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This must be updated to follow RFC 3978/3979, as updated by RFC 4748. Checking nits according to https://www.ietf.org/id-info/1id-guidelines.txt: ---------------------------------------------------------------------------- ** The document seems to lack a 1id_guidelines paragraph about 6 months document validity -- however, there's a paragraph with a matching beginning. Boilerplate error? == There are 35 instances of lines with non-ascii characters in the document. == No 'Intended status' indicated for this document; assuming Proposed Standard Checking nits according to https://www.ietf.org/id-info/checklist : ---------------------------------------------------------------------------- ** The document seems to lack an Authors' Addresses Section. ** The document seems to lack separate sections for Informative/Normative References. 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Found 'MUST not' in this paragraph: A node receiving a label request message including an ER-Hop type that is not supported MUST not progress the label request message to the downstream LSR and MUST send back a "No Route� Notification Message. -- The document seems to lack a disclaimer for pre-RFC5378 work, but may have content which was first submitted before 10 November 2008. If you have contacted all the original authors and they are all willing to grant the BCP78 rights to the IETF Trust, then this is fine, and you can ignore this comment. If not, you may need to add the pre-RFC5378 disclaimer. (See the Legal Provisions document at https://trustee.ietf.org/license-info for more information.) -- The document date (February 2001) is 8465 days in the past. Is this intentional? 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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 1 MPLS Working Group Bilel Jamoussi, Editor 2 Internet Draft Nortel Networks Corp. 3 Expiration Date: August 2001 5 O. Aboul-Magd, L. Andersson, P. Ashwood-Smith, 6 F. Hellstrand, K. Sundell, Nortel Networks Corp. 7 R. Callon, Juniper Networks. 8 R. Dantu, L. Wu, Cisco Systems 9 P. Doolan, T. Worster, Ennovate Networks Corp. 10 N. Feldman, IBM Corp. 11 A. Fredette, PhotonEx Corp. 12 M. Girish, Atoga Systems 13 E. Gray, Sandburst 14 J. Halpern, Longitude Systems, Inc. 15 J. Heinanen, Telia Finland 16 T. Kilty, Newbridge Networks, Inc. 17 A. Malis, Vivace Networks 18 P. Vaananen, Nokia Telecommunications 20 February 2001 22 Constraint-Based LSP Setup using LDP 24 draft-ietf-mpls-cr-ldp-05.txt 26 Status of this Memo 28 This document is an Internet-Draft and is in full conformance with 29 all provisions of Section 10 of RFC2026. 31 Internet-Drafts are working documents of the Internet Engineering 32 Task Force (IETF), its areas, and its working groups. Note that 33 other groups may also distribute working documents as Internet- 34 Drafts. 36 Internet-Drafts are draft documents valid for a maximum of six 37 months and may be updated, replaced, or obsoleted by other documents 38 at any time. It is inappropriate to use Internet-Drafts as reference 39 material or to cite them other than as "work in progress.� 41 The list of current Internet-Drafts can be accessed at 42 http://www.ietf.org/ietf/1id-abstracts.txt 44 The list of Internet-Draft Shadow Directories can be accessed at 45 http://www.ietf.org/shadow.html. 47 Abstract 49 Label Distribution Protocol (LDP) is defined in [1] for distribution 50 of labels inside one MPLS domain. One of the most important 51 services that may be offered using MPLS in general and LDP in 52 particular is support for constraint-based routing of traffic across 54 Jamoussi, et. al. draft-ietf-mpls-crldp-05.txt 1 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] and [3]. 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 [4]. More information 64 about the applicability of CR-LDP can be found in [5]. 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 [6]. 73 Jamoussi, et. al. draft-ietf-mpls-crldp-05.txt 2 74 Table of Contents 76 1. Introduction....................................................4 77 2. Constraint-based Routing Overview...............................4 78 2.1 Strict and Loose Explicit Routes...............................5 79 2.2 Traffic Characteristics........................................5 80 2.3 Pre-emption....................................................6 81 2.4 Route Pinning..................................................6 82 2.5 Resource Class.................................................6 83 3. Solution Overview...............................................6 84 3.1 Required Messages and TLVs.....................................8 85 3.2 Label Request Message..........................................8 86 3.3 Label Mapping Message..........................................9 87 3.4 Notification Message...........................................9 88 3.5 Release , Withdraw, and Abort Messages........................10 89 4. Protocol Specification.........................................10 90 4.1 Explicit Route TLV (ER-TLV)...................................11 91 4.2 Explicit Route Hop TLV (ER-Hop TLV)...........................11 92 4.3 Traffic Parameters TLV........................................12 93 4.3.1 Semantics...................................................14 94 4.3.1.1 Frequency.................................................14 95 4.3.1.2 Peak Rate.................................................14 96 4.3.1.3 Committed Rate............................................14 97 4.3.1.4 Excess Burst Size.........................................15 98 4.3.1.5 Peak Rate Token Bucket....................................15 99 4.3.1.6 Committed Data Rate Token Bucket..........................15 100 4.3.1.7 Weight....................................................16 101 4.3.2 Procedures..................................................16 102 4.3.2.1 Label Request Message.....................................16 103 4.3.2.2 Label Mapping Message.....................................17 104 4.3.2.3 Notification Message......................................17 