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'IANA' on line 1364 looks like a reference Summary: 4 errors (**), 0 flaws (~~), 7 warnings (==), 12 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 MPLS Working Group Bilel Jamoussi, Editor 3 Internet Draft Nortel Networks Corp. 4 Expiration Date: January 2001 6 O. Aboul-Magd, L. Andersson, P. Ashwood-Smith, 7 F. Hellstrand, K. Sundell, Nortel Networks Corp. 8 R. Callon, Juniper Networks. 9 R. Dantu, IPmobile 10 P. Doolan, T. Worster, Ennovate Networks Corp. 11 N. Feldman, IBM Corp. 12 A. Fredette, PhotonEx Corp. 13 M. Girish, Atoga Systems 14 E. Gray, Zaffire, Inc. 15 J. Halpern, Longitude Systems, Inc. 16 J. Heinanen, Telia Finland 17 T. Kilty, Newbridge Networks, Inc. 18 A. Malis, Vivace Networks 19 P. Vaananen, Nokia Telecommunications 20 L. Wu, Cisco Systems 22 July 2000 24 Constraint-Based LSP Setup using LDP 26 draft-ietf-mpls-cr-ldp-04.txt 28 Status of this Memo 30 This document is an Internet-Draft and is in full conformance with 31 all provisions of Section 10 of RFC2026. 33 Internet-Drafts are working documents of the Internet Engineering 34 Task Force (IETF), its areas, and its working groups. Note that 35 other groups may also distribute working documents as Internet- 36 Drafts. 38 Internet-Drafts are draft documents valid for a maximum of six 39 months and may be updated, replaced, or obsoleted by other documents 40 at any time. It is inappropriate to use Internet-Drafts as reference 41 material or to cite them other than as _work in progress._ 43 The list of current Internet-Drafts can be accessed at 44 http://www.ietf.org/ietf/1id-abstracts.txt 46 The list of Internet-Draft Shadow Directories can be accessed at 47 http://www.ietf.org/shadow.html. 49 Abstract 51 Label Distribution Protocol (LDP) is defined in [1] for distribution 52 of labels inside one MPLS domain. One of the most important 53 services that may be offered using MPLS in general and LDP in 54 particular is support for constraint-based routing of traffic across 55 the routed network. Constraint-based routing offers the opportunity 56 to extend the information used to setup paths beyond what is 57 available for the routing protocol. For instance, an LSP can be 58 setup based on explicit route constraints, QoS constraints, and 59 other constraints. Constraint-based routing (CR) is a mechanism used 60 to meet Traffic Engineering requirements that have been proposed by 61 [2], [3] and [4]. These requirements may be met by extending LDP for 62 support of constraint-based routed label switched paths (CR-LSPs). 63 Other uses for CR-LSPs include MPLS-based VPNs [5]. More information 64 about the applicability of CR-LDP can be found in [6]. 66 This draft specifies mechanisms and TLVs for support of CR-LSPs 67 using LDP. 69 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL 70 NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" 71 in this document are to be interpreted as described in RFC 2119 [7]. 73 Table of Contents 75 1. Introduction....................................................4 76 2. Constraint-based Routing Overview...............................4 77 2.1 Strict and Loose Explicit Routes...............................5 78 2.2 Traffic Characteristics........................................5 79 2.3 Pre-emption....................................................6 80 2.4 Route Pinning..................................................6 81 2.5 Resource Class.................................................6 82 3. Solution Overview...............................................7 83 3.1 Required Messages and TLVs.....................................8 84 3.2 Label Request Message..........................................8 85 3.3 Label Mapping Message..........................................9 86 3.4 Notification Message..........................................10 87 3.5 Release , Withdraw, and Abort Messages........................10 88 4. Protocol Specification.........................................10 89 4.1 Explicit Route TLV (ER-TLV)...................................11 90 4.2 Explicit Route Hop TLV (ER-Hop TLV)...........................11 91 4.3 Traffic Parameters TLV........................................12 92 4.3.1 Semantics...................................................14 93 4.3.1.1 Frequency.................................................14 94 4.3.1.2 Peak Rate.................................................14 95 4.3.1.3 Committed Rate............................................15 96 4.3.1.4 Excess Burst Size.........................................15 97 4.3.1.5 Peak Rate Token Bucket....................................15 98 4.3.1.6 Committed Data Rate Token Bucket..........................15 99 4.3.1.7 Weight....................................................16 100 4.3.2 Procedures..................................................16 101 4.3.2.1 Label Request Message.....................................16 102 4.3.2.2 Label Mapping Message.....................................17 103 4.3.2.3 Notification Message......................................17 104 4.4 Preemption TLV................................................17 105 4.5 LSPID TLV.....................................................18 106 4.6 Resource Class (Color) TLV....................................20 107 4.7 ER-Hop semantics..............................................20 108 4.7.1. ER-Hop 1: The IPv4 prefix..................................20 109 4.7.2. ER-Hop 2: The IPv6 address.................................21 110 4.7.3. ER-Hop 3: The autonomous system number....................22 111 4.7.4. ER-Hop 4: LSPID............................................22 112 4.8. Processing of the Explicit Route TLV.........................23 113 4.8.1. Selection of the next hop..................................23 114 4.8.2. Adding ER-Hops to the explicit route TLV...................25 115 4.9 Route Pinning TLV.............................................25 116 4.10 CR-LSP FEC Element...........................................26 117 4.11 TLV Type Summary.............................................26 118 4.12 FEC Type Summary.............................................27 119 4.13 Status Code Summary..........................................27 120 5. IANA Considerations............................................27 121 5.1 TLV Type Name Space...........................................27 122 5.2 FEC Type Name Space...........................................27 123 5.3 Status Code Space.............................................27 124 6. Security.......................................................28 125 7. Acknowledgments................................................28 126 8. Intellectual Property Consideration............................28 127 9. References.....................................................28 128 10. Author's Addresses............................................29 129 Appendix A: CR-LSP Establishment Examples.........................31 130 A.1 Strict Explicit Route Example.................................31 131 A.2 Node Groups and Specific Nodes Example........................32 132 Appendix B. QoS Service Examples..................................35 133 B.1 Service Examples..............................................35 134 B.2 Establishing CR-LSP Supporting Real-Time Applications.........36 135 B.3 Establishing CR-LSP Supporting Delay Insensitive Applications.37 137 1. Introduction 139 The need for constraint-based routing (CR) in MPLS has been explored 140 elsewhere [3], [2], and [4]. Explicit routing is a subset of the 141 more general constraint-based routing function. At the MPLS WG 142 meeting held during the Washington IETF (December 1997) there was 143 consensus that LDP should support explicit routing of LSPs with 144 provision for indication of associated (forwarding) priority. In 145 the Chicago meeting (August 1998), a decision was made that support 146 for explicit path setup in LDP will be moved to a separate document. 147 This document provides that support and it has been accepted as a 148 working document in the Orlando meeting (December 1998). 150 This specification proposes an end-to-end setup mechanism of a 151 constraint-based routed LSP (CR-LSP) initiated by the ingress LSR. 152 We also specify mechanisms to provide means for reservation of 153 resources using LDP. 155 This document introduce TLVs and procedures that provide support 156 for: 157 - Strict and Loose Explicit Routing 158 - Specification of Traffic Parameters 159 - Route Pinning 160 - CR-LSP Pre-emption though setup/holding priorities 161 - Handling Failures 162 - LSPID 163 - Resource Class 165 Section 2 introduces the various constraints defined in this 166 specification. Section 3 outlines the CR-LDP solution. Section 4 167 defines the TLVs and procedures used to setup constraint-based 168 routed label switched paths. Appendix A provides several examples 169 of CR-LSP path setup. Appendix B provides Service Definition 170 Examples. 