idnits 2.17.1 draft-ietf-mpls-mldp-in-band-wildcard-encoding-02.txt: Checking boilerplate required by RFC 5378 and the IETF Trust (see https://trustee.ietf.org/license-info): ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/1id-guidelines.txt: ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/checklist : ---------------------------------------------------------------------------- No issues found here. Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year -- The document date (August 12, 2014) is 3538 days in the past. Is this intentional? Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) ** Obsolete normative reference: RFC 4601 (Obsoleted by RFC 7761) Summary: 1 error (**), 0 flaws (~~), 1 warning (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 MPLS Working Group IJ. Wijnands, Ed. 3 Internet-Draft E. Rosen 4 Updates: 6826,7246 (if approved) Cisco 5 Intended status: Standards Track A. Gulko 6 Expires: February 13, 2015 Thomson Reuters 7 U. Joorde 8 Deutsche Telekom 9 J. Tantsura 10 Ericsson 11 August 12, 2014 13 mLDP In-Band Signaling with Wildcards 14 draft-ietf-mpls-mldp-in-band-wildcard-encoding-02 16 Abstract 18 There are scenarios in which an IP multicast tree traverses an MPLS 19 domain. In these scenarios, it can be desirable to convert the IP 20 multicast tree "seamlessly" to an MPLS multipoint label switched path 21 (MP-LSP) when it enters the MPLS domain, and then to convert it back 22 to an IP multicast tree when it exits the MPLS domain. Previous 23 documents specify procedures that allow certain kinds of IP multicast 24 trees (either "Source-Specific Multicast" trees or "Bidirectional 25 Multicast" trees) to be attached to an MPLS Multipoint Label Switched 26 Path (MP-LSP). However, the previous documents do not specify 27 procedures for attaching IP "Any Source Multicast" trees to MP-LSPs, 28 nor do they specify procedures for aggregating multiple IP multicast 29 trees onto a single MP-LSP. This document specifies the procedures 30 to support these functions. It does so by defining "wildcard" 31 encodings that make it possible to specify, when setting up an MP- 32 LSP, that a set of IP multicast trees, or a shared IP multicast tree, 33 should be attached to that MP-LSP. Support for non-bidirectional IP 34 "Any Source Multicast" trees is subject to certain applicability 35 restrictions that are discussed in this document. This document 36 updates RFCs 6826 and 7246. 38 Status of This Memo 40 This Internet-Draft is submitted in full conformance with the 41 provisions of BCP 78 and BCP 79. 43 Internet-Drafts are working documents of the Internet Engineering 44 Task Force (IETF). Note that other groups may also distribute 45 working documents as Internet-Drafts. The list of current Internet- 46 Drafts is at http://datatracker.ietf.org/drafts/current/. 48 Internet-Drafts are draft documents valid for a maximum of six months 49 and may be updated, replaced, or obsoleted by other documents at any 50 time. It is inappropriate to use Internet-Drafts as reference 51 material or to cite them other than as "work in progress." 53 This Internet-Draft will expire on February 13, 2015. 55 Copyright Notice 57 Copyright (c) 2014 IETF Trust and the persons identified as the 58 document authors. All rights reserved. 60 This document is subject to BCP 78 and the IETF Trust's Legal 61 Provisions Relating to IETF Documents 62 (http://trustee.ietf.org/license-info) in effect on the date of 63 publication of this document. Please review these documents 64 carefully, as they describe your rights and restrictions with respect 65 to this document. Code Components extracted from this document must 66 include Simplified BSD License text as described in Section 4.e of 67 the Trust Legal Provisions and are provided without warranty as 68 described in the Simplified BSD License. 70 Table of Contents 72 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 73 2. Terminology and Definitions . . . . . . . . . . . . . . . . . 5 74 3. Wildcards in mLDP Opaque Value TLVs . . . . . . . . . . . . . 6 75 3.1. Encoding the Wildcards . . . . . . . . . . . . . . . . . 7 76 3.2. Wildcard Semantics . . . . . . . . . . . . . . . . . . . 