105 4.4 Preemption TLV................................................17 106 4.5 LSPID TLV.....................................................18 107 4.6 Resource Class (Color) TLV....................................20 108 4.7 ER-Hop semantics..............................................20 109 4.7.1. ER-Hop 1: The IPv4 prefix..................................20 110 4.7.2. ER-Hop 2: The IPv6 address.................................21 111 4.7.3. ER-Hop 3: The autonomous system number....................21 112 4.7.4. ER-Hop 4: LSPID............................................22 113 4.8. Processing of the Explicit Route TLV.........................23 114 4.8.1. Selection of the next hop..................................23 115 4.8.2. Adding ER-Hops to the explicit route TLV...................25 116 4.9 Route Pinning TLV.............................................25 117 4.10 CR-LSP FEC Element...........................................26 118 5. IANA Considerations............................................26 119 5.1 TLV Type Name Space...........................................26 120 5.2 FEC Type Name Space...........................................27 121 5.3 Status Code Space.............................................27 122 6. Security.......................................................28 123 7. Acknowledgments................................................28 124 8. Intellectual Property Consideration............................28 126 Jamoussi, et. al. draft-ietf-mpls-crldp-05.txt 3 127 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 [2], and [3]. Explicit routing is a subset of the more 141 general constraint-based routing function. At the MPLS WG meeting 142 held during the Washington IETF (December 1997) there was consensus 143 that LDP should support explicit routing of LSPs with provision for 144 indication of associated (forwarding) priority. In the Chicago 145 meeting (August 1998), a decision was made that support for explicit 146 path setup in LDP will be moved to a separate document. This 147 document provides that support and it has been accepted as a working 148 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 [3]. 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 179 Jamoussi, et. al. draft-ietf-mpls-crldp-05.txt 4 180 to provide a network operator with control over the path taken by an 181 LSP. This section is an overview of the various constraints 182 supported by this specification. 184 Like any other LSP a CR-LSP is a path through an MPLS network. The 185 difference is that while other paths are setup solely based on 186 information in routing tables or from a management system, the 187 constraint-based route is calculated at one point at the edge of 188 network based on criteria, including but not limited to routing 189 information. The intention is that this functionality shall give 190 desired special characteristics to the LSP in order to better 191 support the traffic sent over the LSP. The reason for setting up CR- 192 LSPs might be that one wants to assign certain bandwidth or other 193 Service Class characteristics to the LSP, or that one wants to make 194 sure that alternative routes use physically separate paths through 195 the network. 197 2.1 Strict and Loose Explicit Routes 199 An explicit route is represented in a Label Request Message as a 200 list of nodes or groups of nodes along the constraint-based route. 201 When the CR-LSP is established, all or a subset of the nodes in a 202 group may be traversed by the LSP. Certain operations to be 203 performed along the path can also be encoded in the constraint-based 204 route. 206 The capability to specify, in addition to specified nodes, groups of 207 nodes, of which a subset will be traversed by the CR-LSP, allows the 208 system a significant amount of local flexibility in fulfilling a 209 request for a constraint-based route. This allows the generator of 210 the constraint-based route to have some degree of imperfect 211 information about the details of the path. 213 The constraint-based route is encoded as a series of ER-Hops 214 contained in a constraint-based route TLV. Each ER-Hop may identify 215 a group of nodes in the constraint-based route. A constraint-based 216 route is then a path including all of the identified groups of nodes 217 in the order in which they appear in the TLV. 219 To simplify the discussion, we call each group of nodes an abstract 220 node. Thus, we can also say that a constraint-based route is a path 221 including all of the abstract nodes, with the specified operations 222 occurring along that path. 224 2.2 Traffic Characteristics 226 The traffic characteristics of a path are described in the Traffic 227 Parameters TLV in terms of a peak rate, committed rate, and service 228 granularity. The peak and committed rates describe the bandwidth 229 constraints of a path while the service granularity can be used to 230 specify a constraint on the delay variation that the CR-LDP MPLS 231 domain may introduce to a path�s traffic. 233 Jamoussi, et. al. draft-ietf-mpls-crldp-05.txt 5 234 2.3 Pre-emption 236 CR-LDP signals the resources required by a path on each hop of the 237 route. If a route with sufficient resources can not be found, 238 existing paths may be rerouted to reallocate resources to the new 239 path. This is the process of path pre-emption. Setup and holding 240 priorities are used to rank existing paths (holding priority) and 241 the new path (setup priority) to determine if the new path can pre- 242 empt an existing path. 244 The setupPriority of a new CR-LSP and the holdingPriority attributes 245 of the existing CR-LSP are used to specify priorities. Signaling a 246 higher holding priority express that the path, once it has been 247 established, should have a lower chance of being pre-empted. 248 Signaling a higher setup priority expresses the expectation that, in 249 the case that resource are unavailable, the path is more likely to 250 pre-empt other paths. The exact rules determining bumping are an 251 aspect of network policy. 