domain-set due to the fact that when 2944 separate and different PIM-NG multicast domains are connected to 2945 each other, a C-MAPPER inside one domain will add its domain number 2946 to the domain value before sending the AMMT to a peer C-MAPPER in 2947 another domain. So at the end there will be a string of domain 2948 numbers like, 2-1-core2-core1-3-2, which will be used later. But a 2949 C-RP only adds its domain value for any sources that is registered 2950 with it or in a singly multicast domain design with one C-MAPPER 2951 and multiple PEER C-RP'(s), for any source that is received from a 2952 PEER-C-RP before sending it to another PEER-C-RP. This way the 2953 domain-set itself can be used to RPF check. 2955 Figure 31 AMMT compared with MMT 2957 +---------------------------------------+ 2958 | ORIGINATED MULTICAST GROUP 1 | 2959 +---------------------------------------+ 2960 | ORIGINATOR UNICAST ADDRESS | 2961 +---------------------------------------+ 2962 | MULTICAST GROUP(G) | 2963 +---------------------------------------+ 2964 | SOURCE UNICAST ADDRESS | 2965 +---------------------------------------+ 2966 | DOMAIN-SET | 2967 +---------------------------------------+ 2968 | . | 2969 +---------------------------------------+ 2970 | ORIGINATED MULTICAST GROUP N | 2971 +---------------------------------------+ 2972 | . | 2973 +---------------------------------------+ 2974 | DELETED MULTICAST GROUP 1 | 2975 +---------------------------------------+ 2976 | MULTICAST GROUP(G) | 2977 +---------------------------------------+ 2978 | SOURCE UNICAST ADDRESS | 2979 +---------------------------------------+ 2980 | . | 2981 +---------------------------------------+ 2982 | DELETED MULTICAST GROUP M | 2983 +---------------------------------------+ 2984 | . | 2985 +---------------------------------------+ 2986 | SUSPENDED MULTICAST GROUP 1 | 2987 +---------------------------------------+ 2988 | ORIGINATOR UNICAST ADDRESS | 2989 +---------------------------------------+ 2990 | MULTICAST GROUP(G) | 2991 +---------------------------------------+ 2992 | SOURCE UNICAST ADDRESS | 2993 +---------------------------------------+ 2994 | DOMAIN-SET | 2995 +---------------------------------------+ 2996 | . | 2997 +---------------------------------------+ 2998 | SUSPENDED MULTICAST GROUP N | 2999 +---------------------------------------+ 3000 | . | 3001 +---------------------------------------+ 3002 Figure 32 AMMT Format 3004 The above(Figure 32) is the real format of the A-MULTICAST MAPPING 3005 TABLE (AMMT) being exchanged between either peering C-RP'(s) or a C- 3006 RP and a C-MAPPER in case there are multiple PIM-NG domains or peer 3007 C-MAPPERs in the domain ,with the bellow definitions and 3008 specifications : 3010 o In a single multicast domain network design which only one C- 3011 MAPPER exists ,and multiple PEER-C-RPs are considered for 3012 redundancy , each C-RP MUST add its domain value to the domain- 3013 set of the received sources from a peer C-RP before sending them 3014 to another peer C-RP. The domain-set will be used by peer C-RPs 3015 to RPF check the received sources inside the domain. Consider 3016 the bellow network design including 3 C-RPs all part of 3017 multicast domain(1),in which a source registers with R1 and R1 3018 starts to advertise the new originated source to its peers R2 3019 and R3.R3 receives an update for (S,G) with the domain-set of D1 3020 from R1 and another update for (S,G) with domain-set [D1,D1] 3021 from R2.so at this point the received update from R2 fails the 3022 RPF check because of the longer domain-set string and R3 will 3023 only accept the received update from R1. 3025 [R2-D1] 3026 / \ 3027 / \ 3028 / \ 3029 {(S,G),D1} / \{(S,G),D1,D1} 3030 / \ 3031 / \ 3032 / \ 3033 [R1-D1]-------------[R3-D1] 3034 (S,G) {(S,G),D1} 3036 o Suspended multicast group: a C-RP MUST NOT put an entry for a 3037 suspended multicast group. This field MUST only be filled out by 3038 a C-MAPPER or PPER which loses connectivity with its PEER-C- 3039 MAPPER (PPER) from another domain. 3041 Now that the processes related to bringing redundancy to the domain 3042 by using redundant C-RPs in a single multicast domain network and 3043 also the C-RP related processes in such a network has been covered we 3044 are going to explain the reactions of a C-RP in a multiple domain 3045 network and the related concepts. 3047 4.4.2.3.3.4. PIM-NG Anycast RP 3049 Up to this point we have discussed the concepts related to redundant 3050 RPs of up to 2 C-RPs in a domain. In such a multicast domain it won't 3051 be a problem for the C-MAPPER to introduce all existing C-RPs one by 3052 one inside the PDTT. But if the network size becomes bigger with the 3053 need for many C-RPs to bring redundancy and high availability to the 3054 network ,the process of introducing all existing C-RPs in the domain 3055 by C-MAPPER to ALL-PIM-NG-ROUTERs including CLIENTS and any other C- 3056 MAPPERs will be a waste of network resources. 3058 So PIM-NG specifications suggest the use of ANYCAST-RP concept [11] 3059 with bellow specifications and rules: 3061 o Each C-RP MUST use 2 different unicast addresses. One will be 3062 used in the processes related to introducing to existing C- 3063 MAPPER'(s) and PEER-C-RPs. And one unicast address will be used 3064 as the ANYCAST address. So it is better to put it this way, each 3065 C-RP MUST use 2 interface loopbacks for its processes .one 3066 interface with the ANYCAST address and one with the address used 3067 for introductions. 3069 o Clients MUST communicate with the closest C-RP. 3071 o Existing C-MAPPERs MUST become aware of ANYCAST concept usage 3072 in the domain alongside the ANYCAST ADDRESS in use ,by 3073 initiating a command such as : 3075 <#IP PIM-NG ANYCAST ADDRESS [A.B.C.D]> 3077 On any existing C-MAPPER'(s). So that C-MAPPERs will use the 3078 configured ANYCAST address when introducing C-RPs to the domain 3079 which will only be one entry inside the PIM DOMAIN TOPOLOGY 3080 TABLE compared to up to 256 different C-RPs. 3082 o If only one C-MAPPER exists in the domain or the domain is not 3083 connected to other domains, C-RP'(s) won't need to introduce 3084 themselves to the C-MAPPER. But C-RP'(s) MUST become peer with 3085 each other in order to exchange the contents of AMMT with each 3086 other to bring redundancy. 3088 o If the A-BIT in the received C-MAPPER introduction message is 3089 set then each C-RP will have to introduce itself to the closest 3090 C-MAPPER and start exchanging AMMT individually with the closest 3091 C-MAPPER.and in such case it is advised not to peer C-RPs with 3092 each other. This is due to the fact that C-MAPPERs will inform 3093 C-RPs about any new sources that are registered with a C-RP. 3095 4.4.2.3.3.5. PIM-NG C-RP Mesh-Group 3097 Up to this point of explaining PIM-NG specifications we, have 3098 explained the process of bringing redundancy to a PIM-NG domain by 3099 peering C-RPs and in case the network is a large sized network ,the 3100 usage of ANYCAST RP concept with its specifications have been 3101 explained. 3103 In some multicast domain designs, the needs of the network may 3104 dictate the use of many C-RP'(s) in the domain to both bring 3105 redundancy and high availability. ANYCAST RP concept solves a problem 3106 regarding the introduction of C-RPs to the domain in a way that C- 3107 MAPPER'(s) will only need to introduce one unicast address as the 3108 address of the C-RP. But one problem remains unsolved which is 3109 related to the fact that with ANYCAST RP, each C-RP still has to 3110 introduce itself directly to the C-MAPPER and exchange the contents 3111 of A-MULTICAST MAPPPING TABLE. Now if the number of existing C-RPs 3112 goes high, the amount of data that is going to be transferred between 3113 large number of C-RPs and C-MAPPER will waste both network and C- 3114 MAPPER resources. 3116 To solve the above issue PIM-NG specifications introduces the concept 3117 of C-RP MESH-GROUP with bellow specifications: 3119 o A PIM-NG domain can contain up to 25 C-RP Mesh-Groups. With 3120 each group containing up to 10 C-RPs. 3122 o A Mesh-Group priority value between [0-255] MUST be defined 3123 on each C-RP that is going to be a member of a Mesh-Group. 3124 This priority is different from the priority that had been 3125 used at the time of choosing backup or SC-RP and defaults to 3126 100. The higher the better. 3128 o The C-RP with the highest priority in the Mesh-Group will 3129 become the active C-RP and better to say the speaker on 3130 behalf of the Mesh-Group.to do so an election MUST be held 3131 between members of the Mesh-Group : 3133 1. Each C-RP introduces itself to its peers by sending a 3134 multicast introduction to the destination address 3135 239.0.1.189, which contains its GROUP number, and the 3136 priority that will be used in the election process. 3138 2. Each C-RP receiving such introduction message will 3139 compare the priority in the received message with its 3140 own priority and puts an entry in its PEER-MAPPING- 3141 TABLE for that peer with the status of either active or 3142 standby. 3144 3. If the priority associated with a peer in a received 3145 introduction is lower than the priority set on the C- 3146 RP, then that peer will get the status of standby, and 3147 if the associated priority of a peer is higher, that 3148 peer gets an active status. 3150 4. At the end of this election process, each C-RP knows 3151 the active C-RP. 3153 o It is advised by PIM-NG specifications that a mechanism be 3154 implemented and used through configuration, that each member 3155 of a Mesh-Group becomes aware about the number of members 3156 within a Mesh-Group. 3158 o The active C-RP in a Mesh-Group is responsible for 3159 interacting with the closest C-MAPPER and exchanging the 3160 AMMT which contains any sources that registers with any 3161 members of the C-RP Mesh-Group. 3163 o If the current active C-RP dies and doesn't have any SC-RP, 3164 the next C-RP with the highest priority takes its place 3165 immediately. 3167 o Each member of the Mesh-Group MUST inform all the other 3168 members about any changes that occurs. So for instance, if 3169 we have 10 members in a Mesh-Group and C-RP1 receives 3170 information regarding a new source from C-RP2, it MUST NOT 3171 forward it to other members due to the fact that it has been 3172 informed to other members by C-RP2. 3174 o A C-RP can be a member of different Mesh-Groups, but such an 3175 implementation is not advised. 3177 o The above can be done by initiating command lines such as 3178 the bellow command lines on each C-RP : 3180 <#IP PIM-NG RP-MESH GROUP [1-25]> 3182 <#IP PIM-NG RP-MESH GROUP MEM-COUNT [1-10]> 3184 <#IP PIM-NG MESH-PEER GROUP [1-255]> 3186 <#IP PIM-NG MESH-PRIORITY [0-255]> 3187 PIM-NG specifications dictates that, such a command MUST 3188 indicate the use of C-RP Mesh-Group, total number of members 3189 in the Mesh-Group, Mesh-Group that a C-RP is a member of, 3190 Group number of all the members of Mesh-Group that the C-RP 3191 is supposed to become peer with and finally the priority of 3192 the Current C-RP in the Mesh-Group. 3194 4.4.2.3.3.6. Backup C-RP considerations 3196 In a single PIM-NG multicast network design with redundant C-RPs 3197 there seems that no SC-RP is needed to be considered .as each C-RP 3198 can be used as the backup for the other one. 3200 But in larger networks, the existence of backup RP seems necessary 3201 and of high importance due to the fact that the high availability of 3202 each C-RP becomes an important factor. 3204 If any SC-RP should be considered, the processes are as explained 3205 before with one additional table being exchanged between C-RP and SC- 3206 RP, which is the A-MULTICAST-MAPPIN-TABLE. 3208 4.5. C-MAPPER Redundancy in PIM-NG 3210 Peering C-MAPPERs will bring redundancy to existing C-MAPPERs .in 3211 large networks and special designs the redundancy between C-MAPPERs 3212 inside the same domain might become handy. 3214 The main use of peer C-MAPPERs is going to be felt when connecting 2 3215 or more separate PIM-NG domains, which will be discussed later. 3217 So for the sake of simplicity in explaining the processes involved we 3218 are going to explain the processes in a PIM-NG network with one 3219 multicast domain. See Figure 33. 3221 [Figure is presented in PDF version] 3223 Figure 33 network with single multicast domain and redundant C-MAPPERs 3225 As you see in Figure 33 we have a single domain and redundant 3226 MAPPERS. If you look at the picture each C-MAPPER is assigned to a 3227 unique GROUP. 3229 PIM-NG specifications dictate that each C-MAPPER can only communicate 3230 with MAPPERS inside the same GROUP and domain. In other words each 3231 MAPPER can hear the introduction of MAPPERs in other groups sent to 3232 239.0.1.188 but won't show any reaction to it and will only forward 3233 it, unless it is told that it can listen to the introduction of C- 3234 MAPPER's in other groups and use the information inside the 3235 introduction message. 3237 The process begins by telling each C-MAPPER that it is peer with a C- 3238 MAPPER from other groups. Consider the sample network illustrated in 3239 Figure 33. C-MAPPER-WEST(called west for simplicity) which is in 3240 domain 1 and is assigned to GROUP-A is told that it is peer with a C- 3241 MAPPER in domain 1 and GROUP-B which is in this case C-MAPPER- 3242 EAST(called east for simplicity).this must be done on both sides. As 3243 soon as west is told that it is peer with east a series of actions 3244 occurs: 3246 1- West puts an entry for east or simply GROUP-B in a special table 3247 called PEER-MAPPING.and also an entry in the Hold Time field of the 3248 introduction message which shows the keep-alive timer each peer 3249 should set for the C-MAPPER-west . 3251 +--------------------------------------------------------------------+ 3252 |PEER ADDR|Domain|GROUP|Mesh-Group|Priority|status|keep-alive|expiry | 3253 +--------------------------------------------------------------------+ 3254 | | | | | | | | | 3255 +--------------------------------------------------------------------+ 3256 | | | | | | | | | 3257 +--------------------------------------------------------------------+ 3258 Figure 34 PEER-MAPPING Table 3260 o Peer unicast address: unicast address of the peer which will be 3261 later found. 3262 o Status : gets a value of either A(active) or S(standby) 3264 2- West sends a multicast introduction to the destination address of 3265 239.0.1.188 which will be heard by all the MAPPERs .in this 3266 introduction message the west introduces its unicast address plus 3267 the Domain number assigned to it and the GROUP it represents and 3268 sends its AMMT along with the PEER-LIST table. This introduction 3269 messages will be read only by those C-MAPPERs that are supposed to 3270 become peers with the sender, and in this case east. 3272 3- When West becomes peer with a C-MAPPER it sets the A-BIT in its 3273 introduction messages sent to ALL-PIM-NG-CLIENTS and All-C-RPs, so 3274 that C-RPs start sending AMMT to C-MAPPERs. 3276 4- If the C-MAPPERs inside the domain are forming C-MAPPER MESH- 3277 GROUPS (4.5.2. ) then, in its introduction message sent to 3278 239.0.1.188 to find peers from the same domain, west will send its 3279 MESH-PRIORITY value. This priority value is going to be used in an 3280 election process between peer C-MAPPERs forming a MESH-GROUP inside 3281 the same domain which will be discussed later. 3283 5- If the C-MAPPERs are not forming a MESH-GROUP then no priority 3284 needs to be sent. 3286 6- West will keep sending the introduction every 30 seconds until it 3287 receives an acknowledge or simply put introduction from east ,which 3288 can be either a unciast introduction to west sent from east or a 3289 multicast introduction sent from east in order to find its peers. 3291 7- After the introduction from east is heard, and the Domain number 3292 and group numbers are checked and verified, west keeps sending 3293 periodical introduction messages every 60 seconds by default or 3294 every X second equal to the time set in the KEEP-ALIVE-TIMER inside 3295 PEER-LIST. 3297 8- If the Mesh-Priority value of EAST is lower than its own Mesh- 3298 Priority it means that , it is the ACTIVE-C-MAPPER and responsible 3299 of introducing east or any other STANDBY-C-MAPPER(STC-MAPPER) 3300 existing inside the domain to ALL-PIM-NG ROUTERs so that C-RPs will 3301 learn the address of STANBY-C-MAPPERs to use the closest C-MAPPER. 3303 9- Introduction messages will be sent by west under these conditions 3304 : 3306 o Triggered multicast introductions whenever west is told to become 3307 peer with a new C-MAPPER. 3309 o Periodical unicast introductions, which will act as keep-alive 3310 messages after finding the peer. In this type of introduction no 3311 AMMT will be exchanged. 3313 o Triggered unicast introduction to the address of east to inform a 3314 change in the network, like a new entry in the AMMT by setting a 3315 flag called ZONE-TOPOLOGY-CHANGE-NOTIFICATION (ZTCN) and sending 3316 the entire new AMMT. 3318 0 1 2 3 3319 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 3320 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 3321 |PIM Ver| Type | Reserved | Checksum | 3322 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 3323 | D O M A I N | 3324 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 3325 |R| |P| | |Z| | | 3326 |M|A|E| G R O U P |P R I O R I T Y|T| MESH-PRIORITY |RSRVD | 3327 | | |E| | |C| | | 3328 | | |R| | |N| | | 3329 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 3330 | HOLD TIME | RESERVED | 3331 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 3332 | C-MAPPER's unicast address | 3333 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 3334 | SC-MAPPER'S unicast Address | 3335 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 3336 | PIM DOMAIN TOPOLOGY TABLE | 3337 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 3338 | A-MULTICAST MAPPING TABLE | 3339 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 3340 | Core TOPOLOGY TABLE | 3341 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 3342 Figure 35 introduction message format sent to ALL PIM-NG MAPPERS 3343 239.0.1.188 3345 o Type: MAPPER introduction 3346 o Peer field: is set. This field will be check by other C-MAPPERs 3347 that are looking for a peer to differentiate between 3348 packets sent from normal MAPPERs and peer C-MAPPERs. 3349 o Group : C-MAPPER puts its own GROUP in this field 3350 o Domain: holds the domain number associated with the C-MAPPER 3351 o ZTCN: ZONE-TOPOLOGY-CHANGE-NOTIFICATION. Set if any changes 3352 occur. 3354 A-Multicast mapping table 3356 +------------------------------------------------------------------+ 3357 |Source addr|Dest group (G)|Sorce Host|Originator|DOMAIN-set|status| 3358 +------------------------------------------------------------------+ 3359 | | | | | | | 3360 +------------------------------------------------------------------+ 3361 | | | | | | | 3362 +------------------------------------------------------------------+ 3363 +---------------------------------------+ 3364 | ORIGINATED MULTICAST GROUP 1 | 3365 +---------------------------------------+ 3366 | ORIGINATOR UNICAST ADDRESS | 3367 +---------------------------------------+ 3368 | MULTICAST GROUP(G) | 3369 +---------------------------------------+ 3370 | SOURCE UNICAST ADDRESS | 3371 +---------------------------------------+ 3372 | DOMAIN-SET | 3373 +---------------------------------------+ 3374 | . | 3375 +---------------------------------------+ 3376 | ORIGINATED MULTICAST GROUP N | 3377 +---------------------------------------+ 3378 | . | 3379 +---------------------------------------+ 3380 | DELETED MULTICAST GROUP 1 | 3381 +---------------------------------------+ 3382 | MULTICAST GROUP(G) | 3383 +---------------------------------------+ 3384 | SOURCE UNICAST ADDRESS | 3385 +---------------------------------------+ 3386 | . | 3387 +---------------------------------------+ 3388 | DELETED MULTICAST GROUP M | 3389 +---------------------------------------+ 3390 | . | 3391 +---------------------------------------+ 3392 | SUSPENDED MULTICAST GROUP 1 | 3393 +---------------------------------------+ 3394 | ORIGINATOR UNICAST ADDRESS | 3395 +---------------------------------------+ 3396 | MULTICAST GROUP(G) | 3397 +---------------------------------------+ 3398 | SOURCE UNICAST ADDRESS | 3399 +---------------------------------------+ 3400 | DOMAIN-SET | 3401 +---------------------------------------+ 3402 | . | 3403 +---------------------------------------+ 3404 | SUSPENDED MULTICAST GROUP N | 3405 +---------------------------------------+ 3406 | . | 3407 +---------------------------------------+ 3408 Figure 36 A- Multicast MAPPING TABLE 3410 The above table (Figure 36) is the real format of A-MULTICAST MAPPING 3411 TABLE that is exchanged between peer C-MAPPERs with bellow 3412 definitions: 3414 o Originator unicast address: holds the address of the C-MAPPER 3415 that, a source is originated in its domain and it has received 3416 the information regarding the source from a connected C-RP. It 3417 is used by PEER-C-MAPPERs inside the same domain as a means for 3418 RPF check of a received update regarding a source that is inside 3419 their domain. Also the Originator address will be used when a 3420 PIM-NG domain is going to be connected to a PIM-SM domain to 3421 bring compatibility. 3422 o A C-MAPPER MUST change the contents of originator unicast 3423 address field with its own address, for sources that are 3424 originated inside its own domain and received from a downstream 3425 C-RP. 3426 o A C-MAPPER MUST NOT change the contents of originator unicast 3427 address field of sources that are received from a peer C-MAPPER 3428 or PPER. 3429 o Each C-MAPPER MUST add its domain number value to the domain- 3430 set of a received source when sending the AMMT to a peer C- 3431 MAPPER either inside the same domain or in another domain. This 3432 domain-set is used as a means of RPF check which will be 3433 discussed later. 3434 o If a C-MAPPER or PPER wants to send an update to a peer in 3435 another domain, it MUST first remove any additional domain 3436 values equal to its domain value from the string, and then add 3437 its domain value to the string and send it to other domains. The 3438 additional domain values are those added by C-MAPPERs inside the 3439 domain to be used for RPF check. 3440 o Suspended multicast group: holds the information regarding any 3441 multicast sources that MUST be treated as suspended .when a C-RP 3442 receives this information it will not answer to requests from 3443 clients for that source until the sources are again active or 3444 deleted. 3446 Now that west has done its part of the work, it is time to see what 3447 are the processes related to its peer C-MAPPER-EAST. 3449 As soon as east is told that it is peer with Group-A, it will do as 3450 described above .also it will wait to hear a multicast introduction 3451 destined for 239.0.1.188. When east receives such packets it will do 3452 the following: 3454 1- First of all it will check the PEER field to see if it is set. 3455 If this field is set, it means that it is sent from a C-MAPPER 3456 that is looking for a peer or wants to introduce itself to a 3457 peer. In our example east receives a packet destined for 3458 239.0.1.188 .checks the PEER field .and sees that it is set by 3459 sender. 3461 2- East checks the Domain field to see if it is sent from inside 3462 the domain or not. 3464 3- Then east will check the GROUP field to see if the packet 3465 belongs to a group it is looking for and wants to become peer 3466 with. In this case east will see A in the GROUP field. 3468 4- It checks its PEER-MAPPING table and sees an entry for GROUP-A 3469 .so it understands that the packet is sent from its peer. 3471 5- If the Mesh-Group concept is implemented, Then east checks the 3472 Mesh-Priority value to see if the sender has a higher value or 3473 not. And without the Mesh-Group concept EAST MUST start sending 3474 introductions to 239.0.1.190 introducing itself to PIM-NG 3475 population. And use the information regarding WEST to only 3476 exchange information regarding multicast sources. 3478 6- If the Mesh-Priority value is higher it means that it is going 3479 to be in standby mode and only connect with existing C-RPs 3480 through unicast introduction messages it will receive from C- 3481 RPs. And won't send multicast introductions to 239.0.1.190 as 3482 long as the ACTIVE C-MAPPER exists. 3484 7- East will then look in the SOURCE-UNICAST-ADDRESS field to find 3485 the address of the sender. And in our example east finds the 3486 address of west, and puts the west's unicast address in its 3487 PEER-MAPPING table alongside the associated status. 3489 8- Now it is time for east to check the PEER-LIST table inside the 3490 introduction message. It finds an entry for GROUP-A alongside 3491 the associated KEEP-ALIVE timer. East then puts the associated 3492 keep-alive timer in the right field in its PEER-MAPPING table. 3494 9- It will read the content of the AMMT sent from west and enters 3495 the new mappings in its own AMMT for further use. 3497 10- It will send a unicast introduction to the unicast address of 3498 west as an acknowledgement and also for west to learn east's 3499 address. 3501 11- If any C-RP introduces itself to east , then east will have to 3502 send the unicast address of C-RPs to west inside the PDTT so 3503 that west will be able to introduce the existing C-RPs to ALL- 3504 PIM-NG-CLIENTS by sending multicast introduction to 239.0.1.190. 3506 12- East will inform C-RPs connected to it, about any changes 3507 received inside the A-MULTICAST MAPPING table by sending unicast 3508 introductions containing the A-MULTICAST MAPPING table to C-RPs 3509 it knows. 3511 [Figure is presented in PDF version] 3513 Figure 37 sample illustration of the above process 3515 The above concepts are mostly related to a design in which C-MAPPER 3516 Mesh-Group concept is considered to reduce the amount of C-MAPPER 3517 introduction message sent to 239.0.1.190.so without the Mesh-Group 3518 concept: 3520 o each C-MAPPER starts sending introduction messages to 239.0.1.190 3521 individually and since the C-RP'(s), RC'(s) and clients residing 3522 in a PIM-NG multicast domain MUST communicate with the closest C- 3523 MAPPER, then peer C-MAPPERs(WEST,EAST) MUST ONLY exchange AMMT and 3524 do not need to exchange the information regarding C-RP'(s) or 3525 TR'(s). 3527 o In the case of peer C-MAPPERs without the Mesh-Group concept, if 3528 the needs of multicasting in a domain dictates that the 3529 information regarding existing C-RP'(s) or TR'(s) MUST be 3530 exchanged between the peer C-MAPPERs, PIM-NG specification 3531 strongly advices that this MUST be done through command initiation 3532 as an optional feature. 3534 o Duo to the fact that, in designs with more than one existing C- 3535 MAPPER, the amount of C-MAPPER introductions destined for 3536 239.0.1.190 will go high and will consume network resources; it is 3537 STRONGLY advised to use the Mesh-Group concept. 3539 4.5.1. SC-MAPPER considerations 3541 Actions taken by C-MAPPERs and SC-MAPPER are as follows: 3543 1- In the case of existing backup MAPPER'(s), C-MAPPER will send the 3544 learned unicast address of the peers in its PDTT along the new 3545 multicast groups it may learn in its introduction messages to the 3546 SC-MAPPER so in case that the C-MAPPER crashes and dies the SC- 3547 MAPPER will be able to immediately take its place and introduces 3548 itself on behalf of its GROUP to the peering C-MAPPER. C-MAPPER 3549 will inform the SC-MAPPER about any changes in the domain by 3550 sending AMMT. 3552 2- As explained in previous sections, if the SC-MAPPER doesn't 3553 receive a C-MAPPER introduction for 2*30 seconds it will 3554 immediately take its place and send a C-MAPPER introduction to the 3555 domain. And in this case as the SC-MAPPER is aware of the existence 3556 of PEER C-MAPPERs it will send unicast introductions to the unicast 3557 address of peers. 3559 3- If C-MAPPER-EAST (Figure 37) doesn't receive an introduction from 3560 its peer for 70 seconds (default timer+10sec) it will send an 3561 introduction to the address of SC-MAPPER-WEST .although if 3562 everything works accordingly by this time C-MAPPER-EAST must have 3563 received the introduction message of SC-MAPPER-WEST. 3565 4.5.2. C-MAPPER Mesh-Group 3567 In a single PIM-NG multicast domain with needs for redundant C- 3568 MAPPERs or PEER-C-MAPPERs ,a mechanism MUST be used to prevent each 3569 single one of existing C-MAPPERs from sending multicast introduction 3570 messages to the destination group 239.0.1.190 which will be heard by 3571 ALL-PIM-NG-CLIENTS and PIM-NG-C-RPs. this prevention mechanism MUST 3572 be implemented due to the fact that ,if each C-MAPPER is going to 3573 send the mentioned multicast introduction message , the multicast 3574 traffic created will consume lots of bandwidth and network resources. 3576 To do so PIM-NG specifications define the concept of C-MAPPER MESH- 3577 GROUP and ACTIVE-C-MAPPER and STANDBY-C-MAPPER (STC-MAPPER) in a way 3578 that: 3580 o Each Domain can have up to 25 C-MAPPER MESH-GROUPs, with each 3581 group ONLY including up to 10 C-MAPPERs. 3583 o Through an election between the existing C-MAPPERs, one C- 3584 MAPPER becomes the ACTIVE C-MAPPER and all the other C-MAPPERs 3585 become STANDBY C-MAPPERs. 3587 o The ACTIVE C-MAPPER is in charge of introducing other C-MAPPERs 3588 or STC-MAPPERs to ALL-PIM-NG-CLIENTS and C-RPs inside the domain 3589 it is resided in, in case ANYCAST RP is not considered, by means 3590 of sending multicast introduction messages to 239.0.1.190 and 3591 sending the unicast address and role of other C-MAPPERS inside 3592 the PIM domain topology table. So that C-RPs in different parts 3593 of the domain will find the closest C-MAPPER and introduce to 3594 that C-MAPPER, whether it is an ACTIVE or STANBY C-MAPPER. 3596 o STC-MAPPERs will maintain connectivity with the active C- 3597 MAPPER, which the related processes had been explained. 3599 o Each STC-MAPPER will send the information related to new C-RPs 3600 it finds to the ACTIVE-C-MAPPER by sending unicast introduction 3601 messages and sending the PIM domain topology table inside it 3602 which contains the information regarding the newly found C-RPs. 3604 o Active C-MAPPER then introduces the existing C-RPs and TR'(s) 3605 to ALL-PIM-NG-CLIENTS by sending multicast introduction messages 3606 to 239.0.1.190, which include PDTT. Through the above process 3607 each CLIENT will be able to contact the closest C-RP in case it 3608 has a source to register or it needs to find a source. 