172 2. Constraint-based Routing Overview 174 Constraint-based routing is a mechanism that supports the Traffic 175 Engineering requirements defined in [4]. Explicit Routing is a 176 subset of the more general constraint-based routing where the 177 constraint is the explicit route (ER). Other constraints are defined 178 to provide a network operator with control over the path taken by an 179 LSP. This section is an overview of the various constraints 180 supported by this specification. 182 Like any other LSP a CR-LSP is a path through an MPLS network. The 183 difference is that while other paths are setup solely based on 184 information in routing tables or from a management system, the 185 constraint-based route is calculated at one point at the edge of 186 network based on criteria, including but not limited to routing 187 information. The intention is that this functionality shall give 188 desired special characteristics to the LSP in order to better 189 support the traffic sent over the LSP. The reason for setting up CR- 190 LSPs might be that one wants to assign certain bandwidth or other 191 Service Class characteristics to the LSP, or that one wants to make 192 sure that alternative routes use physically separate paths through 193 the network. 195 2.1 Strict and Loose Explicit Routes 197 An explicit route is represented in a Label Request Message as a 198 list of nodes or groups of nodes along the constraint-based route. 199 When the CR-LSP is established, all or a subset of the nodes in a 200 group may be traversed by the LSP. Certain operations to be 201 performed along the path can also be encoded in the constraint-based 202 route. 204 The capability to specify, in addition to specified nodes, groups of 205 nodes, of which a subset will be traversed by the CR-LSP, allows the 206 system a significant amount of local flexibility in fulfilling a 207 request for a constraint-based route. This allows the generator of 208 the constraint-based route to have some degree of imperfect 209 information about the details of the path. 211 The constraint-based route is encoded as a series of ER-Hops 212 contained in a constraint-based route TLV. Each ER-Hop may identify 213 a group of nodes in the constraint-based route. A constraint-based 214 route is then a path including all of the identified groups of nodes 215 in the order in which they appear in the TLV. 217 To simplify the discussion, we call each group of nodes an abstract 218 node. Thus, we can also say that a constraint-based route is a path 219 including all of the abstract nodes, with the specified operations 220 occurring along that path. 222 2.2 Traffic Characteristics 224 The traffic characteristics of a path are described in the Traffic 225 Parameters TLV in terms of a peak rate, committed rate, and service 226 granularity. The peak and committed rates describe the bandwidth 227 constraints of a path while the service granularity can be used to 228 specify a constraint on the delay variation that the CR-LDP MPLS 229 domain may introduce to a path's traffic. 231 2.3 Pre-emption 233 CR-LDP signals the resources required by a path on each hop of the 234 route. If a route with sufficient resources can not be found, 235 existing paths may be rerouted to reallocate resources to the new 236 path. This is the process of path pre-emption. Setup and holding 237 priorities are used to rank existing paths (holding priority) and 238 the new path (setup priority) to determine if the new path can pre- 239 empt an existing path. 241 The setupPriority of a new CR-LSP and the holdingPriority attributes 242 of the existing CR-LSP are used to specify priorities. Signaling a 243 higher holding priority express that the path, once it has been 244 established, should have a lower chance of being pre-empted. 245 Signaling a higher setup priority expresses the expectation that, in 246 the case that resource are unavailable, the path is more likely to 247 pre-empt other paths. The exact rules determining bumping are an 248 aspect of network policy. 250 The allocation of setup and holding priority values to paths is an 251 aspect of network policy. 253 The setup and holding priority values range from zero (0) to seven 254 (7). The value zero (0) is the priority assigned to the most 255 important path. It is referred to as the highest priority. Seven (7) 256 is the priority for the least important path. The use of default 257 priority values is an aspect of network policy. The recommended 258 default value is (4). 260 The setupPriority of a CR-LSP should not be higher (numerically 261 less) than its holdingPriority since it might bump an LSP and be 262 bumped by the next _equivalent_ request. 264 2.4 Route Pinning 266 Route pinning is applicable to segments of an LSP that are loosely 267 routed - i.e. those segments which are specified with a next hop 268 with the _L_ bit set or where the next hop is an _abstract node_. A 269 CR-LSP may be setup using route pinning if it is undesirable to 270 change the path used by an LSP even when a better next hop becomes 271 available at some LSR along the loosely routed portion of the LSP. 273 2.5 Resource Class 275 The network operator may classify network resources in various ways. 276 These classes are also known as _colors_ or _administrative groups_. 277 When a CR-LSP is being established, it's necessary to indicate which 278 resource classes the CR-LSP can draw from. 280 3. Solution Overview 282 CR-LSP over LDP Specification is designed with the following goals: 284 1. Meet the requirements outlined in [4] for performing traffic 285 engineering and provide a solid foundation for performing 286 more general constraint-based routing. 288 2. Build on already specified functionality that meets the 289 requirements whenever possible. Hence, this specification is 290 based on [1]. 292 3. Keep the solution simple. 294 In this document, support for unidirectional point-to-point CR-LSPs 295 is specified. Support for point-to-multipoint, multipoint-to-point, 296 is for further study (FFS). 298 Support for constraint-based routed LSPs in this specification 299 depends on the following minimal LDP behaviors as specified in [1]: 301 - Use of Basic and/or Extended Discovery Mechanisms. 302 - Use of the Label Request Message defined in [1] in downstream 303 on demand label advertisement mode with ordered control. 304 - Use of the Label Mapping Message defined in [1] in downstream 305 on demand mode with ordered control. 306 - Use of the Notification Message defined in [1]. 307 - Use of the Withdraw and Release Messages defined in [1]. 308 - Use of the Loop Detection (in the case of loosely routed 309 segments of a CR-LSP) mechanisms defined in [1]. 311 In addition, the following functionality is added to what's defined 312 in [1]: 314 - The Label Request Message used to setup a CR-LSP includes one 315 or more CR-TLVs defined in Section 4. For instance, the Label 316 Request Message may include the ER-TLV. 317 - An LSR implicitly infers ordered control from the existence of 318 one or more CR-TLVs in the Label Request Message. This means 319 that the LSR can still be configured for independent control 320 for LSPs established as a result of dynamic routing. However, 321 when a Label Request Message includes one or more of the CR- 322 TLVs, then ordered control is used to setup the CR-LSP. Note 323 that this is also true for the loosely routed parts of a CR- 324 LSP. 325 - New status codes are defined to handle error notification for 326 failure of established paths specified in the CR-TLVs. 328 Optional TLVs MUST be implemented to be compliant with the protocol. 329 However, they are optionally carried in the CR-LDP messages to 330 signal certain characteristics of the CR-LSP being established or 331 modified. 333 Examples of CR-LSP establishment are given in Appendix A to 334 illustrate how the mechanisms described in this draft work. 336 3.1 Required Messages and TLVs 338 Any Messages, TLVs, and procedures not defined explicitly in this 339 document are defined in the LDP Specification [1]. The reader can 340 use [8] as an informational document about the state transitions, 341 which relate to CR-LDP messages. 343 The following subsections are meant as a cross-reference to the [1] 344 document and indication of additional functionality beyond what's 345 defined in [1] where necessary. 347 Note that use of the Status TLV is not limited to Notification 348 messages as specified in Section 3.4.6 of [1]. A message other than 349 a Notification message may carry a Status TLV as an Optional 350 Parameter. When a message other than a Notification carries a 351 Status TLV the U-bit of the Status TLV should be set to 1 to 352 indicate that the receiver should silently discard the TLV if 353 unprepared to handle it. 355 3.2 Label Request Message 357 The Label Request Message is as defined in 3.5.8 of [1] with the 358 following modifications (required only if any of the CR-TLVs is 359 included in the Label Request Message): 361 - The Label Request Message MUST include a single FEC-TLV 362 element. The CR-LSP FEC TLV element SHOULD be used. However, 363 the other FEC-TLVs defined in [1] MAY be used instead for 364 certain applications. 366 - The Optional Parameters TLV includes the definition of any of 367 the Constraint-based TLVs specified in Section 4. 369 - The Procedures to handle the Label Request Message are 370 augmented by the procedures for processing of the CR-TLVs as 371 defined in Section 4. 