253 The allocation of setup and holding priority values to paths is an 254 aspect of network policy. 256 The setup and holding priority values range from zero (0) to seven 257 (7). The value zero (0) is the priority assigned to the most 258 important path. It is referred to as the highest priority. Seven (7) 259 is the priority for the least important path. The use of default 260 priority values is an aspect of network policy. The recommended 261 default value is (4). 263 The setupPriority of a CR-LSP should not be higher (numerically 264 less) than its holdingPriority since it might bump an LSP and be 265 bumped by the next "equivalent� request. 267 2.4 Route Pinning 269 Route pinning is applicable to segments of an LSP that are loosely 270 routed - i.e. those segments which are specified with a next hop 271 with the �L� bit set or where the next hop is an �abstract node�. A 272 CR-LSP may be setup using route pinning if it is undesirable to 273 change the path used by an LSP even when a better next hop becomes 274 available at some LSR along the loosely routed portion of the LSP. 276 2.5 Resource Class 278 The network operator may classify network resources in various ways. 279 These classes are also known as "colors� or "administrative groups�. 280 When a CR-LSP is being established, it�s necessary to indicate which 281 resource classes the CR-LSP can draw from. 283 3. Solution Overview 285 Jamoussi, et. al. draft-ietf-mpls-crldp-05.txt 6 286 CR-LSP over LDP Specification is designed with the following goals: 288 1. Meet the requirements outlined in [3] for performing traffic 289 engineering and provide a solid foundation for performing more 290 general constraint-based routing. 292 2. Build on already specified functionality that meets the 293 requirements whenever possible. Hence, this specification is 294 based on [1]. 296 3. Keep the solution simple. 298 In this document, support for unidirectional point-to-point CR-LSPs 299 is specified. Support for point-to-multipoint, multipoint-to-point, 300 is for further study (FFS). 302 Support for constraint-based routed LSPs in this specification 303 depends on the following minimal LDP behaviors as specified in [1]: 305 - Use of Basic and/or Extended Discovery Mechanisms. 306 - Use of the Label Request Message defined in [1] in downstream on 307 demand label advertisement mode with ordered control. 308 - Use of the Label Mapping Message defined in [1] in downstream on 309 demand mode with ordered control. 310 - Use of the Notification Message defined in [1]. 311 - Use of the Withdraw and Release Messages defined in [1]. 312 - Use of the Loop Detection (in the case of loosely routed 313 segments of a CR-LSP) mechanisms defined in [1]. 315 In addition, the following functionality is added to what�s defined 316 in [1]: 318 - The Label Request Message used to setup a CR-LSP includes one or 319 more CR-TLVs defined in Section 4. For instance, the Label Request 320 Message may include the ER-TLV. 322 - An LSR implicitly infers ordered control from the existence of 323 one or more CR-TLVs in the Label Request Message. This means that 324 the LSR can still be configured for independent control for LSPs 325 established as a result of dynamic routing. However, when a Label 326 Request Message includes one or more of the CR-TLVs, then ordered 327 control is used to setup the CR-LSP. Note that this is also true 328 for the loosely routed parts of a CR-LSP. 330 - New status codes are defined to handle error notification for 331 failure of established paths specified in the CR-TLVs. 333 Optional TLVs MUST be implemented to be compliant with the protocol. 334 However, they are optionally carried in the CR-LDP messages to 335 signal certain characteristics of the CR-LSP being established or 336 modified. 338 Jamoussi, et. al. draft-ietf-mpls-crldp-05.txt 7 339 Examples of CR-LSP establishment are given in Appendix A to 340 illustrate how the mechanisms described in this draft work. 342 3.1 Required Messages and TLVs 344 Any Messages, TLVs, and procedures not defined explicitly in this 345 document are defined in the LDP Specification [1]. The reader can 346 use [7] as an informational document about the state transitions, 347 which relate to CR-LDP messages. 349 The following subsections are meant as a cross-reference to the [1] 350 document and indication of additional functionality beyond what�s 351 defined in [1] where necessary. 353 Note that use of the Status TLV is not limited to Notification 354 messages as specified in Section 3.4.6 of [1]. A message other than 355 a Notification message may carry a Status TLV as an Optional 356 Parameter. When a message other than a Notification carries a 357 Status TLV the U-bit of the Status TLV should be set to 1 to 358 indicate that the receiver should silently discard the TLV if 359 unprepared to handle it. 361 3.2 Label Request Message 363 The Label Request Message is as defined in 3.5.8 of [1] with the 364 following modifications (required only if any of the CR-TLVs is 365 included in the Label Request Message): 367 - The Label Request Message MUST include a single FEC-TLV element. 368 The CR-LSP FEC TLV element SHOULD be used. However, the other FEC- 369 TLVs defined in [1] MAY be used instead for certain applications. 371 - The Optional Parameters TLV includes the definition of any of 372 the Constraint-based TLVs specified in Section 4. 374 - The Procedures to handle the Label Request Message are augmented 375 by the procedures for processing of the CR-TLVs as defined in 376 Section 4. 