7 77 3.3. Backwards Compatibility . . . . . . . . . . . . . . . . . 8 78 3.4. Applicability Restrictions with regard to ASM . . . . . . 8 79 4. Some Wildcard Use Cases . . . . . . . . . . . . . . . . . . . 9 80 4.1. PIM shared tree forwarding . . . . . . . . . . . . . . . 9 81 4.2. IGMP/MLD Proxying . . . . . . . . . . . . . . . . . . . . 10 82 4.3. Selective Source mapping . . . . . . . . . . . . . . . . 10 83 5. Procedures for Wildcard Source Usage . . . . . . . . . . . . 11 84 6. Procedures for Wildcard Group Usage . . . . . . . . . . . . . 12 85 7. Determining the MP-LSP Root (Ingress LSR) . . . . . . . . . . 12 86 8. Anycast RP . . . . . . . . . . . . . . . . . . . . . . . . . 13 87 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 13 88 10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13 89 11. Security Considerations . . . . . . . . . . . . . . . . . . . 13 90 12. References . . . . . . . . . . . . . . . . . . . . . . . . . 13 91 12.1. Normative References . . . . . . . . . . . . . . . . . . 13 92 12.2. Informative References . . . . . . . . . . . . . . . . . 14 93 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 14 95 1. Introduction 97 [RFC6826] and [RFC7246] specify procedures for mLDP ("Multicast 98 Extensions to the Label Distribution Protocol") that allow an IP 99 multicast tree (either a "Source-Specific Multicast" tree or a 100 "Bidirectional multicast" tree) to be attached "seamlessly" to an 101 MPLS Multipoint Label Switched Path (MP-LSP). This can be useful, 102 for example, when there is multicast data that originates in a domain 103 that supports IP multicast, then has to be forwarded across a domain 104 that supports MPLS multicast, then has to forwarded across another 105 domain that supports IP multicast. By attaching an IP multicast tree 106 to an MP-LSP, data that is traveling along the IP multicast tree can 107 be moved seamlessly to the MP-LSP when it enters the MPLS multicast 108 domain. The data then travels along the MP-LSP through the MPLS 109 domain. When the data reaches the boundary of the MPLS domain, it 110 can be moved seamlessly to an IP multicast tree. This ability to 111 attach IP multicast trees to MPLS MP-LSPs can be useful in either VPN 112 context or global context. 114 In mLDP, every MP-LSP is identified by the combination of a "root 115 node" (or "Ingress LSR") and an "Opaque Value" that, in the context 116 of the root node, uniquely identifies the MP-LSP. These are encoded 117 into an mLDP "FEC Element". To set up an MP-LSP, the Egress LSRs 118 originate mLDP control messages containing the FEC element. A given 119 FEC Element value identifies a single MP-LSP, and is passed upstream 120 from the Egress LSRs, through the intermediate LSRs, to the Ingress 121 LSR. 123 In IP multicast, a multicast tree is identified by the combination of 124 an IP source address ("S") and an IP group address ("G"), usually 125 written as "(S,G)". A tree carrying traffic of multiple sources is 126 identified by its group address, and the identifier is written as 127 "(*,G)". 129 When an MP-LSP is being set up, the procedures of [RFC6826] and 130 [RFC7246], known as "mLDP In-Band Signaling", allow the Egress LSRs 131 of the MP-LSP to encode the identifier of an IP multicast tree in the 132 "Opaque Value" field of the mLDP FEC Element that identifies the MP- 133 LSP. Only the Egress and Ingress LSRs are aware that the mLDP FEC 134 Elements contain encodings of the IP multicast tree identifier; 135 intermediate nodes along the MP-LSP do not take any account of the 136 internal structure of the FEC Element's Opaque Value, and the 137 internal structure of the Opaque Value does not affect the operation 138 of mLDP. By using mLDP In-Band Signaling, the Egress LSRs of an MP- 139 LSP inform the Ingress LSR that they expect traffic of the identified 140 IP multicast tree (and only that traffic) to be carried on the MP- 141 LSP. That is, mLDP In-Band Signaling not only sets up the MP-LSP, it 142 also binds a given IP multicast tree to the MP-LSP. 144 If multicast is being done in a VPN context [RFC7246], the mLDP FEC 145 elements also contain a "Route Distinguisher" (RD) (see [RFC7246]), 146 as the IP multicast trees are identified not merely by "(S,G)" but by 147 "(RD,S,G)". The procedures of this document are also applicable in 148 this case. Of course, when an Ingress LSR processes an In-Band 149 Signaling Opaque Value that contains an RD, it does so in the context 150 of the VPN associated with that RD. 152 If mLDP In-Band Signaling is not used, some other protocol must be 153 used to bind an IP multicast tree to the MP-LSP, and this requires 154 additional communication mechanisms between the Ingress LSR and the 155 Egress LSRs of the MP-LSP. The purpose of mLDP In-Band Signaling is 156 to eliminate the need for these other protocols. 158 When following the procedures of [RFC6826] and [RFC7246] for non- 159 bidirectional trees, the Opaque Value has an IP Source Address (S) 160 and an IP Group Address (G) encoded into it, thus enabling it to 161 identify a particular IP multicast (S,G) tree. Only a single IP 162 source-specific multicast tree (i.e., a single "(S,G)") can be 163 identified in a given FEC element. As a result, a given MP-LSP can 164 carry data from only a single IP source-specific multicast tree 165 (i.e., a single "(S,G) tree"). However, there are scenarios in which 166 it would be desirable to aggregate a number of (S,G) trees on a 167 single MP-LSP. Aggregation allows a given number of IP multicast 168 trees to use a smaller number of MP-LSPs, thus saving state in the 169 network. 171 In addition, [RFC6826] and [RFC7246] do not support the attachment of 172 an "Any Source Multicast" (ASM) shared tree to an MP-LSP, except in 173 the case where the ASM shared tree is a "bidirectional" tree (i.e., a 174 tree set up by BIDIR-PIM [RFC5015]). However, there are scenarios in 175 which it would be desirable to attach a non-bidirectional ASM shared 176 tree to an MP-LSP. 178 This document specifies a way to encode an mLDP "Opaque Value" in 179 which either the "S" or the "G" or both are replaced by a "wildcard" 180 (written as "*"). Procedures are described for using the wildcard 181 encoding to map non-bidirectional ASM shared trees to MP-LSPs, and 182 for mapping multiple (S,G) trees (with a common value of S or a 183 common value of G) to a single MP-LSP. 185 Some example scenarios where wildcard encoding is useful are: 187 o PIM Shared tree forwarding with "threshold infinity". 189 o IGMP/MLD proxying. 191 o Selective Source mapping. 193 These scenarios are discussed in Section 4. Note that this list of 194 scenarios is not meant to be exhaustive. 196 This draft specifies only the mLDP procedures that are specific to 197 the use of wildcards. mLDP In-Band Signaling procedures that are not 198 specific to the use of wildcards can be found in [RFC6826] and 199 [RFC7246]. Unless otherwise specified in this document, those 200 procedures still apply when wildcards are used. 202 2. Terminology and Definitions 204 Readers of this document are assumed to be familiar with the 205 terminology and concepts of the documents listed as Normative 206 References. For convenience, some of the more frequently used terms 207 appear below. 209 IGMP: 210 Internet Group Management Protocol. 212 In-band signaling: 213 Using the opaque value of a mLDP FEC element to carry the (S,G) or 214 (*,G) identifying a particular IP multicast tree. 216 Ingress LSR: 217 Root node of a MP-LSP. When mLDP In-Band Signaling is used, the 218 Ingress LSR receives mLDP messages about a particular MP-LSP from 219 "downstream", and emits IP multicast control messages "upstream". 220 The set of IP multicast control messages that are emitted upstream 221 depends upon the contents of the LDP Opaque Value TLVs. The 222 Ingress LSR also receives IP multicast data messages from 223 "upstream" and sends them "downstream" as MPLS packets on a MP- 224 LSP. 226 IP multicast tree: 227 An IP multicast distribution tree identified by a IP multicast 228 group address and optionally a Source IP address, also referred to 229 as (S,G) and (*,G). 231 MLD: 232 Multicast Listener Discovery. 234 mLDP: 235 Multipoint LDP. 237 MP-LSP: 238 A P2MP or MP2MP LSP. 240 PIM: 242 Protocol Independent Multicast. 244 PIM-ASM: 245 PIM Any Source Multicast. 