373 The encoding for the CR-LDP Label Request Message is as follows: 375 0 1 2 3 376 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 1 377 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 378 |0| Label Request (0x0401) | Message Length | 379 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 380 | Message ID | 381 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 382 | FEC TLV | 383 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 384 | LSPID TLV (CR-LDP, mandatory) | 385 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 386 | ER-TLV (CR-LDP, optional) | 387 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 388 | Traffic TLV (CR-LDP, optional) | 389 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 390 | Pinning TLV (CR-LDP, optional) | 391 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 392 | Resource Class TLV (CR-LDP, optional) | 393 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 394 | Pre-emption TLV (CR-LDP, optional) | 395 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 397 3.3 Label Mapping Message 399 The Label Mapping Message is as defined in 3.5.7 of [1] with the 400 following modifications: 402 - The Label Mapping Message MUST include a single Label-TLV. 404 - The Label Mapping Message Procedures are limited to downstream 405 on demand ordered control mode. 407 A Mapping message is transmitted by a downstream LSR to an upstream 408 LSR under one of the following conditions: 410 1. The LSR is the egress end of the CR-LSP and an upstream 411 mapping has been requested. 413 2. The LSR received a mapping from its downstream next hop LSR 414 for an CR-LSP for which an upstream request is still 415 pending. 417 The encoding for the CR-LDP Label Mapping Message is as follows: 419 0 1 2 3 420 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 1 421 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 422 |0| Label Mapping (0x0400) | Message Length | 423 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 424 | Message ID | 425 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 426 | FEC TLV | 427 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 428 | Label TLV | 429 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 430 | Label Request Message ID TLV | 431 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 432 | LSPID TLV (CR-LDP, optional) | 433 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 434 | Traffic TLV (CR-LDP, optional) | 435 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 437 3.4 Notification Message 439 The Notification Message is as defined in Section 3.5.1 of [1] and 440 the Status TLV encoding is as defined in Section 3.4.6 of [1]. 441 Establishment of an CR-LSP may fail for a variety of reasons. All 442 such failures are considered advisory conditions and they are 443 signaled by the Notification Message. 445 Notification Messages carry Status TLVs to specify events being 446 signaled. New status codes are defined in Section 4.11 to signal 447 error notifications associated with the establishment of a CR-LSP 448 and the processing of the CR-TLV. 450 The Notification Message MAY carry the LSPID TLV of the 451 corresponding CR-LSP. 453 Notification Messages MUST be forwarded toward the LSR originating 454 the Label Request at each hop and at any time that procedures in 455 this specification - or in [1] - specify sending of a Notification 456 Message in response to a Label Request Message. 458 The encoding of the notification message is as follows: 460 0 1 2 3 461 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 1 462 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 463 |0| Notification (0x0001) | Message Length | 464 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 465 | Message ID | 466 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 467 | Status (TLV) | 468 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 469 | Optional Parameters | 470 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 472 3.5 Release , Withdraw, and Abort Messages 474 The Label Release , Label Withdraw, and Label Abort Request Messages 475 are used as specified in [1]. These messages may also carry the 476 LSPID TLV. 478 4. Protocol Specification 480 The Label Request Message defined in [1] MUST carry the LSPID TLV 481 and MAY carry one or more of the optional Constraint-based Routing 482 TLVs (CR-TLVs) defined in this section. If needed, other constraints 483 can be supported later through the definition of new TLVs. In this 484 specification, the following TLVs are defined: 486 - Explicit Route TLV 487 - Explicit Route Hop TLV 488 - Traffic Parameters TLV 489 - Preemption TLV 490 - LSPID TLV 491 - Route Pinning TLV 492 - Resource Class TLV 493 - CR-LSP FEC TLV 495 4.1 Explicit Route TLV (ER-TLV) 497 The ER-TLV is an object that specifies the path to be taken by the 498 LSP being established. It is composed of one or more Explicit Route 499 Hop TLVs (ER-Hop TLVs) defined in Section 4.2. 501 0 1 2 3 502 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 1 503 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 504 |0|0| Type = 0x0800 | Length | 505 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 506 | ER-Hop TLV 1 | 507 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 508 | ER-Hop TLV 2 | 509 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 510 ~ ............ ~ 511 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 512 | ER-Hop TLV n | 513 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 515 Type 516 A fourteen-bit field carrying the value of the ER-TLV Type = 517 0x0800. 519 Length 520 Specifies the length of the value field in bytes. 522 ER-Hop TLVs 523 One or more ER-Hop TLVs defined in Section 4.2. 525 4.2 Explicit Route Hop TLV (ER-Hop TLV) 527 The contents of an ER-TLV are a series of variable length ER-Hop 528 TLVs. 530 A node receiving a label request message including an ER-Hop type 531 that is not supported MUST not progress the label request message to 532 the downstream LSR and MUST send back a _No Route_ Notification 533 Message. 535 Each ER-Hop TLV has the form: 537 0 1 2 3 538 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 1 539 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 540 |0|0| Type | Length | 541 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 542 |L| Content // | 543 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 545 ER-Hop Type 546 A fourteen-bit field carrying the type of the ER-Hop contents. 547 Currently defined values are: 549 Value Type 550 ------ ------------------------ 551 0x0801 IPv4 prefix 552 0x0802 IPv6 prefix 553 0x0803 Autonomous system number 554 0x0804 LSPID 556 Length 557 Specifies the length of the value field in bytes. 559 L bit 560 The L bit in the ER-Hop is a one-bit attribute. If the L bit 561 is set, then the value of the attribute is _loose._ Otherwise, 562 the value of the attribute is _strict._ For brevity, we say 563 that if the value of the ER-Hop attribute is loose then it is a 564 _loose ER-Hop._ Otherwise, it's a _strict ER-Hop._ Further, 565 we say that the abstract node of a strict or loose ER-Hop is a 566 strict or a loose node, respectively. Loose and strict nodes 567 are always interpreted relative to their prior abstract nodes. 568 The path between a strict node and its prior node MUST include 569 only network nodes from the strict node and its prior abstract 570 node. 572 The path between a loose node and its prior node MAY include 573 other network nodes, which are not part of the strict node or 574 its prior abstract node. 576 Contents 577 A variable length field containing a node or abstract node 578 which is one of the consecutive nodes that make up the 579 explicitly routed LSP. 581 4.3 Traffic Parameters TLV 583 The following sections describe the CR-LSP Traffic Parameters. The 584 required characteristics of a CR-LSP are expressed by the Traffic 585 Parameter values. 587 A Traffic Parameters TLV, is used to signal the Traffic Parameter 588 values. The Traffic Parameters are defined in the subsequent 589 sections. 591 The Traffic Parameters TLV contains a Flags field, a Frequency, a 592 Weight, and the five Traffic Parameters PDR, PBS, CDR, CBS, EBS. 593 The Traffic Parameters TLV is shown below: 595 0 1 2 3 596 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 1 597 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 598 |0|0| Type = 0x0810 | Length = 24 | 599 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 600 | Flags | Frequency | Reserved | Weight | 601 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 602 | Peak Data Rate (PDR) | 603 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 604 | Peak Burst Size (PBS) | 605 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 606 | Committed Data Rate (CDR) | 607 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 608 | Committed Burst Size (CBS) | 609 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 610 | Excess Burst Size (EBS) | 611 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 613 Type 614 A fourteen-bit field carrying the value of the Traffic 615 Parameters TLV Type = 0x0810. 