378 The encoding for the CR-LDP Label Request Message is as follows: 380 0 1 2 3 381 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 1 382 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 383 |0| Label Request (0x0401) | Message Length | 384 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 385 | Message ID | 386 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 387 | FEC TLV | 388 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 389 | LSPID TLV (CR-LDP, mandatory) | 390 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 392 Jamoussi, et. al. draft-ietf-mpls-crldp-05.txt 8 393 | ER-TLV (CR-LDP, optional) | 394 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 395 | Traffic TLV (CR-LDP, optional) | 396 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 397 | Pinning TLV (CR-LDP, optional) | 398 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 399 | Resource Class TLV (CR-LDP, optional) | 400 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 401 | Pre-emption TLV (CR-LDP, optional) | 402 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 404 3.3 Label Mapping Message 406 The Label Mapping Message is as defined in 3.5.7 of [1] with the 407 following modifications: 409 - The Label Mapping Message MUST include a single Label-TLV. 411 - The Label Mapping Message Procedures are limited to downstream 412 on demand ordered control mode. 414 A Mapping message is transmitted by a downstream LSR to an upstream 415 LSR under one of the following conditions: 417 1. The LSR is the egress end of the CR-LSP and an upstream 418 mapping has been requested. 420 2. The LSR received a mapping from its downstream next hop LSR 421 for an CR-LSP for which an upstream request is still pending. 423 The encoding for the CR-LDP Label Mapping Message is as follows: 425 0 1 2 3 426 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 1 427 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 428 |0| Label Mapping (0x0400) | Message Length | 429 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 430 | Message ID | 431 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 432 | FEC TLV | 433 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 434 | Label TLV | 435 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 436 | Label Request Message ID TLV | 437 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 438 | LSPID TLV (CR-LDP, optional) | 439 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 440 | Traffic TLV (CR-LDP, optional) | 441 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 443 3.4 Notification Message 445 Jamoussi, et. al. draft-ietf-mpls-crldp-05.txt 9 446 The Notification Message is as defined in Section 3.5.1 of [1] and 447 the Status TLV encoding is as defined in Section 3.4.6 of [1]. 448 Establishment of an CR-LSP may fail for a variety of reasons. All 449 such failures are considered advisory conditions and they are 450 signaled by the Notification Message. 452 Notification Messages carry Status TLVs to specify events being 453 signaled. New status codes are defined in Section 4.11 to signal 454 error notifications associated with the establishment of a CR-LSP 455 and the processing of the CR-TLV. 457 The Notification Message MAY carry the LSPID TLV of the 458 corresponding CR-LSP. 460 Notification Messages MUST be forwarded toward the LSR originating 461 the Label Request at each hop and at any time that procedures in 462 this specification - or in [1] - specify sending of a Notification 463 Message in response to a Label Request Message. 465 The encoding of the notification message is as follows: 467 0 1 2 3 468 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 1 469 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 470 |0| Notification (0x0001) | Message Length | 471 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 472 | Message ID | 473 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 474 | Status (TLV) | 475 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 476 | Optional Parameters | 477 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 479 3.5 Release , Withdraw, and Abort Messages 481 The Label Release , Label Withdraw, and Label Abort Request Messages 482 are used as specified in [1]. These messages may also carry the 483 LSPID TLV. 485 4. Protocol Specification 487 The Label Request Message defined in [1] MUST carry the LSPID TLV 488 and MAY carry one or more of the optional Constraint-based Routing 489 TLVs (CR-TLVs) defined in this section. If needed, other constraints 490 can be supported later through the definition of new TLVs. In this 491 specification, the following TLVs are defined: 493 - Explicit Route TLV 494 - Explicit Route Hop TLV 495 - Traffic Parameters TLV 496 - Preemption TLV 497 - LSPID TLV 499 Jamoussi, et. al. draft-ietf-mpls-crldp-05.txt 10 500 - Route Pinning TLV 501 - Resource Class TLV 502 - CR-LSP FEC TLV 504 4.1 Explicit Route TLV (ER-TLV) 506 The ER-TLV is an object that specifies the path to be taken by the 507 LSP being established. It is composed of one or more Explicit Route 508 Hop TLVs (ER-Hop TLVs) defined in Section 4.2. 510 0 1 2 3 511 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 1 512 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 513 |0|0| Type = 0x0800 | Length | 514 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 515 | ER-Hop TLV 1 | 516 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 517 | ER-Hop TLV 2 | 518 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 519 ~ ............ ~ 520 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 521 | ER-Hop TLV n | 522 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 524 Type 525 A fourteen-bit field carrying the value of the ER-TLV Type = 526 0x0800. 528 Length 529 Specifies the length of the value field in bytes. 531 ER-Hop TLVs 532 One or more ER-Hop TLVs defined in Section 4.2. 534 4.2 Explicit Route Hop TLV (ER-Hop TLV) 536 The contents of an ER-TLV are a series of variable length ER-Hop 537 TLVs. 539 A node receiving a label request message including an ER-Hop type 540 that is not supported MUST not progress the label request message to 541 the downstream LSR and MUST send back a "No Route� Notification 542 Message. 544 Each ER-Hop TLV has the form: 546 0 1 2 3 547 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 1 548 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 549 |0|0| Type | Length | 550 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 551 |L| Content // | 553 Jamoussi, et. al. draft-ietf-mpls-crldp-05.txt 11 554 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 556 ER-Hop Type 557 A fourteen-bit field carrying the type of the ER-Hop contents. 