3610 o Each C-MAPPER in a MESH-GROUP (STC-MAPPER and ACTIVE-C-MAPPER) 3611 MUST inform other C-MAPPERs about any changes regarding the 3612 existing multicast sources in the domain by updating its AMMT 3613 with the information it receives from its connected C-RPs. This 3614 way if, for instance C-MAPPER1 receives an update from C- 3615 MAPPER2, it will not need to send it to C-MAPPER3 as it has been 3616 done by C-MAPPER2. 3618 o C-MAPPERs, both ACTIVE and PASSIVE, MUST then inform their 3619 connected or downstream C-RPs about any changes regarding the 3620 existing multicast sources by sending the AMMT. This way ALL- 3621 PIM-NG C-RPs in different parts of the network will have enough 3622 information about the domain to answer the requests of clients 3623 in need of finding a source. This process will eliminate the 3624 need for PEER C-RPs. 3626 o If the design of multicast domain, dictates to form more than 3627 one C-MAPPER Mesh-Group, PIM-NG specifications STRONGLY advises 3628 to place a boundary between different Mesh-Group areas by simply 3629 putting PER'(s) where ever needed. This will limit the 3630 propagation of C-MAPPER introduction messages sent by ACTIVE-C- 3631 MAPPER in each Mesh-Group area to other areas and will reduce 3632 the network resources consumption by unwanted multicast traffic. 3634 o If no boundary is considered between different areas, 3635 components of the PIM-NG domain such as C-RP, Client, and ETC, 3636 MUST react to the introduction message of the closest ACTIVE C- 3637 MAPPER according to the contents of the SOURCE UNICAST ADDRESS 3638 field of the introduction message and the information inside the 3639 unicast routing table. The only issue within the domain MUST BE 3640 ONLY the consumption of network resources by unnecessary 3641 multicast traffic related to multiple ACTIVE C-MAPPER 3642 introduction messages. 3644 o In the case of implementing more than one Mesh-Group, each area 3645 separated from other areas by PER'(s) will act normally, and 3646 existing components such as C-RP'(s), Clients and other 3647 components will respond to the introduction messages received 3648 from the active C-MAPPER in the area. 3650 o If a PIM-NG domain is consisted of more than one C-MAPPER Mesh- 3651 Group and separated in to different areas, PIM-NG specification 3652 STRONGLY advises to peer 2 C-MAPPERs from each Mesh-Group with 3653 each other using the static methods so that the information 3654 related to multicast sources in each area reaches other areas. 3655 Using the static method of connecting 2 different Mesh-Group 3656 will eliminate the need for the C-MAPPER introduction messages 3657 sent to 239.0.1.188 to find other C-MAPPERs, to be forwarded by 3658 PER'(s) between areas. 3660 o If a C-MAPPER in a Mesh-Group is becoming peer with a C-MAPPER 3661 in another Group, depending on the needs of multicasting in the 3662 domain, it may need to advertise the information regarding the 3663 existing C-RP'(s) and TR'(s) too, so in case anything happens to 3664 C-RP'(s) or TR'(s) in one area, the network stays stable and 3665 converges automatically. PIM-NG specifications advise to do this 3666 through command initiation on C-MAPPERs as an optional feature. 3668 4.5.2.1. Active C-MAPPER Election 3670 The election process starts as soon as a c-MAPPER inside a domain 3671 becomes aware that it is part of a MESH-GROUP and is peer with a C- 3672 MAPPER inside the same domain but with a different group. The related 3673 processes are explained bellow: 3675 1- As soon as each C-MAPPER becomes aware that it is peer with 3676 another C-MAPPER in a MESH-GROUP in the same domain but with a 3677 different group, it starts the process of sending multicast 3678 introduction messages to ALL-PIM-NG C-MAPPERs destination 3679 address of 239.0.1.188. 3681 2- Each C-MAPPER will set the PEER-BIT, so that incase there are 3682 any SC-MAPPERs inside the network, they won't read the contents 3683 of the message. 3685 3- Each C-MAPPER sends its domain number, group number, alongside 3686 the priority to be used in the process of election. 3688 4- As soon as each C-MAPPER receives an introduction from its peer 3689 C-MAPPER, it will compare the Mesh-Priority value inside the 3690 introduction message with its own Mesh-Priority value. 3692 5- If the received priority value is higher than its own priority 3693 value then, it will put an entry for the peering C-MAPPER inside 3694 its PEER-MAPPING table with the status of ACTIVE. And by this 3695 time the C-MAPPER understands that it is the STC-MAPPER and must 3696 act as one. 3698 6- If the received priority value is lower than its own priority 3699 value then an entry will be put in the PEER-MAPPING table with 3700 the status of STANDBY. And by this time the C-MAPPER knows that 3701 it is the active C-MAPPER and should act as an ACTIVE-C-MAPPER. 3703 7- In case there is more than 2 C-MAPPERs inside the domain, and 3704 thus each C-MAPPER is configured to become peer with more than 1 3705 C-MAPPER from its own domain, then each C-MAPPER must do the 3706 above processes until it finds all of its peers and comes to a 3707 conclusion that who is the ACTIVE-C-MAPPER inside MESH-GROUP in 3708 the domain. 3710 8- It is strongly advised by PIM-NG specification that a mechanism 3711 be implemented through configuration that informs each C-MAPPER 3712 about the total number of C-MAPPERs that are members of a Mesh- 3713 Group. 3715 9- By this time each C-MAPPER knows that which C-MAPPER is the 3716 active one .so without doing much more process, each C-MAPPER 3717 will silently accept its role and starts the related process. 3719 Through the above processes existing C-MAPPERs in a domain can decide 3720 who is the ACTIVE-C-MAPPER and the rest of them will be STC-MAPPERs. 3722 4.5.3. ANYCAST RP rules 3724 When ANYCAST RP is in use, and more than one C-MAPPER is implemented 3725 in the domain, a C-MAPPER MUST NOT send the information regarding any 3726 new C-RP it finds through the introduction processes, to its peers. 3727 This is due to the fact that from the CLIENTS point of view ALL-C-RPs 3728 has the same unicast address. 3730 Each C-MAPPER MUST maintains connectivity with each C-RP it finds. 3732 4.5.4. Configuration process of Redundant C-MAPPERs 3734 With explanations in previous sections the process is straight 3735 forward also refer to Figure 37 if needed: 3737 1- Each component residing inside a domain is supposed to have a 3738 domain number. So it is assumed that up to this point ALL-PIM-NG 3739 routers inside a domain has been configured with a command which 3740 indicates the domain a CLIENT , RP and MAPPER resides in : 3742 <#IP PIM-NG DOMAIN [X]> 3744 The concepts related to DOMAIN are explained in section 4.6.1.1. . 3746 2- Each C-MAPPER needs to be assigned a GROUP number : 3748 <#IP PIM-NG MAPPER GROUP [1-255]> 3750 The above commands tells the C-MAPPER that it belongs to a 3751 specific GROUP, which in our illustrated example will be 3752 GROUP-A(west) and GROUP-B(east).please keep in mind that the 3753 group value is a number between 1 to 255 3755 3- Each C-MAPPER needs to know its peer GROUP and if needed the 3756 address of the peer: 3758 <#IP PIM-NG PEER MAPPER DOMAIN[X] [GROUP [0-255]| [MAPPER address]]> 3760 Or in case of a mesh group 3762 <#IP PIM-NG MAPPER-MESH-GROUP [1-25]> 3764 <#IP PIM-NG MAPPER-MESH-GROUP MEM-COUNT [1-25]> 3766 <#IP PIM-NG MESH-PEER MAPPER DOMAIN[X] [GROUP [0-255]| [MAPPER 3767 address]]> 3769 <#IP PIM-NG MESH-PRIORITY [0-255(default 100]> 3771 THE above command lines dictates to the C-MAPPER that it must become 3772 peer with a C-MAPPER from DOMAIN X and GROUP[0-255] ,which in our 3773 example will be GROUP-B for west and GROUP-A from east. And also it 3774 should use the configured priority value to be used in ACTIVE-C- 3775 MAPPER election. 3777 Or in case of implementing the Mesh-Group concept dictates the Mesh- 3778 Group Number, total number of Mesh-Group members, group number of the 3779 peer or the unicast address of the peer C-MAPPER and finally the 3780 priority used in the Active C-MAPPER election. 3782 4- In case the unicast address of the peering C-MAPPER is used the 3783 router will send unicast introduction messages to its peer. 3784 Although not advised because of the dynamic nature of this process, 3785 and especially when there are backup peers in each group, but it is 3786 a way to do it. 3788 4.5.5. C-RP and Redundant C-MAPPERs 3790 In such network designs with redundant C-MAPPERs, Active C-MAPPER 3791 informs the C-RPs about the existing C-MAPPERs inside the domain by 3792 sending multicast introduction messages to ALL-PIM-NG-CLIENTS 3793 destination address 239.0.1.190. 3795 Also as described before as soon as a C-MAPPER becomes peer with 3796 another C-MAPPER it will set the A-BIT when sending introduction 3797 messages to either ALL-PIM-NG-CLIENTs (239.0.1.190) or unicast 3798 address of a C-RP. 3800 The above processes dictate to the existing C-RPs that they MUST: 3802 o Find the closest C-MAPPER based on the unicast address of the 3803 C-MAPPER and the information inside the unicast routing 3804 information base. 3806 o Introduce to the closest C-MAPPER. 3808 o If any changes occur inside the domain like, the registration 3809 of a new source or deletion of a new source, each C-RP must 3810 inform the C-MAPPER by sending the AMMT to the C-MAPPER. This 3811 way other C-RPs inside the domain will receive the information 3812 regarding a new source registration inside the network from 3813 their closest C-MAPPER which they had introduced themselves to 3814 it. 3816 o If a C-RP receives a request from a CLIENT for a source, C-RP 3817 MUST send the Domain-set associated with a source to the 3818 client, so that the client knows that where the source is 3819 generated and use the DOMAIN-SET later when sending a join 3820 request to the source. 3822 4.6. Multiple multicast domains 3824 Throughout the specifications of PIM-NG up to this point the concepts 3825 and processes that occur in a single PIM-NG multicast domain have 3826 been explained. 3828 But in large sized networks such as an enterprise network or the 3829 World Wide Web (WWW) itself, the need for using multiple multicast 3830 domains instead of a single multicast domain is needed to be 3831 considered. 3833 Examples of such cases can be: 3835 o Enterprise networks ,which the needs of the network dictates to 3836 divide the multicast domain in to 2 or more separate domains 3837 to have a better control over the propagation of the multicast 3838 traffic. 3840 o Enterprises or companies, with buildings and networks in 3841 different places. With each network or building connected by 3842 means of GRE-TUNNELs or MP-BGP to carry multicast traffic. 3844 o The internet as the biggest network of all, which is divided to 3845 different multicast domains, each connected to the other ones 3846 by different methods like MP-BGP as the carrier protocol of 3847 multicast traffic. 3849 connecting 2 or more PIM-NG multicast domains to exchange the 3850 information regarding the multicast sources originated in each 3851 domain, is done through making 2 or more C-MAPPERs from one domain 3852 peer with one or more C-MAPPER'(s) in the other domain. The C-MAPPERs 3853 then will start to exchange their AMMT'(s) with each other through 3854 sending unicast-encapsulated introduction messages to each other. And 3855 because of the bellow facts: 3857 o The propagation of multicast introduction messages of one 3858 domain in to other domains is not desired. 3860 o A PIM-NG domain may be 1 or more Autonomous Systems away. 3862 o There may be a transitory AS between 2 PIM-NG domains, which 3863 only provides the connectivity in terms of forwarding 3864 multicast traffic destined for group (G) or join/prune 3865 messages. Such a scenario can be seen in designs where 2 PIM- 3866 NG domains are either connected through an ISP or a PIM-SM 3867 network. 3869 o There might be one or more AS'(s) or networks between 2 PIM-NG 3870 domains, that must not receive the information regarding some 3871 of the sources that are being originated, or must not receive 3872 them at all. But their network infrastructure is needed to 3873 forward join/prune messages and multicast traffics. 3875 C-MAPPERs MUST NOT use the automated mechanisms described up to this 3876 point to become peers and MUST use the unicast address of their 3877 desired peers in other domains. 3879 Also PIM-NG uses a unique method to RPF check the received 3880 information regarding multicast sources which provides the existence 3881 of transitory Ass unlike the RPF check method used in PIM-SM and MSDP 3882 which has some limitations in this part. 3884 So PIM-NG specifications uses some rules, processes and definitions 3885 specific to PIM-NG to connect different PIM-NG domains or a network 3886 of PIM-NG domains with a network of PIM-SM domains, which are 3887 explained in the following sections. 3889 [Figure is presented in PDF version] 3891 Figure 38 network with 2 PIM-NG multicast domains 3893 4.6.1. Definitions and concepts 3895 In the following sections different features and rules that are used 3896 when connecting multiple PIM-NG multicast domains, and related 3897 definitions and concepts are explained. 3899 4.6.1.1. Domain 3901 PIM-NG introduces the concept of domain in a way that each domain is 3902 distinguished from the other domains by the domain number or value. 3903 Each domain has its separate set of CLIENTS, C-RPs, TRs and C- 3904 MAPPERs. 3906 PIM-NG uses a 32 bit domain field to support future needs of 3907 multicasting and classifies the range in to 4 groups which are 3908 explained bellow. But PIM-NG specifications suggest to different 3909 methods of domain number assignment which both of them classifies the 3910 range in to 4 groups: 3912 1- This method is unique to PIM-NG specifications and we STRONGLY 3913 advise the use of this method which will need the domain numbers 3914 to be either globally unique and assigned by IANA or locally 3915 unique and assigned by either the RIRs or an entity or enterprise 3916 with a unique PIM-NG-CORE-DOMAIN number: 3918 o Domain range [1-9900] as PIM-NG-DOMAIN. 3920 o Domain range [9901-9999] as PIM-NG-DOMAIN for private, 3921 experimental and documentation use. 3923 o DOMAIN range [10000-4294000000] as PIM-NG-Core-DOMAIN. 3925 o Domain range [4294000001-4294967293] as PIM-NG-Core-DOMAIN for 3926 private, experimental and documentation use. 3928 o Domain numbers 0 and 4294967294 are reserved. 3930 2- This method won't need any assignment by IANA or any RIR, since a 3931 domain number will be the same as the globally unique autonomous 3932 system number (AS number) assigned by IANA to be used as PIM-NG- 3933 CORE-DOMAIN numbers, and PIM-NG-DOMAIN numbers will be chosen from 3934 the private ranges. But this method is only introduced to make the 3935 domain number assignment easier and is not the advised method: 3937 o Domain range [1-64511] and [64536-4200000000] as PIM-NG-CORE- 3938 DOMAIN numbers which due to the fact the numbers are assigned 3939 by IANA as AS numbers, they are globally unique. 3941 o Domain range [64512-65512] as PIM-NG-DOMAIN numbers. This range 3942 needs to be locally unique from the RIR-CORE-DOMAIN point of 3943 view or the CORE-DOMAIN of an entity or enterprise. 3945 o DOMAIN range [65513-65535] as PIM-NG-DOMAIN numbers for 3946 private, experimental and documentation use. 3948 o Domain range [4200000001-4294967293] as PIM-NG-Core-DOMAIN for 3949 private, experimental and documentation use. 3951 o Domain numbers 0 and 4294967294 are reserved. 3953 Now that the domain number classifications are explained, we are 3954 going to explain the rules and specifications that apply to the above 3955 classifications. 3957 The bellow specifications and rules apply to ALL-PIM-NG domains: 3959 1- All clients inside a domain MUST have the same domain number. 3961 2- All C-RPs inside a domain MUST have the same domain number, as 3962 the clients. 3964 3- All C-MAPPERs inside a domain MUST have the same domain number 3965 as the CLIENTs. 3967 4- All TRs inside a domain MUST have the same domain number as the 3968 C-MAPPER. 3970 5- Clients MUST only respond to or accept HELLO messages from a 3971 neighbor with matching domain number. 3973 6- Clients MUST only accept and respond to C-MAPPER introduction 3974 messages sent to 239.0.1.190, which has a matching domain 3975 number. 3977 7- C-RPs MUST only accept and respond to C-MAPPER introduction 3978 messages sent to 239.0.1.190 or unicast C-MAPPER introduction 3979 messages with matching domain number. 3981 8- C-RPs can only become peer with C-RPs inside the same domain, 3982 so a C-RP MUST NOT accept or respond to the C-RP introduction 3983 message sent to 239.0.1.189 from other domains. 3985 9- C-MAPPERs can become peer with C-MAPPERs from the same domain 3986 or from other domains. 3988 10- C-MAPPERs MUST BE the only means to exchange the information 3989 regarding the existing sources in each domain by exchanging A- 3990 MULTICAST MAPPING TABLES. 3992 11- IF a DOMAIN is needed to be connected to another domain it MUST 3993 be connected through one or more PIM-EDGE-ROUTERs (PER/PPER) to 3994 prevent the propagation of unnecessary multicast introduction 3995 traffic in each domain. In case an enterprise needs to divide 3996 its multicast domain in to 2 or more sub-domains, it is strongly 3997 advised to use PERs to prevent the fellow of unnecessary 3998 multicast introduction traffic of one domain to other domains. 4000 12- C-MAPPER'(s) MUST introduce all existing C-RPs and TRs they 4001 find inside the domain to ALL-PIM-NG-ROUTERs inside the domain 4002 (230.0.1.190). 4004 13- C-MAPPERs MUST remove any private DOMAIN, private CORE-DOMAIN 4005 or sub-domain number before advertising any multicast source 4006 globally or to be more specific to a peer C-MAPPER in another 4007 domain. 4009 The bellow specifications and rules apply to PIM-NG-DOMAINs: 4011 1- PIM-NG-DOMAIN number values MUST be unique from the connected 4012 PIM-NG-CORE-DOMAIN point of view .so the values MUST be assigned 4013 by a local organization or Regional Internet Registry who has a 4014 globally unique PIM-NG-CORE-DOMAIN number, in case the 4015 enterprise doesn't have a PIM-NG-CORE-DOMAIN number which is 4016 globally unique. 4018 2- A PIM-NG-DOMAIN can be either a public network or a private 4019 network which is connected to the public network by using the 4020 NETWORK ADDRESS TRANSLATION. And by private PIM-NG specification 4021 means that all the components of the PIM-NG domain such as C- 4022 MAPPERs and even sources can use private unicast addresses. 4024 3- An enterprise can use any PIM-NG-DOMAIN number from the 4025 classified range freely as long as it doesn't need to advertise 4026 its multicast sources globally and by advertise from now on we 4027 mean sending any existing multicast sources to a peer C-MAPPER 4028 inside a PIM-NG-CORE-DOMAIN with a globally unique domain number 4029 by sending A-MULTICAST-MAPPING-TABLE inside the unicast- 4030 encapsulated C-MAPPER introduction message. 4032 4- If an enterprise needs to advertise its multicast sources 4033 globally but does not wish to or doesn't need to apply to get a 4034 globally unique PIM-NG-CORE-DOMAIN number , it MUST apply to get 4035 a unique PIM-NG-DOMAIN number from the Regional Internet 4036 Registry and advertise its multicast sources through the 4037 Regional Internet Registry's PIM-NG-CORE-DOMAIN. 4039 5- If an enterprise with more than one PIM-NG-DOMAINs all 4040 connected through an Internet Service Provider(ISP) backbone 4041 ,doesn't need to advertise its multicast sources globally and 4042 only needs to use them internally , it doesn't not need to 4043 become connected to the ISP by making one or more C-MAPPERs peer 4044 with a C-MAPPER inside the ISP backbone ,due to the fact that 4045 PIM-NG specifications uses its special unicast introduction 4046 method to make C-MAPPERs in different domains peer alongside its 4047 RPF check method unique to PIM-NG ,and doesn't use MSDP. 4049 6- If a multicast source inside a PIM-NG-DOMAIN needs to be 4050 globally accessible it MUST be first advertised to a peer C- 4051 MAPPER inside an existing PIM-NG-CORE-DOMAIN. 4053 7- If an enterprise needs to divide its multicast domain into 2 or 4054 more multicast domains, without the need of applying to get more 4055 than one locally unique PIM-NG-DOMAIN number from the Regional 4056 Internet Registry, it can do so by dividing its multicast domain 4057 into 2 or more domains as sub-domains of the main domain which 4058 is assigned by the Regional Internet Registry. The related 4059 concepts will be discussed later. 4061 8- A PIM-NG-DOMAIN can be connected to a PIM-NG-CORE-DOMAIN 4062 through another PIM-NG-DOMAIN or even an existing PIM-SM domain 4063 and does not need to be directly connected to send join/prune 4064 messages or receive traffic for a multicast destination group. 4065 But in order to advertise its multicast sources globally it MUST 4066 be connected to either the neighbor PIM-NG-DOMAIN which is 4067 connected to a core domain or directly to the PIM-NG-CORE-DOMAIN 4068 and by connected PIM-NG specifications dictates that at least 4069 ONE C-MAPPER inside the PIM-NG-DOMAIN MUST be a peer with either 4070 a C-MAPPER inside the neighbor domain or inside the core domain. 4072 9- Normal domains can have one or more Tree-Roots(TR).if TR exists 4073 in a domain the join/prune messages MUST first be forwarded 4074 towards the existing TR, and then towards the source. 4076 10- If the network is consisted of PIM-NG-CORE-DOMAINs (CD) and a 4077 client is in need of sending join/prune towards a source which 4078 can be reached through an existing PIM-NG-CORE-DOMAIN, and TR or 4079 TRs are considered in each PIM-NG-DOMAIN, each client MUST first 4080 send its join request for a source towards the TR residing 4081 inside its domain and then after the join/prune message reached 4082 the local TR it MUST be forwarded towards the TR inside the PIM- 4083 NG-CORE-DOMAIN . So all clients residing inside PIM-NG-DOMAIN 4084 MUST have knowledge about the existence of the CORE-DOMAIN TR or 4085 TRs. 4087 11- When a PER/PPER receives join/prune message on an external 4088 interface which is connected to either another domain or public 4089 networks, destined for a source inside its domain or a TR inside 4090 an existing PIM-NG-CORE-DOMAIN or a source in another domain it 4091 MUST forward it first toward the closest TR inside its own 4092 domain by setting the R-BIT inside the source address field of 4093 the received join/prune and putting the address of the closest 4094 TR in the appropriate field and then the TR will forward the 4095 traffic towards the source or existing TR inside the PIM-NG- 4096 CORE-DOMAIN if it is dictated inside the join/prune message. 4097 This process will eliminate unnecessary join message traffic 4098 towards a source in case many CLIENTS will need the same 4099 specific traffic. Or a new CLIENT may ask to receive the same 4100 traffic. 4102 12- A C-MAPPER MUST add its domain number to the domain-set of any 4103 received multicast sources received from PEER-C-MAPPERs in other 4104 domains before advertising them to other PEER-C-MAPPERs in other 4105 domains. 4107 13- A C-MAPPER inside a PIM-NG-DOMAIN MUST add its domain number 4108 to the domain-set of any received multicast sources from other 4109 domains when advertising to a PEER-C-MAPPER inside the same 4110 domain. These additional prepended domain values will be use by 4111 C-MAPPERs inside the domain for RPF check. 4113 14- A C-MAPPER inside a PIM-NG-DOMAIN MUST add its domain number 4114 to the domain-set of any received multicast sources from peer C- 4115 MAPPERs inside the domain to a PEER-C-MAPPER inside the same 4116 domain. These additional prepended domain values will be use by 4117 C-MAPPERs inside the domain for RPF check. 4119 15- If a C-MAPPER loses its connectivity with a PEER-C-MAPPER 4120 inside other domains whether a PIM-NG-DOMAIN or a PIM-NG-CORE- 4121 DOMAIN it MUST NOT immediately remove the multicast sources 4122 received from that PEER-C-MAPPER .instead in such a case the C- 4123 MAPPER MUST set a 5 minute timer by-default which is called the 4124 source-suspension timer and inform other PEER-C-MAPPERs about 4125 the incident by sending AMMT with the sources it has been 4126 receiving from that PEER being entered as suspended. This way 4127 the C-RPs inside other domain will see the suspend flag and will 4128 know that they MUST NOT answer to client requests sent for those 4129 sources until further notice ,which will be either activating 4130 the sources again or removing them. 4132 16- If a C-MAPPER loses its connectivity with a PEER-C-MAPPER 4133 inside the same domain, it MUST only set the suspend flag for 4134 the sources that the lost PEER was receiving from outside 4135 domains. This is due to the fact that when inside a domain a C- 4136 MAPPER is dead C-RPs will use other existing C-MAPPERs 4137 immediately. So there will be no need to set the suspend flag 4138 for the sources that are being generated inside the domain. 4140 17- C-MAPPERs MUST remove any private DOMAIN or sub-domain number 4141 before advertising any multicast source to peer C-MAPPERs inside 4142 the domain or globally to a peer C-MAPPER in another domain. 4144 18- C-MAPPER or PPER with peers in other domains MUST remove the 4145 additional prepended 4147 The bellow specifications and rules apply to PIM-NG-CORE-DOMAIN (CD): 4149 1- PIM-NG-CORE-DOMAINs number MUST be globally unique to be able 4150 to advertise any multicast source meant to be used globally by 4151 any user connected to the World Wide Web. 4153 2- PIM-NG-CORE-DOMAIN number assignment MUST be done by an 4154 international organization such as IANA. 4156 3- A PIM-NG-CORE-DOMAIN can be simply consisted of one or more C- 4157 MAPPERs and PERs in the core of an enterprise network to 4158 advertise the multicast sources received from peer C-MAPPERs in 4159 connected PIM-NG-DOMAINs of the enterprise. Or can be the 4160 internet backbone of a country connecting the countries network 4161 infrastructure to other countries internet backbone. 4163 4- A PIM-NG-CORE-DOMAIN can be the backbone of an Internet Service 4164 Provider (ISP) from its customer's point of view. in this case 4165 if a customer has 2 different networks connected through an ISP, 4166 if it needs to advertise its multicast sources globally it will 4167 need to do it through the ISP's PIM-NG-CORE-DOMAIN if it doesn't 4168 wish or doesn't need to receive a unique core domain number, by 4169 peering at least one C-MAPPER in one of its domains with a C- 4170 MAPPER inside ISP backbone. 4172 5- A PIM-NG-CORE-DOMAIN can be either a public network or a 4173 private network which is connected to the public network by 4174 using the NETWORK ADDRESS TRANSLATION. And by private PIM-NG 4175 specification means that all the components of the PIM-NG domain 4176 such as C-MAPPERs and even sources can use private unicast 4177 addresses. 4179 6- If an enterprise does not wish to advertise its multicast 4180 sources globally but needs to use one or more PIM-NG-CORE- 4181 DOMAIN'(s) it can freely use a domain value from the private 4182 range. But in case they need to advertise any multicast source 4183 globally to be used by users connected to other PIM-NG-CORE- 4184 DOMAINs, it MUST apply to get a unique domain number. 4186 7- If an enterprise is using private PIM-NG-CORE-DOMAIN numbers 4187 for its internal use and needs to advertise its multicast 4188 sources globally without getting a unique PIM-NG-CORE-DOMAIN 4189 number, it can do so by applying to get a locally unique PIM-NG- 4190 DOMAIN number to advertise its multicast sources through the 4191 Regional Internet Registry's PIM-NG-CORE-DOMAIN. In this case 4192 the private core domain number must be set to be a sub-domain of 4193 the assigned PIM-NG-DOMAIN number, which the related concepts 4194 will be discussed later. 4196 8- CORE-DOMAIN C-MAPPERs are responsible for connecting different 4197 CORE-DOMAINs to each other. 4199 9- A C-MAPPER MUST add its domain number to the domain-set of any 4200 received multicast sources received from PEER-C-MAPPERs in other 4201 domains before advertising them to other PEER-C-MAPPERs in other 4202 domains. 4204 10- A C-MAPPER inside a PIM-NG-CORE-DOMAIN MUST add its domain 4205 number to the domain-set of any received multicast sources from 4206 other domains when advertising to a PEER-C-MAPPER inside the 4207 same domain. These additional prepended domain values will be 4208 use by C-MAPPERs inside the domain for RPF check. 4210 11- A C-MAPPER inside a PIM-NG-CORE-DOMAIN MUST add its domain 4211 number to the domain-set of any received multicast sources from 4212 peer C-MAPPERs inside the domain to a PEER-C-MAPPER inside the 4213 same domain. These additional prepended domain values will be 4214 use by C-MAPPERs inside the domain for RPF check. 4216 12- C-MAPPERs MUST remove any private DOMAIN or sub-domain number 4217 before advertising any multicast source globally or to be more 4218 specific to a peer C-MAPPER in another CORE-DOMAIN. 4220 13- A C-MAPPER MUST remove additional domains in domain-set of a 4221 received multicast source from a PIM-NG-DOMAIN, except the first 4222 domain number in the domain-set which shows the domain in which 4223 a source is generated, when advertising a multicast source to a 4224 neighbor PIM-NG-CORE-DOMAIN. 4226 14- A C-MAPPER MUST NOT remove additional domains from the domain- 4227 set of a received multicast source when advertising to PEER-C- 4228 MAPPERs inside a PIM-NG-DOMAIN. 