617 Length 618 Specifies the length of the value field in bytes = 24. 620 Flags 621 The Flags field is shown below: 623 +--+--+--+--+--+--+--+--+ 624 | Res |F6|F5|F4|F3|F2|F1| 625 +--+--+--+--+--+--+--+--+ 627 Res - These bits are reserved. 628 Zero on transmission. 629 Ignored on receipt. 630 F1 - Corresponds to the PDR. 631 F2 - Corresponds to the PBS. 632 F3 - Corresponds to the CDR. 633 F4 - Corresponds to the CBS. 634 F5 - Corresponds to the EBS. 635 F6 - Corresponds to the Weight. 637 Each flag Fi is a Negotiable Flag corresponding to a Traffic 638 Parameter. The Negotiable Flag value zero denotes NotNegotiable 639 and value one denotes Negotiable. 641 Frequency 642 The Frequency field is coded as an 8 bit unsigned integer with 643 the following code points defined: 645 0- Unspecified 646 1- Frequent 647 2- VeryFrequent 648 3-255 - Reserved 649 Reserved - Zero on transmission. Ignored on receipt. 651 Weight 652 An 8 bit unsigned integer indicating the weight of the CR-LSP. 653 Valid weight values are from 1 to 255. The value 0 means that 654 weight is not applicable for the CR-LSP. 656 Traffic Parameters 657 Each Traffic Parameter is encoded as a 32-bit IEEE single- 658 precision floating-point number. A value of positive infinity 659 is represented as an IEEE single-precision floating-point 660 number with an exponent of all ones (255) and a sign and 661 mantissa of all zeros. The values PDR and CDR are in units of 662 bytes per second. The values PBS, CBS and EBS are in units of 663 bytes. 665 The value of PDR MUST be greater than or equal to the value of 666 CDR in a correctly encoded Traffic Parameters TLV. 668 4.3.1 Semantics 670 4.3.1.1 Frequency 672 The Frequency specifies at what granularity the CDR allocated to the 673 CR-LSP is made available. The value VeryFrequent means that the 674 available rate should average at least the CDR when measured over 675 any time interval equal to or longer than the shortest packet time 676 at the CDR. The value Frequent means that the available rate should 677 average at least the CDR when measured over any time interval equal 678 to or longer than a small number of shortest packet times at the 679 CDR. 681 The value Unspecified means that the CDR MAY be provided at any 682 granularity. 684 4.3.1.2 Peak Rate 686 The Peak Rate defines the maximum rate at which traffic SHOULD be 687 sent to the CR-LSP. The Peak Rate is useful for the purpose of 688 resource allocation. If resource allocation within the MPLS domain 689 depends on the Peak Rate value then it should be enforced at the 690 ingress to the MPLS domain. 692 The Peak Rate is defined in terms of the two Traffic Parameters PDR 693 and PBS, see section 4.3.1.5 below. 695 4.3.1.3 Committed Rate 697 The Committed Rate defines the rate that the MPLS domain commits to 698 be available to the CR-LSP. 700 The Committed Rate is defined in terms of the two Traffic Parameters 701 CDR and CBS, see section 4.3.1.6 below. 703 4.3.1.4 Excess Burst Size 705 The Excess Burst Size may be used at the edge of an MPLS domain for 706 the purpose of traffic conditioning. The EBS MAY be used to measure 707 the extent by which the traffic sent on a CR-LSP exceeds the 708 committed rate. 710 The possible traffic conditioning actions, such as passing, marking 711 or dropping, are specific to the MPLS domain. 713 The Excess Burst Size is defined together with the Committed Rate, 714 see section 4.3.1.6 below. 716 4.3.1.5 Peak Rate Token Bucket 718 The Peak Rate of a CR-LSP is specified in terms of a token bucket P 719 with token rate PDR and maximum token bucket size PBS. 721 The token bucket P is initially (at time 0) full, i.e., the token 722 count Tp(0) = PBS. Thereafter, the token count Tp, if less than 723 PBS, is incremented by one PDR times per second. When a packet of 724 size B bytes arrives at time t, the following happens: 726 - If Tp(t)-B >= 0, the packet is not in excess of the peak rate 727 and Tp is decremented by B down to the minimum value of 0, else 729 - the packet is in excess of the peak rate and Tp is not 730 decremented. 732 Note that according to the above definition, a positive infinite 733 value of either PDR or PBS implies that arriving packets are never 734 in excess of the peak rate. 736 The actual implementation of an LSR doesn't need to be modeled 737 according to the above formal token bucket specification. 739 4.3.1.6 Committed Data Rate Token Bucket 741 The committed rate of a CR-LSP is specified in terms of a token 742 bucket C with rate CDR. The extent by which the offered rate 743 exceeds the committed rate MAY be measured in terms of another token 744 bucket E, which also operates at rate CDR. The maximum size of the 745 token bucket C is CBS and the maximum size of the token bucket E is 746 EBS. 748 The token buckets C and E are initially (at time 0) full, i.e., the 749 token count Tc(0) = CBS and the token count Te(0) = EBS. 750 Thereafter, the token counts Tc and Te are updated CDR times per 751 second as follows: 753 - If Tc is less than CBS, Tc is incremented by one, else 754 - if Te is less then EBS, Te is incremented by one, else 755 - neither Tc nor Te is incremented. 757 When a packet of size B bytes arrives at time t, the following 758 happens: 760 - If Tc(t)-B >= 0, the packet is not in excess of the Committed 761 Rate and Tc is decremented by B down to the minimum value of 0, 762 else 763 - if Te(t)-B >= 0, the packet is in excess of the Committed rate 764 but is not in excess of the EBS and Te is decremented by B down 765 to the minimum value of 0, else 766 - the packet is in excess of both the Committed Rate and the EBS 767 and neither Tc nor Te is decremented. 769 Note that according to the above specification, a CDR value of 770 positive infinity implies that arriving packets are never in excess 771 of either the Committed Rate or EBS. A positive infinite value of 772 either CBS or EBS implies that the respective limit cannot be 773 exceeded. 775 The actual implementation of an LSR doesn't need to be modeled 776 according to the above formal specification. 778 4.3.1.7 Weight 780 The weight determines the CR-LSP's relative share of the possible 781 excess bandwidth above its committed rate. The definition of 782 _relative share_ is MPLS domain specific. 784 4.3.2 Procedures 786 4.3.2.1 Label Request Message 788 If an LSR receives an incorrectly encoded Traffic Parameters TLV in 789 which the value of PDR is less than the value of CDR then it MUST 790 send a Notification Message including the Status code _Traffic 791 Parameters Unavailable_ to the upstream LSR from which it received 792 the erroneous message. 794 If a Traffic Parameter is indicated as Negotiable in the Label 795 Request Message by the corresponding Negotiable Flag then an LSR MAY 796 replace the Traffic Parameter value with a smaller value. 798 If the Weight is indicated as Negotiable in the Label Request 799 Message by the corresponding Negotiable Flag then an LSR may replace 800 the Weight value with a lower value (down to 0). 802 If, after possible Traffic Parameter negotiation, an LSR can support 803 the CR-LSP Traffic Parameters then the LSR MUST reserve the 804 corresponding resources for the CR-LSP. 806 If, after possible Traffic Parameter negotiation, an LSR cannot 807 support the CR-LSP Traffic Parameters then the LSR MUST send a 808 Notification Message that contains the _Resource Unavailable_ status 809 code. 811 4.3.2.2 Label Mapping Message 813 If an LSR receives an incorrectly encoded Traffic Parameters TLV in 814 which the value of PDR is less than the value of CDR then it MUST 815 send a Label Release message containing the Status code _Traffic 816 Parameters Unavailable_ to the LSR from which it received the 817 erroneous message. In addition, the LSP should send a Notification 818 Message upstream with the status code _Label Request Aborted_. 820 If the negotiation flag was set in the label request message, the 821 egress LSR MUST include the (possibly negotiated) Traffic Parameters 822 and Weight in the Label Mapping message. 824 The Traffic Parameters and the Weight in a Label Mapping message 825 MUST be forwarded unchanged. 827 An LSR SHOULD adjust the resources that it reserved for a CR-LSP 828 when it receives a Label Mapping Message if the Traffic Parameters 829 differ from those in the corresponding Label Request Message. 831 4.3.2.3 Notification Message 833 If an LSR receives a Notification Message for a CR-LSP, it SHOULD 834 release any resources that it possibly had reserved for the CR-LSP. 835 In addition, on receiving a Notification Message from a Downstream 836 LSR that is associated with a Label Request from an upstream LSR, 837 the local LSR MUST propagate the Notification message using the 838 procedures in [1]. 840 4.4 Preemption TLV 842 The defualt value of the setup and holding priorities should be in 843 the middle of the range (e.g., 4) so that this feature can be turned 844 on gradually in an operational network by increasing or decreasing 845 the priority starting at the middle of the range. 847 Since the Preemption TLV is an optional TLV, LSPs that are setup 848 without an explicitly signaled preemption TLV SHOULD be treated as 849 LSPs with the default setup and holding priorities (e.g., 4). 