558 Currently defined values are: 560 Value Type 561 ------ ------------------------ 562 0x0801 IPv4 prefix 563 0x0802 IPv6 prefix 564 0x0803 Autonomous system number 565 0x0804 LSPID 567 Length 568 Specifies the length of the value field in bytes. 570 L bit 571 The L bit in the ER-Hop is a one-bit attribute. If the L bit 572 is set, then the value of the attribute is "loose.� Otherwise, 573 the value of the attribute is "strict.� For brevity, we say 574 that if the value of the ER-Hop attribute is loose then it is a 575 "loose ER-Hop.� Otherwise, it�s a "strict ER-Hop.� Further, 576 we say that the abstract node of a strict or loose ER-Hop is a 577 strict or a loose node, respectively. Loose and strict nodes 578 are always interpreted relative to their prior abstract nodes. 579 The path between a strict node and its prior node MUST include 580 only network nodes from the strict node and its prior abstract 581 node. 583 The path between a loose node and its prior node MAY include 584 other network nodes, which are not part of the strict node or 585 its prior abstract node. 587 Contents 588 A variable length field containing a node or abstract node 589 which is one of the consecutive nodes that make up the 590 explicitly routed LSP. 592 4.3 Traffic Parameters TLV 594 The following sections describe the CR-LSP Traffic Parameters. The 595 required characteristics of a CR-LSP are expressed by the Traffic 596 Parameter values. 598 A Traffic Parameters TLV, is used to signal the Traffic Parameter 599 values. The Traffic Parameters are defined in the subsequent 600 sections. 602 The Traffic Parameters TLV contains a Flags field, a Frequency, a 603 Weight, and the five Traffic Parameters PDR, PBS, CDR, CBS, EBS. 604 The Traffic Parameters TLV is shown below: 606 Jamoussi, et. al. draft-ietf-mpls-crldp-05.txt 12 607 0 1 2 3 608 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 1 609 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 610 |0|0| Type = 0x0810 | Length = 24 | 611 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 612 | Flags | Frequency | Reserved | Weight | 613 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 614 | Peak Data Rate (PDR) | 615 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 616 | Peak Burst Size (PBS) | 617 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 618 | Committed Data Rate (CDR) | 619 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 620 | Committed Burst Size (CBS) | 621 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 622 | Excess Burst Size (EBS) | 623 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 625 Type 626 A fourteen-bit field carrying the value of the Traffic 627 Parameters TLV Type = 0x0810. 629 Length 630 Specifies the length of the value field in bytes = 24. 632 Flags 633 The Flags field is shown below: 635 +--+--+--+--+--+--+--+--+ 636 | Res |F6|F5|F4|F3|F2|F1| 637 +--+--+--+--+--+--+--+--+ 639 Res - These bits are reserved. 640 Zero on transmission. 641 Ignored on receipt. 642 F1 - Corresponds to the PDR. 643 F2 - Corresponds to the PBS. 644 F3 - Corresponds to the CDR. 645 F4 - Corresponds to the CBS. 646 F5 - Corresponds to the EBS. 647 F6 - Corresponds to the Weight. 649 Each flag Fi is a Negotiable Flag corresponding to a Traffic 650 Parameter. The Negotiable Flag value zero denotes NotNegotiable 651 and value one denotes Negotiable. 653 Frequency 654 The Frequency field is coded as an 8 bit unsigned integer with 655 the following code points defined: 657 0- Unspecified 658 1- Frequent 660 Jamoussi, et. al. draft-ietf-mpls-crldp-05.txt 13 661 2- VeryFrequent 662 3-255 - Reserved 663 Reserved - Zero on transmission. Ignored on receipt. 665 Weight 666 An 8 bit unsigned integer indicating the weight of the CR-LSP. 667 Valid weight values are from 1 to 255. The value 0 means that 668 weight is not applicable for the CR-LSP. 670 Traffic Parameters 671 Each Traffic Parameter is encoded as a 32-bit IEEE single- 672 precision floating-point number. A value of positive infinity 673 is represented as an IEEE single-precision floating-point 674 number with an exponent of all ones (255) and a sign and 675 mantissa of all zeros. The values PDR and CDR are in units of 676 bytes per second. The values PBS, CBS and EBS are in units of 677 bytes. 679 The value of PDR MUST be greater than or equal to the value of 680 CDR in a correctly encoded Traffic Parameters TLV. 682 4.3.1 Semantics 684 4.3.1.1 Frequency 686 The Frequency specifies at what granularity the CDR allocated to the 687 CR-LSP is made available. The value VeryFrequent means that the 688 available rate should average at least the CDR when measured over 689 any time interval equal to or longer than the shortest packet time 690 at the CDR. The value Frequent means that the available rate should 691 average at least the CDR when measured over any time interval equal 692 to or longer than a small number of shortest packet times at the 693 CDR. 695 The value Unspecified means that the CDR MAY be provided at any 696 granularity. 698 4.3.1.2 Peak Rate 700 The Peak Rate defines the maximum rate at which traffic SHOULD be 701 sent to the CR-LSP. The Peak Rate is useful for the purpose of 702 resource allocation. If resource allocation within the MPLS domain 703 depends on the Peak Rate value then it should be enforced at the 704 ingress to the MPLS domain. 706 The Peak Rate is defined in terms of the two Traffic Parameters PDR 707 and PBS, see section 4.3.1.5 below. 709 4.3.1.3 Committed Rate 711 The Committed Rate defines the rate that the MPLS domain commits to 712 be available to the CR-LSP. 714 Jamoussi, et. al. draft-ietf-mpls-crldp-05.txt 14 715 The Committed Rate is defined in terms of the two Traffic Parameters 716 CDR and CBS, see section 4.3.1.6 below. 718 4.3.1.4 Excess Burst Size 720 The Excess Burst Size may be used at the edge of an MPLS domain for 721 the purpose of traffic conditioning. The EBS MAY be used to measure 722 the extent by which the traffic sent on a CR-LSP exceeds the 723 committed rate. 725 The possible traffic conditioning actions, such as passing, marking 726 or dropping, are specific to the MPLS domain. 