4230 15- If a C-MAPPER loses its connectivity with a PEER-C-MAPPER 4231 either inside the same domain or other domains whether a PIM-NG- 4232 DOMAIN or a PIM-NG-CORE-DOMAIN it MUST NOT immediately remove 4233 the multicast sources received from that PEER-C-MAPPER .instead 4234 in such a case the C-MAPPER MUST set a 5 minute timer by-default 4235 which is called the source-suspension timer and inform other 4236 PEER-C-MAPPERs about the incident by setting the SUSPEND flag 4237 inside the A-MULTICAST-MAPPING-TABLE for the sources it has been 4238 receiving from that PEER and send the table with the suspend 4239 flag to other peers. This way the C-RPs inside other domain will 4240 see the suspend flag and will know that they MUST NOT answer to 4241 client requests sent for those sources until further notice 4242 ,which will be either activating the sources again or removing 4243 them. 4245 16- If a C-MAPPER loses its connectivity with a PEER-C-MAPPER 4246 inside the same domain, it MUST only set the suspend flag for 4247 the sources that the lost PEER was receiving from outside 4248 domains. This is due to the fact that when inside a domain a C- 4249 MAPPER is dead C-RPs will use other existing C-MAPPERs 4250 immediately. So there will be no need to set the suspend flag 4251 for the sources that are being generated inside the domain. 4253 17- CORE-DOMAIN C-MAPPER'(s) MUST introduce any existing CORE- 4254 DOMAIN TR'(s) to normal domains for further use. 4256 18- CORE-DOMAINs MUST have one or more TR'(s). 4258 4.6.1.2. PIM-EDGE-ROUTER (PER/PPER) 4260 As described in the previous section each domain is distinguished 4261 from the other domains by a unique domain number. 4263 Each domain MUST be completely isolated from the other domains, and 4264 in case for example all domains are located under one roof inside one 4265 network infrastructure and using one united dynamic routing protocol 4266 it is strongly advised to use PERs to reduce the propagation of 4267 unnecessary multicast introduction message of C-MAPPERs or C-RP'(s) 4268 in search of their peers. 4270 An example of such network can be an enterprise network trying to 4271 divide its current network infrastructure in to 2 or more PIM-NG 4272 multicast domains or Sub-Domains. If these connected multicast 4273 domains are not isolated somehow we will see unnecessary multicast 4274 traffic inside each domain, which in the PIM-NG case will be the 4275 multicast traffics related to C-MAPPER introduction messages to ALL- 4276 PIM-CLIENTs(239.0.1.190) or C-RP introduction messages(239.0.1.189) 4277 sent out to find PEER-C-RPs which are intended to circulate inside 4278 one domain and since PIM-NG-ROUTERs inside other domains wont react 4279 to such messages from other domains it will be a waste of network 4280 resources. 4282 Another example could be the World Wide Web itself, in which each 4283 multicast domain is connected to other multicast domains by either 4284 using one or more edge routers connected to other multicast domains 4285 by using MP-BGP or a simple tunnel between each 2 multicast domain to 4286 give multicast traffic transfer ability. And such designs are due to 4287 the fact that in reality not all routers between each multicast 4288 domain support the needs of multicast traffic transfer. 4290 Because of the above facts PIM-NG introduces the concept of PIM-EDGE- 4291 ROUTER with 2 different classifications: 4293 1- PIM-EDGE-ROUTER(PER):a PER is simply a PIM-NG-AWARE router that 4294 acts as the boundary between either 2 PIM-NG domains, Sub-Domain 4295 or a domain and outside networks and will control the propagation 4296 of unnecessary or unwanted PIM-NG introduction messages. 4298 2- PRIVATE-PIM-EDGE-ROUTER (PPER): a PPER is a PIM-NG-AWARE router at 4299 the edge of the network which is responsible for NETWORK ADDRESS 4300 TRANSLATION (NAT) operations. PPER is responsible of becoming peer 4301 with other PPERs in other domains in order to exchange AMMT'(s) 4302 between different private PIM-NG domains. It is seen as a normal 4303 C-MAPPER by other domains, and is seen as PPER by internal C- 4304 MAPPERs in a way that an existing C-MAPPER inside the domain will 4305 only exchange the contents of AMMT with a PPER and won't introduce 4306 it to the domain. 4308 Below specifications and rules apply to PIM-EDGE-ROUTERs (PER): 4310 o A PIM-NG-AWARE router connecting 2 or more PIM-NG multicast 4311 domains to each other is considered a PIM-EDGE-ROUTER(PER) 4313 o A PIM-EDGE-ROUTER connecting a public PIM-NG domain to other 4314 PIM-NG multicast domains is called a PER. And by public PIM-NG 4315 specifications means that either every PIM-NG-AWARE router 4316 inside the domain is using public class IPs or at least C- 4317 MAPPERs or ALL-SOURCES inside the domain use public IP 4318 addresses. In the case of public PIM-NG multicast domain ,if the 4319 domain is connected to other domains by a protocol capable of 4320 transferring multicast traffic ,such as MP-BGP it is advise to 4321 put the PER at the edge of the network. If PERs in separate 4322 domains are connected by using a tunnel, they can be placed 4323 anywhere. 4325 o PERs can use an interface loopback as their unicast address 4326 when introducing to C-MAPPERs or any other interface connected 4327 to the DOMAIN. 4329 o Since all interfaces of a PIM-NG-AWARE ROUTER are considered 4330 internal interfaces by default, a PIM-NG PER MUST have one or 4331 more external interfaces connected to the outside networks or 4332 domain. so a PER can have one or more interface inside domain[X] 4333 and one or more inside domain[Y]. 4335 o A PER MUST NOT forward any multicast introduction messages 4336 received on an internal interface to its external interface. 4337 Unless it is dictated to the PER to forward a specific multicast 4338 introduction which MUST BE done based on the domain number 4339 indicated in the introduction message. 4341 o A PER can act as the boundary between to C-MAPPER Mesh-Group 4342 Areas inside a domain to prevent the propagation of ACTIVE C- 4343 MAPPER introductions from one area to the other area. In this 4344 case the PER MUST BE configured to have one or more interface in 4345 each area. These areas are ONLY meaningful to the PER, so that 4346 the PER will not forward multicast introductions from one area 4347 to the other one. 4349 o A PER which is acting as the boundary between Sub-Domains, MUST 4350 know the main domain number in which it is resided and also the 4351 Sub-Domain numbers to which it is connected. This is duo to the 4352 fact that in some designs the need for multicasting in PIM-NG 4353 will need the PER to forward the ACTIVE C-MAPPER introduction 4354 messages sent to 239.0.1.190 in the main domain by checking the 4355 domain number of the received introduction messages. The 4356 concepts related to Sub-Domain are explained in section 4.6.5. . 4358 o A PER acts as the boundary between 2 domains, Sub-Domains and 4359 areas, so it MUST NOT forward multicast introduction messages 4360 sent to 239.0.1.188, 239.0.1.189, 239.0.1.190 received from one 4361 domain, Sub-Domain and area to the other. ONLY in case of Sub- 4362 Domain and Area a PER acting as the boundary between the 2 can 4363 forward such traffic and ONLY if it is dictated to do so. 4365 o A PER can act as a BORDER-PIM-NG-ROUTER (BPR) when connecting a 4366 PIM-NG domain to a PIM-SM domain. In such designs PER MUST have 4367 one or more hands or interfaces in PIM-NG domain and one or more 4368 hands in PIM-SM domain. 4370 o A PER MUST introduce itself to the closest C-MAPPER only in 4371 case, it has the role of a BPR too, so that the C-MAPPER starts 4372 sending AMMT to the PER. PER will use the contents of AMMT in 4373 the process of forwarding join/prune messages received from the 4374 connected PIM-SM network to the PIM-NG network. 4376 o If in a network design such as a network containing PIM-NG SUB- 4377 DOMAINs ,it is needed that the PER forwards the multicast 4378 traffic destined for 239.0.1.188 and 239.0.1.190 in the main 4379 domain ,it MUST become aware of the situation to be able to 4380 forward that specific traffic. 4382 o In case TR exists in the domain, each PER MUST set the R-BIT of 4383 the Source Unicast Address which shows that the join/prune 4384 message MUST be forwarded towards the TR first and put the 4385 address of the closest TR in the appropriate field before 4386 forwarding it in the domain. 4388 The bellow specifications and rules apply to PRIVATE-PIM-EDGE- 4389 ROUTERS (PPER): 4391 o A PIM-EDGE-ROUTER connecting a private PIM-NG multicast domain 4392 to other domains ,whether private or public ,and typically is 4393 responsible for doing the NETWORK ADDRESS TRANSLATION will 4394 introduce itself as a PRIVATE-PIM-EDGE-ROUTER(PPER) to the C- 4395 MAPPERs inside the domain. It will be done by the EDGE-ROUTER at 4396 the time of introducing itself to the C-MAPPER, and by setting 4397 the PRIVATE (P)-BIT in the introduction message. And by private 4398 PIM-NG specifications means that all components of the domain 4399 such as C-MAPPERs and even sources use private IP addresses, or 4400 at least some of the sources inside the domain are using private 4401 addresses which need to be accessed from the outside. 4403 o In a network design in which all C-MAPPERs inside the domain 4404 are using private unicest addresses, PPER is responsible of 4405 becoming PEER with other PPERs or C-MAPPERs in other domains in 4406 order to provide the ability of exchanging the information 4407 regarding the existing multicast sources in different domains, 4408 through exchanging the AMMT between PPERs or C-MAPPERs in other 4409 domains and C-MAPPERs inside their own domain. So in such a 4410 design a PPER is seen as a PEER-C-MAPPER by PPERs or C-MAPPERs 4411 in other domains and MUST also be configured as a C-MAPPER. 4413 o A PPER is seen as only a PPER by C-MAPPERs inside the domain 4414 and the information related to it such as the unicast address, 4415 MUST NOT be advertised inside the domain in C-MAPPER 4416 introduction messages sent to 239.0.1.190. Such information is 4417 only usable by existing C-MAPPER'(s). And C-MAPPER uses the 4418 information regarding PPER to send the contents of AMMT to the 4419 PPER'(s). 4421 o In designs in which at least one C-MAPPER inside the domain is 4422 using publicly routable IP address, and is configured to 4423 directly become peer with C-MAPPER'(s) or PPER'(s) in other 4424 domains on behalf of the domain a PPER may not need to play the 4425 role of C-MAPPER too, and will only play the role of PPER and 4426 receive the A-MULTICAST MAPPING TABLE for further use. 4428 o In a network design in which all C-MAPPERs inside the domain 4429 are using private unicast addresses ,PPER is responsible of 4430 becoming MSDP-PEER with RP'(s) inside any neighboring PIM-SM 4431 domain , in case each domain needs to become aware of the 4432 sources that are being generated in the other domain. 4434 o A PPER can act as a BORDER-PIM-NG-ROUTER (BPR) when connecting 4435 a private PIM-NG domain to a PIM-SM domain. In such designs PER 4436 MUST have one or more hands or interfaces in PIM-NG domain and 4437 one or more hands in PIM-SM domain. 4439 o Each PPER MUST send unicast introduction messages to the 4440 unicast address of the closest C-MAPPER, Introducing itself so 4441 that the C-MAPPERs can start sending their A-MULTICAST MAPPING 4442 TABLEs. 4444 o To find the closest C-MAPPER, a PPER MUST listen to the 4445 introduction messages sent by the C-MAPPER in the domain or in 4446 case of existing C-MAPPER Mesh-Groups the introduction messages 4447 sent by the Active C-MAPPER. 4449 o In case of a multicast domain with more than one C-MAPPER Mesh- 4450 Group isolated and separated in to 2 or more Mesh-Group areas by 4451 setting up boundaries using PERs, it is STRONGLY advised to 4452 statically introduce at least one C-MAPPER from other Mesh- 4453 Groups to the PPER. This is a MUST due to the fact that the PPER 4454 will definitely hear the introduction message of the active C- 4455 MAPPER in area it is resided in, but it needs to also be aware 4456 of at least one C-MAPPER from the other Mesh-Groups. 4458 o Each PPER MUST inform the C-MAPPERs inside the domain about the 4459 received multicast sources from other domains by sending the 4460 AMMT to the closest C-MAPPER to which it has introduced itself 4461 to in the first place. 4463 o When a PPER receives information regarding multicast sources 4464 inside its own domain, since it is at the edge of a private 4465 network it MUST first save the information related to the 4466 unicast address of each source with private IP address in a 4467 table specific to PPER called INTERNAL-MULTICAST-SOURCE TABLE 4468 (IMST) and then it MUST change the unicast address of the 4469 sources with its public unicast address before sending the AMMT 4470 to PEER PPERs or MSDP-PEERs. The process of changing source 4471 unicast address of multicast groups MUST be done based on an 4472 existing ACL or route-map, due to the fact that some multicast 4473 groups may use public unicast addresses, and we don't want 4474 ending up changing those addresses too. So if a source unicast 4475 address needs to be changed it MUST be chosen by an ACL. 4477 o If a PPER receives a join/prune message on an external 4478 interface with its own unicast address as the source of the 4479 multicast group, it MUST check the contents of IMST and find the 4480 real unicast address of the source that is originating traffic 4481 for multicast group (G) and replace it with the address inside 4482 the join/prune message and forward it to the domain. 4484 o If a domain is connected to outside networks through more than 4485 one PPERs , and each PPER is acting as a C-MAPPER to become peer 4486 with PPER'(s) or C-MAPPER'(S) in other domains on behalf of C- 4487 MAPPERs inside its domain , a mechanism MUST BE used so that all 4488 the PPERs use one united publicly routable IP address as the 4489 originator address of the sources that are originated inside the 4490 domain, and also in case there are multicast sources using 4491 private IP addresses that must be advertised to other domains, 4492 as the source unicast address of such multicast sources. This is 4493 due to the fact that we don't want to end up advertising our 4494 multicast sources with different originator address or source 4495 unicast addresses to other domains. So we advise that on each 4496 PPER a united publically routable address be configured as the 4497 originator address if the PPERs also have the role of C-MAPPER. 4499 o In case TR exists in the domain, each PPER MUST set the R-BIT 4500 of the Source Unicast Address which shows that the join/prune 4501 message MUST be forwarded towards the TR first and put the 4502 address of the closest TR in the appropriate field before 4503 forwarding it in the domain. 4505 o EACH PPER MUST change the originator unicast address of the 4506 sources created inside its domain with its own public address. 4508 This address or the originator unicast address will be used in 4509 case a PIM-SM domain is needed to become connected to a network 4510 of PIM-NG domains in the process of RPF check. 4512 o PPER MUST maintain connectivity with C-MAPPER through its 4513 unicast introduction messages and in case it loses its 4514 connectivity with the C-MAPPER and if SC-MAPPER exists, it MUST 4515 immediately query the SC-MAPPER. This is duo the fact that a 4516 PPER is acting as the C-MAPPER and any existing SC-MAPPER from 4517 the peer C-MAPPER's point of view. PPER MUST send periodic 4518 introductions every 30 seconds. 4520 0 1 2 3 4521 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 4522 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 4523 |PIM Ver| Type | Reserved | Checksum | 4524 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 4525 | D O M A I N | 4526 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 4527 |P|Z|B| reserved | 4528 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 4529 | EDGE unicast address | 4530 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 4531 | A-MULTICAST MAPPING TABLE | 4532 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 4533 Figure 39 PER introduction message 4535 o TYPE :EDGE 4537 o Z-BIT: whenever a PPER needs to inform a change about its 4538 connected neighbor DOMAINs to C-MAPPER it will set this BIT 4539 and then send the information. 4541 o P-BIT: when set indicates to the receiving C-MAPPER that it 4542 is a PPER. 4544 o B-BIT: Border-PIM-NG-ROUTER BIT is set when a PER has the 4545 role of BPR. 4547 +---------------------------------------------------+ 4548 |source address | Destination Group| source host | 4549 +---------------------------------------------------+ 4550 | | | | 4551 +---------------------------------------------------+ 4552 | | | | 4553 +---------------------------------------------------+ 4554 Figure 40 Internal Multicast Source Table 4556 4.6.1.3. Tree Root (TR) 4558 Up to this point of explaining PIM-NG specifications, although the 4559 existence of a component named TR was mentioned, clients were to make 4560 direct contact with a source and send their join message directly to 4561 the desired source. The processes have been explained this way to 4562 give a good understanding of the underlying processes. 4564 They still can, but to support the needs of multicasting, PIM-NG 4565 introduces the concept of TREE-ROOT (TR). This concept has been 4566 introduced, duo to the fact that, there might be many clients in each 4567 domain in need of listening to a particular multicast traffic and if 4568 they were all to send their join messages directly to that source or 4569 the TR residing in the core domain, the final result will be the 4570 waste of bandwidth and the waste of source and CORE-DOMAIN-TR 4571 resources. 4573 The below specifications apply to TR: 4575 o Each normal domain can have one or more TR'(s) which it is 4576 strongly advised to be used. 4578 o Each core-domain MUST have one or more TR'(s). 4580 o ALL-PIM-NG-TR'(s) MUST introduce themselves to the closest C- 4581 MAPPER by sending uicast introduction messages ,so that the C- 4582 MAPPER learns the TR's unicast address and introduce it to the 4583 domain . 4585 o If any core-domain is considered, the C-MAPPERs inside the 4586 core-domain MUST introduce any existing TR inside the core- 4587 domain to all normal domains connected to it so that the entire 4588 PIM-NG multicast network will become aware of the existence of 4589 core-domain TR'(s). 4591 o If a TR is receiving multicast traffic (G), and other TR'(s) 4592 exist in the domain, it MUST make the other TR'(s) aware of the 4593 traffic it is receiving by sending an introduction message 4594 containing the JOINED-GROUP-TABLE, to the unicast address of the 4595 other TR'(s) it receives from C-MAPPER inside PDTT. This is done 4596 due to fact that other clients may become interested in 4597 receiving such traffic later, so if they send their join to 4598 another TR which is closer to them and not aware of the 4599 multicast traffic, it can be double act of sending joins out of 4600 a domain and a waste of resources. 4602 o When a TR receives a join/prune message with the R-BIT of 4603 Source Unicast address being set, which means that the message 4604 MUST reach the desired TR first, it MUST check the address of 4605 the TR and if the address is its own address it MUST clear the 4606 R-BIT, which means that the message has reached the desired TR 4607 in the domain and then forward it towards the desired source. 4609 o If in a PIM-NG multicast domain more than one TR exists, and a 4610 TR receives a join/prune message for (S, G), before clearing the 4611 R-BIT and forwarding the message to the next hop, it MUST first 4612 check its JOINED-GROUPS TABLE to see if other TR'(s) has joined 4613 the SPT for that (S, G). and if an entry is found in the JOINED- 4614 GROUP table received from other TR'(s), then if and ONLY IF the 4615 cost of reaching the TR which already joined the SPT for (S, 4616 G)based on the calculations done by the underlying unicast 4617 routing protocol is better than the cost to reach the source, it 4618 MUST leave the R-BIT and MUST NOT clear it and MUST put the 4619 address of the TR which has already joined the SPT for (S,G) in 4620 the appropriate field and forward the join/prune message to the 4621 next hop in the best path towards that TR. Otherwise in case the 4622 cost of reaching the source is better than the cost of reaching 4623 the next TR which is already joined the SPT for (s, G), it MUST 4624 clear the R-BIT and forward the join/prune message to the next 4625 hop in the best path towards the source. 4627 o If an RP has the role of TR, receiving a join/prune message of 4628 (*, G, RPT) with the RP address as the TR address means that the 4629 RP MUST NOT send back the (S) for (G) to the client and MUST 4630 find that source unicast address of (G) in either MMT or AMMT 4631 and put the address in the appropriate field and forward the 4632 packet towards the source. 4634 o If a TR is also a C-RP, then TR introduction messages MUST NOT 4635 BE sent and only a C-RP introduction message with the TR-BIT set 4636 WILL be enough. 4638 o Each TR MUST maintain connectivity with the C-MAPPER by sending 4639 periodic introductions every 30 seconds. 4641 o If more than 1 TR exists within a domain in order to reduce the 4642 size of PDTT in C-MAPPER introduction messages sent to 4643 239.0.1.190 it is advised to use the ANYCAST concept in the 4644 Domain. to use the ANYCAST concept each TR MUST be configured 4645 with both the ANYCAST address which is used by all clients and 4646 introduced by C-MAPPER in its instruction messages and an 4647 additional unicast address which will be used in TR to C-MAPPER 4648 and TR to TR communications. If the ANYCAST concept is used the 4649 ANYCAST address MUST be defined on the C-MAPPER or Active C- 4650 MAPPER to be used in PDTT by C-MAPPER when sending introductions 4651 t0 239.0.1.190. 4653 o If the ANYCAST concept is used the C-MAPPER MUST send the 4654 unicast address of all existing TR'(s) that it finds to existing 4655 TR'(s) within its unicast introduction messages sent to TR'(s) 4656 for further use by TR'(s). 4658 At the end it must be noted that the TR do not need to be a separate 4659 component, and each existing C-MAPPER or C-RP in the domain is the 4660 best choice to also play the role of an TR. But PIM-NG specifications 4661 STRONGLY advise the use of C-RP if it is a must. 4663 0 1 2 3 4664 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 4665 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 4666 |PIM Ver| Type | Reserved | Checksum | 4667 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 4668 | D O M A I N | 4669 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 4670 |Z| reserved | 4671 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 4672 | TR unicast address | 4673 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 4674 | JOINED GROUP TABLE | 4675 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 4676 Figure 41 TR introduction message 4678 o Type : TR 4680 o Z-BIT: if set indicates to the receiver that there has been a 4681 change in the joined-group-table. 4683 +---------------------------+ 4684 | JOINED-GROUP1 | 4685 +---------------------------+ 4686 | MULTICAST GROUP (G) | 4687 +---------------------------+ 4688 | SOURCE UNICAST ADDRESS | 4689 +---------------------------+ 4690 | . | 4691 +---------------------------+ 4692 | JOINED-GROUP N | 4693 +---------------------------+ 4694 | MULTICAST GROUP (G | 4695 +---------------------------+ 4696 | SOURCE UNICAST ADDRESS | 4697 +---------------------------+ 4698 . Source Unicast address Field holds the unicast address of either 4699 a TR or Client who is joined a tree for (G). it is set to all 0s 4700 if the TR itself is joined to the Tree for (G) 4702 Figure 42 Joined-Groups table used by both TR'(s) and Clients 4704 4.6.1.4. Domain-set and RPF check 4706 PIM-NG Domain-Set is similar to BGP AS-Path sequence in a way that 4707 each C-MAPPER MUST add its PIM-NG domain number to the domain-set of 4708 any multicast source before advertising it to a peer C-MAPPER .so at 4709 the end Domain-Set of a multicast source is a string of domains a 4710 multicast source has passed to reach its current domain or better to 4711 say to reach the C-MAPPER inside the current domain. From this 4712 perspective Domain-Set can be called Domain-Path sequence. 4714 Domain-set is what a PIM-NG C-MAPPER uses to RPF check a multicast 4715 source it receives from its peer in other domains. Unlike the RPF 4716 check method used in PIM-SM and MSDP which has some limitations like: 4718 o The network of multicast domains cannot have a transitory AS, 4719 due to the fact that for a Source Active message to pass the 4720 RPF check, the first AS in best path to the originator RP MUST 4721 BE equal to the MSDP peer. So if a customer's Autonomous 4722 System is connected to an ISP's Autonomous system, the RP 4723 inside the customer network must be MSDP peer with the RP 4724 inside the ISP network. 4726 o Filtering SA messages can be a hard task, because of the RPF 4727 check rule in a way that, you cannot have a transitory AS 4728 between to autonomous systems. such a case can be seen when 4729 administrators does not wish to update all of the SAs or some 4730 of the SAs created inside their PIM-SM domain to the neighbor 4731 Autonomous System , but they need to update them to a MSDP- 4732 PEER in an Autonomous System which is (i.e.)2 AS away. 4734 o . . . 4736 The RPF check method used in PIM-NG provides the ability of having 4737 transitory Autonomous Systems. Examples of such designs are: 4739 o Different PIM-NG domains are connected by an ISP's backbone and 4740 the ISP is only needed to provide UNICAST-REACHABILITY between 4741 different PIM-NG domains or different Autonomous Systems. 4743 o an enterprise does not wish to update all of its multicast 4744 sources to the neighbor Autonomous System or PIM-NG multicast 4745 domain , but it needs all of its multicast sources to be 4746 advertised to an AS which can be reached through this AS. 4747 consider the bellow illustration in which (i.e.) AS1 needs to 4748 advertise its multicast sources to AS3 and AS4 but doesn't 4749 want AS2 to become aware of those multicast sources or at 4750 least part of the multicast sources : 4752 AS1 (D1) ----AS2 (D2) ----AS3 (D3) ----AS4 (D4) 4754 MSDP specifications suggest that such work cannot be done and 4755 there will be a RPF check failure. But in PIM-NG such a work 4756 can be done. 4758 So if a source (S) is generating multicast traffic (G) in AS1 which 4759 is assigned a PIM-NG domain number of 1(D1) in the above 4760 illustration, the C-MAPPER inside D1 will advertise the (S,G) with 4761 the domain-set (1) to the peer C-MAPPER in D2 and likewise the C- 4762 MAPPER in D2 will advertise the (S,G) to its peer in D3 with domain- 4763 set of (1,2) and at the end the C-MAPPER inside D4 will receive the 4764 (S,G) with domain-set (1,2,3). 4766 The bellow rules apply to the DOMAIN-SET: 4768 o Each C-MAPPER or PPER MUST add its domain number to the domain- 4769 set of a multicast source before advertising it to its peers in 4770 other domains. 4772 o If inside a domain , more than one C-MAPPER is considered, each 4773 C-MAPPER MUST add its domain number to the domain-set of a 4774 multicast source before advertising it to its peers inside the 4775 domain, unless the C-MAPPER MESH-GROUP concept is in use. This 4776 process is more like prepending the domain number to the domain- 4777 set. 4779 o If A C-MAPPER(i.e. C-MAPPER-A) is a member of more than one 4780 Mesh-Group, or a member of a Mesh-Group and also is peer with a 4781 C-MAPPER which is a member of another Mesh-Group, which in this 4782 case C-MAPPER-A is acting as a connection or bridge between the 4783 2 Mesh-Groups, and it receives an update regarding a multicast 4784 source from a peer inside the same Mesh-Group, it MUST prepend 4785 its Domain number to the Domain-Set of the multicast source 4786 before advertising it to its peers in other Mesh-Groups. 4788 o A C-MAPPER or PPER MUST remove any prepended domain numbers 4789 from the domain-set of a source received from C-MAPPERs inside 4790 the domain , before advertising the multicast source to a peer 4791 C-MAPPER or PPER in other domains. 4793 o Since the PIM-NG-DOMAIN numbers are only significant from a 4794 connected PIM-NG-CORE-DOMAIN point of view, C-MAPPERs or PPERs 4795 in a CORE-DOMAIN MUST remove any PIM-NG-DOMAIN number, EXCEPT 4796 the domain number associated to the domain in which a multicast 4797 source resides, from the domain-set of a multicast source before 4798 advertising it to C-MAPPERs or PPERs in other PIM-NG-CORE- 4799 DOMAINs. 4801 o C-MAPPERs or PPERs in a CORE-DOMAIN MUST NOT remove any PIM-NG- 4802 DOMAIN number from the domain-set of a multicast source before 4803 advertising it C-MAPPERs or PPERs in other PIM-NG-DOMAINs which 4804 are connected to it and need to receive the updates regarding 4805 those multicast sources. 4807 PIM-NG RPF check method uses the bellow rules: 4809 o The (S, G) update received in the AMMT with the shorter domain 4810 sequence in Domain-Set passes the RPF check. 4812 (S,G,D1) 4813 (S,G)AS1(D1)---------AS2(D2)-----------AS4(D4) 4814 | / 4815 | / 4816 (S,G,D1)| /(S,G,D1,D3) 4817 | / 4818 | / 4819 AS3(D3) 4821 Figure 43 Inter-domain connectivity and RPF check 4823 As shown in Figure 43 a multicast source (s) in AS1 with PIM-NG 4824 domain number 1(D1) is generating multicast traffic destined to 4825 (G) and the C-MAPPER in the domain is advertising the (S, G) to 4826 its peers in D2 and D3. C-MAPPERs in D2 and D3 receive the 4827 update. C-MAPPER in D3 advertises the (S, G) to its peer in D2 4828 with the domain-set (D1, D3). C-MAPPER in D2 receives 2 updates 4829 for (S,G) with different domain-sets , one is (D1) and the 4830 other is (D1,D3) . So at this point the update received from D1 4831 passes the RPF check and the update received from R3 fails the 4832 RPF check. 4833 o If there is a tie in the domain-set of a multicast source 4834 received from peers in 2 different domains , the update 4835 received from the sender in the best path towards the 4836 originator according to the unicast routing information MUST 4837 pass the RPF check. In the above example if D3 is connected to 4838 D4 by making a C-MAPPER from each domain peer with the other 4839 one, then C-MAPPER in D4 will receive the update about (S, G) 4840 with equal domain sets of (D1, D2) and (D1, D3), which in this 4841 case the update received from the C-MAPPER in D2 which is in 4842 the best path towards the originator C-MAPPER in D1 passes the 4843 RPF check. 4844 o If inside a domain more than one C-MAPPER exists and the MESH- 4845 GROUP concept is not used, the above rules MUST be followed. 