851 When an established LSP is preempted, the LSR that initiates the 852 preemption sends a Withdraw Message upstream and a Release Message 853 downstream. 855 When an LSP in the process of being established (outstanding Label 856 Request without getting a Label Mapping back) is preempted, the LSR 857 that initiates the preemption, sends a Notification Message upstream 858 and an Abort Message downstream. 860 0 1 2 3 861 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 1 862 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 863 |0|0| Type = 0x0820 | Length = 4 | 864 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 865 | SetPrio | HoldPrio | Reserved | 866 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 868 Type 869 A fourteen-bit field carrying the value of the Preemption-TLV 870 Type = 0x0820. 872 Length 873 Specifies the length of the value field in bytes = 4. 875 Reserved 876 Zero on transmission. Ignored on receipt. 878 SetPrio 879 A SetupPriority of value zero (0) is the priority assigned to 880 the most important path. It is referred to as the highest 881 priority. Seven (7) is the priority for the least important 882 path. The higher the setup priority, the more paths CR-LDP can 883 bump to set up the path. The default value should be 4. 885 HoldPrio 886 A HoldingPriority of value zero (0) is the priority assigned to 887 the most important path. It is referred to as the highest 888 priority. Seven (7) is the priority for the least important 889 path. The default value should be 4. 890 The higher the holding priority, the less likely it is for CR- 891 LDP to reallocate its bandwidth to a new path. 893 4.5 LSPID TLV 895 LSPID is a unique identifier of a CR-LSP within an MPLS network. 897 The LSPID is composed of the ingress LSR Router ID (or any of its 898 own Ipv4 addresses) and a Locally unique CR-LSP ID to that LSR. 900 The LSPID is useful in network management, in CR-LSP repair, and in 901 using an already established CR-LSP as a hop in an ER-TLV. 903 An _action indicator flag_ is carried in the LSPID TLV. This _action 904 indicator flag_ indicates explicitly the action that should be taken 905 if the LSP already exists on the LSR receiving the message. 907 After a CR-LSP is set up, its bandwidth reservation may need to be 908 changed by the network operator, due to the new requirements for the 909 traffic carried on that CR-LSP. The _action indicator flag_ is used 910 indicate the need to modify the bandwidth and possibly other 911 parameters of an established CR-LSP without service interruption. 912 This feature has application in dynamic network resources management 913 where traffic of different priorities and service classes is 914 involved. 916 The procedure for the code point _modify_ is defined in [9]. The 917 procedures for other flags are FFS. 919 0 1 2 3 920 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 1 921 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 922 |0|0| Type = 0x0821 | Length = 4 | 923 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 924 | Reserved |ActFlg | Local CR-LSP ID | 925 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 926 | Ingress LSR Router ID | 927 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 929 Type 930 A fourteen-bit field carrying the value of the LSPID-TLV 931 Type = 0x0821. 933 Length 934 Specifies the length of the value field in bytes = 4. 936 ActFlg 937 Action Indicator Flag: A 4-bit field that indicates explicitly 938 the action that should be taken if the LSP already exists on 939 the LSR receiving the message. A set of indicator code points 940 is proposed as follows: 942 0000: indicates initial LSP setup 943 0001: indicates modify LSP 944 Reserved 945 Zero on transmission. Ignored on receipt. 947 Local CR-LSP ID 948 The Local LSP ID is an identifier of the CR-LSP locally unique 949 within the Ingress LSR originating the CR-LSP. 951 Ingress LSR Router ID 952 An LSR may use any of its own IPv4 addresses in this field. 954 4.6 Resource Class (Color) TLV 956 The Resource Class as defined in [4] is used to specify which links 957 are acceptable by this CR-LSP. This information allows for the 958 network's topology to be pruned. 960 0 1 2 3 961 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 1 962 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 963 |0|0| Type = 0x0822 | Length = 4 | 964 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 965 | RsCls | 966 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 968 Type 969 A fourteen-bit field carrying the value of the ResCls-TLV Type 970 = 0x0822. 972 Length 973 Specifies the length of the value field in bytes = 4. 975 RsCls 976 The Resource Class bit mask indicating which of the 32 977 _administrative groups_ or _colors_ of links the CR-LSP can 978 traverse. 980 4.7 ER-Hop semantics 982 4.7.1. ER-Hop 1: The IPv4 prefix 984 The abstract node represented by this ER-Hop is the set of nodes, 985 which have an IP address, which lies within this prefix. Note that 986 a prefix length of 32 indicates a single IPv4 node. 988 0 1 2 3 989 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 1 990 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 991 |0|0| Type = 0x0801 | Length = 8 | 992 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 993 |L| Reserved | PreLen | 994 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 995 | IPv4 Address (4 bytes) | 996 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 998 Type 999 A fourteen-bit field carrying the value of the ER-Hop 1, IPv4 1000 Address, Type = 0x0801 1002 Length 1003 Specifies the length of the value field in bytes = 8. 1005 L Bit 1006 Set to indicate Loose hop. 1007 Cleared to indicate a strict hop. 1009 Reserved 1010 Zero on transmission. Ignored on receipt. 1012 PreLen 1013 Prefix Length 1-32 1015 IP Address 1016 A four-byte field indicating the IP Address. 1018 4.7.2. ER-Hop 2: The IPv6 address 1020 0 1 2 3 1021 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 1022 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1023 |0|0| 0x0802 | Length = 20 | 1024 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1025 |L| Reserved | PreLen | 1026 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1027 | IPV6 address | 1028 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1029 | IPV6 address (continued) | 1030 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1031 | IPV6 address (continued) | 1032 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1033 | IPV6 address (continued) | 1034 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1036 Type 1037 A fourteen-bit field carrying the value of the ER-Hop 2, IPv6 1038 Address, Type = 0x0802 1040 Length 1041 Specifies the length of the value field in bytes = 20. 1043 L Bit 1044 Set to indicate Loose hop. 1045 Cleared to indicate a strict hop. 1047 Reserved 1048 Zero on transmission. Ignored on receipt. 1050 PreLen 1051 Prefix Length 1-128 1053 IPv6 address 1054 A 128-bit unicast host address. 1056 4.7.3. ER-Hop 3: The autonomous system number 1058 The abstract node represented by this ER-Hop is the set of nodes 1059 belonging to the autonomous system. 1061 0 1 2 3 1062 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 1063 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1064 |0|0| 0x0803 | Length = 4 | 1065 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1066 |L| Reserved | AS Number | 1067 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1069 Type 1070 A fourteen-bit field carrying the value of the ER-Hop 3, AS 1071 Number, Type = 0x0803 1073 Length 1074 Specifies the length of the value field in bytes = 4. 1076 L Bit 1077 Set to indicate Loose hop. 1078 Cleared to indicate a strict hop. 1080 Reserved 1081 Zero on transmission. Ignored on receipt. 1083 AS Number 1084 Autonomous System number 1086 4.7.4. ER-Hop 4: LSPID 1088 The LSPID is used to identify the tunnel ingress point as the next 1089 hop in the ER. This ER-Hop allows for stacking new CR-LSPs within an 1090 already established CR-LSP. It also allows for splicing the CR-LSP 1091 being established with an existing CR-LSP. 1093 If an LSPID Hop is the last ER-Hop in an ER-TLV, than the LSR may 1094 splice the CR-LSP of the incoming Label Request to the CR-LSP that 1095 currently exists with this LSPID. This is useful, for example, at 1096 the point at which a Label Request used for local repair arrives at 1097 the next ER-Hop after the loosely specified CR-LSP segment. Use of 1098 the LSPID Hop in this scenario eliminates the need for ER-Hops to 1099 keep the entire remaining ER-TLV at each LSR that is at either 1100 (upstream or downstream) end of a loosely specified CR-LSP segment 1101 as part of its state information. This is due to the fact that the 1102 upstream LSR needs only to keep the next ER-Hop and the LSPID and 1103 the downstream LSR needs only to keep the LSPID in order for each 1104 end to be able to recognize that the same LSP is being identified. 