728 The Excess Burst Size is defined together with the Committed Rate, 729 see section 4.3.1.6 below. 731 4.3.1.5 Peak Rate Token Bucket 733 The Peak Rate of a CR-LSP is specified in terms of a token bucket P 734 with token rate PDR and maximum token bucket size PBS. 736 The token bucket P is initially (at time 0) full, i.e., the token 737 count Tp(0) = PBS. Thereafter, the token count Tp, if less than 738 PBS, is incremented by one PDR times per second. When a packet of 739 size B bytes arrives at time t, the following happens: 741 - If Tp(t)-B >= 0, the packet is not in excess of the peak rate 742 and Tp is decremented by B down to the minimum value of 0, else 744 - the packet is in excess of the peak rate and Tp is not 745 decremented. 747 Note that according to the above definition, a positive infinite 748 value of either PDR or PBS implies that arriving packets are never 749 in excess of the peak rate. 751 The actual implementation of an LSR doesn�t need to be modeled 752 according to the above formal token bucket specification. 754 4.3.1.6 Committed Data Rate Token Bucket 756 The committed rate of a CR-LSP is specified in terms of a token 757 bucket C with rate CDR. The extent by which the offered rate 758 exceeds the committed rate MAY be measured in terms of another token 759 bucket E, which also operates at rate CDR. The maximum size of the 760 token bucket C is CBS and the maximum size of the token bucket E is 761 EBS. 763 The token buckets C and E are initially (at time 0) full, i.e., the 764 token count Tc(0) = CBS and the token count Te(0) = EBS. 766 Jamoussi, et. al. draft-ietf-mpls-crldp-05.txt 15 767 Thereafter, the token counts Tc and Te are updated CDR times per 768 second as follows: 770 - If Tc is less than CBS, Tc is incremented by one, else 771 - if Te is less then EBS, Te is incremented by one, else 772 neither Tc nor Te is incremented. 774 When a packet of size B bytes arrives at time t, the following 775 happens: 777 - If Tc(t)-B >= 0, the packet is not in excess of the Committed 778 Rate and Tc is decremented by B down to the minimum value of 0, 779 else 781 - if Te(t)-B >= 0, the packet is in excess of the Committed rate 782 but is not in excess of the EBS and Te is decremented by B down to 783 the minimum value of 0, else 785 - the packet is in excess of both the Committed Rate and the EBS 786 and neither Tc nor Te is decremented. 788 Note that according to the above specification, a CDR value of 789 positive infinity implies that arriving packets are never in excess 790 of either the Committed Rate or EBS. A positive infinite value of 791 either CBS or EBS implies that the respective limit cannot be 792 exceeded. 794 The actual implementation of an LSR doesn�t need to be modeled 795 according to the above formal specification. 797 4.3.1.7 Weight 799 The weight determines the CR-LSP�s relative share of the possible 800 excess bandwidth above its committed rate. The definition of 801 "relative share� is MPLS domain specific. 803 4.3.2 Procedures 805 4.3.2.1 Label Request Message 807 If an LSR receives an incorrectly encoded Traffic Parameters TLV in 808 which the value of PDR is less than the value of CDR then it MUST 809 send a Notification Message including the Status code "Traffic 810 Parameters Unavailable� to the upstream LSR from which it received 811 the erroneous message. 813 If a Traffic Parameter is indicated as Negotiable in the Label 814 Request Message by the corresponding Negotiable Flag then an LSR MAY 815 replace the Traffic Parameter value with a smaller value. 817 Jamoussi, et. al. draft-ietf-mpls-crldp-05.txt 16 818 If the Weight is indicated as Negotiable in the Label Request 819 Message by the corresponding Negotiable Flag then an LSR may replace 820 the Weight value with a lower value (down to 0). 822 If, after possible Traffic Parameter negotiation, an LSR can support 823 the CR-LSP Traffic Parameters then the LSR MUST reserve the 824 corresponding resources for the CR-LSP. 826 If, after possible Traffic Parameter negotiation, an LSR cannot 827 support the CR-LSP Traffic Parameters then the LSR MUST send a 828 Notification Message that contains the "Resource Unavailable� status 829 code. 831 4.3.2.2 Label Mapping Message 833 If an LSR receives an incorrectly encoded Traffic Parameters TLV in 834 which the value of PDR is less than the value of CDR then it MUST 835 send a Label Release message containing the Status code "Traffic 836 Parameters Unavailable� to the LSR from which it received the 837 erroneous message. In addition, the LSP should send a Notification 838 Message upstream with the status code "Label Request Aborted�. 840 If the negotiation flag was set in the label request message, the 841 egress LSR MUST include the (possibly negotiated) Traffic Parameters 842 and Weight in the Label Mapping message. 844 The Traffic Parameters and the Weight in a Label Mapping message 845 MUST be forwarded unchanged. 847 An LSR SHOULD adjust the resources that it reserved for a CR-LSP 848 when it receives a Label Mapping Message if the Traffic Parameters 849 differ from those in the corresponding Label Request Message. 851 4.3.2.3 Notification Message 853 If an LSR receives a Notification Message for a CR-LSP, it SHOULD 854 release any resources that it possibly had reserved for the CR-LSP. 855 In addition, on receiving a Notification Message from a Downstream 856 LSR that is associated with a Label Request from an upstream LSR, 857 the local LSR MUST propagate the Notification message using the 858 procedures in [1]. 860 4.4 Preemption TLV 862 The defualt value of the setup and holding priorities should be in 863 the middle of the range (e.g., 4) so that this feature can be turned 864 on gradually in an operational network by increasing or decreasing 865 the priority starting at the middle of the range. 867 Since the Preemption TLV is an optional TLV, LSPs that are setup 868 without an explicitly signaled preemption TLV SHOULD be treated as 869 LSPs with the default setup and holding priorities (e.g., 4). 