4847 (S,G,D1) 4848 (S,G)C-MAPPER1-D1--------------C-MAPPER2-D1 4849 \ / 4850 \ / 4851 (S,G,D1)\ /(S,G,D1,D1) 4852 \ / 4853 \ / 4854 C-MAPPER3-D1 4855 Figure 44 Intra-Domain connectivity and RPF check 4857 As illustrated in Figure 44, C-MAPPER1 is advertising an update 4858 about a newly originated source (S,G) with domain-set (D1) to 4859 its peers C-MAPPER2 and C-MAPPER3.C-MAPPERs 2 and 3 receive the 4860 update and start advertising the update to each other , so at 4861 this point and after the advertisement C-MAPPER2(i.e.) receives 4862 another update for (S,G) from C-MAPPER3 with domain-set (D1,D1) 4863 and since the domain sequence of the second received update 4864 from C-MAPPER3 is longer than the one received from C-MAPPER1 , 4865 it fails the RPF check. 4866 o The above rules are applicable in different situations 4867 regarding RPF check, and bring so much flexibility to work with 4868 multicast sources and the updates regarding those sources. 4869 o If a C-MAPPER inside a CORE-DOMAIN receives an update about a 4870 multicast source from a peer C-MAPPER in a CORE-DOMAIN and ALSO 4871 from a peer C-MAPPER in a PIM-NG-DOMAIN , the update received 4872 from the peer in CORE-DOMAIN MUST pass the RPF check without 4873 considering the DOMAIN-SET. 4875 4.6.2. Inter-domain connectivity concepts 4877 PIM-NG Inter-domain connectivity is mainly focused on the processes 4878 involved in exchanging the information regarding multicast sources 4879 being originated in different multicast domains, as for now like PIM- 4880 SM, PIM-NG uses the underlying unicast routing protocol information 4881 in order to send join/prune messages from a client in need of 4882 receiving a multicast traffic to the final destination which can be a 4883 server generating the multicast traffic. 4885 Although, PIM-NG specification processes and features are designed in 4886 a way that makes it possible to use a multicast routing protocol 4887 unique to PIM-NG in order to send join/prune messages from a receiver 4888 client to the originator of a multicast traffic, but since it is out 4889 of the scope of this document ,we are going to only explain the 4890 processes related to connecting 2 multicast domains and exchange the 4891 A-MULTICAST MAPPING TABLE'(s) between them ,which shall be enough to 4892 find a source and through using the underlying unicast routing 4893 protocols information reach the source. 4895 The related concepts are going to be explained in 2 different 4896 sections, which are Public Domain connectivity and Private Domain 4897 Connectivity. 4899 4.6.2.1. Public Domains 4901 A public domain is considered by PIM-NG specifications to be either a 4902 domain in which C-MAPPERs and sources use public IP addresses or a 4903 domain divided in to 2 domains or sub-domains in which the unicast 4904 address of C-MAPPERs and existing multicast sources are known to the 4905 population, and there is no need to use a PPER and domains are 4906 separated by PER'(s) which act as the domain boundary. 4908 Concepts are explained in 2 different sections called inter-domain 4909 concepts and intra-domain concepts. Inter-domain section is focused 4910 of connectivity of 2 different PIM-NG domains in terms of exchanging 4911 information regarding originated multicast sources in each domain and 4912 the process in which a CLIENT sends join/prune message to a source. 4913 And intra-domain section which is the following section is focused 4914 mainly on the communication between any existing TR with C-MAPPER and 4915 finally clients, which is actually the only feature of PIM-NG 4916 specifications that hasn't been described yet. 4918 4.6.2.1.1. Intra-domain concepts 4920 As said before, TR is responsible of sending join messages on behalf 4921 of CLIENTs inside the domain to a source inside the domain or other 4922 domains. 4924 If CORE-DOMAIN implementations are considered and CORE-DOMAINs do 4925 exist, and the domain-set of a multicast source indicates that the 4926 source of the multicast traffic can be reached by passing a PIM-NG- 4927 CORE-DOMAIN then the client creating the join/prune message MUST set 4928 the C-BIT of source unicast address and put the address of the CORE- 4929 DOMAIN-TR in the appropriate field and then send the message to the 4930 next hop. 4932 But first a PIM-NG-AWARE-ROUTER inside each domain must be chosen to 4933 act as the TR. and as mentioned before; each existing C-MAPPER can 4934 take the role of a TR to, which eliminates the need for a separate 4935 router to be used. 4937 Commands such as the commands bellow are initiated on the chosen 4938 router: 4940 <#IP PIM-NG TR> 4942 <#IP PIM-NG SOURCE INTERFACE LOOPBACK X> 4944 <#IP PIM-NG DOMAIN [X]> 4946 <#IP PIM-NG INTERFACE X,Y,Z> 4948 The above command lines will tell the router that it is the TR of 4949 PIM-NG domain X ,and it should use its interface loopback defined in 4950 the command as the unicast address it is going to introduce itself 4951 with it to the C-MAPPER. 4953 Although it may seem useful to have backup TR in the domain, we 4954 advise the use of a new TR instead of backup TR for bringing both 4955 redundancy and high availability at the same time to the domain. So 4956 no back-up TR is considered .the only case which there might be a 4957 back up TR implementation is when a C-RP has the role of TR and a SC- 4958 RP is considered. 4960 In case C-RP'(s) is going to have the role of TR too, and the concept 4961 of ANYCAST-RP is in use in the domain, the following rules MUST be 4962 obeyed: 4964 o Since ANYCAST-RP concept causes the clients to contact the 4965 closest RP unicast address according to their unicast routing 4966 tables, if C-RP is going to act as a TR, then ALL-C-RPs in a 4967 multicast domain MUST be configured to act as a TR too. 4969 o The active C-MAPPER MUST become aware of the situation which 4970 can be done by a command line initiated on ALL-C-MAPPERs. So the 4971 active C-MAPPER introduces only one TR unicast address which 4972 will be the ANYCAST address used for C-RPs. 4974 o Each TR in this particular design MUST use 2 different 4975 addresses. One for the ANYCAST address and one for introducing 4976 itself to the closest C-MAPPER. The addresses MUST be the 4977 addresses used for C-RP processes which had been explained 4978 before. 4980 o C-MAPPERs then MUST introduce ALL the other TRs to each TR they 4981 find, inside the PDTT sent with the unicast-encapsulated 4982 introduction messages they send to each TR. This MUST be done so 4983 that TRs can send their JOIN-GROUP TABLE to each other. 4985 After the TR is configured it will do the following processes: 4987 1- It waits to hear the introduction message of the C-MAPPER sent to 4988 239.0.1.190 to learn its unicast address. 4990 2- As soon as TR receives the C-MAPPER introduction it will update 4991 its internal PDTT with the address of C-MAPPER and other 4992 information included in the table. 4994 3- TR starts to send unicast introduction messages to the unicast 4995 address of C-MAPPER, which includes its unicast address. 4997 4- TR will send these introductions as keep-alive messages every 4998 30sec to the C-MAPPER. 5000 5- If it's joined to any multicast group (G), and by joining we mean 5001 receiving traffic for that group, it MUST put an entry for that 5002 group in its JOINED-GROUP-TABLE for further use. 5004 6- If in the introduction received from the C-MAPPER it receives 5005 the address of other TRs, it MUST send its JOINED-GROUP-TABLE to 5006 other TRs by sending unicast TR introduction messages to the 5007 address of those TRs. This MUST be done so that if a new client in 5008 another side of the domain sends a join for the same group to 5009 another TR, the TR will only send a join for that group to the TR 5010 which is already receiving the traffic for the group (G). 5012 7- The introduction messages between different existing TRs are only 5013 sent at the time, there is a change in the JOINED-GROUP-TABLE by 5014 setting the Z-BIT. This is due to the fact that TR'(s) communicate 5015 with C-MAPPER and this communication and periodical introductions 5016 acts as a keep-alive so there will be no need for the TRs to send 5017 periodical introductions as Keep-Alive to each other. 5019 After the C-MAPPER receives an introduction from the TR it will: 5021 1- Update its PIM domain topology table, and send an introduction 5022 message to ALL-PIM-NG-CLIENTS for further use. 5024 2- C-MAPPER maintains connectivity with the TR by sending unicast 5025 acknowledgement every 30 second back to the TR in response to TR 5026 introduction. 5028 3- If ANYCAST concept is needed to be implemented in a domain with 5029 more than one TR , then the C-MAPPER MUST know the address used as 5030 the ANYCAST address and only send that address to ALL-PIM-NG- 5031 CLIENTs. 5033 4.6.2.1.2. Inter-domain concepts 5035 In a Public PIM-NG Multicast domain a C-MAPPER can directly become 5036 peer with a C-MAPPER in another domain. And ALL Multicast Sources use 5037 public IP addresses. The processes regarding to peering the C-MAPPERs 5038 are much like the processes related to peering C-MAPPERs inside the 5039 same domain. The only difference between the concepts is: 5041 o A C-MAPPER MUST NOT send a multicast C-MAPPER introduction 5042 message to find its peer in another domain. Instead a C- 5043 MAPPER'(s) MUST send a unicast-encapsulated C-MAPPER 5044 introduction message to the unicast address of its peer in 5045 another domain. 5047 Figure 45 which illustrates a multicast network with 2 public PIM-NG 5048 multicast domains will be used for further explainations. 5050 [Figure is presented in PDF version] 5052 Figure 45 network with 2 multicast domains 5054 For the sake of simplicity in explaining the processes lets accept 5055 the fact that , there is unicast reachability between the 2 domains 5056 by using either a dynamic routing protocol capable of carrying 5057 multicast traffic like MBGP or a tunnel between the 2 domains. 5059 The processes to connect the 2 multicast domains are as follows: 5061 o In Each domain a C-MAPPER which uses a publically routable 5062 unicast address MUST be chosen, so makes it possible to directly 5063 make the C-MAPPERs peers. 5065 o C-MAPPER-WEST (WEST from now one) becomes peer with C-MAPPER- 5066 EAST (EAST from now one) using the unicast address of EAST to 5067 send the introduction message. the same is done on east: 5069 <#IP PIM-NG PEER MAPPER DOMAIN 2 ADDRESS EAST> 5071 And on east: 5073 <#IP PIM-NG PEER MAPPER DOMAIN 1 ADDRESS WEST> 5075 o WEST starts sending unicast-encapsulated introduction messages 5076 to EAST every 30 seconds until it receives the unicast- 5077 encapsulated introduction message of EAST. 5079 o After receiving the first introduction message, both C- 5080 MAPPER'(s) MUST send their introduction messages periodically 5081 every 60 seconds to maintain connectivity with each other as 5082 keep-alive messages. 5084 o If any SC-MAPPER is considered in a domain, its address MUST be 5085 introduced to the peer in the introduction message. 5087 o If WEST needs to inform its peer which is EAST about a change 5088 in the contents of AMMT, it MUST set the ZTCN-BIT in the 5089 introduction message and send the AMMT. 5091 o WEST MUST add its domain number to the domain-set of any newly 5092 originated multicast sources before sending an update about it 5093 to EAST. The same MUST be done by EAST. 5095 o Each C-MAPPER will then send the received update from the peer 5096 to the C-RPs residing in the domain 5098 Now bellow the processes related to communication between clients and 5099 sources are explained: 5101 o A host (H1) in domain1 (D1) wants to receive the multicast 5102 traffic destined for 228.9.9.9(i.e.) which is being generated in 5103 domain2 (D2). 5105 o H1 shows its desire to receive the traffic through IGMP 5106 messages it sends to the upstream router. 5108 o Client 2 becomes aware that a host inside the network behind it 5109 needs to receive the traffic destined for 228.9.9.9. 5111 o Client2 checks its PDTT to find the closest C-RP, and chooses 5112 C-RP-EAST(i.e.).since the RP and existing TR are not the same , 5113 H1 MUST send a unicast-encapsulated request for source message 5114 to C-RP. 5116 o Client2 sends a unicast-encapsulated PIM-NG request message to 5117 the C-RP. And receives a unicast acknowledge from the C-RP 5118 containing the unicast address of the source generating the 5119 multicast traffic in the format of (10.2.2.10, 228.9.9.9). 5121 o Client2 creates a join/prune message for (10.2.2.10,228.9.9.9) 5122 and since a TR exists in the domain and the domain-set of the 5123 source received from the C-RP doesn't contain any CORE-DOMAIN in 5124 the path , H1 sets the R-BIT of source unicast address and puts 5125 the address of the TR(10.1.1.20) in the appropriate field which 5126 shows that the join/prune message MUST first be sent towards the 5127 TR and sends the join/prune message towards the next hop or PIM- 5128 NG neighbor and joins the (S,G,RPT) rooted at TR which is 5129 considered to be the best path to reach the source. 5131 o TR receives the join/prune message and clears the R-BIT and its 5132 unicast address from the TR unicast address field, and forwards 5133 the message towards the next hop in the best path towards the 5134 source. 5136 o PER-EAST in domain2 (D2) receives a join/prune message on its 5137 external interface for multicast group 228.9.9.9 and must 5138 forward it to the next hop in the best path towards the source 5139 which is 10.2.2.10. 5141 o Since a TR exists in the domain PER-EAST MUST set the R-BIT 5142 again and put the address of TR(10.2.2.20) in the appropriate 5143 field and forward the join/prune message towards the source and 5144 actually join the (S,G,RPT) rooted at TR. 5146 o The join/prune message reaches the TR in D2, and TR again 5147 clears both the R-BIT and the TR unicast address field and 5148 forwards the message to the next hope. 5150 o Finally join/prune message for multicast destination 228.9.9.9 5151 arrives at 10.2.2.10 and source becomes aware that a client 5152 somewhere is in need of receiving the traffic and it MUST join 5153 the Shortest path tree which is actually the current (S,G,RPT) 5154 rooted at the TRs in each domain. So at the end 10.2.2.10 starts 5155 forwarding the traffic. 5157 Now a new host in D1 which is going to be H2 needs to receive the 5158 same traffic: 5160 o H2 shows its interest through IGMP to the upstream router which 5161 is client3. 5163 o Client3 goes through the same process as client2 to find the 5164 source unicast address of (G) and receives it from closest C- 5165 RP. 5167 o Client3 sends the join/prune message towards the TR. 5169 o TR receives a join/prune message for (S,G) which it already 5170 joined the shortest path tree for it , so without forwarding 5171 the join/prune message any further ,TR starts to forward the 5172 traffic for (10.2.2.10,228.9.9.9) down the new SPT towards 5173 client3. 5175 4.6.2.2. Private domains 5177 A private domain is considered by PIM-NG specifications to be a 5178 multicast domain in which all multicast sources or at least some of 5179 the multicast sources use private IP addresses. 5181 In such a domain: 5183 o If the C-MAPPERs inside the domain use private IP addresses, 5184 then one or more PPER'(s) MUST act as the C-MAPPER to become 5185 peer with C-MAPPERs in other domains on behalf of the C- 5186 MAPPERs inside the domain. And also a mechanism MUST be used 5187 so that PPER'(s) use a united public IP address as the 5188 originator of the multicast sources originated inside the 5189 domain and also as the source unicast address of the sources 5190 using private IP addresses. 5192 o If C-MAPPER'(s) inside the domain use public IP addresses, then 5193 there is no need for PPER'(s) to have the role of C-MAPPER 5194 too. Although, there might be some multicast designs in which 5195 it is needed for the PPER'(s) to act as C-MAPPER too. In such 5196 domains with a C-MAPPER using public IP address, a mechanism 5197 MUST be used so that the PPER'(s) become aware of the unicast 5198 address that is used by C-MAPPER'(s) as the source unicast 5199 address of the multicast sources using private IP addresses. 5201 In Figure 36 a network, including 2 private PIM-NG multicast domains 5202 is illustrated as an example. In this example that is going to be 5203 used to explain the processes involved, Domain1 (D1 for simplicity) 5204 is a PIM-NG domain in which ALL multicast sources and the C-MAPPER 5205 use private IP addresses and Domain2 (D2 for simplicity) is a PIM-NG 5206 domain in which the C-MAPPER uses public IP address and is 5207 responsible to directly become peer with a C-MAPPER in D1 and a group 5208 of multicast sources use Public IP Addresses and a group use Private 5209 IP Addresses. 5211 In D1 PPER-WEST with the unicast address 192.168.1.10 is going to act 5212 as the C-MAPPER and will become peer with C-MAPPER-EAST (EAST for 5213 simplicity) with the unicast address 192.168.2.10. And in D2 EAST 5214 will become peer with PPER-WEST. 5216 [Figure is presented in PDF version] 5218 Figure 46 Multicast network with private PIM-NG domains 5220 Different processes regarding the advertisement of multicast sources 5221 being generated in each domain to the other domain, and how the 5222 join/prune message is going to reach its final destination, are going 5223 to be explained in the following sections. 5225 4.6.2.2.1. Intra-Domain processes 5227 Since most of the processes and concepts regarding the connection 5228 between C-MAPPERs, clients, C-RP and TR in a PIM-NG domain have been 5229 explained up to this point ,processes referred to as Intra-domain 5230 processes will be related to the unexplained parts which are 5231 processes a C-MAPPER and the PPER'(s) are involved in within the 5232 Domain which in our example are D1 and D2 .Before starting to explain 5233 the processes a C-MAPPER and a PER or PPER are involved in ,we are 5234 going to take a look at an example of the steps related to make the 5235 PER ready and after that an example of how to make a PPER ready : 5237 Bellow the processes related to preparing a PER is explained: 5239 o A PIM-NG-AWARE router is chosen to act as the PER. 5241 o a set of commands are initiated on the router: 5243 <#IP PIM-NG EDGE> 5245 <#IP PIM-NG DOMAIN [X]> 5247 <#IP PIM-NG EDGE SOURCE INTERFACE [TYPE] [NUMBER]> 5249 <# IP PIM-NG INTERFACE [type] [number] INTERNAL> 5251 <#IP PIM-NG INTERFACE [TYPE] [NUMBER] EXTERNAL> 5253 Or in case the PER is connected directly to 2 domains 5255 <#IP PIM-NG DOMAIN [X] INTERFACE [TYPE] [NUMBER]> 5257 <#IP PIM-NG DOMAIN[Y] INTERFACE [TYPE] [NUMBER]> 5259 Or incase a PER is acting as a BPR: 5261 <#IP PIM-NG DOMAIN [X] INTERFACE [TYPE] [NUMBER]> 5263 <#IP PIM-SM INTERFACE [TYPE] [NUMBER]> 5265 o The above set of commands tells the router that it is a PER 5266 inside domain-X .and it MUST bring the interfaces mentioned in 5267 the command set in to the game of PIM-NG. 5269 o Interfaces marked as internal are going to be the ones 5270 connected to the internal domain and the one marked with 5271 external are going to be the ones connected to the outside 5272 networks. 5274 o In case PER is placed right between 2 domains or sub-domains it 5275 MUST have one or more interface inside one domain and one or 5276 more interfaces inside the other domain. 5278 o If a PER is placed between a PIM-NG domain and PIM-SM domain, 5279 It MUST have one or more interfaces inside PIM-NG domain and one 5280 or more interfaces in the PIM-SM domain. Such design may be seen 5281 in enterprise networks migrating from PIM-SM t PIM-NG over a 5282 period of time or in network designs where a PIM-SM domain is 5283 going to be connected to a network of PIM-NG domains or 2 or 5284 more PIM-NG domains are suppose to be connected through either 5285 an ISP's backbone which is still using PIM-SM or a transitory AS 5286 using PIM-SM and the PIM-SM domain'(s)are to be used to forward 5287 the join/prune messages. Such a PER is called a BPR, and the PER 5288 MUST introduce itself to the closest C-MAPPER with the B-BIT in 5289 the introduction message being set. BPR concepts will be 5290 discussed in the appropriate section. 5292 Bellow the processes related to preparing a PPER are explained: 5294 o A PIM-NG-AWARE router at the edge of the domain is chosen to 5295 play the role of PPER. PPER-WEST and PPER-EAST in Figure 46. 5297 o The router MUST be configured and become aware of its role 5298 inside the domain and in case it is going to act as the C- 5299 MAPPER to become peer with other PPERs or C-MAPPERs in other 5300 domains. As before we are going to go through the steps by 5301 initiating some commands on the router to make the process of 5302 explanation easier: 5304 <#IP PIM-NG EDGE-PRIVATE> 5306 <# PIM-NG DOMAIN [X]> 5308 <# PIM-NG INTERFACE [TYPE] [NUMBER] INTERNAL> 5310 <# PIM-NG INTERFACE [TYPE] [NUMBER] EXTERNAL> 5312 <# PIM-NG EDGE SOURCE INTERFACE [TYPE] [NUMBER]> 5314 The above commands tells the router that it is PPER in a PIM- 5315 NG domain[X](D1/D2) .also the above commands dictates to the 5316 router that it has some internal interfaces which are 5317 connected to the inside network and some external interfaces 5318 which are connected to the outside world . 5320 One other thing that the router must become aware of is the 5321 address it must use when introducing itself as the PPER to the 5322 C-MAPPERs inside the domain which in our example is going to 5323 be 10.1.1.50 for PPER-WEST and 10.2.2.50 for PPER-EAST. This 5324 address MUST be an address known to the domain in which the 5325 PPER resides. And it is advised to use a loopback interface as 5326 the source. 5328 o If the PPER is supposed to act as a C-MAPPER too (PPER-WEST in 5329 Figure 46), it MUST become aware of the new role and also MUST 5330 know the address of its peers. one other thing that MUST be 5331 configured is the address that must be used as the C-MAPPER 5332 address which MUST be a public IP address : 5334 <#IP PIM-NG MAPPER> 5336 <# PIM-NG MAPPER SOURCE {INTERFACE [TYPE] [NUMBER]}|ADDR> 5338 <# PIM-NG PEER MAPPER DOMAIN[Y] PEER-ADDRESS [A.B.C.D]> 5340 Or if the peer PPER is a connected PIM-NG-AWARE router 5342 <# PIM-NG PEER MAPPER DOMAIN[Y] INTERFACE [TYPE] [NUMBER]> 5344 o The address that is going to be used in the process of finding 5345 and communicating with a peer PPER or C-MAPPER, will be used as 5346 the Originator Unicast Address and source unicast address of the 5347 multicast sources that are originated inside the domain the PPER 5348 resides and use a private IP address. In Figure 44 the address 5349 used for PPER-WEST is 192.168.1.10 in D1 and the address used 5350 for the C-MAPPER-EAST in D2 is 192.168.2.10. 5352 o If the domain is connected to other domains by more than one 5353 PPER a mechanism MUST be used so that if PPERs has the role of 5354 C-MAPPER they all use one united public IP address as the 5355 Originator and source unicast address of the sources that are 5356 originated inside the domain and use private addresses. This is 5357 due to the fact that we don't want to end up advertising our 5358 sources with different source unicast addresses or originator 5359 addresses ,so PIM-NG specification suggests to configure on all 5360 PPERs an IP address from the public IP address range that is 5361 assigned to the AS or network. This can be done by a command 5362 like: 5364 <#PIM-NG ORIGINATOR-ADDRESS [A.B.C.D]> 5366 o if a C-MAPPER inside the domain with public IP address is used 5367 to become peer with C-MAPPERs or PPERs in other domains and the 5368 PPERs doesn't have the role of C-MAPPER they MUST become aware 5369 of the IP address that the C-MAPPER is using as the originator 5370 and source unicast address of the multicast sources that are 5371 generated inside the domain and use private IP addresses. This 5372 MUST be done due to the fact that a PPER may receive a 5373 join/prune message for a multicast source inside the domain 5374 which its unicast address is the address of the C-MAPPER and 5375 will be routed towards the C-MAPPER and that MUST NOT be done. 5376 So we suggest dictating to PPERs that if they receive a 5377 join/prune message on an external interface with the address of 5378 the C-MAPPER as the source unicast address, it IS NOT meant to 5379 be forwarded towards the C-MAPPER and the address MUST be 5380 changed with the real address of the multicast source. this can 5381 be done by a command like the one mentioned above or: 5383 <#IP PIM-NG SOURCE-ADDRESS [A.B.C.D]> 5385 In Figure 46 this address is going to be 192.168.2.10 which is 5386 the address of C-MAPPER-EAST and MUST be set on PPER-EAST. 5388 Processes related to PER will be discussed later when a PIM-NG domain 5389 needs to be connected to a PIM-SM domain. So in this section only 5390 PPER related processes are going to be explained. 5392 o As soon as PPER is configured and becomes aware of its role in 5393 the domain, it MUST communicate with the closest C-MAPPER 5394 according to the information received in the C-MAPPER 5395 introduction message and incase there are more than one C-MAPPER 5396 in domain based on the information it finds inside the PDTT, by 5397 sending an EDGE introduction message. PPER MUST set the P-BIT in 5398 EDGE introduction message which indicates to the C-MAPPER that 5399 it is sent from a PPER. PPER MUST send its unicast address 5400 inside the message so that C-MAPPER'(s) can use it to 5401 communicate with the PPER. So both PPERs in figure 44 start 5402 introducing themselves to the C-MAPPERs inside the domain. 5404 o Each PPER MUST send the introduction messages every 30 seconds 5405 to the C-MAPPER which acts as the keep-alive message. 5407 o Both C-MAPPERs in D1 and D2 MUST start sending A-MMT'(s) to the 5408 PPERs of their domain. The received information will be used by 5409 PPERs differently, due to the fact that PPER-WEST is also a C- 5410 MAPPER and PPER-EAST is only PPER. 5412 o Both PPERs MUST save the information regarding multicast 5413 sources that are originated inside their domain in IMST for 5414 further use. 5416 o PPER-WEST which has the role of a C-MAPPER too MUST send any 5417 received information regarding the multicast sources being 5418 generated in D1 which it receives from C-MAPPER-WEST to C- 5419 MAPPER-EAST by setting the Z-BIT in the introduction message and 5420 sending the updates inside the A-MMT. If only some of multicast 5421 sources MUST be advertised, it can be done through filtering 5422 process. 5424 o Since ALL multicast sources inside D1 are using private IP 5425 addresses, those multicast sources that are needed to be 5426 advertised to D2 MUST be chosen through an ACL, so that at the 5427 time of updating to C-MAPPER-EAST, PPER-WEST changes the 5428 originator address and source unicast address of those sources 5429 with its own public unicast address which is 192.168.1.10 in 5430 Figure 46. 5432 This can be done by choosing the multicast source addresses 5433 needed to be advertised in an ACL and initiating a command line 5434 (i.e.) on PPER-WEST: 5436 <#IP PIM-NG ACL X ORIGINATOR-ADDRESS [SELF| (A.B.C.D)]> 5438 Which dictates to the PPER that it MUST change the originator 5439 address and source unicast address of multicast sources chosen 5440 by the ACL X(i.e.) with its own public IP address or incase 5441 there are more than one PPER with the address indicated by the 5442 command. 5444 o Since C-MAPPER-WEST is not peer with any C-MAPPER in other 5445 domains it MUST maintain connectivity with PPER'(s) of its 5446 domain in order to receive information regarding multicast 5447 sources in other domains and advertise multicast sources in its 5448 domain to other domains. 5450 o In D2, C-MAPPER-EAST is directly involved in the process of 5451 becoming peer with a C-MAPPER in another domain which is PPER- 5452 EAST, so it MUST only send the information regarding multicast 5453 sources being originated inside its domain to PPER-EAST, UNLESS 5454 it becomes aware that PPER-EAST is also BPR and connected to a 5455 PIM-SM domain, which in this case it MUST send the full A- 5456 MULTICAST MAPPING TABLE which may include multicast sources 5457 being originated in other domains. 5459 o Since C-MAPPER-EAST is going to advertise multicast sources 5460 originated inside the domain (D2) to its peer in D1, it MUST 5461 change the source unicast address of multicast sources 5462 originated inside D2 with private IP addresses, with its own 5463 public IP address which is 192.168.2.10 in Figure 44. It MUST be 5464 done based on an ACL or route-map like what had been done on 5465 PPER-WEST , since there are multicast sources in D2 with public 5466 source unicast address that their address must not be changed. 5468 o Since PPER-EAST is only acting as PPER it MUST become aware 5469 about the address the C-MAPPER is using as source unicast 5470 address when advertising multicast sources with private IP 5471 addresses to other domains, so that when it receives a 5472 join/prune message on its external interface with that source 5473 unicast address, it can act properly. This can be done by 5474 initiating a command line(i.e.) on PPER-EAST like: 5476 <#IP PIM-NG SOURCE-ADDRESS [A.B.C.D]> 5478 Instead of A.B.C.D, the public IP address being used by C-MAPPER 5479 in such process MUST BE used, which in our example is 5480 192.168.2.10. 5482 4.6.2.2.2. Inter-domain concepts 5484 Inter-domain connectivity concepts are mostly focused on the process 5485 of exchanging information regarding multicast sources between the 2 5486 domains and the process through which a CLIENT will send join/prune 5487 message for a multicast group inside another domain which is using a 5488 private IP address inside the destination domain. 5490 First the processes regarding the exchange of A-MULTICAST MAPPING 5491 TABLES between the 2 domains of Figure 46 will be explained and then 5492 to explain the process of sending the join/prune message and 5493 receiving multicast traffic, an example in which hosts in D1 are in 5494 need to receive multicast traffic which is generated in D2 will be 5495 explained. 5497 1- Exchanging AMMT between the 2 domains : 5499 o Since PPER-WEST has the role of C-MAPPER, it will become peer 5500 with C-MAPPER-EAST on behalf of the C-MAPPER-WEST. And C- 5501 MAPPER-EAST will become peer with PPER-WEST which is seen by 5502 C-MAPPER-EAST as C-MAPPER-WEST or the C-MAPPER residing in 5503 D1. 