1106 If the LSPID Hop is not the last hop in an ER-TLV, the LSR must 1107 remove the LSP-ID Hop and forward the remaining ER-TLV in a Label 1108 Request message using an LDP session established with the LSR that 1109 is the specified CR-LSP's egress. That LSR will continue processing 1110 of the CR-LSP Label Request Message. The result is a tunneled, or 1111 stacked, CR-LSP. 1113 To support labels negotiated for tunneled CR-LSP segments, an LDP 1114 session is required [1] between tunnel end points - possibly using 1115 the existing CR-LSP. Use of the existence of the CR-LSP in lieu of 1116 a session, or other possible session-less approaches, is FFS. 1118 0 1 2 3 1119 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 1120 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1121 |0|0| 0x0804 | Length = 8 | 1122 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1123 |L| Reserved | Local LSPID | 1124 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1125 | Ingress LSR Router ID | 1126 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1128 Type 1129 A fourteen-bit field carrying the value of the ER-Hop 4, LSPID, 1130 Type = 0x0804 1132 Length 1133 Specifies the length of the value field in bytes = 8. 1135 L Bit 1136 Set to indicate Loose hop. 1137 Cleared to indicate a strict hop. 1139 Reserved 1140 Zero on transmission. Ignored on receipt. 1142 Local LSPID 1143 A 2 byte field indicating the LSPID which is unique with 1144 reference to its Ingress LSR. 1146 Ingress LSR Router ID 1147 An LSR may use any of its own IPv4 addresses in this field. 1149 4.8. Processing of the Explicit Route TLV 1151 4.8.1. Selection of the next hop 1153 A Label Request Message containing an explicit route TLV must 1154 determine the next hop for this path. Selection of this next hop 1155 may involve a selection from a set of possible alternatives. The 1156 mechanism for making a selection from this set is implementation 1157 dependent and is outside of the scope of this specification. 1159 Selection of particular paths is also outside of the scope of this 1160 specification, but it is assumed that each node will make a best 1161 effort attempt to determine a loop-free path. Note that such best 1162 efforts may be overridden by local policy. 1164 To determine the next hop for the path, a node performs the 1165 following steps: 1167 1. The node receiving the Label Request Message must first 1168 evaluate the first ER-Hop. If the L bit is not set in the 1169 first ER-Hop and if the node is not part of the abstract node 1170 described by the first ER-Hop, it has received the message in 1171 error, and should return a _Bad Initial ER-Hop_ error. If the 1172 L bit is set and the local node is not part of the abstract 1173 node described by the first ER-Hop, the node selects a next 1174 hop that is along the path to the abstract node described by 1175 the first ER-Hop. If there is no first ER-Hop, the message is 1176 also in error and the system should return a _Bad Explicit 1177 Routing TLV_ error using a Notification Message sent upstream. 1179 2. If there is no second ER-Hop, this indicates the end of the 1180 explicit route. The explicit route TLV should be removed from 1181 the Label Request Message. This node may or may not be the 1182 end of the LSP. Processing continues with section 4.8.2, 1183 where a new explicit route TLV may be added to the Label 1184 Request Message. 1186 3. If the node is also a part of the abstract node described by 1187 the second ER-Hop, then the node deletes the first ER-Hop and 1188 continues processing with step 2, above. Note that this makes 1189 the second ER-Hop into the first ER-Hop of the next iteration. 1191 4. The node determines if it is topologically adjacent to the 1192 abstract node described by the second ER-Hop. If so, the node 1193 selects a particular next hop which is a member of the 1194 abstract node. The node then deletes the first ER-Hop and 1195 continues processing with section 4.8.2. 1197 5. Next, the node selects a next hop within the abstract node of 1198 the first ER-Hop that is along the path to the abstract node 1199 of the second ER-Hop. If no such path exists then there are 1200 two cases: 1202 5.a If the second ER-Hop is a strict ER-Hop, then there is 1203 an error and the node should return a _Bad Strict Node_ 1204 error. 1206 5.b Otherwise, if the second ER-Hop is a loose ER-Hop, then 1207 the node selects any next hop that is along the path to the 1208 next abstract node. If no path exists within the MPLS 1209 domain, then there is an error, and the node should return a 1210 _Bad loose node_ error. 1212 6. Finally, the node replaces the first ER-Hop with any ER-Hop 1213 that denotes an abstract node containing the next hop. This 1214 is necessary so that when the explicit route is received by 1215 the next hop, it will be accepted. 1217 7. Progress the Label Request Message to the next hop. 1219 4.8.2. Adding ER-Hops to the explicit route TLV 1221 After selecting a next hop, the node may alter the explicit route in 1222 the following ways. 1224 If, as part of executing the algorithm in section 4.8.1, the 1225 explicit route TLV is removed, the node may add a new explicit route 1226 TLV. 1228 Otherwise, if the node is a member of the abstract node for the 1229 first ER-Hop, then a series of ER-Hops may be inserted before the 1230 first ER-Hop or may replace the first ER-Hop. Each ER-Hop in this 1231 series must denote an abstract node that is a subset of the current 1232 abstract node. 1234 Alternately, if the first ER-Hop is a loose ER-Hop, an arbitrary 1235 series of ER-Hops may be inserted prior to the first ER-Hop. 1237 4.9 Route Pinning TLV 1239 Section 2.4 describes the use of route pinning. The encoding of the 1240 Route Pinning TLV is as follows: 1242 0 1 2 3 1243 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 1244 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1245 |0|0| Type = 0x0823 | Length = 4 | 1246 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1247 |P| Reserved | 1248 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1250 Type 1251 A fourteen-bit field carrying the value of the Pinning-TLV 1252 Type = 0x0823 1254 Length 1255 Specifies the length of the value field in bytes = 4. 1257 P Bit 1258 The P bit is set to 1 to indicate that route pinning is 1259 requested. 1260 The P bit is set to 0 to indicate that route pinning is not 1261 requested 1262 Reserved 1263 Zero on transmission. Ignored on receipt. 1265 4.10 CR-LSP FEC Element 1267 A new FEC element is introduced in this specification to support CR- 1268 LSPs. A FEC TLV containing a FEC of Element type CR-LSP (0x04) is a 1269 CR-LSP FEC TLV. The CR-LSP FEC Element is an opaque FEC to be used 1270 only in Messages of CR-LSPs. 1272 A single FEC element MUST be included in the Label Request Message. 1273 The FEC Element SHOULD be the CR-LSP FEC Element. However, one of 1274 the other FEC elements (Type=0x01, 0x02, 0x03) defined in [1] MAY be 1275 in CR-LDP messages instead of the CR-LSP FEC Element for certain 1276 applications. A FEC TLV containing a FEC of Element type CR-LSP 1277 (0x04) is a CR-LSP FEC TLV. 1279 FEC Element Type Value 1280 Type name 1282 CR-LSP 0x04 No value; i.e., 0 value octets; 1284 The CR-LSP FEC TLV encoding is as follows: 1286 0 1 2 3 1287 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 1288 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1289 |0|0| Type = 0x0100 | Length = 1 | 1290 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1291 | CR-LSP (4) | 1292 +-+-+-+-+-+-+-+-+ 1294 Type 1295 A fourteen-bit field carrying the value of the FEC TLV 1296 Type = 0x0100 1298 Length 1299 Specifies the length of the value field in bytes = 1. 1301 CR-LSP FEC Element Type 1302 0x04 1304 4.11 TLV Type Summary 1306 TLV Type 1307 -------------------------------------- ---------- 1308 Explicit Route TLV 0x0800 1309 Ipv4 Prefix ER-Hop TLV 0x0801 1310 Ipv6 Prefix ER-Hop TLV 0x0802 1311 Autonomous System Number ER-Hop TLV 0x0803 1312 LSP-ID ER-Hop TLV 0x0804 1313 Traffic Parameters TLV 0x0810 1314 Preemption TLV 0x0820 1315 LSPID TLV 0x0821 1316 Resource Class TLV 0x0822 1317 Route Pinning TLV 0x0823 1319 4.12 FEC Type Summary 1321 FEC Element TLV Type 1322 -------------------------------------- ---------- 1323 CR-LSP FEC Element TLV 0x0100 1325 4.13 Status Code Summary 1327 Status Code Type 1328 -------------------------------------- ---------- 1329 Bad Explicit Routing TLV Error 0x44000001 1330 Bad Strict Node Error 0x44000002 1331 Bad Loose Node Error 0x44000003 1332 Bad Initial ER-Hop Error 0x44000004 1333 Resource Unavailable 0x44000005 1334 Traffic Parameters Unavailable 0x44000006 1335 LSP Preempted 0x44000007 1336 Modify Request Not Supported 0x44000008 1337 Setup Abort (Label Request Aborted in [1]) 0x04000015 1339 5. IANA Considerations 1341 CR-LDP defines the following name spaces, which require management: 1343 - TLV types. 1344 - FEC types. 1345 - Status codes. 1347 The following sections provide guidelines for managing these name 1348 spaces. 1350 5.1 TLV Type Name Space 1352 TLV types in the range 0x0800 - 0x08FF are allocated to CR-LDP base 1353 protocol. Following the policies outlined in [IANA], TLV types in 1354 this range are allocated through an IETF Consensus action. 