871 Jamoussi, et. al. draft-ietf-mpls-crldp-05.txt 17 872 When an established LSP is preempted, the LSR that initiates the 873 preemption sends a Withdraw Message upstream and a Release Message 874 downstream. 876 When an LSP in the process of being established (outstanding Label 877 Request without getting a Label Mapping back) is preempted, the LSR 878 that initiates the preemption, sends a Notification Message upstream 879 and an Abort Message downstream. 881 0 1 2 3 882 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 1 883 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 884 |0|0| Type = 0x0820 | Length = 4 | 885 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 886 | SetPrio | HoldPrio | Reserved | 887 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 889 Type 890 A fourteen-bit field carrying the value of the Preemption-TLV 891 Type = 0x0820. 893 Length 894 Specifies the length of the value field in bytes = 4. 896 Reserved 897 Zero on transmission. Ignored on receipt. 899 SetPrio 900 A SetupPriority of value zero (0) is the priority assigned to 901 the most important path. It is referred to as the highest 902 priority. Seven (7) is the priority for the least important 903 path. The higher the setup priority, the more paths CR-LDP can 904 bump to set up the path. The default value should be 4. 906 HoldPrio 907 A HoldingPriority of value zero (0) is the priority assigned to 908 the most important path. It is referred to as the highest 909 priority. Seven (7) is the priority for the least important 910 path. The default value should be 4. 911 The higher the holding priority, the less likely it is for CR- 912 LDP to reallocate its bandwidth to a new path. 914 4.5 LSPID TLV 916 LSPID is a unique identifier of a CR-LSP within an MPLS network. 918 The LSPID is composed of the ingress LSR Router ID (or any of its 919 own Ipv4 addresses) and a Locally unique CR-LSP ID to that LSR. 921 The LSPID is useful in network management, in CR-LSP repair, and in 922 using an already established CR-LSP as a hop in an ER-TLV. 924 Jamoussi, et. al. draft-ietf-mpls-crldp-05.txt 18 925 An "action indicator flag� is carried in the LSPID TLV. This "action 926 indicator flag� indicates explicitly the action that should be taken 927 if the LSP already exists on the LSR receiving the message. 929 After a CR-LSP is set up, its bandwidth reservation may need to be 930 changed by the network operator, due to the new requirements for the 931 traffic carried on that CR-LSP. The "action indicator flag� is used 932 indicate the need to modify the bandwidth and possibly other 933 parameters of an established CR-LSP without service interruption. 934 This feature has application in dynamic network resources management 935 where traffic of different priorities and service classes is 936 involved. 938 The procedure for the code point "modify� is defined in [8]. The 939 procedures for other flags are FFS. 941 0 1 2 3 942 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 1 943 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 944 |0|0| Type = 0x0821 | Length = 4 | 945 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 946 | Reserved |ActFlg | Local CR-LSP ID | 947 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 948 | Ingress LSR Router ID | 949 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 951 Type 952 A fourteen-bit field carrying the value of the LSPID-TLV 953 Type = 0x0821. 955 Length 956 Specifies the length of the value field in bytes = 4. 958 ActFlg 959 Action Indicator Flag: A 4-bit field that indicates explicitly 960 the action that should be taken if the LSP already exists on 961 the LSR receiving the message. A set of indicator code points 962 is proposed as follows: 964 0000: indicates initial LSP setup 965 0001: indicates modify LSP 966 Reserved 967 Zero on transmission. Ignored on receipt. 969 Local CR-LSP ID 970 The Local LSP ID is an identifier of the CR-LSP locally unique 971 within the Ingress LSR originating the CR-LSP. 973 Ingress LSR Router ID 974 An LSR may use any of its own IPv4 addresses in this field. 976 Jamoussi, et. al. draft-ietf-mpls-crldp-05.txt 19 977 4.6 Resource Class (Color) TLV 979 The Resource Class as defined in [3] is used to specify which links 980 are acceptable by this CR-LSP. This information allows for the 981 network�s topology to be pruned. 983 0 1 2 3 984 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 1 985 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 986 |0|0| Type = 0x0822 | Length = 4 | 987 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 988 | RsCls | 989 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 991 Type 992 A fourteen-bit field carrying the value of the ResCls-TLV Type 993 = 0x0822. 995 Length 996 Specifies the length of the value field in bytes = 4. 998 RsCls 999 The Resource Class bit mask indicating which of the 32 1000 "administrative groups� or "colors� of links the CR-LSP can 1001 traverse. 1003 4.7 ER-Hop semantics 1005 4.7.1. ER-Hop 1: The IPv4 prefix 1007 The abstract node represented by this ER-Hop is the set of nodes, 1008 which have an IP address, which lies within this prefix. Note that 1009 a prefix length of 32 indicates a single IPv4 node. 1011 0 1 2 3 1012 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 1013 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1014 |0|0| Type = 0x0801 | Length = 8 | 1015 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1016 |L| Reserved | PreLen | 1017 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1018 | IPv4 Address (4 bytes) | 1019 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1021 Type 1022 A fourteen-bit field carrying the value of the ER-Hop 1, IPv4 1023 Address, Type = 0x0801 1025 Length 1026 Specifies the length of the value field in bytes = 8. 1028 L Bit 1030 Jamoussi, et. al. draft-ietf-mpls-crldp-05.txt 20 1031 Set to indicate Loose hop. 1032 Cleared to indicate a strict hop. 1034 Reserved 1035 Zero on transmission. Ignored on receipt. 