247 PIM-SM: 248 PIM Sparse Mode 250 PIM-SSM: 251 PIM Source Specific Multicast. 253 RP: 254 The PIM Rendezvous Point. 256 Egress LSR: 257 The Egress LSRs of an MP-LSP are LSPs that receive MPLS multicast 258 data packets from "upstream" on that MP-LSP, and that forward that 259 data "downstream" as IP multicast data packets. The Egress LSRs 260 also receive IP multicast control messages from "downstream", and 261 send mLDP control messages "upstream". When In-Band Signaling is 262 used, the Egress LSRs construct Opaque Value TLVs that contain IP 263 source and/or group addresses, based on the contents of the IP 264 multicast control messages received from downstream. 266 Threshold Infinity: 267 A PIM-SM procedure where no source specific multicast (S,G) trees 268 are created for multicast packets that are forwarded down the 269 shared tree (*,G). 271 TLV: 272 A protocol element consisting of a type field, followed by a 273 length field, followed by a value field. Note that the value 274 field of a TLV may be sub-divided into a number of sub-fields. 276 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 277 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 278 "OPTIONAL" in this document are to be interpreted as described in RFC 279 2119 [RFC2119]. 281 3. Wildcards in mLDP Opaque Value TLVs 283 [RFC6826] and [RFC7246] define the following Opaque Value TLVs: 284 Transit IPv4 Source TLV, Transit IPv6 Source TLV, Transit VPNv4 285 Source TLV, and Transit VPNv6 Source TLV. The value field of each 286 such TLV is divided into a number of sub-fields, one of which 287 contains an IP source address, and one of which contains an IP group 288 address. Per those documents, these fields must contain valid IP 289 addresses. 291 This document extends the definition of those TLVs by allowing either 292 the IP Source Address field or the IP Group Address field (or both) 293 to specify a "wildcard" rather than a valid IP address. 295 3.1. Encoding the Wildcards 297 A value of all zeroes in the IP Source Address sub-field is used to 298 represent a wildcard source address. A value of all zeroes in the IP 299 Group Address sub-field is used to represent the wildcard group 300 address. Note that the lengths of these sub-fields are as specified 301 in the previous documents. 303 3.2. Wildcard Semantics 305 If the IP Source Address sub-field contains the wildcard, and the IP 306 Group Address sub-field contains an IP multicast group address that 307 is NOT in the SSM address range (see Section 4.8 of [RFC4601]), the 308 TLV identifies a PIM-SM shared tree. Please see Section 3.4 for the 309 applicability restrictions that apply to this case. 311 If the IP Source Address sub-field contains the wildcard, and the IP 312 Group Address sub-field contains an IP multicast group address that 313 is in the SSM address range, the TLV identifies the collection of PIM 314 trees with the given group address. 316 If the IP Source Address sub-field contains a non-zero IP address, 317 and the IP Group Address sub-field contains the wildcard, the TLV 318 identifies the collection of PIM-SSM trees that have the source 319 address as their root. 321 Procedures for the use of the wildcards are discussed in Sections 4, 322 5 and 6. Please note that, as always, the structure of an Opaque 323 Value TLV does not affect the operation of mLDP. The structure is 324 meaningful only to the IP multicast modules at the ingress and egress 325 LSRs. 327 Procedures for the use of a wildcard group in the following TLVs 328 (defined in [RFC6826] or [RFC7246]) are outside the scope of the 329 current document: Transit IPv4 Bidir TLV, Transit IPv6 Bidir TLV, 330 Transit VPNv4 Bidir TLV, Transit VPNv6 Bidir TLV. 332 Procedures for the use of both a wildcard source and a wildcard group 333 in the same TLV are outside the scope of the current document. 335 Note that the Bidir TLVs do not have a "Source Address" sub-field, 336 and hence the notion of a wildcard source is not applicable to them. 338 3.3. Backwards Compatibility 340 The procedures of this document do not change the behavior described 341 in [RFC6826] and [RFC7246]. 