1356 5.2 FEC Type Name Space 1358 FEC Type 100 is allocated to CR-LDP. 1360 5.3 Status Code Space 1362 The range for Status Codes is 0x44000000 - 0x440000FF. 1364 Following the policies outlined in [IANA], Status Codes in the range 1365 0x44000000 - 0x440000FF are allocated through an IETF Consensus 1366 action. 1368 6. Security 1370 CR-LDP inherits the same security mechanism described in Section 4.0 1371 of [1] to protect against the introduction of spoofed TCP segments 1372 into LDP session connection streams. 1374 7. Acknowledgments 1376 The messages used to signal the CR-LSP setup are based on the work 1377 done by the [1] team. 1379 The authors would also like to acknowledge the careful review and 1380 comments of Ken Hayward, Greg Wright, Geetha Brown, Brian Williams, 1381 Paul Beaubien, Matthew Yuen, Liam Casey, Ankur Anand, Adrian Farrel. 1383 8. Intellectual Property Consideration 1385 The IETF has been notified of intellectual property rights claimed 1386 in regard to some or all of the specification contained in this 1387 document. For more information consult the online list of claimed 1388 rights. 1390 9. References 1392 1 Andersson et al, "Label Distribution Protocol Specification" 1393 work in progress (draft-ietf-mpls-ldp-08), June 2000. 1395 2 Callon et al, "Framework for Multiprotocol Label Switching", 1396 work in progress (draft-ietf-mpls-framework-05), September 1999. 1398 3 Rosen et al, "Multiprotocol Label Switching Architecture", 1399 work in progress (draft-ietf-mpls-arch-06), August 1999. 1401 4 Awduche et al, "Requirements for Traffic Engineering Over 1402 MPLS", RFC 2702, September 1999. 1404 5 B. Gleeson, et. al., "A Framework for IP Based Virtual Private 1405 Networks", RFC 2764, February 2000. 1407 6 B. Jamoussi, et. al., _Applicability Statement for CR-LDP_, work 1408 in progress, (draft-ietf-mpls-crldp-applic-01), June 2000. 1410 7 S. Bradner, "Key words for use in RFCs to Indicate Requirement 1411 Levels_, RFC 2119, March 1997. 1413 8 L. Wu, et. al., "LDP State Machine", work in progress, 1414 (draft-ietf-mpls-ldp-state-03), January 2000. 1416 9 J. Ash, et. al., "LSP Modification Using CR-LDP", work in 1417 progress, (draft-ietf-mpls-crlsp-modify-01), February 2000. 1419 10. Author's Addresses 1421 Osama S. Aboul-Magd Loa Andersson 1422 Nortel Networks Nortel Networks 1423 P O Box 3511 Station C S:t Eriksgatan 115 1424 Ottawa, ON K1Y 4H7 PO Box 6701 1425 Canada 113 85 Stockholm 1426 Phone: +1 613 763-5827 Tel: +46 8 508 835 00 1427 Osama@nortelnetworks.com Fax: +46 8 508 835 01 1428 Loa_andersson@nortelnetworks.com 1430 Peter Ashwood-Smith Ross Callon 1431 Nortel Networks Juniper Networks 1432 P O Box 3511 Station C 1194 North Mathilda Avenue, 1433 Ottawa, ON K1Y 4H7 Sunnyvale, CA 94089 1434 Canada 978-692-6724 1435 Phone: +1 613 763-4534 rcallon@juniper.net 1436 Petera@nortelnetworks.com 1438 Ram Dantu Paul Doolan 1439 IPmobile Ennovate Networks 1440 1651 North Glenville, Suite 216 330 Codman Hill Rd 1441 Richardson, TX 75081 Marlborough MA 01719 1442 +1-972-234-6070 extension 211 Phone: 978-263-2002 1443 rdantu@ipmobile.com Pdoolan@ennovatenetworks.com 1445 Nancy Feldman Andre Fredette 1446 IBM Corp. PhotonEx Corporation 1447 17 Skyline Drive 135 South Road 1448 Hawthorne NY 10532 Bedford, MA 01730 1449 Phone: 914-784-3254 email: fredette@photonex.com 1450 Nkf@us.ibm.com phone: 781-275-8500 1452 Eric Gray Joel M. Halpern 1453 Zaffire, Inc Longitude Systems, Inc. 1454 2630 Orchard Parkway, 1319 Shepard Road 1455 San Jose, CA 95134-2020 Sterling, VA 20164 1456 Phone: 408-894-7362 703-433-0808 x207 1457 egray@zaffire.com joel@longsys.com 1459 Juha Heinanen Fiffi Hellstrand 1460 Telia Finland, Inc. Nortel Networks 1461 Myyrmaentie 2 S:t Eriksgatan 115 1462 01600 VANTAA PO Box 6701, 113 85 Stockholm 1463 Finland Sweden 1464 Tel: +358 41 500 4808 +46705593687 1465 Jh@telia.fi fiffi@nortelnetworks.com 1466 Bilel Jamoussi Timothy E. Kilty 1467 Nortel Networks Corp. Newbridge Networks, Inc. 1468 600 Technology Park Drive 5 Corporate Drive 1469 Billerica, MA 01821 Andover, MA 01810 1470 USA USA 1471 Phone: +1 978 288-4506 phone: 978 691-4656 1472 Jamoussi@nortelnetworks.com tkilty@northchurch.net 1474 Andrew G. Malis Muckai K Girish 1475 Vivace Networks Atoga Systems 1476 2730 Orchard Parkway 49026 Milmont Drive 1477 San Jose, CA 95134 Fremont, CA 94538 1478 Andy.Malis@vivacenetworks.com E-mail: muckai@atoga.com 1479 Tel: +1 408 383 7223 1480 Fax: +1 408 904 4748 1482 Kenneth Sundell Pasi Vaananen 1483 Nortel Networks Nokia Telecommunications 1484 S:t Eriksgatan 115 3 Burlington Woods Drive, 1485 PO Box 6701 Burlington, MA 01803 1486 113 85 Stockholm Phone: +1-781-238-4981 1487 Tel: +46 8 508 835 00 pasi.vaananen@nokia.com 1488 Fax: +46 8 508 835 01 1489 Ksundell@nortelnetworks.com 1491 Tom Worster Liwen Wu 1492 Ennovate Networks Cisco Systems 1493 60 Codman Hill Rd 250 Apollo Drive 1494 Boxborough Chelmsford, MA. 01824 1495 MA 01719 Tel: 978-244-3087. 1496 tworster@ennovatenetworks.com liwwu@cisco.com 1497 Appendix A: CR-LSP Establishment Examples 1499 A.1 Strict Explicit Route Example 1501 This appendix provides an example for the setup of a strictly routed 1502 CR-LSP. In this example, a specific node represents each abstract 1503 node. 1505 The sample network used here is a four node network with two edge 1506 LSRs and two core LSRs as follows: 1508 abc 1509 LSR1------LSR2------LSR3------LSR4 1511 LSR1 generates a Label Request Message as described in Section 3.1 1512 of this draft and sends it to LSR2. This message includes the CR- 1513 TLV. 1515 A vector of three ER-Hop TLVs composes the ER-TLV. 1516 The ER-Hop TLVs used in this example are of type 0x0801 (IPv4 1517 prefix) with a prefix length of 32. Hence, each ER-Hop TLV 1518 identifies a specific node as opposed to a group of nodes. 1519 At LSR2, the following processing of the ER-TLV per Section 4.8.1 of 1520 this draft takes place: 1522 1) The node LSR2 is part of the abstract node described by the 1523 first hop . Therefore, the first step passes the test. 1524 Go to step 2. 1526 2) There is a second ER-Hop, . Go to step 3. 1528 3) LSR2 is not part of the abstract node described by the 1529 second ER-Hop . Go to Step 4. 1531 4) LSR2 determines that it is topologically adjacent to the 1532 abstract node described by the second ER-Hop . LSR2 1533 selects a next hop (LSR3) which is the abstract node. LSR2 1534 deletes the first ER-Hop from the ER-TLV, which now 1535 becomes . Processing continues with Section 4.8.2. 1537 At LSR2, the following processing of Section 4.8.2 takes place: 1538 Executing algorithm 4.8.1 did not result in the removal of the ER- 1539 TLV. 1541 Also, LSR2 is not a member of the abstract node described by the 1542 first ER-Hop . 1544 Finally, the first ER-Hop is a strict hop. 1546 Therefore, processing section 4.8.2 does not result in the insertion 1547 of new ER-Hops. The selection of the next hop has been already done 1548 is step 4 of Section 4.8.1 and the processing of the ER-TLV is 1549 completed at LSR2. In this case, the Label Request Message including 1550 the ER-TLV is progressed by LSR2 to LSR3. 1552 At LSR3, a similar processing to the ER-TLV takes place except that 1553 the incoming ER-TLV = and the outgoing ER-TLV is . 1555 At LSR4, the following processing of section 4.8.1 takes place: 1557 1) The node LSR4 is part of the abstract node described by the 1558 first hop . Therefore, the first step passes the test. Go 1559 to step 2. 1560 2) There is no second ER-Hop, this indicates the end of the CR- 1561 LSP. The ER-TLV is removed from the Label Request Message. 1562 Processing continues with Section 4.8.2. 1564 At LSR4, the following processing of Section 4.8.2 takes place: 1565 Executing algorithm 4.8.1 resulted in the removal of the ER-TLV. 1566 LSR4 does not add a new ER-TLV. 1568 Therefore, processing section 4.8.2 does not result in the insertion 1569 of new ER-Hops. This indicates the end of the CR-LSP and the 1570 processing of the ER-TLV is completed at LSR4. 1572 At LSR4, processing of Section 3.2 is invoked. The first condition 1573 is satisfied (LSR4 is the egress end of the CR-LSP and upstream 1574 mapping has been requested). Therefore, a Label Mapping Message is 1575 generated by LSR4 and sent to LSR3. 1577 At LSR3, the processing of Section 3.2 is invoked. The second 1578 condition is satisfied (LSR3 received a mapping from its downstream 1579 next hop LSR4 for a CR-LSP for which an upstream request is still 1580 pending). Therefore, a Label Mapping Message is generated by LSR3 1581 and sent to LSR2. 1583 At LSR2, a similar processing to LSR 3 takes place and a Label 1584 Mapping Message is sent back to LSR1, which completes the end-to-end 1585 CR-LSP setup. 1587 A.2 Node Groups and Specific Nodes Example 1589 A request at ingress LSR to setup a CR-LSP might originate from a 1590 management system or an application, the details are implementation 1591 specific. 1593 The ingress LSR uses information provided by the management system 1594 or the application and possibly also information from the routing 1595 database to calculate the explicit route and to create the Label 1596 Request Message. 