5505 o Both PPER-WEST and C-MAPPER-EAST MUST use the public unicast 5506 address of the other one to send unicast-encapsulated 5507 introduction messages to both introduce themselves to each 5508 other and exchange the contents of their A-MULTICAST MAPPING 5509 TABLEs which holds the information regarding multicast 5510 sources being originated in either of the domains. So PPER- 5511 WEST MUST use the unicast address 192.168.2.10 (Figure 46) 5512 which is the address of C-MAPPER-EAST, as its peer address. 5513 And C-MAPPER-EAST MUST use unicast address 192.168.1.10 5514 (Figure 46) as its peer address. 5516 o As explained before both PPER-WEST and C-MAPPER-EAST MUST do 5517 some modifications on the information regarding multicast 5518 sources generated inside their domains with private IP 5519 addresses before advertising them to the other domain. So 5520 considering Figure 46 , C-MAPPER-EAST MUST change the source 5521 unicast address of the source generating traffic for 5522 228.9.9.9 which is a private IP address with its own public 5523 address which is 192.168.2.10 , and send it to PPER-WEST. 5525 o The rest of the process of becoming peer C-MAPPERs is as 5526 before, in terms of sending unicast-encapsulated introduction 5527 message to the peer and maintaining connectivity with the 5528 peer by sending introduction messages every 60 seconds as 5529 Keep-Alive messages. 5531 o If any changes occur inside (i.e.) D1 regarding the multicast 5532 sources, PPER-WEST MUST first set the ZTCN-BIT and inform the 5533 change by sending its AMMT to C-MAPPER-EAST. 5535 o Also both PPER-WEST and C-MAPPER-EAST MUST add their domain 5536 number to the domain-set of any multicast source they are 5537 going to advertise to the other one. 5539 2- Sending join/prune message for a multicast group inside a private 5540 PIM-NG domain: 5542 o Considering Figure 46 as our example network, H1 and H2 in 5543 D1 need to receive multicast traffic destined for 228.9.9.9 5544 and 228.6.6.6 which are being originated in D2. 5546 o So H1 starts the process by sending an IGMP message to the 5547 upstream router. And the request will reach CLIENT2. 5549 o So CLIENT2 starts the process of finding the unicast address 5550 of the source generating traffic destined for 228.9.9.9 by 5551 sending a unicast-encapsulated request to the closest C-RP. 5553 o As the source generating the traffic destined for 228.9.9.9 5554 is using Private IP address within D2, C-MAPPER-EAST had 5555 changed the unicast address of the source with its own 5556 public IP address at the time of advertising to PPER-WEST. 5557 So C-RP will answer to the CLIENT2's request by sending 5558 back the unicast address of the source in the format of (S, 5559 G, domain-set) or (192.168.2.10, 228.9.9.9, 2). 5561 o Client 2 receives the C-RP acknowledge and sends a (S, G, 5562 RPT) join/prune message rooted at the TR to the next hop in 5563 the best path towards the TR. 5565 o TR receives the join/prune message. Clears both the R-BIT 5566 and its address from TR unicast address field and forwards 5567 the message to the next hop in the best path toward the 5568 source of multicast group 228.9.9.9 in D2. 5570 o PPER-EAST receives a join/prune message on its external 5571 interface with the SOURCE UNICAST ADDRESS of 192.168.2.10, 5572 and since PPER-EAST is told that this is the source address 5573 that is used for sources generating multicast traffic 5574 inside its domain (D2) which are using private IP addresses 5575 and not the real address of the source, it knows that some 5576 modifications MUST be done to the message before forwarding 5577 it to the next hop in the best path towards the existing TR 5578 in D2. 5580 o PPER-EAST MUST check the contents of IMST to find the real 5581 unicast address of the source generating traffic destined 5582 to 228.9.9.9, which is 10.2.2.10. 5584 o After finding the real unicast address of the source, PPER- 5585 EAST modifies the join/prune message by changing the source 5586 unicast address inside the message which is 192.168.2.10 5587 with the real address which is 10.2.2.10. 5589 o Since a TR exists inside the domain PPER-EAST MUST set the 5590 R-BIT of source unicast address and put the address of TR 5591 in the appropriate field and forwards the message to the 5592 next hop in the best path towards the TR. 5594 o TR receives the join/prune message and joins the (S, G, RPT) 5595 tree and after clearing both R-BIT and TR unicast address, 5596 forwards the message to the next hop in the best path 5597 towards 10.2.2.10. 5599 o 10.2.2.10 receives the join/prune message and joins the (S, 5600 G, RPT) tree and starts forwarding the traffic destined for 5601 228.9.9.9 down the tree towards the receiver which is 5602 client2 in D1. 5604 o Now H2 behind client3 in D1 shows interest in receiving 5605 multicast traffic destined for 228.6.6.6. 5607 o Client3 goes through the same process to receive the unicast 5608 address of the source generating traffic for 228.6.6.6. And 5609 after receiving the unicast address which is 192.168.2.50 5610 in the format of (S, G, Domain-set) or (192.168.2.50, 5611 228.6.6.6, 2), goes through the same process as client2 to 5612 send the join/prune message. 5614 o The join/prune message reaches PPER-EAST. Since the source 5615 unicast address is not changed, PPER-EAST MUST forward the 5616 packet to the next hop in the best path towards the 5617 existing TR, without any modifications. 5619 o TR receives the join/prune message and after clearing both 5620 R-BIT and TR unicast address field sends the message to the 5621 next hop in the best path towards 192.168.2.50. 5623 o 192.168.2.50 receives the join/prune message, and joins the 5624 (S, G, RPT) tree and starts forwarding the multicast 5625 traffic destined for 228.6.6.6 down the (S, G, RPT) tree 5626 which is considered to be the SPT towards the receiver in 5627 D1 which is client3. 5629 The above processes are involved in connecting 2 PIM-NG domains in 5630 order to both advertise multicast sources from one private domain to 5631 another and sending join/prune messages from one private domain to 5632 another domain. The related processes were explained through an 5633 example to both simplify the explanation process and understanding 5634 the need for PPER existence in PIM-NG specifications. 5636 In the next sections the concepts regarding PIM-NG-CORE-DOMAIN 5637 through an example will be explained, and after that 2 new concepts 5638 called PIM-NG SUB-DOMAIN and PIM-NG STUB-DOMAIN will be explained and 5639 defined. 5641 4.6.3. Core-Domain implementation 5643 Up to this point of PIM-NG specifications process explanation, almost 5644 all of the related concepts have been explained. Bellow we are going 5645 to list them to review what has been explained: 5647 o Interaction between a source and C-RP and how a source 5648 registers. 5650 o Interaction between a Client and a C-RP to find a source for a 5651 multicast group (G). 5653 o Interaction between a Client and a source. 5655 o The processes by which the PIM-NG population find the C-RP'(s) 5656 in a multicast domain. And the interaction between C-RP and C- 5657 MAPPER. 5659 o Interaction between TR and C-MAPPER. 5661 o C-MAPPER and C-RP interaction to exchange the information 5662 regarding registered multicast sources in a domain. 5664 o Interaction between C-MAPPERs inside the same domain and 5665 different PIM-NG domains, regarding the exchange of information 5666 related to existing multicast source in each domain. 5668 o Processes involved in connecting multiple PIM-NG multicast 5669 domains. 5671 o . . . 5673 One thing that has remained unexplained is related to a multicast 5674 network design in which PIM-NG-CORE-Domain with TR is considered. 5676 As explained earlier: 5678 o ONLY when a PIM-NG-DOMAIN is connected to the outside network 5679 through a PIM-NG-CORE-DOMAIN 5681 o And ONLY when it is receiving the information regarding 5682 existing multicast sources in other domains through the Core- 5683 Domain, and Core-Domain is consisted of TR'(s). 5685 a client MUST send, its join/prune message for a multicast source 5686 that can be reached through the Core-Domain cloud, first towards the 5687 TR inside to Core-Domain to join the (S,G,RPT) rooted at both any 5688 existing TR inside client's domain and then the TR inside the Core- 5689 Domain. 5691 The above mechanism will eliminate future join/prune messages for the 5692 same multicast source which might be sent from Clients in other 5693 domains. 5695 So with the above being said, a series of processes will be involved 5696 which are as follows: 5698 o A C-MAPPER'(s) inside a Core-Domain MUST introduce at least one 5699 TR to its peer C-MAPPER in connected PIM-NG-DOMAINs. 5701 o If a CORE-DOMAIN is consisted of more than one TR,PIM-NG 5702 specifications suggests the use of ANYCAST concept, so that the 5703 C-MAPPER'(s) inside the CORE-DOMAIN will only send one unified 5704 TR unicast address to peers in connected PIM-NG-DOMAINs, which 5705 reduces the amount of data being sent in C-MAPPER introduction 5706 message. 5708 o PIM-NG specifications suggests that the unicast address of the 5709 desired TR'(s) to be introduced to peers in PIM-NG-DOMAINs be 5710 dictated to C-MAPPER'(s). This process is actually a MUST as 5711 there might be TRs inside the CORE-DOMAIN cloud that are using 5712 private addresses or must not be introduced to connected PIM-NG- 5713 DOMAINs. 5715 o C-MAPPER'(s) inside the CORE-DOMAIN MUST introduce existing 5716 TR'(s) to peers in PIM-NG-DOMAINs, by sending the unicast 5717 address of the TR'(s) inside the CORE TOPOLOGY TABLE (CTT), 5718 which only contains the information regarding existing TR'(s) in 5719 the CORE-DOMAIN. 5721 o If a PIM-NG-DOMAIN is connected to a PIM-NG-CORE-DOMAIN through 5722 another PIM-NG-DOMAIN, the CTT MUST reach that domain too. For 5723 instance, if D1 is connected to D2 and D2 is connected to CORE- 5724 DOMAIN D10001, then C-MAPPER inside D2 MUST pass the received 5725 CTT to peer C-MAPPER in D1. This process is a MUST if D1 is 5726 receiving information regarding multicast sources in other 5727 domains through D2 and needs to reach outside sources. 5729 o A client in a PIM-NG-DOMAIN in need to receive a multicast 5730 traffic , that the associated DOMAIN-SET shows it can be reached 5731 through a CORE-DOMAIN , MUST use the information regarding the 5732 existing TR'(s) in CORE-DOMAIN at the time of creating 5733 join/prune message . This MUST be done by setting the C-BIT of 5734 source unicast address and putting the address of the CORE- 5735 DOMAIN-TR in the appropriate field, so that it will reach the TR 5736 inside the CORE-DOMAIN. The logic behind this process will be 5737 explained through an example multicast network. 5739 o After the join/prune message reaches the desired CORE-DOMAIN- 5740 TR, the TR'(s) MUST clear both the C-BIT and information inside 5741 the CORE DOMAIN Tree Root ADDRESS field and then forward the 5742 message to the next hop in the best path towards the source. 5744 Bellow the above processes and the logic behind the above behavior of 5745 PIM-NG specifications at the presence of CORE-DOMAIN-TR will be 5746 explained through an example. 5748 [Figure is presented in PDF version] 5750 Figure 47 core domain implementation 5752 In the multicast network design illustrated Figure 47 as an example 5753 we have 2 CORE-DOMAINs with domain numbers 10001 and 10002.D10001 is 5754 connected to D1, D2 and D3 and also connected to D10002, while D10002 5755 is connected to D1. 5757 A multicast source starts generating multicast traffic destined for 5758 (G) in D1 behind 10002 and the information regarding the source is 5759 passed from C-MAPPER in D1 to C-MAPPER in D10002 as (S, G) with 5760 domain-set (D1). (S, G) is advertised to D10001 by C-MAPPER in D10002 5761 as (S, G) with domain-set (D1, 10002). And finally the information 5762 regarding the multicast source reaches D1, D2 and D3 behind D10001 as 5763 (S, G) with domain-set (D1, 10002, 10001). 5765 As it is illustrated in Figure 47, D3 behind D10001 has direct 5766 unicast connectivity to D1 behind D10002 through a tunnel which is 5767 capable of carrying multicast traffic. 5769 As an example, a client/host in D3 shows interest in receiving 5770 multicast traffic destined for (G) and after receiving the unicast 5771 address of the source generating that traffic, it is going to create 5772 a join/prune message and send it towards the next hop in the best 5773 path towards the source. It is assumed in this example that the best 5774 path is the tunnel interface between D3 and D1. So if the join/prune 5775 message is going to be directed through the tunnel, what happens if 5776 for instance another client in (i.e.) D1 behind D10001 comes up later 5777 and asks to receive the same traffic?. Let's assume that the 5778 join/prune from client in D3 is directed through the tunnel and both 5779 the source in D1 and client in D3 join the SPT for (S, G). Now a new 5780 client in D1 behind D10001 comes up and sends a join/prune message 5781 towards the source in D1 behind D10002, and finally both the source 5782 in D1 and client in D1 behind D10001 join SPT for (S, G). At this 5783 point we see that the source has joined 2 different SPTs to send the 5784 traffic to almost the same destination up to D10001, which is 5785 considered by PIM-NG specifications a waste of resources. 5787 Instead of the above processes , since the domain-set associated with 5788 (S,G) indicates that the update regarding (S,G) passed through CORE- 5789 DOMAIN10001, the client in D3 MUST send its join/prune message in a 5790 way ,so that it will reach the CORE-DOMAIN ,by setting the C-BIT of 5791 the source unicast address filed in join/prune message and putting 5792 the address of the CORE-DOMAIN-TR it had received from the C-MAPPER 5793 in D3 in the appropriate field and then send the message to the next 5794 hop in the best path first towards any existing TR inside D3 and then 5795 after the message reaches the D3-TR and the R-BIT is cleared 5796 towards the CORE-DOMAIN-TR. 5798 This way, as the message reaches the next hop and the next hope sees 5799 that the R-BIT is set in case of existing TR in D3, and also sees 5800 that the C-BIT is set which indicates that the message MUST be first 5801 forwarded towards the CORE-DOMAIN-TR. 5803 the message reaches the CORE-DOMAIN-TR and the TR clears the C-BIT 5804 and forwards the message to the next hop in the best path towards the 5805 source .and finally the client in D3, the TR in D3, the TR in CORE- 5806 DOMAIN and the source join the (S, G, RPT) rooted at existing TRs in 5807 each domain which is considered the Shortest Path Tree by PIM-NG 5808 specifications, and source starts sending traffic to (G) down the 5809 SPT. 5811 Now if the client in D1 behind D10001 comes up and sends the 5812 join/prune message to receive the same traffic, the join/prune 5813 message will only need to go up to the CORE-DOMAIN-TR, and since the 5814 CORE-DOMAIN-TR has already joined the SPT for (S, G) it will start 5815 forwarding traffic destined for (G) down the SPT towards the client 5816 in D1. 5818 Although the above process may seem unnecessary, it MUST be done to 5819 reduce the amount of join/prune messages that might be sent towards a 5820 source from different domains behind a CORE-DOMAIN and ONLY MUST BE 5821 done whenever the domain-set associated with a multicast source 5822 indicates that it can be reached through a CORE-DOMAIN. 5824 [Figure is presented in PDF version] 5826 Figure 48 join/prune message being sent towards the source 5828 4.6.4. Multiple multicast domains scenario 5830 Up to this point of explaining PIM-NG specifications almost all of 5831 the concepts regarding registering a new multicast source, connecting 5832 2 multicast domains, advertising the information regarding a new 5833 multicast source to another domain and many other concepts unique to 5834 PIM-NG have been explained. Now in this section we are going to check 5835 most of the concepts regarding a multicast network consisted of 5836 multiple PIM-NG domains through an example. In Figure 49 a multicast 5837 network consisted of multiple PIM-NG-CORE-DOMAINs and PIM-NG-DOMAINs 5838 is illustrated. 5840 [Figure is presented in PDF version] 5842 Figure 49 network with multiple multicast domains 5844 In the illustrated network, you will see 5 PIM-NG-CORE-DOMAINs, 2 of 5845 which connected to some PIM-NG-DOMAINs. we have a PIM-NG-CORE-DOMAIN 5846 which is actually a SERVICE PROVIDER Autonomous System, a transitive 5847 multicast domain which is unique to PIM-NG as the nature of MSDP and 5848 its RPF check method doesn't allow PIM-SM to have a transitive 5849 multicast domain or Autonomous System, an AS which can be considered 5850 an enterprise network that divided its multicast domain in to 5851 multiple PIM-NG-DOMAINs which are all connected to outside world 5852 through the CORE-DOMAIN, and 2 other CORE-DOMAINs that are needed to 5853 make the explanation of RPF check concept and transitory AS/multicast 5854 domain easier. 5856 In Figure 49, the Service Provider network is shown as AS-64500 and 5857 DOMAIN-10001(D10001 from now on) which is a CORE-DOMAIN number, and 5858 is connected to its customer A with PIM-NG-DOMAIN number 1 which is 5859 assigned by the Service Provider to make the customer able of 5860 receiving multicast updates from outside and also send multicast 5861 updates to the outside world. Customer A has divided its network to 2 5862 domains using a private domain number for the second domain. Also the 5863 Service Provider network has another customer connected to it, which 5864 is named Customer B, which is using the SP's network to only connect 5865 its multicast domains and doesn't wish to advertise any multicast 5866 source to the outside world or receive any, and to be more specific 5867 it has a closed and private multicast domain. This D10001 is 5868 connected to another CORE-DOMAIN which is D10002 with AS number 5869 64501. 5871 D10002 is then connected to AS-64502 with DOMAIN number D-10003 which 5872 is assumed to be a transitive AS or multicast domain. D-10003 is only 5873 providing unicast reach ability so that the join/prune messages or 5874 multicast traffic can reach from one domain to other domains. Also 5875 please be noted that this transitive domain can be a PIM-SM domain 5876 which is only providing the unicast reach ability between PIM-NG 5877 domains. It is connected to AS-64503 with Domain number D-10004 and 5878 AS-64504 with Domain number D-10005. D-10004 is only being used to 5879 review the RPF check method used in PIM-NG and D-10005 is considered 5880 to be an organization's Autonomous System which has divided its 5881 multicast domain to multiple domains to have a better control over 5882 its multicast network. 5884 With the above being explained , now it's time to overview the 5885 involved concepts through Figure 50, which shows the network in 5886 Figure 49 but with the multicast sources being advertised from one 5887 domain to other domains. 5889 [Figure is presented in PDF version] 5891 Figure 50 multicast network and multicast advertisements 5893 As illustrated in Figure 50: 5895 o Since customer-B's multicast domain behind D10001 is assumed to 5896 be a private and closed multicast domain, the multicast 5897 sources originated inside its D1 will only be advertised to 5898 D20 which is also customer-B's multicast domain, and will not 5899 be advertised to outside world or better to say to the C- 5900 MAPPER inside D10001. And customer-B is only using multicast 5901 network of D10001 as a mean to exchange multicast traffic 5902 between its multicast domains. 5904 o As it is illustrated in Figure 50, customer-A's multicast 5905 domain is divided in to 2 multicast domains both connected to 5906 D10001 and since customer-A has some sources that needed to be 5907 globally accessible, it has received PIM-NG-DOMAIN number 5908 1(D1) from D10001 (Service Provider). Customer-A uses a 5909 private domain number (D9901) for its second domain, and as it 5910 is illustrated the C-MAPPERs inside D1 and D9901 are directly 5911 connected as a mean to exchange information regarding 5912 multicast sources internally. And D1 is using a PPER to 5913 connect to a C-MAPPER in D10001 in order to exchange 5914 information regarding multicast sources globally/externally. 5916 o A multicast source inside D9901 is originating multicast 5917 traffic destined for (G), and the update about it is 5918 advertised to the peer C-MAPPER in D1 as (S2, G2, D9901). And 5919 since the domain number 9901 is a private domain number, the 5920 PPER in D1 will remove D9901 from the domain-set of (S2,G2) 5921 before advertising it to the C-MAPPER in D10001,and sends the 5922 update as (S2,G2,D1). 5924 o C-MAPPER in D10001 receives the update and advertises it to its 5925 peer in D10002 as (S2, G2, D1, 10001). The C-MAPPER in D10002 5926 is also peer with C-MAPPERs in D10003, D10004 and D10005. As 5927 illustrated in Figure 50, a multicast source (S3) comes up in 5928 D10002 and starts generating traffic destined for (G3). So the 5929 C-MAPPER in D10002 starts advertising information about this 5930 new source too its peers as (S3, G3, D10002). 5932 o D10003 is assumed to be a transitive domain only providing 5933 multicast reachability between D10002, 10004 and 10005. And as 5934 it is illustrated in Figure 50, C-MAPPER in D10002 is only 5935 advertising information about multicast sources that are 5936 generated inside its domain and not those generated in D10001. 5937 This being said, C-MAPPER in D10002 advertises the multicast 5938 source created in its domain as (S3, G3, 10002) to C-MAPPER in 5939 D10003. 5941 o D10004 and D10005 need to receive the multicast updates 5942 completely, so the C-MAPPER in D10002 peers with C-MAPPER'(s) 5943 or PPER'(s) in D10004 and D10005 and starts sending updates 5944 about multicast sources it knows as (S2,G2,D1,D10001,D10002) 5945 and (S3,G3,D10002) to them. 5947 o Up to this point, C-MAPPER in D10004 and PPER in D10005 as 5948 illustrated in Figure 50 have received the updates. Now the C- 5949 MAPPER in D10004 starts to advertise the received updates to 5950 its peer in D10005. So it advertises them as 5951 (S2,G2,D1,D10001,D10002,D10004) and (S3,G3,D10002,D10004) to 5952 D10005. 5954 o PPER in D10005 receives the updates from its peer in D10004 and 5955 since it has received an update from its peer in D10002, about 5956 the same multicast sources, it starts the RPF check mechanism. 5958 o PPER in D10005, first, compares the DOMAIN-SET of the 2 5959 received updates and the result of the comparison will be 5960 that, the updates received from D10004 will fail the RPF 5961 check. This is due to the fact that the domain set of the 5962 received updates from D10004 are longer than the ones received 5963 from D10002. 5965 o At the end the PPER in D10005 sends the updates to the closest 5966 C-MAPPER inside its domain and the C-MAPPER in D10005 5967 advertises those updates to its peers in D1 and D2. 5969 As explained above, PIM-NG specifications allow the existence of 5970 transitive multicast domain or Autonomous Systems, which due to the 5971 MSDP RPF check nature hasn't been totally implementable. 5973 And also because of the unique RPF check method used by PIM-NG, the 5974 control over filtering the updates about multicast sources is 5975 easier and more enhanced. Which is also mostly because of the RPF 5976 check method used by PIM-NG which allows the existence of 5977 transitory domains or an intermediary multicast domain which only 5978 needs to receive partial updates, like D10003 in Figure 48. 5980 In the following sections, the remaining concepts of PIM-NG 5981 regarding multiple multicast domain connectivity such as SUB-DOMIAN 5982 and PIM-SM-COMPATIBILITY, and controlling the updates received from 5983 a PIM-NG-DOMAIN to improve the security of the multicast network by 5984 STUB-DOMAIN concept will be explained. 5986 4.6.5. PIM-NG Sub-Domain 5988 PIM-NG Sub-Domain concept is introduced to cover 2 areas: 5990 o To control the propagation of multicast traffic inside one 5991 multicast domain, which from this perspective the Sub-Domain 5992 concept is more like dividing a multicast domain in to different 5993 areas. 5995 o To give the administrators a robust control over a multicast 5996 domain, by dividing it in to different sub-domains. And make 5997 modifications in one sub-domain in a way that no multicast 5998 source updates are accepted from that part of the domain 5999 through using the concept of Stub-Domain, which will be 6000 discussed later, or do FILTEING on the multicast sources that 6001 are usable in a Sub-Domain. 6003 Bellow specifications and rules apply to PIM-NG Sub-Domain: 6005 o A PIM-NG Domain can be divided to up to 254 Sub-domains. This 6006 number is derived from the maximum number of available C- 6007 MAPPERs inside a PIM-NG domain. As said before C-MAPPERs can 6008 have up to 255 different groups and the fact that each C- 6009 MAPPER is already a member of the main PIM-NG domain, gives us 6010 the equation 255-1=254. 6012 o The sub-domain numbers MUST be different from the main domain 6013 number, so that, the C-MAPPER introduction messages meant for 6014 the main domain won't be read by the components of each Sub- 6015 Domain. 6017 o If a PIM-NG domain is divided in to Sub-Domains, all the C-RPs, 6018 TR'(s) and clients resided is a Sub-Domain MUST only be 6019 configured with Sub-Domain number to use it as their domain 6020 number. 6022 o The only components of a PIM-NG domain which MUST be aware of 6023 both the main PIM-NG domain number and the Sub-Domain number 6024 they reside in are C-MAPPERs, PER'(s), PPER'(s) and TR'(s). 6026 o Since the main purpose of dividing a PIM-NG Domain to Sub- 6027 Domains is to have a better control over the propagation of 6028 the information regarding the existing multicast sources, in a 6029 way that either a Sub-Domain doesn't receive the information 6030 regarding specific multicast sources or in a Sub-Domain no 6031 sources are allowed to do exist and send register messages to 6032 C-RPs in the Sub-Domain, any mechanism used such as filtering 6033 or defining a Sub-Domain as an STUB-Domain, MUST BE applied 6034 within Sub-Domains and at the time the information regarding 6035 multicast sources are advertised within the Sub-Domain to 6036 existing C-RP'(s). 6038 o PIM-NG specification suggests the use of one or more PER'(s) as 6039 the boundary between each 2 Sub-Domain to limit the 6040 propagation of multicast introductions sent by C-MAPPER'(s) 6041 and C-RP'(s) in each Sub-Domain. 6043 o If in a PIM-NG multicast domain , only one C-MAPPER is 6044 considered, then the multicast domain can be divided to ONLY 2 6045 Sub-Domains and the C-MAPPER MUST act as the PER or boundary 6046 between the 2 Sub-Domains with one hand in each Sub-Domain.in 6047 this case the C-MAPPER MUST NOT forward the multicast 6048 introduction messages of one Sub-Domain to the other one. 6050 o If in PIM-NG SUB-DOMAINs, redundancy and high availability of 6051 the C-MAPPERs are needed to be considered, then each SUB- 6052 DOMAIN CAN use as many C-MAPPERs within the Sub-Domain to 6053 support the needs of multicasting in the Sub-Domain But ONLY 2 6054 C-MAPPERs, MUST BE and ARE allowed to be both a member of the 6055 main domain and the Sub-Domain.and the rest of the C-MAPPERs 6056 will only be a member of the Sub-Domain. So if it is not 6057 needed, PIM-NG specifications STRONGLY suggests using 2 C- 6058 MAPPERs in each Sub-Domain.so if redundancy must be considered 6059 the number of Sub-Domains will reduce to 127. 6061 o In the case of redundant C-MAPPERs in each Sub-Domain, the 6062 Mesh-Group concept described in section 4.5.2 MUST BE used 6063 inside each Sub-Domain so only the active C-MAPPER will be 6064 able to send introduction messages destined to 239.0.1.190. so 6065 first C-MAPPERs MUST send their multicast introductions 6066 destined to 239.0.1.188 using the Sub-Domain number, to find 6067 their peers if the dynamic methods are in use and elect the 6068 active C-MAPPER within the Sub-Domain and after that they MUST 6069 send multicast introductions using their main domain number to 6070 find their peers in the main domain if the dynamic methods are 6071 in use. 6073 o As explained in section 4.5.2. , a PIM-NG domain CAN use up to 6074 25 C-MAPPER Mesh-Groups. In this case each 10 C-MAPPER within 6075 either 10 or 5 Sub-Domains, CAN form a C-MAPPER Mesh-Group in 6076 the main domain. for instance, if a PIM-NG multicast domain 6077 with domain number D1, is divided in to 10 Sub-Domains(Sub- 6078 Domain 2-11), with each Sub-Domain including 2 C-MAPPERs for 6079 redundancy and high availability, C-MAPPERs inside Sub-Domains 6080 2-6 can form Mesh-Group1 in D1 and C-MAPPERs in Sub-Domains 7- 6081 11 can form Mesh-Group2 in D1. 6083 o When a C-MAPPER is a member of the main domain and also a Sub- 6084 Domain, The concept of Active and Standby C-MAPPER in a mesh 6085 group described in section 4.5.2.1. , MUST BE applied to each 6086 Sub-Domain and depending on the needs of the PIM-NG multicast 6087 domain the Active and Standby C-MAPPER concept CAN be applied 6088 in the main domain. So for instance, if D1 is divided into 2 6089 Sub-Domains (Sub-Domain 2-3) with 2 C-MAPPERs in each Sub- 6090 Domain being a member of both the PIM-NG domain and the Sub- 6091 Domain, C-MAPPERs in Sub-Domains2 will form Mesh-Group1 in 6092 Sub-Domain2 and C-MAPPERs in Sub-Domain3 will form Mesh-Group1 6093 in Sub-Domain3. And ALL 4 C-MAPPERs as C-MAPPERs of Domain1 6094 will either form MeSh-Group1 in Domain1 to begin the process 6095 of Active C-MAPPER election in Domain1 between the 4 of them 6096 or simply will become peer C-MAPPERs in Domain1 to exchange 6097 their A-Multicast Mapping Tables and other information needed. 6099 o The Mesh-Groups in the main domain (i.e. D1) are formed to 6100 elect the ACTIVE C-MAPPER ONLY under these circumstances: 6102 1. If a PIM-NG domain which is divided to Sub-Domains, is 6103 connected to outside world or other PIM-NG domains or a 6104 PIM-SM domain by using the PPER concept, and since 6105 PPER'(s) MUST communicate with the closest C-MAPPER in 6106 the PIM-NG domain to receive the full AMMT which is being 6107 exchanged between the C-MAPPERs in the main domain, ONLY 6108 IF the needs of multicast Domain DICTATES TO USE the 6109 dynamic method for the communication of PPER'(s) with C- 6110 MAPPER'(s) in the Domain, then the C-MAPPERs MUST form 6111 Mesh-Group'(s) in the PIM-NG Domain and the active C- 6112 MAPPER MUST ONLY introduce existing C-MAPPERs in the main 6113 domain in its introduction messages sent to 239.0.1.190. 