343 A correctly operating Egress LSR that supports [RFC6826] and/or 344 [RFC7246], but that does not support this document, will never 345 generate mLDP FEC Element Opaque values that contain source or group 346 wildcards. 348 Neither [RFC6826] nor [RFC7246] specifies the behavior of an Ingress 349 LSR that receives mLDP FEC Element Opaque values that contain zeroes 350 in the Source Address or Group Address sub-fields. However, if an 351 Ingress LSR supports [RFC6826] and/or [RFC7246], but does not support 352 this document, it has no choice but to treat any such received FEC 353 elements as invalid; the procedures specified in [RFC6826] and 354 [RFC7246] do not work when the Opaque values contain zeroes in the 355 Source Address or Group Address sub-fields. 357 The procedures of this document thus presuppose that if an Egress LSR 358 uses wildcard encodings when setting up an MP-LSP, then the Ingress 359 LSR (i.e., the root of the multipoint LSP) supports the procedures of 360 this document. An Egress LSR MUST NOT use wildcard encodings when 361 setting up a particular multipoint LSP unless it is known a priori 362 that the Ingress LSR supports the procedures of this document. How 363 this is known is outside the scope of this document. 365 3.4. Applicability Restrictions with regard to ASM 367 In general, support for non-bidirectional PIM ASM trees requires (a) 368 a procedure for determining the set of sources for a given ASM tree 369 ("source discovery"), and (b) a procedure for pruning a particular 370 source off a shared tree ("source pruning"). No such procedures are 371 specified in this document. Therefore the combination of a wildcard 372 source with an ASM group address MUST NOT be used unless it is known 373 a priori that neither source discovery nor source pruning are needed. 374 How this is known is outside the scope of this document. Section 4 375 describes some use cases in which source discovery and source pruning 376 are not needed. 378 There are of course use cases where source discovery and/or source 379 pruning is needed. These can be handled with procedures such as 380 those specified in [RFC6513], [RFC6514], and 381 [I-D.zzhang-l3vpn-mvpn-global-table-mcast]. Use of mLDP In-Band 382 Signaling is NOT RECOMMENDED for those cases. 384 4. Some Wildcard Use Cases 386 This section discusses a number of wildcard use cases. The set of 387 use cases here is not meant to be exhaustive. In each of these use 388 cases, the Egress LSRs construct mLDP Opaque Value TLVs that contain 389 wildcards in the IP Source Address or IP Group Address sub-fields. 391 4.1. PIM shared tree forwarding 393 PIM [RFC4601] has the concept of a "shared tree", identified as 394 (*,G). This concept is only applicable when G is an IP Multicast 395 Group address that is not in the SSM address range (i.e., is an ASM 396 group address). Every ASM group is associated with a Rendezvous 397 Point (RP), and the (*,G) tree is built towards the RP (i.e., its 398 root is the RP). The RP for group G is responsible for forwarding 399 packets down the (*,G) tree. The packets forwarded down the (*,G) 400 tree may be from any multicast source, as long as they have an IP 401 destination address of G. 403 The RP learns about all the multicast sources for a given group, and 404 then joins a source-specific tree for each such source. I.e., when 405 the RP for G learns that S has multicast data to send to G, the RP 406 joins the (S,G) tree. When the RP receives multicast data from S 407 that is destined to G, the RP forwards the data down the (*,G) tree. 408 There are several different ways that the RP may learn about the 409 sources for a given group. The RP may learn of sources via PIM 410 Register messages [RFC4601], via MSDP [RFC3618] or by observing 411 packets from a source that is directly connected to the RP. 413 In PIM, a PIM router that has receivers for a particular ASM 414 multicast group G (known as a "last hop" router for G) will first 415 join the (*,G) tree. As it receives multicast traffic on the (*,G) 416 tree, it learns (by examining the IP headers of the multicast data 417 packets) the sources that are transmitting to G. Typically, when a 418 last hop router for group G learns that source S is transmitting to 419 G, the last hop router joins the (S,G) tree, and "prunes" S off the 420 (*,G) tree. This allows each last hop router to receive the 421 multicast data along the shortest path from the source to the last 422 hop router. (Full details of this behavior can be found in 423 [RFC4601].) 