1598 The Label request message carries together with other necessary 1599 information an ER-TLV defining the explicitly routed path. In our 1600 example the list of hops in the ER-Hop TLV is supposed to contain an 1601 abstract node representing a group of nodes, an abstract node 1602 representing a specific node, another abstract node representing a 1603 group of nodes, and an abstract node representing a specific egress 1604 point. 1606 In--{Group 1}--{Specific A}--{Group 2}--{Specific Out: B} 1607 The ER-TLV contains four ER-Hop TLVs: 1609 1. An ER-Hop TLV that specifies a group of LSR valid for the 1610 first abstract node representing a group of nodes (Group 1). 1612 2. An ER-Hop TLV that indicates the specific node (Node A). 1614 3. An ER-Hop TLV that specifies a group of LSRs valid for the 1615 second abstract node representing a group of nodes (Group 1616 2). 1618 4. An ER-Hop TLV that indicates the specific egress point for 1619 the CR-LSP (Node B). 1621 All the ER-Hop TLVs are strictly routed nodes. 1622 The setup procedure for this CR-LSP works as follows: 1624 1. The ingress node sends the Label Request Message to a node 1625 that is a member the group of nodes indicated in the first 1626 ER-Hop TLV, following normal routing for the specific node 1627 (A). 1629 2. The node that receives the message identifies itself as part 1630 of the group indicated in the first ER-Hop TLV, and that it 1631 is not the specific node (A) in the second. Further it 1632 realizes that the specific node (A) is not one of its next 1633 hops. 1635 3. It keeps the ER-Hop TLVs intact and sends a Label Request 1636 Message to another node that is part of the group indicated 1637 in the first ER-Hop TLV (Group 1), following normal routing 1638 for the specific node (A). 1640 4. The node that receives the message identifies itself as part 1641 of the group indicated in the first ER-Hop TLV, and that it 1642 is not the specific node (A) in the second ER-Hop TLV. 1643 Further it realizes that the specific node (A) is one of its 1644 next hops. 1646 5. It removes the first ER-Hop TLVs and sends a Label Request 1647 Message to the specific node (A). 1649 6. The specific node (A) recognizes itself in the first ER-Hop 1650 TLV. Removes the specific ER-Hop TLV. 1652 7. It sends a Label Request Message to a node that is a member 1653 of the group (Group 2) indicated in the ER-Hop TLV. 1655 8. The node that receives the message identifies itself as part 1656 of the group indicated in the first ER-Hop TLV, further it 1657 realizes that the specific egress node (B) is one of its 1658 next hops. 1660 9. It sends a Label Request Message to the specific egress node 1661 (B). 1663 10.The specific egress node (B) recognizes itself as the egress 1664 for the CR-LSP, it returns a Label Mapping Message, that 1665 will traverse the same path as the Label Request Message in 1666 the opposite direction. 1668 Appendix B. QoS Service Examples 1670 B.1 Service Examples 1672 Construction of an end-to-end service is the result of the rules 1673 enforced at the edge and the treatment that packets receive at the 1674 network nodes. The rules define the traffic conditioning actions 1675 that are implemented at the edge and they include policing with 1676 pass, mark, and drop capabilities. The edge rules are expected tobe 1677 defined by the mutual agreements between the service providers and 1678 their customers and they will constitute an essential part of the 1679 SLA. Therefore edge rules are not included in the signaling 1680 protocol. 1682 Packet treatment at a network node is usually referred to as the 1683 local behavior. Local behavior could be specified in many ways. One 1684 example for local behavior specification is the service frequency 1685 introduced in section 4.3.2.1, together with the resource 1686 reservation rules implemented at the nodes. 1688 Edge rules and local behaviors can be viewed as the main building 1689 blocks for the end-to-end service construction. The following table 1690 illustrates the applicability of the building block approach for 1691 constructing different services including those defined for ATM. 1693 Service PDR PBS CDR CBS EBS Service Conditioning 1694 Examples Frequency Action 1696 DS S S =PDR =PBS 0 Frequent drop>PDR 1698 TS S S S S 0 Unspecified drop>PDR,PBS 1699 mark>CDR,CBS 1701 BE inf inf inf inf 0 Unspecified - 1703 FRS S S CIR ~B_C ~B_E Unspecified drop>PDR,PBS 1704 mark>CDR,CBS,EBS 1706 ATM-CBR PCR CDVT =PCR =CDVT 0 VeryFrequent drop>PCR 1708 ATM-VBR.3(rt) PCR CDVT SCR MBS 0 Frequent drop>PCR 1709 mark>SCR,MBS 1711 ATM-VBR.3(nrt) PCR CDVT SCR MBS 0 Unspecified drop>PCR 1712 mark>SCR,MBS 1714 ATM-UBR PCR CDVT - - 0 Unspecified drop>PCR 1716 ATM-GFR.1 PCR CDVT MCR MBS 0 Unspecified drop>PCR 1718 ATM-GFR.2 PCR CDVT MCR MBS 0 Unspecified drop>PCR 1719 mark>MCR,MFS 1720 int-serv-CL p m r b 0 Frequent drop>p 1721 drop>r,b 1723 S= User specified 1725 In the above table, the DS refers to a delay sensitive service where 1726 the network commits to deliver with high probability user datagrams 1727 at a rate of PDR with minimum delay and delay requirements. 1728 Datagrams in excess of PDR will be discarded. 1730 The TS refers to a generic throughput sensitive service where the 1731 network commits to deliver with high probability user datagrams at a 1732 rate of at least CDR. The user may transmit at a rate higher than 1733 CDR but datagrams in excess of CDR would have a lower probability of 1734 being delivered. 1736 The BE is the best effort service and it implies that there are no 1737 expected service guarantees from the network. 1739 B.2 Establishing CR-LSP Supporting Real-Time Applications 1741 In this scenario the customer needs to establish an LSP for 1742 supporting real-time applications such as voice and video. The 1743 Delay-sensitive (DS) service is requested in this case. 1745 The first step is the specification of the traffic parameters in the 1746 signaling message. The two parameters of interest to the DS service 1747 are the PDR and the PBS and the user based on his requirements 1748 specifies their values. Since all the traffic parameters are 1749 included in the signaling message, appropriate values must be 1750 assigned to all of them. For DS service, the CDR and the CBS values 1751 are set equal to the PDR and the PBS respectively. An indication of 1752 whether the parameter values are subject to negotiation is flagged. 1754 The transport characteristics of the DS service require Frequent 1755 frequency to be requested to reflect the real-time delay 1756 requirements of the service. 1758 In addition to the transport characteristics, both the network 1759 provider and the customer need to agree on the actions enforced at 1760 the edge. The specification of those actions is expected to be a 1761 part of the service level agreement (SLA) negotiation and is not 1762 included in the signaling protocol. For DS service, the edge action 1763 is to drop packets that exceed the PDR and the PBS specifications. 1764 The signaling message will be sent in the direction of the ER path 1765 and the LSP is established following the normal LDP procedures. Each 1766 LSR applies its admission control rules. If sufficient resources are 1767 not available and the parameter values are subject to negotiation, 1768 then the LSR could negotiate down the PDR, the PBS, or both. 1770 The new parameter values are echoed back in the Label Mapping 1771 Message. LSRs might need to re-adjust their resource reservations 1772 based on the new traffic parameter values. 1774 B.3 Establishing CR-LSP Supporting Delay Insensitive Applications 1776 In this example we assume that a throughput sensitive (TS) service 1777 is requested. For resource allocation the user assigns values for 1778 PDR, PBS, CDR, and CBS. The negotiation flag is set if the traffic 1779 parameters are subject to negotiation. 1780 Since the service is delay insensitive by definition, the 1781 Unspecified frequency is signaled to indicate that the service 1782 frequency is not an issue. 1784 Similar to the previous example, the edge actions are not subject 1785 for signaling and are specified in the service level agreement 1786 between the user and the network provider. 1788 For TS service, the edge rules might include marking to indicate 1789 high discard precedence values for all packets that exceed CDR and 1790 the CBS. The edge rules will also include dropping of packets that 1791 conform to neither PDR nor PBS. 1793 Each LSR of the LSP is expected to run its admission control rules 1794 and negotiate traffic parameters down if sufficient resources do not 1795 exist. The new parameter values are echoed back in the Label Mapping 1796 Message. LSRs might need to re-adjust their resources based on the 1797 new traffic parameter values. 1799 Full Copyright Statement 1800 _Copyright c The Internet Society (date). All Rights Reserved. This 1801 document and translations of it may be copied and furnished to 1802 others, and derivative works that comment on or otherwise explain it 1803 or assist in its implementation may be prepared, copied, published 1804 and distributed, in whole or in part, without restriction of any 1805 kind, provided that the above copyright notice and this paragraph 1806 are included on all such copies and derivative works. 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