6115 2. If a PIM-NG domain which is divided to Sub-Domains, is 6116 connected to a PIM-SM domain by using the PER concept, 6117 and since in such design PER'(s) MUST communicate with 6118 the closest C-MAPPER in the PIM-NG domain to receive the 6119 full AMMT which is being exchanged between the C-MAPPERs 6120 in the main domain, ONLY IF the needs of multicast Domain 6121 DICTATES TO USE the dynamic method for the communication 6122 of PER'(s) with C-MAPPER'(s) in the Domain, then the C- 6123 MAPPERs MUST form Mesh-Group'(s) in the PIM-NG Domain and 6124 the active C-MAPPER MUST ONLY introduce existing C- 6125 MAPPERs in the main domain in its introduction messages 6126 sent to 239.0.1.190. 6128 o If Mesh-Group'(s) are formed in the main domain so that through 6129 an election the ACTIVE C-MAPPER starts introducing in the main 6130 domain, then ONLY the PER'(s) acting as the boundary between 6131 Sub-Domains MUST be dictated to pass the introduction messages 6132 sent to 239.0.1.190 which are generated ONLY BY the ACTIVE C- 6133 MAPPER in the main domain and NOT Sub-Domains. 6135 o If a PIM-NG Domain which is divided to Sub-Domains is connected 6136 to other Domains using PPER concept or is connected to a PIM- 6137 SM domain, To reduce the bandwidth and network resources 6138 consumption IF the needs of multicasting in the Domain does 6139 not dictate to use the dynamic methods for the communication 6140 between PPER'(s) or PER'(s) and C-MAPPERs, PIM-NG 6141 specifications Strongly SUGGESTS to statically introduce C- 6142 MAPPER'(s) to each PPER or PER through command initiation on 6143 PPER'(s) and PER'(s). 6145 o If the C-MAPPERs are statically introduced to PER'(s) and 6146 PPER'(s), then a mechanism MUST be used so that the C-MAPPERs 6147 which are member of a Mesh-Group in the main domain, don't 6148 elect the Active C-MAPPER. This way the C-MAPPERs which are 6149 members of the Mesh-Group in the main domain will only 6150 exchange their AMMT'(s) and if needed the information 6151 regarding the existing TR'(s). and Since no Active C-MAPPER is 6152 elected the PER'(s) acting as boundary between the Sub-Domains 6153 MUST NOT be dictated to forward the C-MAPPER introductions 6154 sent to 239.0.1.190 which are generated by the ACTIVE in the 6155 main domain. So PIM-NG specification SUGGESTS doing above 6156 through command initiation as an option. 6158 o Also in case that the C-MAPPER'(s) are introduced to PER'(s) or 6159 PPER'(s) statically, PIM-NG specifications SUGGESTS that the 6160 C-MAPPERs in the main domain simply become peer and don't form 6161 Mesh-Groups, which eliminates the need to use the above 6162 mentioned mechanism. 6164 o With the above concepts, each C-MAPPER within each Mesh-Group 6165 in the main domain, will inform ALL the other members of the 6166 Mesh-Group as soon as any changes occurs within a Sub-Domain. 6168 o If in a PIM-NG Domain divided to Sub-Domains, the C-MAPPERs are 6169 to form Mesh-Group'(s) in the main domain through dynamic 6170 method explained in section 4.5.2. , the PER'(s) acting as the 6171 boundary between Sub-Domains MUST BE dictated to forward the 6172 C-MAPPER introduction messages destined to 239.0.1.188 and 6173 generated ONLY by C-MAPPERs in the main domain. so if Domain1 6174 is divided to Sub-Domains 2 and 3, then the PER'(s) between 6175 Sub-Domain2 and Sub-Domain3 MUST BE dictated to forward the C- 6176 MAPPER introduction messages destined to 239.0.1.188 with 6177 Domain-Value set to1 (Domain1). 6179 o To reduce the bandwidth and network resources consumption in 6180 the above case, in which C-MAPPERs are to form Mesh-Group'(s) 6181 in the main domain, PIM-NG Specifications Suggests to peer the 6182 C-MAPPERs using the unicast Address of each C-MAPPER and not 6183 the GROUP number of C-MAPPERs which will eventually make the 6184 C-MAPPERs to send multicast introductions to 239.0.1.188 to 6185 find their peers. This being said, the dynamic method is still 6186 the preferred method IF the network infrastructure and 6187 resources can support ALL the needs of PIM-NG multicast 6188 Domain. 6190 o If in the main domain, the C-MAPPER Mesh-Group concept is 6191 implemented with more than one Mesh-Group, then it is advised 6192 to ONLY peer 2 C-MAPPERs from each Mesh-Group with 2 C-MAPPERs 6193 from the other Mesh-Group'(s). The peering of C-MAPPERs inside 6194 different Mesh-Groups formed in the Main domain MUST BE done 6195 using the static method and there MUST be a boundary between 6196 the 2 Mesh-Groups. For instance, if D1 is divided in to 10 6197 Sub-Domains (Sub-Domains 2-11) and C-MAPPERs in Sub-Domains2-6 6198 are forming Mesh-Group1 and C-MAPPERs in Sub-Domains7-11 are 6199 forming Mesh-Group2, then 2 C-MAPPERs from Mesh-Group1 will 6200 become peer with 2 C-MAPPERs in Mesh-Group2 using the static 6201 method to bring redundancy to the entire domain. and it is 6202 STRONGLY advised by PIM-NG specifications to use a PER as the 6203 boundary between Sub-Domains 2-6 and Sun-Domains 7-11 so that 6204 no multicast introduction messages will be forwarded from the 6205 side including Sub-Domains 2-6 to the side including Sub- 6206 Domains 7-11. The above method of connecting different Mesh- 6207 Groups will become necessary in designs with more than 2 Sub- 6208 Domains and many C-MAPPERs in use to reduce the amount of 6209 introduction message traffic in the domain. 6211 o Each Sub-Domain MUST BE treated as a PIM-NG Domain, in which 6212 all the components of the domain including Clients, C-RP'(s), 6213 TR'(s) and C-MAPPER'(s) use the same domain or better to say 6214 Sub-Domain number with the C-MAPPER'(s) and TR'(s) as the only 6215 components being the member of the main domain and Sub-Domain. 6216 So clients, C-RPs and TR'(S) inside a Sub-Domain MUST only 6217 listen to C-MAPPER introduction messages with the same domain 6218 number. 6220 o Since each Sub-Domain MUST BE treated as a separate Domain, 6221 each Sub-Domain can have up to 255 C-RP and TRs if needed, and 6222 the all the PIM-NG specifications and rules that apply to 6223 exiting C-RP'(s) and TR'(s) in a single multicast domain, are 6224 applicable here. 6226 o C-MAPPERs in a Sub-Domain MUST become peer with other C-MAPPERs 6227 in other Sub-Domains using their main domain number, in order 6228 to advertise the information regarding multicast sources 6229 inside their Sub-Domain to other Sub-domains. So if (i.e.) if 6230 we have C-MAPPER-A and C-MAPPER-B inside D1, and C-MAPPER-A is 6231 a member of sub-Domain-2(SD2) and C-MAPPER-B is a member of 6232 SD-3 , then C-MAPPER-A MUST become peer with C-MAPPER-B which 6233 is inside D1 and not D3. 6235 o As explained in section 4.5.2. ,when there are more than one C- 6236 MAPPER in a PIM-NG domain , each STC-MAPPER MUST send the 6237 information regarding newly found C-RPs or TR'(s) to the 6238 active C-MAPPER in the domain ,so that the active C-MAPPER 6239 will be able to introduce the C-RPs or TRs to the PIM-NG 6240 population by sending introduction messages to 239.0.1.190. 6241 but PIM-NG specifications dictates that in multicast design 6242 including Sub-Domain implementation ,C-MAPPERs MUST NOT send 6243 the information regarding the existing C-RPs in their Sub- 6244 Domain to other C-MAPPERs from different Sub-Domain'(s). And 6245 this is due to the fact that each Sub-Domain MUST BE treated 6246 as a separate Domain. so such information MUST only be 6247 exchanged within the Sub-Domain. 6249 o If TR'(s) are considered in a PIM-NG domain which is divided 6250 into Sub-Domains, since the communication between the TR and a 6251 client is limited to the join/prune messages, then C-MAPPERs 6252 in different Sub-Domains MUST send the information regarding 6253 TR'(s) they find inside their Sub-Domain to their peer C- 6254 MAPPERs which are resided in other Sub-Domains so that : 6256 1. Clients in other Sub-Domains become aware of the 6257 existence of TR and use its unicast address to send the 6258 join/prune message towards the closest TR. 6260 2. TR'(s) will find each other to communicate regarding the 6261 exchange of JOINED-GROUP TABLE. 6263 o In case of existing TR'(s) in a PIM-NG domain divided to Sub- 6264 Domains, PIM-NG specifications STRONGLY suggests : 6266 1. To Use a separate router as the TR if applicable 6267 2. To Use the ANYCAST concept to introduce the existing TR'(s) 6268 to the clients. 6270 3. NOT TO use C-RP'(s) as the TR if possible, due to the fact 6271 that in this case because of the method used by PIM-NG to 6272 send a join/prune message when C-RP and TR are both the 6273 same, there might be some issues if the C-RPs in one Sub- 6274 Domain go offline and after this the clients in this Sub- 6275 Domain may chose to send their join/prune messages toward an 6276 TR/C-RP resided in another Sub-Domain which doesn't have the 6277 full A-MULTICAST MAPPING TABLE, because of multicast source 6278 filtering in that Sub-Domain. 6280 4. That if the design needs dictates to use C-RP'(s) as TR'(s) 6281 in each Sub-Domain, the TR ANYCAST address used in each Sub- 6282 Domain be different from other Sub-Domains, and C-MAPPERs be 6283 dictated through command initiation as an option NOT TO send 6284 the information regarding the TR'(s) in their Sub-Domain to 6285 other C-MAPPERs which are resided in other Sub-Domains. This 6286 way each single Sub-Domain will totally act as a separate 6287 Domain. 6289 o If more than one TR exists in a PIM-NG Domain which is divided 6290 to Sub-Domains, and the information regarding the TRs is being 6291 exchanged among C-MAPPER so that the clients become aware of 6292 the existence of TR'(s) and also TR'(s) can communicate with 6293 each other using the dynamic method, then TR'(s) MUST use 6294 their main domain number when sending introductions containing 6295 JOINED-GROUPS TABLE to each other and not the SUB-Domain 6296 number, as the only thing that 2 TR CAN share and HAVE in 6297 common is the main domain number. 6299 o TR'(s) MUST introduce themselves to the ACTIVE C-MAPPER in the 6300 Sub-Domain and not an ACTIVE C-MAPPER in the main domain. 6302 o Each C-MAPPER MUST send the information regarding new multicast 6303 sources being originated inside its Sub-Domain to their peer 6304 C-MAPPER'(s) by exchanging the contents of A-MULTICAST MAPPING 6305 TABLE. 6307 o C-MAPPER'(s) that are both a member of a Sub-Domain and the 6308 main domain, MUST remove the Sub-Domain number from the 6309 domain-set of multicast sources inside their Sub-Domain, 6310 before advertising them to their peer C-MAPPER(s)in other Sub- 6311 Domains or outside their multicast domain. After the deletion 6312 of Sub-Domain number, ALL the rules and specifications related 6313 to Domain-Set and RPF check will be applied. This is due to 6314 the fact that from other C-MAPPERs point of view, whether in 6315 the same PIM-NG domain (i.e. D1) or another PIM-NG domain 6316 (i.e. D2) the updates MUST be seen as generated in D1. 6318 o If any FILTERING in regards to multicast sources needed to be 6319 done, so that a Sub-Domain does not receive the information 6320 regarding an specific multicast source or a group of multicast 6321 sources, it MUST ONLY BE done within each Sub-Domain in a way 6322 that the C-MAPPER'(s) within a Sub-Domain which ARE a member 6323 of the main domain do the filtering on the contents of A- 6324 MULTICAST MAPPING TABLE at the time of advertising to C- 6325 MAPPERs that are only a member of the Sub-Domain or C-RP'(s) 6326 within the Sub-Domain. 6328 o C-MAPPERs in a PIM-NG Domain which is divided to Sub-Domains 6329 MUST exchange the full A-MULTICAST MAPPING TABLE between 6330 themselves without any filtering, and as said above any 6331 filtering MUST ONLY BE done within each Sub-Domain at the time 6332 of advertising to C-RPs within a Sub-Domain. This MUST be done 6333 so that any PER'(s) or PPER'(s) connecting the PIM-NG Domain 6334 to other domain'(s) or PIM-SM domain'(s) receive the full A- 6335 MULTICAST MAPPING TABLE. 6337 o If a PER is placed between 2 PIM-NG Sub-Domains to isolate 6338 them, then the PER MUST know the main domain number it is 6339 resided in. this is a MUST so that where ever the needs of 6340 multicasting dictates the PER will forward the C-MAPPER 6341 introduction messages which are meant to be heard by C-MAPPERs 6342 and PER or PPERs in the main domain. 6344 o If Sub-Domains are isolated from each other by using PER'(s)and 6345 the dynamic C-MAPPER peering methods are used among different 6346 Sub-Domains, then each PER MUST be dictated to let the C- 6347 MAPPER introduction messages destined to 239.0.1.188 and are 6348 meant to finding other C-MAPPER in the main domain ,to be 6349 forwarded from one Sub-domain to the other. As explained 6350 above, up to 2 C-MAPPERs from each Sub-Domain with total 6351 number of 10 C-MAPPERs are allowed to form C-MAPPER Mesh-Group 6352 in the main domain to propagate the information regarding 6353 multicast sources in each Sub-Domain, so it is vital that the 6354 C-MAPPER introduction messages meant for the main Domain are 6355 forwarded by the PER. 6357 o If the C-MAPPERs in existing Sub-Domain have formed more than 6358 one Mesh-Group in the main domain , PIM-NG specifications 6359 STRONGLY suggests that the PER'(s) between the 2 Mesh-Group 6360 areas DO NOT pass the C-MAPPER introduction messages sent to 6361 239.0.1.188 from one Mesh-Group area to the other. This is 6362 needed to be taken in to consideration when the number of C- 6363 MAPPERs and mesh groups in a multicast domain increase, to 6364 limit the propagation of such traffic. So as explained above 6365 it is STRONGLY suggested to choose at least 2 C-MAPPERs from 6366 each Mesh-Group and make them peer with C-MAPPERs in other 6367 Mesh-Groups using the static methods. consider the bellow 6368 design in which Domain1(D1) is divided in to 4 Sub- 6369 Domains(SD2-5) : 6371 [Figure is presented in PDF version] 6373 Figure 51 Mesh-Groups and C-MAPPER peering 6375 o If a PIM-NG domain divided to Sub-Domains is connected to a 6376 PIM-SM domain and the 2 domains are separated by a PER which is 6377 acting as the BORDER-PIM-ROUTER(BPR) too, then the PER MUST 6378 become aware of both main PIM-NG domain number and the PIM-NG 6379 Sub-Domain number it resides in, and introduce itself to the 6380 closest C-MAPPER in the main domain if the dynamic method is in 6381 use or to any C-MAPPER that is statically introduced to the PER 6382 using the main domain number and not the Sub-Domain number. 6384 o If a PIM-NG domain is divided to Sub-Domains, and the PIM-NG 6385 domain is connected to other PIM-NG domains using PPER'(s), then 6386 the PPER MUST know both the main domain number and the Sub- 6387 Domain number it is resided in, and MUST automatically 6388 communicate with the closest C-MAPPER in the main Domain and 6389 not the Sub-Domain, if the dynamic method is in use and the 6390 ACTIVE C-MAPPER within the main domain is chosen to introduce 6391 all existing C-MAPPERs in the PIM-NG domain by sending 6392 introductions destined to 239.0.1.190, or communicate with any 6393 C-MAPPER that is introduced to it in the main domain. 6395 o When a C-MAPPER in a PIM-NG Domain which is divided to Sub- 6396 Domains with multicast source filtering being applied to Sub- 6397 Domains, receives a PER or PPER introduction, it MUST exchange 6398 the full A-MULTICAST MAPPING TABLE with the PER or PPER so that 6399 the PER or PPER has a complete knowledge about existing 6400 multicast sources. This is why such PER or PPER MUST introduce 6401 itself to the C-MAPPERs within the main domain and not the sub- 6402 domain. as explained earlier each Sub-Domain can have as many C- 6403 MAPPERs as needed but only 2 of them are allowed to be a member 6404 of both main domain and Sub-Domain, and if such PER or PPER 6405 introduces itself to the closest C-MAPPER within a Sub-Domain 6406 that multicast source filtering is applied in it, there is a 6407 possibility that the PER or PPER introduces itself to a C-MAPPER 6408 which is only a member of the Sub-Domain and doesn't have the 6409 full A-MULTICAST MAPPING TABLE. 6411 o If a PIM-NG domain is divided to Sub-Domains and the existing 6412 C-MAPPERs within each Sub-Domain are to form C-MAPPER Mesh-Group 6413 with other C-MAPPERs in other Sub-Domains in the main domain 6414 using the dynamic method used by PIM-NG specifications , the 6415 PERs acting as the boundary between Sub-Domains MUST forward the 6416 C-MAPPER introduction messages sent to 239.0.1.188 and 6417 239.0.1.190(active C-MAPPER introduction). This is advised to be 6418 done through command initiation as an option. 6420 o If a PIM-NG domain which is divided to Sub-Domains is connected 6421 to other PIM-NG domains using PPER concept, and the C-MAPPERs in 6422 PIM-NG domain are forming Mesh-Groups then the PERs acting as 6423 the boundary between the Sub-Domains MUST pass the introduction 6424 message of ACTIVE C-MAPPER in the main domain sent to 6425 239.0.1.190, so that the PPER connecting the PIM-NG domain to 6426 other PIM-NG domains will automatically learn the address of the 6427 C-MAPPERs and communicate with them. 6429 o If a PIM-NG domain which is divided to Sub-Domains is connected 6430 to a PIM-SM domain, and the C-MAPPERs in PIM-NG domain are 6431 forming Mesh-Groups then the PERs acting as the boundary between 6432 the Sub-Domains MUST pass the introduction message of ACTIVE C- 6433 MAPPER in the main domain sent to 239.0.1.190, so that the PER 6434 connecting the PIM-NG domain to PIM-SM domain will automatically 6435 learn the address of the C-MAPPERs and communicate with them. 6437 o If in a PIM-NG Domain which is divided to Sub-Domains and 6438 connected to outside Domains using PPER'(s) or PIM-SM domains 6439 using PER'(s) which act as BPR, more than one C-MAPPER Mesh- 6440 Group is considered , Since it is STRONGLY suggested by PIM-NG 6441 specifications to use a PER between the 2 Mesh-Group area, so 6442 that the ACTIVE C-MAPPER introductions of one area IS NOT 6443 forwarded to other areas, PIM-NG specifications SUGGESTs to 6444 statically introduce at least 2 C-MAPPERs from other Mesh-Groups 6445 that such PER or PPER is not resided in the associated area to 6446 the PER or PPER so that if the connection between the PER or 6447 PPER with the C-MAPPERs inside the closer Mesh-Group area is 6448 lost, the PER or PPERs will be able to communicate with the C- 6449 MAPPERs in other areas. 6451 [Figure is presented in PDF version] 6453 Figure 52 PPER and PER communication with C-MAPPER 6455 As explained above throughout different rules and specifications that 6456 apply to PIM-NG Sub-Domain'(s), the Sub-Domain concept is introduced 6457 to give administrators and designers the ability to divide the 6458 multicast domain to different areas and provide a robust control over 6459 the propagation or advertisement of the multicast sources within each 6460 area or better to say Sub-Domain or as a security feature treat a 6461 Sub-Domain in a way that no multicast source registration is allowed 6462 in an specific area or Sub-Domain by applying the STUB-DOMAIN concept 6463 to that Sub-Domain . In Figure 53 a PIM-NG domain divided to Sub- 6464 Domains is illustrated. 6466 [Figure is presented in PDF version] 6468 Figure 53 Sample PIM-NG domain Divided to Sub-Domains 6470 4.6.6. PIM-NG Stub-Domain 6472 PIM-NG introduces the STUB-DOMAIN concept as a security feature when 6473 dealing with multiple PIM-NG Domains or PIM-NG Sub-Domains. Through 6474 implementing the STUB-DOMAIN concept, a PIM-NG Domain or Sub-Domain 6475 is treated as a multicast domain in which only receivers for 6476 multicast traffic exist. 6478 The bellow specifications and rules apply to a PIM-NG STUB-DOMAIN: 6480 o A STUB-DOMAIN is a domain in which, no multicast source exists. 6482 o A STUB-DOMAIN is a domain in which, ONLY multicast traffic 6483 receivers MUST exist. 6485 o If a Domain is considered to be STUB-DOMAIN, the C-RP'(s) 6486 within the Domain MUST BE dictated NOT TO accept any source 6487 register messages. To do so PIM-NG specifications Suggests that, 6488 at the time of configuring the domain number in which a C-RP 6489 exists, the C-RP be dictated that the domain it is resided in is 6490 a STUB-DOMAIN. 6492 o If a Domain is considered to be a STUB-DOMAIN, the C-MAPPERs 6493 inside the Domain MUST BE dictated NOT TO accept any multicast 6494 source advertisement from existing C-RP'(s), or better to say 6495 the C-MAPPER'(s) inside a STUB-DOMAIN MUST NOT receive any AMMT 6496 from the C-RP'(s) inside the domain, and if any A-MULTICAST 6497 MAPPING TABLE is received from C-RP'(s) it MUST NOT be accepted. 6499 o If a PIM-NG Domain is divided to PIM-NG Sub-Domains, and one or 6500 more Sub-Domain'(s) MUST be treated as a STUB-DOMAIN, then ALL 6501 C-RP'(s) inside such Sub-Domain'(s) MUST become aware about the 6502 situation, so that they WILL NOT accept any source register 6503 messages. 6505 o If a PIM-NG Domain is divided to PIM-NG Sub-Domains, and one or 6506 more Sub-Domain'(s) MUST be treated as a STUB-DOMAIN, then C- 6507 MAPPER'(s) inside such Sub-Domain'(s) MUST NOT accept any AMMT 6508 from the C-RP'(s) inside the Sub-Domain. 6510 o If 2 separate PIM-NG multicast domains (i.e. D1 and D2) are 6511 connected and one of them (i.e. D1) is considered by the other 6512 Domain (i.e. D2) a STUB-DOMAIN, then the C-MAPPER'(s) or 6513 PPER'(s) in the Domain which is not a Stub-Domain (i.e. D2) MUST 6514 NOT accept any multicast source advertisements from the peer C- 6515 MAPPERs in the Domain that is considered a STUB-DOMAIN (i.e. 6516 D1). PIM-NG specifications suggests that this be done at the 6517 time of introducing the peer C-MAPPERs.for instance by 6518 initiating a command like this : 6520 <#IP PIM-NG PEER MAPPER DOMAIN[value] MAPPER-ADDR[X.Y.Z.W] STUB> 6522 o No AMMT MUST BE received or accepted from a peer C-MAPPER which 6523 is considered to be in a STUB-DOMAIN. 6525 o The C-RP'(s) inside a STUB-DOMAIN MUST only receive AMMT from 6526 C-MAPPER'(s) in the domain and MUST NOT generate any AMMT. 6528 o Since as dictated by PIM-NG specifications NO advertisements 6529 regarding multicast sources can be accepted from a STUB-DOMAIN, 6530 In a multicast network design with a STUB-DOMAIN in the middle 6531 of 2 normal domains PIM-NG specifications suggest 2 different 6532 approaches: 6534 1. If possible, C-MAPPER'(s) from the normal Domains MUST 6535 become peer with each other and also the C-MAPPER'(s) in 6536 the STUB-DOMAIN, so that the C-MAPPER'(s) in the normal 6537 Domains can exchange information regarding multicast 6538 sources originated in their domains and only advertise 6539 them to the C-MAPPER'(s) in the middle domain. in this 6540 method the STUB-DOMAIN acts as a transitory multicast 6541 domain and actually is used by the normal domains as a 6542 path to send join/prune messages and receive the desired 6543 multicast traffic. 6545 2. If it is not possible to make the C-MAPPERs in normal 6546 domains peer with each other, PIM-NG specifications 6547 suggest to use a mechanism as an optional feature in 6548 regards to STUB-DOMAIN, so that the C-MAPPER'(s) in 6549 normal domains become peer with the C-MAPPER'(s) in the 6550 STUB-DOMAIN and accept receiving advertisements 6551 regarding multicast sources or better to say accept the 6552 received AMMT from C-MAPPER'(s) in the STUB-DOMAIN, BUT 6553 filter any information regarding multicast sources that 6554 are generated within the STUB-DOMAIN. 6556 o The above approach is unique to PIM-NG because of its unique 6557 RPF check method, which allows the existence of transitory 6558 multicast domains or Autonomous Systems. The above 6559 explanations can be seen in Figure 54. 6561 o If a PIM-NG domain is connected to a PIM-SM domain, and the 6562 PIM-SM domain is considered to be a STUB-DOMAIN, PIM-NG 6563 specifications follows 2 different approaches: 6565 1. If the PIM-SM domain is between 2 PIM-NG domains, the 6566 C-MAPPER'(s) which is becoming MSDP-PEER with RP'(s) in 6567 the PIM-SM domain MUST BE dictated not to accept any 6568 Source Active messages from their MSDP-PEER'(s). And C- 6569 MAPPERs within the PIM-NG domains MUST become peer with 6570 each other. 6572 2. if the PIM-NG domain is connected to a network of PIM- 6573 SM domains and the directly connected PIM-SM domain must 6574 be considered a STUB-DOMAIN, the C-MAPPER'(s) in the 6575 PIM-NG domain MUST be dictated as an optional feature to 6576 perform filtering on the received Source Active messages 6577 received from the MSDP-PEER in the STUB-DOMAIN, so that 6578 any source with the originator address equal to the 6579 address of the MSDP-PEER is filtered. 6581 [Figure is presented in PDF version] 6583 Figure 54 Stub-Domain as the transitory multicast domain 6585 The above specifications and rules apply to a PIM-NG STUB-DOMAIN. and 6586 the reason that the Stub-Domain concept is explained as a part of the 6587 concepts related to PIM-NG and multiple multicast domains, is that 6588 this concept is only meaningful and applicable when we are dealing 6589 with multiple multicast domains, and the STUB-DOMAIN concept can be 6590 used as a security measure when dealing with multicast domains that 6591 no multicast source'(s) are expected to be advertised from them, to 6592 eliminate the possibility of existing attackers. 6594 4.7. PIM-NG Bidirectional logic 6596 One of PIM-NG's features that can make it by far a suitable candidate 6597 for scenarios with huge number of sources and receivers for the same 6598 multicast group and specially data centers is its Bidirectional PIM 6599 logic. Current implementation and concept cannot allow for the 6600 existence of redundant roots per bidirectional tree which is a 6601 desirable factor especially in data centers where we can face a huge 6602 number of receivers and sources for the same multicast group (G). 6603 Other than redundant roots being able to benefit from redundant trees 6604 per bidirectional group can be considered another desirable factor 6605 which currently needs to use other protocols in conjunction with PIM- 6606 SM. 6608 PIM-NG can provide both redundant roots per bidirectional tree and 6609 redundant trees per multicast group by making use of some of the 6610 processes and specifications which has been explained up to this 6611 point alongside its unique Bidirectional logic. 6613 In addition to the above PIM-NG introduces a new method of 6614 Bidirectional multicast group discovery unique to PIM-NG called 6615 Bidirectional Group Auto Sense mechanism which allows a multicast 6616 domain to automatically sense the existence of Bidirectional Groups 6617 and change the logic of the domain for those groups to Bidirectional. 6619 In the following sections different concepts and specifications of 6620 PIM-NG bidirectional logic will be discussed. 6622 4.7.1. Requirements 6624 . For Bidirectional PIM-NG logic to be implemented in a well 6625 organized manner at least 1 TR MUST do exist in a PIM-NG multicast 6626 domain. 6628 . All PIM-NG aware routers MUST be Bidirectional PIM aware too by 6629 default. 6631 4.7.2. Bidirectional Multicast Group Discovery 6633 Before getting involved in how Bidirectional trees are formed, we 6634 need to understand how Bidirectional Multicast Groups within a Domain 6635 are discovered so we will be able to deliver the desired traffic 6636 destined for (G) from sources to receivers. 6638 PIM-NG uses 2 different methods for Bidirectional source discovery 6639 which are called Manual mode and autosense mode. No matter what type 6640 is used it is mandatory that a PIM-NG domain in which the 6641 bidirectional logic is going to be used have 1 or more TR'(s). That 6642 being said at least 1 TR MUST exist in such domains. 6644 4.7.2.1. Manual Mode 6646 Bidirectional Multicast source discovery manual mode specifications 6647 are as follows: 6649 1- In this mode The Bidirectional Multicast Group'(s) are defined and 6650 configured manually on the existing C-MAPPER or Active C-MAPPER if 6651 more than 1 C-MAPPER is considered. 6653 2- For this mode to be activated the Active C-MAPPER MUST be 6654 configured appropriately by the administrator and the C-MAPPER 6655 MUST inform all the population by setting the B-BIT in its 6656 introduction messages sent to 239.0.1.190. 6658 3- After the Groups with Bidirectional logic are defined and 6659 configured on the C-MAPPER, the C-MAPPER MUST notify the entire 6660 population of PIM-NG aware routers about the existence of such 6661 Groups so that the domain's logic will change to Bidirectional for 6662 those group'(s). This is done by the C-MAPPER through sending a 6663 special table called "Bidirectional Groups Table (BGT)" in its 6664 introduction messages sent to 239.0.1.190. 6666 +--------------------------------------+ 6667 |Bidirectional Group| TR Group |R-flag | 6668 +--------------------------------------+ 6669 | | | | 6670 +--------------------------------------+ 6671 | | | | 6672 +--------------------------------------+ 6673 Figure 55 Bidirectional Groups Table (BGT) 6675 . R-Flag: set by a C-RP or C-MAPPER to inform the C-MAPPER to 6676 remove a multicast group from its BGT table. If this flag is 6677 set it means that the group is not active anymore. 6679 Figure 55 shows the format of BGT in which C-MAPPER announces the 6680 Multicast Groups for which the logic of the Domain MUST change to 6681 Bidirectional. Also the C-MAPPER announces a TR group which 6682 defaults to 0 and its use will be discussed further when there are 6683 lots of TR'(s) in a multicast domain and the needs of multicasting 6684 dictates to use a handful of TRs for different sets of 6685 Bidirectional Multicast groups as the ROOT. So for the sake of 6686 simplicity it assumed that there are not so many TRs. 6688 4- After the C-MAPPER sends BGT in its introduction messages all the 6689 PIM-NG aware routers will know about any multicast group that must 6690 be treated as a Bidirectional Group and sources and receivers will 6691 immediately join the SPT rooted at the closest TR for that 6692 group'(s) without registering with C-RP'(s). 6694 5- In scenarios with SUB-Domains implemented it is possible to filter 6695 any desired Bidirectional Multicast group from being updated to 6696 the Active C-MAPPER within each Sub-Domain by the Active C-MAPPER 6697 in the main domain. 6699 6- BGT MUST BE exchanged between neighbor clients when a new client 6700 is added at the time of synchronization. 6702 7- If a Group (G) is removed the C-MAPPER MUST announces this event 6703 by sending the BGT and setting the R-Flag for that (G). 