425 In some cases, however, a last hop router for group G may decide not 426 to join the source trees, but rather to keep receiving all the 427 traffic for G from the (*,G) tree. In this case, we say that the 428 last hop router has "threshold infinity" for group G. This is 429 optional behaviour documented in [RFC4601]. "Threshold infinity" is 430 often used in deployments where the RP is between the multicast 431 sources and the multicast receivers for group G, i.e., in deployments 432 where it is known that the shortest path from any source to any 433 receiver of the group goes through the RP. In these deployments, 434 there is no advantage for a last hop router to join a source tree, 435 since the data is already traveling along the shortest path. The 436 only effect of executing the complicated procedures for joining a 437 source tree and pruning the source off the shared tree would be to 438 increase the amount of multicast routing state that has to be 439 maintained in the network. 441 To efficiently use mLDP In-Band Signaling in this scenario, it is 442 necessary for the Egress LSRs to construct an Opaque Value TLV that 443 identifies a (*,G) tree. This is done by using the wildcard in the 444 IP Source Address sub-field, and setting the IP Group Address sub- 445 field to G. 447 Note that these mLDP In-Band Signaling procedures do not support PIM- 448 ASM in scenarios where "threshold infinity" is not used. 450 4.2. IGMP/MLD Proxying 452 There are scenarios where the multicast senders and receivers are 453 directly connected to an MPLS routing domain, and where it is desired 454 to use mLDP rather than PIM to set up "trees" through that domain. 456 In these scenarios we can apply "IGMP/MLD proxying" and eliminate the 457 use of PIM. The senders and receivers consider the MPLS domain to be 458 single hop between each other. [RFC4605] documents procedures where 459 a multicast routing protocol is not necessary to build a 'simple 460 tree'. Within the MPLS domain, mLDP will be used to build a MP-LSP, 461 but this is hidden from the senders and receivers. The procedures 462 defined in [RFC4605] are applicable, since the senders and receivers 463 are considered to be one hop away from each other. 465 For mLDP to build the necessary MP-LSP, it needs to know the root of 466 the tree. Following the procedures as defined in [RFC4605] we depend 467 on manual configuration of the mLDP root for the ASM multicast group. 468 Since the MP-LSP for a given ASM multicast group will carry traffic 469 from all the sources for that group, the Opaque Value TLV used to 470 construct the MP-LSP will contain a wildcard in the IP Source Address 471 sub-field. 473 4.3. Selective Source mapping 475 In many IPTV deployments, the content servers are gathered into a 476 small number of sites. Popular channels are often statically 477 configured, and forwarded over a core MPLS network to the Egress 478 routers. Since these channels are statically defined, they MAY also 479 be forwarded over a multipoint LSP with wildcard encoding. The sort 480 of wildcard encoding that needs to be used (Source and/or Group) 481 depends on the Source/Group allocation policy of the IPTV provider. 482 Other options are to use MSDP [RFC3618] or BGP "Auto-Discovery" 483 procedures [RFC6513] for source discovery by the Ingress LSR. Based 484 on the received wildcard, the Ingress LSR can select from the set of 485 IP multicast streams for which it has state. 487 5. Procedures for Wildcard Source Usage 489 The decision to use mLDP In-Band Signaling is made by the IP 490 multicast component of an Egress LSR, based on provisioned policy. 