6705 8- In scenarios with Core Domain implementations, in which 1 or more 6706 Domains are connected to a Core domain and senders and receivers 6707 are distributed in different domains, Bidirectional Groups MUST be 6708 configured and defined on an Active C-MAPPER within the Core 6709 Domain and then be updated to C-MAPPERs inside connected Domains. 6711 9- When Bidirectional groups are defined on C-MAPPERs within a core 6712 domain, PIM-NG strongly advises to update it based on domains in 6713 which any sender or receiver of Group G exists. to make it more 6714 clear it must be said that it is suggested to use a mechanism 6715 through which it will be possible to send the BGT to desired C- 6716 MAPPER neighbors within connected domains or if needed to all the 6717 C-MAPPERs. This way senders and receivers within any desired 6718 domain can join the Bidirectional tree for group G within their 6719 domain and eventually the tree in the core domain. 6721 10-If 2 PIM-NG multicast domains are going to communicate using 6722 Bidirectional PIM, then at least one C-MAPPER in any one of the 6723 domains MUST be configured with appropriate Bidirectional 6724 information and pass the information to the other C-MAPPER by 6725 exchanging BGT. 6727 11-When a Bidirectional Group is removed from the BGT of a C-MAPPER 6728 the C-MAPPER MUST notify all the population of PIM-NG aware 6729 routers within its domain and in case of domains connected to a 6730 core domain all the C-MAPPERs within each domain or desired domain 6731 about the change by sending a BGT with the R-Flag of the removed 6732 Multicast Group being set to 1. 6734 This process is much like what is happing in current implementations 6735 except for the fact that it allows for the existence of many TR's 6736 within a domain and thus redundant roots per Bidirectional group, 6737 which will be discussed later. 6739 4.7.2.2. Autosense mechanism 6741 PIM-NG allows a multicast domain to automatically sense the existence 6742 of Bidirectional groups and change the logic of the Domain for such 6743 groups. This is accomplished due to the fact that the Source registry 6744 mechanism and the processes through which a client finds the source 6745 of a multicast address are performed in a complete different and 6746 innovative way than current implementations. 6748 As explained in chapter 4.2. PIM-NG uses a new mechanism for 6749 registering the source and the way a client or end host finds its 6750 desired multicast source. Involved mechanisms like saving the 6751 information of active sources in MMT by C-RP'(s) and also the unicast 6752 nature of Source discovery messages sent from clients to C-RP'(s) 6753 provides the ability of keep track of existing multicast sources and 6754 receivers or better to say how many receivers and sources do exist 6755 for the same multicast group. 6757 By definition a Bidirectional Multicast Group is a group for which 6758 lots of simultaneous senders and receivers do exist or better to say 6759 it is a group for which a sender is also a receiver. 6761 PIM-NG Bidirectional specifications with regards to Autosense are as 6762 follows 6764 1- Autosense is the default mode of PIM-NG Bidirectional logic. 6766 2- Autosense is suitable for any type of multicast domain and MUST 6767 only be used when there is only one multicast domain. That being 6768 said it is not advised to use it in scenarios with multiple 6769 domains connected to or through a core domain. For such scenarios 6770 it is suggested to ONLY use the Manual mode. 6772 3- In PIM-NG a multicast group G for which at least 1 unicast address 6773 is seen by C-RP as both the source and receiver IS considered a 6774 Bidirectional multicast group. So in a PIM-NG domain with 6775 Bidirectional Source Autosense discovery mechanism activated on 6776 its C-RPs and C-MAPPER'(s) when a C-RP receives a Request for 6777 source type of message for multicast group G from a client whose 6778 unicast address is also registered as the source of that same 6779 multicast Group G the C-RP becomes aware that it is dealing with a 6780 Bidirectional multicast group and thus it immediately informs the 6781 closest C-MAPPER about it by sending the so called Bidirectional 6782 Groups Table in its unicast introductions to the C-MAPPER 6783 containing the multicast Group with both the TR group and R-Flag 6784 fields being set to 0. 6786 4- As soon as a Multicast Group (G) is announced as a Bidirectional 6787 Multicast Group, the Logic of the Domain for that (G) MUST change 6788 to Bidirectional and Sources and receivers MUST immediately join 6789 the SPT rooted at closest TR or better to say receivers which are 6790 also considered sources will send their join to the TR as the 6791 Source. 6793 5- The C-RP'(s) MUST send the BGT to C-MAPPER immediately whenever it 6794 senses a change by setting the ZTCN bit in its message. 6796 6- Receiving the message containing the BGT from a C-RP, the C-MAPPER 6797 MUST immediately inform all the existing Clients by sending an 6798 introduction message containing the BGT to 239.0.1.190. 6800 7- When the Active C-MAPPER receives an introduction from either a C- 6801 RP or other C-MAPPERs containing BGT it MUST immediately inform 6802 all the other C-MAPPERs it is in contact with so that all the C- 6803 MAPPERs become aware of the situation. 6805 8- If more than 1 C-MAPPER exists and due to the fact that in such 6806 cases and with regards to chapter 4.5.2. The Active C-MAPPER is 6807 responsible for all the introductions sent to 239.0.1.190, any C- 6808 MAPPER that receives a BGT showing a change MUST inform the Active 6809 C-MAPPER. So in case of multiple C-MAPPERs each C-MAPPER receiving 6810 a BGT with the R-Flag being set, MUST inform the Active and if the 6811 Active doesn't receive a BGT with the associated R-Flag of 6812 Bidirectional group (G) not beibg set which shows that there are 6813 still senders and receivers, in the next 15+2 minutes it MUST 6814 inform all the population about the change and removal of that 6815 group from Bidirectional logic. 6817 9- If the SUB-Domain concept is implemented the Active C-MAPPER in 6818 the main domain MUST inform all C-MAPPERs inside Sub-Domains by 6819 sending BGT to them. 6821 10- In scenarios with SUB-Domains implemented it is possible to 6822 filter any desired Bidirectional Multicast group from being 6823 updated to the Active C-MAPPER within each Sub-Domain by the 6824 Active C-MAPPER in the main domain. 6826 11- BGT MUST BE exchanged between neighbor clients when a new client 6827 is added at the time of synchronization. 6829 12- When the Autosense mechanism is used, it is possible to remove a 6830 multicast group from the Bidirectional logic or announce it 6831 deactivated. This can be done by defining the group (G) on the C- 6832 MAPPER or Active C-MAPPER and introduce it to population by 6833 setting the R-Flag in the BGT. 6835 13- If a PIM-NG aware router senses that it is in ideal state for a 6836 Bidirectional Group for 60 minutes or better to say it hasn't 6837 received any updates from the C-MAPPER about group (G) nor it has 6838 been part of the Bidirectional Tree for that (G) it MUST remove it 6839 from its internal BGT and change its logic until further notice 6840 from the C-MAPPER. 6842 14- Each TR MUST send an empty BGT to the closest C-MAPPER every 10 6843 minutes to the C-MAPPER. This empty table is a sign that all the 6844 groups that are announced by the C-MAPPER are active. And 6845 eventually C-MAPPERs MUST inform the Active C-MAPPER about the 6846 situation. 6848 15- If a TR is pruned from the Bidirectional Tree of group (G)or 6849 better to say it is not part of the Bidirectional tree of (G) for 6850 20 minutes it announces this to C-MAPPER by sending the BGT and 6851 putting an entry for that group (G) in the table plus setting the 6852 R-Flag for that group 6854 16- If C-MAPPER or Active C-MAPPER doesn't receive a BGT from at 6855 least one TR showing that all the announced Bidirectional Groups 6856 are active for 50 minutes or 5 times to the default time TRs must 6857 send their periodical messages containing BGT to C-MAPPER , it 6858 MUST announce that (G) not active by sending a BGT and setting the 6859 associated R-Flag of that Group so that all the population will 6860 remove that group until further notice or better to say until at 6861 least one source for that group becomes active. 6863 17- If a PIM-NG aware router doesn't need to be anymore part of the 6864 Bidirectional Tree for (G) it will send a Prune to upstream 6865 routers and all the rules with regards to a prune message and 6866 shared networks in which more than one router are connected 6867 through a shared media are applicable. 6869 4.7.3. Redundant TRs 6871 This section is dedicated to talk about a special feature of PIM-NG 6872 Bidirectional logic which makes it possible to use multiple redundant 6873 Tree Roots per bidirectional Multicast group and eventually as it is 6874 described later to have redundant Bidirectional Trees per multicast 6875 group rooted at existing TRs. 6877 In a PIM-NG multicast domain with at least 2 TRs, it is possible to 6878 use either all existing TRs in a redundant manner or use a handful of 6879 TRs and associate them with 1 set of bidirectional multicast groups 6880 and associate other TRs to other groups depending on the needs of 6881 multicasting. 6883 Both of the above mentioned factors are desirable in dense 6884 environments with many senders and receivers for the same G and 6885 residing in different parts of the domain. In the following sections 6886 I am going to explain the 2 different approaches PIM-NG provides with 6887 regards to existing TRs and redundancy of Tree Roots. 6889 4.7.3.1. ANYCAST Approach 6891 As the name suggests, this method uses the ANYCAST concept with 6892 regards to the available TRs within a multicast domain and how they 6893 are introduced by the C-MAPPER. 6895 By using this method it doesn't matter how many TRs exist in a PIM-NG 6896 multicast domain, because the C-MAPPER updates only one unicast 6897 address for existing TRs in its PDTT with the TR group field being 6898 set to 0. 6900 As soon as Clients receive the information about the unicast address 6901 of the TRs and with regards to Bidirectional logic explained so far, 6902 each client immediately joins the SPT for G rooted at the closest TR 6903 by setting the source unicast address to the unicast address of the 6904 TR and also setting the R-bit of the source address which indicates 6905 that the join message should be forwarded towards the TR. 6907 PIM-NG specifications dictates that a join message in which the 6908 source unicast address and Tree Root addresses are the same is a sign 6909 of a Bidirectional join message and thus in addition to the Multicast 6910 group address received in BGT tells intermediary clients that their 6911 logic MUST change to Bidirectional for such messages. 6913 At the end of above procedure each client that needs to be part of 6914 the Bidirectional Tree for G joins the SPT rooted at the closest TR. 6916 4.7.3.2. TR Grouping 6918 There are scenarios in which it is not desirable to use all the 6919 available TRs in Bidirectional processes or it is needed to use some 6920 of the available TRs as the redundant roots of a set of Bidirectional 6921 Groups and other TRs for other sets. 6923 PIM-NG makes such implementation possible through its well mannered 6924 design in a way that it is now possible to consider any one of the 6925 bellow approaches that suits well: 6927 1- Use the ANYCAST method of TR introduction alongside the Grouping 6928 of TRs. In this approach all the TRs are introduced for normal 6929 multicast routing using the ANYCAST address and a selected group 6930 of TRs can be introduced in addition to the ANYCAST with their 6931 unicast address used for communication between TRs and C-MAPPERs 6932 alongside their TR group which is manually configured on the 6933 Active C-MAPPER. In such case clients MUST only use the TRs with 6934 TR Group number other than 0 when dealing with Bidirectional 6935 multicast groups. 6937 2- Use only Grouping of TRs. In this approach only the unicast 6938 address of available TRs are updated by the C-MAPPER alongside 6939 their TR group which is set manually on the Active C-MAPPER. It is 6940 also possible to use more than one Anycast Address when using TR 6941 Grouping. In this manner each group of TRs will be assigned a 6942 separate and unique Anycast Address which will eventually reduced 6943 the size and entries of PDTT. 6945 Both of the above methods are usable, although, the second approach 6946 will result in huge amount of data in PDTT updated by C-MAPPER. No 6947 matter which method is used clients will use the groupings ONLY when 6948 dealing with Bidirectional multicast groups. 6950 For this method to be implemented a series of processes MUST take 6951 place which are listed below: 6953 1- TRs MUST be manually grouped on the C-MAPPER or the Active C- 6954 MAPPER. This is done by simply assigning a group number with a 6955 value between 0 and 255 to each desired set of TRs, with value 0 6956 being reserved for introducing TRs using ANYCAST method and value 6957 255 reserved for introducing a TR which is part of all 6958 Bidirectional Groups. This group value is used later by clients at 6959 the time of choosing which TR they must send their join towards as 6960 the root of the Bidirectional tree. 6962 2- A TR which is part of all TR groups which is introduced to the 6963 population by TR group value of 255, is called Bidirectional 6964 Translator TR and is used later in inter-domain Bidirectional 6965 connectivity. 6967 3- Then the C-MAPPER MUST update the groupings in its PDTT when 6968 sending its introduction to 239.0.1.190 by setting the TR Group 6969 field associated with each TR to the configured value and send it 6970 to all the population of PIM-NG aware routers so that even 6971 existing TRs will become aware of this groupings. 6973 4- A mapping between existing and activated Bidirectional Multicast 6974 groups and the configured TR Groups on the Active C-MAPPER MUST be 6975 done either through manual configuration or an algorithm which 6976 through a hashing mechanism assigns and maps each set of 6977 Bidirectional multicast group to a TR group. It is suggested to 6978 use the automated method through the proposed algorithm which is 6979 useful when dealing with the Autosense mechanism of Bidirectional 6980 source discovery or big multicast domains. 6982 5- Finally when the C-MAPPER is going to notify the PIM-NG population 6983 about activated Bidirectional Groups by sending the BGT in its 6984 introduction messages, it MUST set the TR Group field associated 6985 to each Bidirectional Multicast group with the related and mapped 6986 TR group. 6988 6- Clients will receive the mappings in the BGT and since they know 6989 which TR belongs to which Group because they have received it 6990 before in PDTT sent by C-MAPPER, they eventually know which TR 6991 should be used as the root of each Tree and will use the unicast 6992 address of the appropriate TR which is the closest one to them to 6993 join SPT. 6995 7- A TR CAN BE a member of multiple groups and a C-MAPPER MUST send 6996 the groupings as individual entries in its PDTT. The only 6997 exception is for Bidirectional translator TR'(s) that are 6998 identified by TR group 255. 7000 8- If a TR which is member of a group is lost and by lost PIM-NG 7001 specifications means the loss of connectivity between TR and C- 7002 MAPPER in a way it is sensed by C-MAPPER, the C-MAPPER MUST choose 7003 a suitable TR to replace the lost TR and automatically update it 7004 by sending the unicast address of the new TR and associated group 7005 in its PDTT. By suitable, PIM-NG specifications means the closest 7006 TR to the current TR based on the information found in RIB. 7008 9- If the above happens and a TR from a group is lost and a new TR is 7009 chosen automatically and the chosen TR is already member of other 7010 TR group'(s), then C-MAPPER MUST update all the Groups the TR is a 7011 member of in its PDTT as separate entries again. This is a MUST as 7012 if a TR is a member of group A and it is also chosen to become a 7013 member of group B, if the C-MAPPER send an update with only an 7014 entry for group B, clients MUST and will take it as if the TR can 7015 be used ONLY for Bidirectional Groups with associated TR group B. 7017 10-If a lost TR part of a TR group becomes alive again, the C-MAPPER 7018 MUST send an update including PDTT with an entry for the activated 7019 TR and removing the TR which was automatically chosen as its 7020 replacement. 7022 4.7.4. Bidirectional Tree formation 7024 Tree formation can be considered the most important part of PIM-NG 7025 Bidirectional logic as it provides the ability to benefit from 7026 redundant Roots per Bidirectional Tree and eventually redundant 7027 Bidirectional trees per multicast group. 7029 The basic rule of Bidirectional PIM with regards to tree formation 7030 and joining the SPT rooted at the TR applies to PIM-NG too, except 7031 for the fact that in PIM-NG actually no shared path tree exists and 7032 join messages carry the unicast address of a TR as the source of 7033 multicast group in (S, G) format. So in the following sections I will 7034 explain the process through which a Bidirectional Tree is formed 7035 between TRs and the how clients join the Tree rooted at the closest 7036 TR. 7038 4.7.4.1. Tree formation between TRs 7040 As described before in a PIM-NG domain each TR knows the unicast 7041 address of other TRs because they receive it from the C-MAPPER. This 7042 address is not the ANYCAST address but the address used by TRs to 7043 introduce themselves to the closest C-MAPPER and communicate with the 7044 C-MAPPER and other TRs to exchange their joined groups table. 7046 Because of the above feature of PIM-NG with regards to TRs, it is 7047 very easy to make the TRs join a Tree using the unicast address of 7048 other TRs as the source address of a multicast group (G). 7050 The above approach works well in normal PIM-NG multicast 7051 communications because it might be needed to forward a received join 7052 message towards a TR which already joined the SPT for (S, G) and is 7053 closer than the source itself and can be placed anywhere in the 7054 domain, but when it comes to Bidirectional communications and tree 7055 formation between the TRs PIM-NG's approach is a little different. 7057 PIM-NG specifications and processes with regards to Tree formation 7058 between TRs are as follows: 7060 1- If a TR receives a join message for Bidirectional Group (G) it 7061 MUST first check the contents of its internal Joined Groups Table 7062 which indicates all the multicast groups other TRs residing in the 7063 domain already joined the Tree for. 7065 2- If an entry matching Bidirectional group (G) is found in the 7066 Joined Groups table, TR MUST forward the received join message 7067 towards the TR which is already joined the Bidirectional Tree for 7068 (G) by changing the Source unicast address and TR unicast address 7069 of the join message with the unicast address of the TR which is 7070 already joined the Bidirectional Tree for (G) without touching the 7071 R-Bit. 7073 3- If multiple entries matching Bidirectional group (G) are found, TR 7074 MUST forward the join message towards the closest TR. 7076 4- If a TR receives a join message for a Bidirectional Group (G) and 7077 ONLY if there are no entries matching Bidirectional Group (G) in 7078 joined Groups table, it MUST inform other TRs by updating its 7079 Joined Groups table and send it in its introduction message to 7080 other TRs. 7082 5- If the ANYCAST TR approach is used the Joined Groups table MUST be 7083 sent to all the existing TRs. 7085 6- If the TR grouping approach is used, the Joined Groups Table MUST 7086 be sent to all the TRs that are member of the same group and 7087 specifically to Bidirectional Translator TR'(s) which are a member 7088 of all existing Groups and are used in Inter-Domain connectivity. 7090 7- The above method will form a distributed Bidirectional Tree for 7091 group (G) with multiple TRs as the Roots of the tree and more 7092 importantly this tree is formed whenever it is demanded and won't 7093 waste much bandwidth. 7095 8- Please refer to section 4.7.5. For information about Bidirectional 7096 Tree formation between different PIM-NG multicast domains. 7098 Through the above approach and process at the end a Bidirectional 7099 Tree with multiple TRs as its redundant roots forms nicely between 7100 existing TRs whether the ANYCAST approach or the TR grouping approach 7101 is used. All the TRs are working redundantly which provides higher 7102 Bidirectional communications speed due to the fact that each client 7103 can simply get connected to its closest TR. This approach is mostly 7104 beneficial in dense environments such as data centers where we are 7105 dealing with high number of senders and receivers who are in 7106 different parts of the domain. 7108 Also needless to say this approach provides the possibility of inter- 7109 domain Bidirectional connectivity wherever applicable with bellow 7110 specifications: 7112 1- A C-MAPPER in the remote multicast domain or core domain MUST 7113 become aware of the activated Bidirectional Groups through 7114 receiving a BGT from its neighbor or manual configuration. To make 7115 it clear the 2 domains MUST be neighbors or better to say a 7116 neighbor ship between C-MAPPERs in desired domains MUST be 7117 established. 7119 4.7.4.2. Completing the Tree formation 7121 Final stage of a full Bidirectional Tree formation will be clients to 7122 join the Tree for (G). 7124 Each Client with need to send and receive the traffic of 7125 Bidirectional Multicast group (G) MUST join the SPT rooted at the 7126 closest TR. 7128 If the ANYCAST approach is used then each client MUST use the ANYCAST 7129 address as the Root address and also unicast address of the source 7130 for (G) when sending the join message. And in case of TR grouping the 7131 unicast address of the closest TR associated to (G) with respect to 7132 the information it has received from C-MAPPER in BGT and PDTT. 7134 At the end a distributed redundant Bidirectional tree with regards to 7135 the Roots and Tree formation between clients and Roots will form 7136 which covers an entire domain and is a feature desirable in dense 7137 environments. 7139 [Figure is presented in PDF version] 7141 Figure 56 Bidirectional Tree formation with ANYCAST TR Address 7143 [Figure is presented in PDF version] 7145 Figure 57 Bidirectional Tree formation with TR grouping 7147 4.7.5. Inter-Domain Bidirectional connectivity rules 7149 1- As described previously a C-MAPPER in a core domain MUST introduce 7150 existing TR'(s) within its domain to their neighboring C-MAPPERs 7151 in connected domain'(s). This procedure is a MUST in Bidirectional 7152 logic to help TR'(s) in domains communicate with TR'(s) in core 7153 domains to exchange their joined groups table. 7155 2- C-MAPPER'(s) within PIM-NG domains MUST introduce at least one TR 7156 to their neighbors alongside the associated Domain number so that 7157 the TR is distinguishable. This is done by exchanging the unicast 7158 address of selected TR'(s) in PDTT. PIM-NG specifications dictates 7159 that the ONLY time a C-MAPPER uses its PDTT to send any 7160 information to its neighbors in other domains is when 7161 Bidirectional logic is being used and only the information of 7162 TR'(s) MUST be exchanged between C-MAPPER'(s) in normal domains or 7163 between a C-MAPPER in a normal domain and a C-MAPPER in the core 7164 domain. 7166 3- Unicast address of any TR that is received in PDTT from a neighbor 7167 C-MAPPER in another domain MUST only be sent to existing TRs and 7168 not all the population alongside the Domain number value 7169 associated to the TR to make the TR distinguishable. This is 7170 different from what happens with TRs in a core domain because as 7171 it had been explained the unicast address of TR'(s) within a core 7172 domain received in Core Domain topology Table MUST be sent to all 7173 the population by the C-MAPPER or Active C-MAPPER. 7175 4- When dealing with inter-domain Bidirectional connectivity 7176 scenarios, PIM-NG STRONGLY advises to use ANYCAST method explained 7177 in chapter 4.7.3.1. In all the involved domains to ease the 7178 processes. 7180 5- As explained before it is also possible to update selected TRs to 7181 other domains through manual configuration. This being said, if in 7182 a domain TR grouping method is and must be used, then one or more 7183 TRs must be chosen to act as Bidirectional Translator TR with TR 7184 group number of 255 and the unicast address of the Bidirectional 7185 translators MUST be updated in either PDTT or Core Domain Topology 7186 Table. This is due to the fact that only a TR which is part of all 7187 TR groups or better to say can be aware of all active or to be 7188 active Bidirectional Groups can be involved in inter-domain 7189 connectivity. 7191 6- The joined groups table exchanged between TR's in different 7192 multicast domains MUST only contain the information regarding 7193 Bidirectional Groups. 7195 7- If the TR grouping approach is used, ONLY the Bidirectional 7196 Translator TR'(S) MUST send Joined Groups Table to TR'(s) in other 7197 domains when dealing with Bidirectional Groups. This is due to the 7198 fact a Translator TR is the only TR within a PIM-NG domain to know 7199 about all the active multicast groups and will receive the Joined 7200 Groups Table from all existing TRs member of any available TR 7201 group. 7203 8- When a TR receives a join for (G) from a client and there is no 7204 entry for (G) in its Joined Groups Table matching (G) it MUST 7205 inform other TRs. 7207 9- If the ANYCAST approach is used then TRs in other domains will 7208 receive the Joined Groups table too and if they receive a join 7209 from a client they will forward the join towards TR'(s) in other 7210 domains which are already joined the Bidirectional Tree for (G). 7212 10- If TR grouping is used and since only the Translator TR is 7213 allowed to communicate with TRs in other Domains, the joined 7214 Groups table MUST be sent to the Translator TR and Translator TR 7215 MUST inform TRs in other Domains no matter if it is already joined 7216 the Bidirectional tree for (G) or not. 7218 11- When a PER or PPER receives a join for a Bidirectional Group form 7219 outside its domain and the TR grouping is used, it MUST forward it 7220 towards the closest Translator TR. 7222 12- When a PER or PPER receives a join for a Bidirectional Group form 7223 outside its domain and the ANYCAST approach is used, it MUST 7224 forward it towards the closest TR. 7226 13- When a Translator TR receives a join for Bidirectional Group (G) 7227 it MUST forward the join towards the closest TR already joined the 7228 tree for (G) based on the TR grouping information associated with 7229 the TRs and its internal Joined Groups Table mappings. This is why 7230 it is called a Translator as it allows to connect a domain in 7231 which ANYCAST is used to a domain in which TR grouping is used or 7232 the other way around or to connect domains with different TR 7233 groupings in use. 7235 14- When a Translator TR receives a join message for (G) and ONLY if 7236 there are no entries matching (G) in its Joined Groups Table it 7237 MUST inform other TRs based on TR grouping and mappings to 7238 Bidirectional Groups. 7240 15- Since by definition a TR only accepts control plain packets from 7241 TRs inside its domain, a mechanism MUST be taken into 7242 consideration with regards to ONLY Bidirectional logic so that 7243 TR's accept Joined Groups Table from desired TRs with regards to 7244 the domain in which they reside. This can be simply a manual 7245 configuration through which a TR becomes aware of to which TR in 7246 which Multicast domain it can send Joined Groups table and from 7247 which TRs it can accept such table. 7249 16- It is STRONGLY advised not to use the Autosense mechanism 7250 explained in(4.7.2.2. ) when dealing with Inter-domain 7251 connectivity. 7253 17- If in involved domains the Autosense mechanism (4.7.2.2. ) is 7254 needed to be implemented, then C-MAPPERs in involved domains MUST 7255 exchange their BGTs to inform each other about any changes. 7257 18- If Autosense mechanism is implemented and Bidirectional group (G) 7258 is needed to become deactivated totally, it MUST only be done 7259 within the domain the C-MAPPER or Active C-MAPPER is resided and 7260 it MUST NOT be announced to C-MAPPERs in other domains.. 7262 At the end through all the above specifications, definitions and 7263 concepts PIM-NG provides the ability to easily benefit from having a 7264 distributed Bidirectional Tree for group (G) with redundant Tree 7265 ROOTs and Redundant Trees. This behavior is one of the many features 7266 it provides and is specifically beneficial for data centers or 7267 whatever multicast domain with huge number of distributed multicast 7268 sources and receivers for the same group (G). 7270 Also as explained it also provides the possibility to bring the 7271 Inter-Domain connectivity concept with regards to Bidirectional Tree 7272 which makes it a good choice for such scenarios. 7274 4.8. PIM-SM compatibility 7276 Up to this point of explaining different concepts of PIM-NG as a new 7277 multicast protocol, almost ALL aspects of PIM-NG specifications have 7278 been covered. 7280 Now it is time to make it compatible with its predecessor PIM-SM, so 7281 that PIM-NG multicast domains can be connected to PIM-SM domains or a 7282 network of PIM-SM domains. Compatibility of PIM-NG with PIM-SM is 7283 related to the bellow fields: 7285 o Exchanging the information regarding the multicast sources 7286 originated in either the PIM-NG Domain'(s) or PIM-SM Domain'(s), 7287 so that receivers can find the source for their desired 7288 multicast traffic and send join/prune messages towards the 7289 desired multicast source, whether it is inside a PIM-NG Domain 7290 or PIM-SM Domain. 7292 o The transformation of PIM-NG join/prune messages to PIM-SM 7293 messages so that routers that are only PIM-SM aware will be able 7294 to forward the join/prune messages to the final destination. 