491 The decision to use (or not to use) a wildcard in the IP Source 492 Address sub-field of an mLDP Opaque Value TLV is also made by the IP 493 multicast component, again based on provisioned policy. Following 494 are some example policies that may be useful: 496 1. Suppose that PIM is enabled, an Egress LSR needs to join a non- 497 bidirectional ASM group G, and the RP for G is reachable via a 498 BGP route. The Egress LSR may choose the BGP Next Hop of the 499 route to the RP to be the Ingress LSR (root node) of the MP-LSP 500 corresponding to the (*,G) tree. (See also Section 7.) The 501 Egress LSR may identify the (*,G) tree by using an mLDP Opaque 502 Value TLV whose IP Source Address sub-field contains a wildcard, 503 and whose IP Group Address sub-field contains G. 505 2. Suppose that PIM is not enabled for group G, and an IGMP/MLD 506 group membership report for G has been received by an Egress LSR. 507 The Egress LSR may determine the "proxy device" for G (see 508 Section 4.2). It can then set up an MP-LSP for which the proxy 509 device is the Ingress LSR. The Egress LSR needs to signal the 510 Ingress LSR that the MP-LSP is to carry traffic belonging to 511 group G; it does this by using an Opaque Value TLV whose IP 512 Source Address sub-field contains a wildcard, and whose IP Group 513 Address sub-field contains G. 515 As the policies needed in any one deployment may be very different 516 than the policies needed in another, this document does not specify 517 any particular set of policies as being mandatory to implement. 519 When the Ingress LSR receives an mLDP Opaque Value TLV that has been 520 defined for In-Band Signaling, the information from the sub-fields of 521 that TLV is passed to the IP multicast component of the Ingress LSR. 522 If the IP Source Address sub-field contains a wildcard, the IP 523 multicast component must determine how to process it. The processing 524 MUST follow the rules below: 526 1. If PIM is enabled and the group identified in the Opaque Value 527 TLV is a non-bidirectional ASM group, the Ingress LSR acts as if 528 it had received a (*,G) IGMP/MLD report from a downstream node, 529 and the procedures defined in [RFC4601] are followed. 531 2. If PIM is enabled and the identified group is a PIM-SSM group, 532 all multicast sources known for the group on the Ingress LSR are 533 to be forwarded down the MP-LSP. In this scenario, it is assumed 534 that the Ingress LSR is already receiving all the necessary 535 traffic. How the Ingress LSR receives this traffic is outside 536 the scope of this document. 538 3. If PIM is not enabled for the identified group, the Ingress LSR 539 acts as if it had received a (*,G) IGMP/MLD report from a 540 downstream node, and the procedures as defined in [RFC4605] are 541 followed. The ingress LSR should forward the (*,G) packets to 542 the egress LSR through the MP-LSP identified by the Opaque Value 543 TLV. (See also Section 4.2.) 545 6. Procedures for Wildcard Group Usage 547 The decision to use mLDP In-Band Signaling is made by the IP 548 multicast component of an Egress LSR, based on provisioned policy. 549 The decision to use (or not to use) a wildcard in the IP Group 550 Address sub-field of an mLDP Opaque Value TLV is also made by the IP 551 multicast component of the Egress LSR, again based on provisioned 552 policy. As the policies needed in any one deployment may be very 553 different than the policies needed in another, this document does not 554 specify any particular set of policies as being mandatory to 555 implement. 557 When the Ingress LSR (i.e., the root node of the MP-LSP) receives an 558 mLDP Opaque Value TLV that has been defined for In-Band Signaling, 559 the information from the sub-fields of that TLV is passed to the IP 560 multicast component of the Ingress LSR. If the IP Group Address sub- 561 field contains a wildcard, the Ingress LSR examines its IP multicast 562 routing table, to find all the IP multicast streams whose IP source 563 address is the address specified in the IP Source Address sub-field 564 of the TLV. All these streams SHOULD be forwarded down the MP-LSP 565 identified by the Opaque Value TLV. Note that some of these streams 566 may have SSM group addresses, while some may have ASM group 567 addresses. 569 7. Determining the MP-LSP Root (Ingress LSR) 571 Documents [RFC6826] and [RFC7246] describe procedures by which an 572 Egress LSR may determine the MP-LSP root node address corresponding 573 to a given IP multicast stream, based upon the IP address of the 574 source of the IP multicast stream. When a wildcard source encoding 575 is used, PIM is enabled, and the group is a non-bidirectional ASM 576 group, a similar procedure is applied. The only difference from the 577 above mentioned procedures is that the Proxy device or RP address is 578 used instead of the Source to discover the mLDP root node address. 580 Other procedures for determining the root node are also allowed, as 581 determined by policy. 583 8. Anycast RP 585 In the scenarios where mLDP In-Band Signaling is used, it is unlikely 586 that the RP-to-Group mappings are being dynamically distributed over 587 the MPLS core. It is more likely that the RP address is statically 588 configured at each multicast site. In these scenarios, it is 589 advisable to configure an Anycast RP Address at each site, in order 590 to provide redundancy. See [RFC3446] for more details. 592 9. Acknowledgements 594 We would like to thank Loa Andersson, Pranjal Dutta, Lizhong Jin, and 595 Curtis Villamizar for their review and comments. 597 10. IANA Considerations 599 There are no new allocations required from IANA. 601 11. Security Considerations 603 There are no security considerations other then ones already 604 mentioned in [RFC6826] and [RFC7246]. 606 12. References 608 12.1. Normative References 610 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 611 Requirement Levels", BCP 14, RFC 2119, March 1997. 613 [RFC4601] Fenner, B., Handley, M., Holbrook, H., and I. Kouvelas, 614 "Protocol Independent Multicast - Sparse Mode (PIM-SM): 615 Protocol Specification (Revised)", RFC 4601, August 2006. 617 [RFC4605] Fenner, B., He, H., Haberman, B., and H. Sandick, 618 "Internet Group Management Protocol (IGMP) / Multicast 619 Listener Discovery (MLD)-Based Multicast Forwarding 620 ("IGMP/MLD Proxying")", RFC 4605, August 2006. 622 [RFC6826] Wijnands, IJ., Eckert, T., Leymann, N., and M. Napierala, 623 "Multipoint LDP In-Band Signaling for Point-to-Multipoint 624 and Multipoint-to-Multipoint Label Switched Paths", RFC 625 6826, January 2013. 627 [RFC7246] Wijnands, IJ., Hitchen, P., Leymann, N., Henderickx, W., 628 Gulko, A., and J. Tantsura, "Multipoint Label Distribution 629 Protocol In-Band Signaling in a Virtual Routing and 630 Forwarding (VRF) Table Context", RFC 7246, June 2014. 632 12.2. Informative References 634 [I-D.zzhang-l3vpn-mvpn-global-table-mcast] 635 Zhang, J., Giuliano, L., Rosen, E., Subramanian, K., 636 Pacella, D., and J. Schiller, "Global Table Multicast with 637 BGP-MVPN Procedures", draft-zzhang-l3vpn-mvpn-global- 638 table-mcast-04 (work in progress), May 2014. 640 [RFC3446] Kim, D., Meyer, D., Kilmer, H., and D. Farinacci, "Anycast 641 Rendevous Point (RP) mechanism using Protocol Independent 642 Multicast (PIM) and Multicast Source Discovery Protocol 643 (MSDP)", RFC 3446, January 2003. 645 [RFC3618] Fenner, B. and D. Meyer, "Multicast Source Discovery 646 Protocol (MSDP)", RFC 3618, October 2003. 648 [RFC5015] Handley, M., Kouvelas, I., Speakman, T., and L. Vicisano, 649 "Bidirectional Protocol Independent Multicast (BIDIR- 650 PIM)", RFC 5015, October 2007. 652 [RFC6513] Rosen, E. and R. Aggarwal, "Multicast in MPLS/BGP IP 653 VPNs", RFC 6513, February 2012. 655 [RFC6514] Aggarwal, R., Rosen, E., Morin, T., and Y. Rekhter, "BGP 656 Encodings and Procedures for Multicast in MPLS/BGP IP 657 VPNs", RFC 6514, February 2012. 659 Authors' Addresses 661 IJsbrand Wijnands (editor) 662 Cisco 663 De kleetlaan 6a 664 Diegem 1831 665 Belgium 667 Email: ice@cisco.com 668 Eric Rosen 669 Cisco 670 1414 Massachusetts Avenue 671 Boxborough, MA 01719 672 USA 674 Email: erosen@cisco.com 676 Arkadiy Gulko 677 Thomson Reuters 678 195 Broadway 679 New York NY 10007 680 USA 682 Email: arkadiy.gulko@thomsonreuters.com 684 Uwe Joorde 685 Deutsche Telekom 686 Hammer Str. 216-226 687 Muenster D-48153 688 DE 690 Email: Uwe.Joorde@telekom.de 692 Jeff Tantsura 693 Ericsson 694 300 Holger Way 695 San Jose, california 95134 696 usa 698 Email: jeff.tantsura@ericsson.com