7296 o The transformation of PIM-SM join/prune messages to PIM-NG 7297 join/prune messages so that the join/prune message can be 7298 forwarded according to PIM-NG specifications within the network 7299 of PIM-NG Domains. 7301 In the following sections, different concepts, specifications and 7302 rules in regards to connecting a PIM-NG multicast domain to a PIM-SM 7303 multicast domain will be discussed. First the concepts regarding the 7304 exchange of information regarding originated multicast sources in the 7305 form of Source Active (SA) messages will be discussed and after that 7306 the concepts related to sending join/prune messages will be 7307 discussed. 7309 4.8.1. PIM-SM compatibility and SA messages 7311 As described by RFC 3610[9], the information regarding originated 7312 multicast sources MUST be exchanged between RPs that are MSDP peer. 7313 And such information is sent from one RP to another RP, in a Source 7314 Active (SA) message, which contains: 7316 o Originator address or the unicast address of the originating RP 7318 o Source address or the unicast address of the source generating 7319 the traffic 7321 o Group address the source sends data to 7323 And In PIM-NG as described in section 4.5. , the information 7324 regarding newly originated multicast sources is carried inside AMMT 7325 and between peer C-MAPPERs using unicast-encapsulated C-MAPPER 7326 introductions, which contains: 7328 o Originator address or the unicast address of the originating RP 7330 o Source address or the unicast address of the source generating 7331 the traffic 7333 o Group address the source sends data to 7335 o Domain-Set 7337 As it has been described, the format of AMMT and the information 7338 related to newly originated multicast sources is similar to the 7339 contents of SA messages used by PIM-SM MSDP peers, which makes it 7340 easier to connect a PIM-NG Domain or a network of PIM-NG multicast 7341 domains to a PIM-SM Domain or a network of PIM-SM multicast Domains. 7342 And by connecting in this section PIM-NG specifications refers to the 7343 exchange of information regarding multicast sources. 7345 The rules, concepts and specifications regarding compatibility of 7346 PIM-NG and PIM-SM are as follows: 7348 o Depending on whether we are dealing with a public or private 7349 PIM-NG domain, a C-MAPPER or PPER in the PIM-NG Domain MUST BE 7350 chosen to become MSDP-PEER with an RP in the PIM-SM Domain. 7352 o All the rules that apply to MSDP [9] MUST be applied when a C- 7353 MAPPER or PPER becomes MSDP-PEER with an RP. 7355 o Whenever a C-MAPPER which is also MSDP-PEER with an RP, 7356 receives an update regarding newly originated multicast sources 7357 inside the AMMT from a PEER C-MAPPER and needs to advertise the 7358 received update to the MSDP-PEER'(s): 7360 1. It MUST remove the DOMAIN-SET of any multicast sources 7361 that are to be advertised to the MSDP-PEER'(s) 7363 2. It MUST create a Source Active message containing 7364 information regarding ALL multicast sources that are to be 7365 advertised to the MSDP-PEER'(s). 7367 3. The SA message contains ONLY: 7369 o Originator address 7371 o Source unicast address 7373 o Group destination 7375 Which is exactly what an SA carries. 7377 o Then the C-MAPPER MUST send the SA message to its MSDP-PEER'(s) 7378 the way explained by MSDP specifications [9] to bring 7379 compatibility to PIM-SM. 7381 o Because of the RPF method used by MSDP, the C-MAPPER or PPER 7382 which is becoming MSDP-PEER with an RP MUST reside in the first 7383 Autonomous System in the best path towards the AS in which the 7384 originator C-MAPPER exists. 7386 o As explained by PIM-NG specifications, each multicast source 7387 has a Domain-Set associated with it, which shows that in which 7388 domain a source is being originated and also is used for PIM-NG 7389 RPF check. So when a C-MAPPER receives an SA message from a 7390 MSDP-PEER (RP), and needs to advertise the information to a PEER 7391 C-MAPPER, it MUST add the following to the Domain-Set: 7393 1. Its own domain number 7395 2. A value equal to letter "S" which shows that this source 7396 is received from a network of PIM-SM Domain'(s). So if C- 7397 MAPPER in Domain1 receives an update for (S, G) from its 7398 MSDP-PEER, and needs to update it to its PEER C-MAPPER'(s), 7399 it MUST modify the Domain-Set as explained and advertise 7400 the associated Domain-set as (D S, 1). 7402 o If a C-MAPPER receives an update for (S,G) from a MSDP-PEER, 7403 and an update for the same (S,G) from a peer C-MAPPER which the 7404 associated Domain-Set indicates that (S,G) is originated inside 7405 a PIM-NG Domain and not a PIM-SM domain, then the update 7406 received from the peer C-MAPPER MUST pass the RPF check. 7408 o If a C-MAPPER receives an update for (S,G) from a MSDP-PEER, 7409 and an update for the same (S,G) from a peer C-MAPPER which the 7410 associated Domain-Set indicates that (S,G) is originated inside 7411 a PIM-SM Domain and not a PIM-NG domain, then the update 7412 received from the MSDP-PEER MUST pass the RPF check. 7414 o If a C-MAPPER receives an update from a peer C-MAPPER regarding 7415 sources that MUST be considered as SUSPENDED, the C-MAPPER MUST 7416 NOT send any SA message to MSDP-PEER'(s) until the suspension 7417 time is over and the multicast sources are either deleted or 7418 active again. 7420 o If a C-MAPPER loses its connectivity with its MSDP-PEER, it 7421 MUST start the suspension timer and send an update about the 7422 suspended multicast sources to peer C-MAPPER, and if after the 7423 suspension duration which defaults to 5 minutes, the connection 7424 with the MSDP-PEER is not established again, it MUST delete the 7425 received multicast sources from that MSPD-PEER and inform peer 7426 C-MAPPER'(s).or if it has been receiving updates regarding those 7427 sources from a peer C-MAPPER or MSDP-PEER it MUST put the 7428 received updates from those peers in it's a-MULTICAST MAPPING 7429 TABLE and inform its PEER'(s). 7431 o . 7433 4.8.2. PIM-SM compatibility and join/prune messages 7435 A PIM-NG multicast Domain is connected to a PIM-SM multicast Domain, 7436 using a PER or PPER to isolate the 2 multicast Domains and prevent 7437 the propagation of multicast introduction messages of PIM-NG Domain 7438 in to PIM-SM Domain and also to prevent the propagation of PIM-SM 7439 multicast traffic related to BSR[9] and RP'(s) within the PIM-SM 7440 domain. 7442 As mentioned in different parts of PIM-NG specifications, a PER or 7443 PPER which acts as boundary between a PIM-NG Multicast Domain and a 7444 PIM-SM Multicast Domain is called a BORDER-PIM-ROUTER(BPR). And the 7445 responsibility of exchanging join/prune messages between the 2 7446 Domains is on the BPR. But due to the fact that PIM-NG uses its own 7447 version of join/prune message which is different from that of PIM-SM 7448 in parts related to the Tree Root UNICAST ADDRESS, a BPR MUST modify 7449 the join/prune messages received from a PIM-SM Domain and likewise it 7450 MUST do the same when forwarding join/prune messages from a PIM-NG 7451 Domain to a PIM-SM Domain. 7453 Bellow specifications, concepts and rules apply when a join/prune 7454 message is forwarded from a PIM-NG domain to a PIM-SM domain and 7455 likewise from a PIM-SM Domain to a PIM-NG Domain: 7457 o If a PER is chosen to act as a BPR, then as soon as the PER is 7458 configured and becomes aware that it is connected to a PIM-SM 7459 Multicast Domain, it MUST introduce itself to the closest C- 7460 MAPPER within the PIM-NG Multicast Domain. The BPR introduction 7461 is done by the PER and through sending a unicast-encapsulated 7462 introduction message (4.6.1.2. ) to the closest C-MAPPER or any 7463 C-MAPPER that is introduced to the PER. The type of the 7464 introduction message is set to BPR, and the B-BIT in the 7465 introduction message MUST BE set which indicates to the 7466 receiving C-MAPPER that it's Domain is connected to a PIM-SM 7467 Domain and it MUST start sending the full AMMT to the PER. 7469 o If a PPER is chosen to act as BPR the introduction process as 7470 the BPR is not needed due to the fact that the PPER MUST 7471 introduce itself to the closest C-MAPPER or any C-MAPPER that is 7472 introduced to it as soon as it is configured to be a PPER. 7474 o A BPR has 2 types of interfaces: 7476 1. Internal: an internal interface is connected to the PIM- 7477 NG Domain. 7479 2. External: an external interface is connected to the PIM- 7480 SM Domain. 7482 o A BPR MUST convert any PIM-NG join/prune messages for (S,G) it 7483 receives from within the PIM-NG Domain or better to say on an 7484 internal interface to a PIM-SM join/prune message, before 7485 forwarding it on an external interface which is connected to a 7486 PIM-SM Domain. The conversion process is not time consuming, due 7487 to the fact that the PIM-NG join/prune messages are designed to 7488 be similar to PIM-SM join/prune messages as much as possible. 7490 o A BPR MUST convert the join/prune messages it receives on an 7491 external interface connected to a PIM-SM Domain, ONLY under 7492 these conditions: 7494 1. At least one TR MUST do exist in the PIM-NG Domain. 7496 2. If no TR exists inside the PIM-NG Domain, then For each 7497 (S,G) in the join/prune message, the BPR MUST first check 7498 it's AMMT which it receives from the C-MAPPER'(s) inside 7499 the PIM-NG Domain. And ONLY IF: 7501 o It finds an entry inside the AMMT for the (S,G). 7503 o The Domain-Set associated with the (S, G) indicates 7504 that the (S, G) is reachable via a connected PIM-NG- 7505 CORE-DOMAIN, or better to say the update regarding 7506 the (S,G) is passed through a PIM-NG-CORE-DOMAIN. 7508 The BPR MUST convert the PIM-SM join/prune message to PIM-NG 7509 join/prune message, and fill out the required fields related 7510 to the TR UNICAST ADDRESS and CORE TR UNICAST ADDRESS. 7512 o If none of the above conditions are meat, PIM-NG specifications 7513 STRONGLY ADVISES that the BPR DO NOT convert the PIM-SM 7514 join/prune message and only forward it to the next hop in the 7515 best path towards the source. 7517 o The above being said, ALL PIM-NG-AWARE routers MUST BE PIM-SM 7518 Compatible in parts mostly related to forwarding join/prune 7519 messages. 7521 o if a BPR receives a join/prune message for (G) on an external 7522 interface connected to PIM-SM with the S-BIT of SOURCE UNICAST 7523 ADDRESS being set, which means that the join/prune is a PIM 7524 version 1 type of message it MUST NOT convert the PIM-SM 7525 join/prune to PIM-NG join/prune. 7527 4.9. Loop prevention 7529 In order to have a loop free multicast domain PIM-NG suggest the use 7530 of Reverse Path Forwarding check(RPF)to prevent any loops from 7531 occurring. 7533 Such loops can be under one of the bellow categories: 7535 o C-MAPPER multicast introduction or notification messages 7536 destined to 239.0.1.190 and sent to ALL-PIM-NG-AWARE routers 7537 within a multicast domain. 7539 o C-MAPPER multicast introductions destined to 239.0.1.188 which 7540 is used by existing C-MAPPER'(s) to find either a backup or peer 7541 C-MAPPER. 7543 o C-RP multicast introductions destined to 239.0.1.189 which is 7544 used by existing C-RP'(s) to find either a backup or peer C-RP. 7546 o Loops occurring due to a join/prune message which is sent hop 7547 by hop towards an existing source by a client which needs to 7548 join the SPT for (S, G) in scenarios which clients are connected 7549 to each other through switches and within a LAN. 7551 To eliminate and prevent such loops PIM-NG uses the RPF check method 7552 and concept used by PIM-SM which is the best current practice. And 7553 since no shared tree (*, G, rpt) rooted at RP forms in PIM-NG there 7554 won't be any need for such RPF check although since PIM-NG-AWARE 7555 routers are by default PIM-SM compatible it MUST be considered. 7557 The bellow rules MUST be applied to prevent any loops by the unwanted 7558 propagation of such multicast introductions: 7560 o PIM-NG boundary routers such as PER, PPER, BPR or EDGE- 7561 CLIENT'(S) MUST NOT forward such introduction messages to 7562 other domain'(s) in case of PER, PPER and BPR and down the 7563 MULTI-ACCESS network in case of EDGE-CLIENT'(S). 7565 o C-MAPPER'(S) which receive an introduction message destined to 7566 either 239.0.1.190 or 239.0.1.188 with the source address 7567 being equal to C-MAPPER'(s) address MUST discard the packet 7568 and NOT forward any further. 7570 o C-RP'(S) which receive an introduction message destined to 7571 either 239.0.1.189 with the source address being equal to C- 7572 MAPPER'(s) address MUST discard the packet and NOT forward any 7573 further. 7575 4.10. DR election and PIM Assert Message 7577 PIM-NG specifications suggest using the processes and concepts 7578 introduced and defined by PIM-SM [7] with regards to Assert messages 7579 and DR election as the best current practice when dealing with 7580 scenarios and topologies involving multi-access LAN'(s). 7582 The only place that the DR election is different from that of PIM-SM 7583 is in implementations and topologies in which EDGE-CLIENT'(s) are 7584 considered at the edge of a multi-access network which allows the 7585 administrators to dictate the DR for the Multi-Access network by 7586 manipulating the priority of Edge-Clients. So the Edge-Client with 7587 higher priority becomes the DR for the entire Multi-Access network. 7589 5. Security Considerations 7591 This section is going to cover some of the security concerns related 7592 to PIM-NG specifications covered in this document, and possible 7593 solutions for those security issues. As this document is an earlier 7594 version of PIM-NG specifications, only related security issues are 7595 going to be covered. 7597 5.1. Attacks based on forged messages 7599 The extent of possible damages depends on the type of messages that 7600 are forged. PIM-NG processes use different kinds of messages like 7601 link-local messages, multicast messages and unicast messages. And 7602 each type of message will be discussed separately. 7604 5.1.1. Unicast forged messages 7606 As Register, join and leave messages alongside C-RP introduction 7607 messages sent to C-MAPPER are forwarded by intermediate routers to 7608 their destination using normal IP forwarding, without authentication 7609 there is a high possibility for an attacker anywhere inside the 7610 network, to forge these messages .the effects of such forgery can be 7611 as follows: 7613 1- By forging a register message an attacker can inject forged 7614 traffic into the RP and to the entire PIM-NG domain. 7616 2- By forging join message ,an attacker may become able to act as the 7617 man in the middle and receive a traffic that is not meant for that 7618 receiver .or traffic can be delivered to parts of the network that 7619 no legitimate receivers exists ,which can cause waste of bandwidth. 7621 3- By forging leave message, an attacker can prevent a legitimate 7622 receiver from receiving the traffic it needs. 7624 4- By forging a C-RP introduction message sent to the C-MAPPER, an 7625 attacker can become a real threat to the entire domain, by 7626 injecting false information to the domain. 7628 5- By forging a TR introduction message sent to C-MAPPER, an attacker 7629 can become a real threat to the domain, by becoming a man in the 7630 middle and receive a copy of all the multicast traffic that is 7631 passing through the TR or by dropping the received join/prunes 7632 which can cause the connectivity problems. 7634 5.1.2. Forged link local messages 7636 As Forged Hello messages are sent to link-local ALL-PIM-ROUTERS and 7637 are not forwarded by the compliant router, they can cause problems 7638 such as: 7640 1- If the source of forged message is inside a Multi-access LAN or to 7641 be more specific a local client, it can give an attacker the 7642 possibility of playing the role of an EDGE-CLIENT, and prevent the 7643 legitimate receivers from receiving the desired traffic or reaching 7644 the desired sources. 7646 2- By forging a Hello message an unauthorized client may become able 7647 to play the role of designated router (DR) for a LAN and become 7648 responsible for forwarding traffic on behalf of local members or 7649 hosts. This can prevent hosts from receiving the desired traffic. 7651 3- By forging a Hello message, an unauthorized router in a PIM-NG 7652 domain can become part of the domain and cause damages such as 7653 preventing its neighbors from receiving C-MAPPER introductions or 7654 injecting false information inside the PIM domain topology table. 7656 5.1.3. Forged multicast messages 7658 C-MAPPER introduction messages sent to ALL-PIM-NG clients , MAPPER 7659 introduction messages sent to ALL-PIM-NG-MAPPERs in order to finding 7660 the PEER-C_MAPPERs or SC-MAPPERs and C-RP introduction messages sent 7661 to ALL-PIM-NG-RPs are PIM-NG multicast messages required for the 7662 processes of PIM-NG. But an attacker might become able to forge such 7663 messages and cause damages. The damages that can be done to a PIM-NG 7664 domain are as follows: 7666 1- By forging a C-MAPPER introduction message sent to ALL-PIM-NG- 7667 CLIENTS (239.0.1.190), an attacker can inject false information in 7668 to the domain, by either injecting false data into the PIM domain 7669 topology table. 7671 2- By forging a C-MAPPER introduction message sent to ALL-PIM-NG- 7672 CLIENTS, an attacker can take the role of C-MAPPER and introduce 7673 itself to C-RPs and finally , can cause the clients not to be able 7674 to find the existing C-RPs , and prevent them from receiving the 7675 desired traffic. 7677 3- By forging MAPPER introduction message sent to ALL-PIM-MAPPERs ,an 7678 attacker can become able to take the role of ACTIVE C-MAPPER in the 7679 process of ACTIVE-C-MAPPER election, and also become peer with 7680 other C-MAPPER'(s) and cause damage to the domain by injecting 7681 false data into the A-MULTCAST MAPPING table. 7683 4- By forging RP introduction message sent to ALL-PIM-RPs, an 7684 attacker can be able to take the role of C-RP in the process of C- 7685 RP election or become the ACTIVE C-RP in a C-RP Mesh-Group and also 7686 become peer with other existing C-RP'(s) in search of its peer and 7687 cause problems by injecting false data in to either MULTICAST 7688 MAPPING table or A-MULTICAST MAPPING TABLE. And preventing 7689 legitimate receivers from receiving the desired traffic. 7691 5.2. Non-cryptographic authentication mechanisms 7693 A PIM-NG router should provide an option to limit the set of 7694 neighbors from which it accepts join/prune, Assert, and hello 7695 messages, by either static configuration of IP addresses or an IPSEC 7696 security association CAN be used. And a PIM-NG router should not 7697 accept protocol messages from a router from which it has not yet 7698 received a valid hello message. Also a PIM-NG router SHOULD NOT 7699 accept any hello message from a router that is not within the same 7700 PIM-NG Domain unless it is a PIM-EDGE-ROUTER acting as the boundary 7701 between different PIM-NG Domains. 7703 A Designated Router MUST NOT register-encapsulate a packet and send 7704 it to the C-RP if the source address of the packet is not a legal 7705 address for the subnet on which the packet was received. Similarly, a 7706 PIM EDGE-CLIENT MUST NOT accept a register message from its 7707 downstream PIM-NG Clients, if the source address of the register 7708 message is not a legal address for the subnet on which the register 7709 message is received. 7711 A Designated Router MUST NOT accept a C-RP acknowledge packet whose 7712 IP source address is not a valid C-RP address for the local Domain. 7713 Similarly, a PIM EDGE-CLIENT MUST NOT accept a C-RP acknowledge 7714 packet whose IP source address is not a valid C-RP address for the 7715 local Domain. 7717 A mechanism MUST be considered as an option so that a C-RP restricts 7718 the range of source addresses from which it accepts Register- 7719 Encapsulated packets. Also it is STRONGLY advised to consider a 7720 mechanism through which a C-RP restricts the range of source 7721 addresses from which it accepts C-MAPPER or C-RP introduction 7722 messages, so that a possible attacker cannot send such messages or 7723 such messages from unknown ranges are not accepted. Also as explained 7724 throughout PIM-NG specifications a C-RP MUST NOT accept source 7725 register, C-RP, C-MAPPER messages with different Domain number from 7726 the one dictated to the C-RP. 7728 A mechanism MUST be considered as an option so that a C-MAPPER 7729 restricts the range of source addresses from which it accepts 7730 unicast-encapsulated C-MAPPER, C-RP, PER, PPER, and TR messages 7731 within the same Domain, due to the fact that if dynamic methods 7732 explained by PIM-NG specifications are used if this ranges are not 7733 restricted an attacker may try to introduce itself to the C-MAPPER as 7734 a legitimate component of a PIM-NG Domain. As explained throughout 7735 the PIM-NG specifications, a C-MAPPER MUST ONLY accept C-RP, TR, PER 7736 and PPER introduction messages that carry the same Domain number as 7737 the Domain number dictated to the C-MAPPER. 7739 All options that restrict the range of addresses from which packets 7740 are accepted MUST default to allowing all packets. 7742 5.3. Authentication 7744 Like PIM-SM [7], PIM-NG specifications recommends to use IPSEC [4] 7745 transport mode using the Authentication Header (AH) to prevent the 7746 above attacks against PIM. 7748 The proposed methods of protecting: 7750 o Link-Local Multicast Messages 7752 o Unicast register messages 7754 By PIM-NG, are the methods recommended by PIM-SM Specifications [7] 7755 as the best current method of protecting the above PIM messages. 7757 Since PIM-NG uses processes different from that of PIM-SM in parts 7758 related to: 7760 o The unicast C-RP acknowledge to the DR instead of sending 7761 register stop message. 7763 o Unicast introduction messages, sent from C-RP to C-MAPPER. 7765 o Unicast introduction messages, sent between the C-RPs. 7767 o Unicast introduction messages, sent between the C-MAPPERs. 7769 o Unicast introduction messages, sent from BPR, PPER, and any 7770 existing TR to C-MAPPER. 7772 o Unicast introduction messages, sent between existing TRs. 7774 a mechanism MUST BE taken in to consideration to protect such 7775 messages. 7777 With the above being said, PIM-NG recommends to use, the Register 7778 Message protection method and Register-Stop protection mechanism 7779 recommended by PIM-SM[7] which is considered the best current method 7780 of protecting unicast Messages. 7782 5.3.1. Protecting Multicast Introduction Message 7784 One important security threat to a PIM Domain that is not covered is 7785 related to the multicast messages sent from a C-MAPPER to all PIM-NG 7786 routers which is similar to the process related to BSR[9]. since when 7787 in a PIM Domain the dynamic methods of finding RP (PIM-SM), C-RP 7788 (PIM-NG) are in use, the multicast messages sent from a C-MAPPER or 7789 BSR play the main role in the process of introducing existing C-RP or 7790 RP to all PIM-NG or PIM-SM routers, a mechanism MUST be taken in to 7791 consideration so that a PIM-NG CLIENT or simply put a PIM router 7792 doesn't accept an unauthorized C-MAPPER introduction message. 7794 in order to protect such a message, PIM-NG recommends that an SA and 7795 SPI be defined on existing legitimate C-MAPPERs and on all PIM-NG 7796 routers by the network administrator to authenticate such multicast 7797 messages. So if an unauthorized C-MAPPER multicast introduction 7798 message is received by the first PIM-NG-AWARE router, it will be 7799 rejected (dropped without process) and won't be forwarded any 7800 further. 7802 5.4. Denial-Of-Service attacks 7804 There are number of denial-of-service attacks against PIM-NG that can 7805 be caused by generating false PIM-NG protocol messages or false 7806 traffic. Using the authentication methods can prevent some, but not 7807 all, of these attacks. Some of the most possible attacks are: 7809 o Sending packets to many different group addresses quickly can 7810 be considered a denial-of-attack, which can cause many register 7811 packets, loading the DR, the C-RP, the C-MAPPERs when more than 7812 one C-MAPPER exists and finally the routers between these 7813 components. 7815 o Many forged join messages can cause many multicast trees to be 7816 set up and consume network resources. 7818 o With regards to PIM-NG, many forged join messages can cause 7819 many Request For Source messages that will be sent from a CLIENT 7820 to the C-RP, and can be considered a denial of service attack. 7822 To reduce the possibility of the creation of unwanted register 7823 messages, if applicable, PIM-NG specifications STRONGLY suggest using 7824 the STUB-DOMAIN concept (4.5.6) in Domains that no multicast source 7825 is supposed to exist. 7827 6. IANA Considerations 7829 6.1. PIM-NG multicast destination group addresses 7831 PIM-NG processes require to use 3 multicast addresses from the 7832 internetwork control block (RFC 5771[2]).for the simplicity of 7833 explanation process in this documents these 3 addresses are chosen 7834 from the scoped multicast ranges. The addresses are needed for the 7835 bellow processes: 7837 o Destination group address used for C-MAPPER introduction 7838 process. The multicast introduction message is sent to ALL-PIM- 7839 NG routers. 7841 o Destination group address used for C-MAPPER introduction 7842 process so that C-MAPPERs can find each other dynamically. The 7843 multicast introduction message is sent to ALL-PIM-NG C-MAPPERs. 7845 o Destination group address used for C-RP introduction process so 7846 that C-RPs can find each other dynamically. The multicast 7847 introduction message is sent to ALL-PIM-NG C-RPs. 7849 These addresses are needed to be assigned by IANA after this document 7850 is approved. 7852 6.2. PIM-NG packets and values of type field 7854 New type values in PIM-NG packet header and new packet formats 7855 designed specifically for PIM-NG to support the needs of the 7856 different processes of PIM-NG, and will need to be reviewed by the 7857 experts and assignments need to be made. 7859 6.3. PIM-NG Domain numbers 7861 The PIM-NG Domain number field is considered as a 32 bit field to 7862 support the future needs of multicasting, in regards to PIM-NG 7863 Multicast Protocol. 7865 Domain Number (4.6.1.1) has a vital role in PIM-NG processes and 7866 functionality, which provides the possibility of using Sub-Domain 7867 concept as a security feature. Also it MUST BE noted that through 7868 using the Domain numbers, PIM-NG is able to use a unique RPF method 7869 and a simple multicast domain isolation and separation method, which 7870 provides many features in comparison to the previous versions of PIM 7871 protocol. 7873 CORE-DOMAIN assignments are needed to be done by IANA as the 7874 controlling entity, so that, no conflict can happen as explained 7875 throughout this document. 7877 7. Conclusions 7879 PIM-NG is a multicast protocol that , although may seem to have lots 7880 of features compared to previous protocols like PIM-SM, but through 7881 its many features and processes, provides a robust and sound control 7882 over the propagation of the information regarding the existing 7883 multicast sources. Its processes are enhanced, so that a host in 7884 search of the source of a multicast traffic can communicate with the 7885 desired source as fast as possible, by eliminating the need to 7886 necessarily join the RPT rooted at an RP within a multicast domain. 7888 Also duo to its unique method of RPF check provides the ability of 7889 implementing transitory multicast domains which was not implementable 7890 before. And because of using the Domain concept provides many 7891 features in parts related to security and controlling over the 7892 propagation of multicast information inside a PIM-NG multicast 7893 Domain. 7895 8. References 7897 8.1. Normative References 7899 [1] Bradner, S., "Key words for use in RFCs to Indicate Requirement 7900 Levels", BCP 14, RFC 2119, March 1997. 7902 [2] Cotton, M., L. Vegoda and D. Meyer, "IANA Guidelines for IPV4 7903 Multicast Address Assignments", RFC 5771, March 2010. 7905 [3] Cain, B., Deering, S., Kouvelas, I., Fenner, B., and A. 7906 Thyagarajan, "Internet Group Management Protocol, version 3", 7907 RFC 3376, October 2002. 7909 [4] Kent, S. and K. Seo, "Security Architecture for the Internet 7910 Protocol", RFC 4301, December 2005. 7912 [5] Narten, T. and H. Alvetrand, "Guildlines for Writing an IANA 7913 considerations section in RFCs", BCP 26, RFC 5226, May 2008. 7915 [6] Holbrook, H. and B. Cain, "Source-Specific Multicast for IP", 7916 RFC 4607, August 2006. 7918 8.2. Informative References 7920 [7] Fenner, B., Handley, M., Holbrook, H., and I. Kouvelas, 7921 "Protocol Independent Multicast - Sparse Mode (PIM-SM): 7922 Protocol Specification (Revised)", RFC 4601, August 2006. 7924 [8] Fenner, B. and D. Meyer, "Multicast Source Discovery 7925 Protocol (MSDP)", RFC 3618, October 2003. 7927 [9] Bhaskar, N., Gall, A., Lingard, J., and S. Venaas, "Bootstrap 7928 Router (BSR) Mechanism for PIM Sparse Mode", Work in Progress, 7929 May 2006. 7931 [10] Hardjono, T. and B. Weis, "The Multicast Group Security 7932 Architecture", RFC 3740, March 2004. 7933 [11] Handley, M., Kouvelas, I., Speakman, T., and L. Vicisano, 7934 "Bidirectional Protocol Independent Multicast" (BIDIR-PIM), RFC 7935 5015, October 2007. 7937 [12] Kim, D., Meyer, D., Kilmer, H., and D. Farinacci, "Anycast 7938 Rendezvous Point (RP) mechanism using Protocol Independent 7939 Multicast (PIM) and Multicast Source Discovery Protocol 7940 (MSDP)", RFC 3446, January 2003. 7941 [13] Savola, P., Lehtonen, R., and D. Meyer, "Protocol Independent 7942 Multicast - Sparse Mode (PIM-SM) Multicast Routing Security 7943 Issues and Enhancements", RFC 4609, August 2006. 7945 9. Acknowledgments 7947 The author would like to thank Mr.Reza Izadi for his review and kind 7948 comments, corrections and support throughout the process of designing 7949 and writing different concepts of PIM-NG Multicast Protocol. Also the 7950 author would like to thank Mr.Stig Venas for his review and comments 7951 which helped to make this draft complete. 7953 This document was prepared using 2-Word-v2.0.template.dot. 7955 Authors' Addresses 7957 Saeed Sami 7958 P.O.BOX 1466955316 7959 Unit.4 7960 No.47 th Saadatabad 35 .St 7961 Khovardin.Blvd 7962 Sanat.SQ 7963 Tehran. Iran 7965 Phone: +989123844205 7966 Email: sami@ssami.biz 7967 sami.biz.email@gmail.com