1037 PreLen 1038 Prefix Length 1-32 1040 IP Address 1041 A four-byte field indicating the IP Address. 1043 4.7.2. ER-Hop 2: The IPv6 address 1045 0 1 2 3 1046 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 1047 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1048 |0|0| 0x0802 | Length = 20 | 1049 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1050 |L| Reserved | PreLen | 1051 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1052 | IPV6 address | 1053 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1054 | IPV6 address (continued) | 1055 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1056 | IPV6 address (continued) | 1057 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1058 | IPV6 address (continued) | 1059 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1061 Type 1062 A fourteen-bit field carrying the value of the ER-Hop 2, IPv6 1063 Address, Type = 0x0802 1065 Length 1066 Specifies the length of the value field in bytes = 20. 1068 L Bit 1069 Set to indicate Loose hop. 1070 Cleared to indicate a strict hop. 1072 Reserved 1073 Zero on transmission. Ignored on receipt. 1075 PreLen 1076 Prefix Length 1-128 1078 IPv6 address 1079 A 128-bit unicast host address. 1081 4.7.3. ER-Hop 3: The autonomous system number 1083 Jamoussi, et. al. draft-ietf-mpls-crldp-05.txt 21 1084 The abstract node represented by this ER-Hop is the set of nodes 1085 belonging to the autonomous system. 1087 0 1 2 3 1088 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 1089 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1090 |0|0| 0x0803 | Length = 4 | 1091 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1092 |L| Reserved | AS Number | 1093 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1095 Type 1096 A fourteen-bit field carrying the value of the ER-Hop 3, AS 1097 Number, Type = 0x0803 1099 Length 1100 Specifies the length of the value field in bytes = 4. 1102 L Bit 1103 Set to indicate Loose hop. 1104 Cleared to indicate a strict hop. 1106 Reserved 1107 Zero on transmission. Ignored on receipt. 1109 AS Number 1110 Autonomous System number 1112 4.7.4. ER-Hop 4: LSPID 1114 The LSPID is used to identify the tunnel ingress point as the next 1115 hop in the ER. This ER-Hop allows for stacking new CR-LSPs within an 1116 already established CR-LSP. It also allows for splicing the CR-LSP 1117 being established with an existing CR-LSP. 1119 If an LSPID Hop is the last ER-Hop in an ER-TLV, than the LSR may 1120 splice the CR-LSP of the incoming Label Request to the CR-LSP that 1121 currently exists with this LSPID. This is useful, for example, at 1122 the point at which a Label Request used for local repair arrives at 1123 the next ER-Hop after the loosely specified CR-LSP segment. Use of 1124 the LSPID Hop in this scenario eliminates the need for ER-Hops to 1125 keep the entire remaining ER-TLV at each LSR that is at either 1126 (upstream or downstream) end of a loosely specified CR-LSP segment 1127 as part of its state information. This is due to the fact that the 1128 upstream LSR needs only to keep the next ER-Hop and the LSPID and 1129 the downstream LSR needs only to keep the LSPID in order for each 1130 end to be able to recognize that the same LSP is being identified. 1132 If the LSPID Hop is not the last hop in an ER-TLV, the LSR must 1133 remove the LSP-ID Hop and forward the remaining ER-TLV in a Label 1134 Request message using an LDP session established with the LSR that 1135 is the specified CR-LSP's egress. That LSR will continue processing 1137 Jamoussi, et. al. draft-ietf-mpls-crldp-05.txt 22 1138 of the CR-LSP Label Request Message. The result is a tunneled, or 1139 stacked, CR-LSP. 1141 To support labels negotiated for tunneled CR-LSP segments, an LDP 1142 session is required [1] between tunnel end points - possibly using 1143 the existing CR-LSP. Use of the existence of the CR-LSP in lieu of 1144 a session, or other possible session-less approaches, is FFS. 1146 0 1 2 3 1147 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 1148 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1149 |0|0| 0x0804 | Length = 8 | 1150 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1151 |L| Reserved | Local LSPID | 1152 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1153 | Ingress LSR Router ID | 1154 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1156 Type 1157 A fourteen-bit field carrying the value of the ER-Hop 4, LSPID, 1158 Type = 0x0804 1160 Length 1161 Specifies the length of the value field in bytes = 8. 1163 L Bit 1164 Set to indicate Loose hop. 1165 Cleared to indicate a strict hop. 1167 Reserved 1168 Zero on transmission. Ignored on receipt. 1170 Local LSPID 1171 A 2 byte field indicating the LSPID which is unique with 1172 reference to its Ingress LSR. 1174 Ingress LSR Router ID 1175 An LSR may use any of its own IPv4 addresses in this field. 1177 4.8. Processing of the Explicit Route TLV 1179 4.8.1. Selection of the next hop 1181 A Label Request Message containing an explicit route TLV must 1182 determine the next hop for this path. Selection of this next hop 1183 may involve a selection from a set of possible alternatives. The 1184 mechanism for making a selection from this set is implementation 1185 dependent and is outside of the scope of this specification. 1186 Selection of particular paths is also outside of the scope of this 1187 specification, but it is assumed that each node will make a best 1189 Jamoussi, et. al. draft-ietf-mpls-crldp-05.txt 23 1190 effort attempt to determine a loop-free path. Note that such best 1191 efforts may be overridden by local policy. 1193 To determine the next hop for the path, a node performs the 1194 following steps: 1196 1. The node receiving the Label Request Message must first 1197 evaluate the first ER-Hop. If the L bit is not set in the first 1198 ER-Hop and if the node is not part of the abstract node described 1199 by the first ER-Hop, it has received the message in error, and 1200 should return a "Bad Initial ER-Hop� error. If the L bit is set 1201 and the local node is not part of the abstract node described by 1202 the first ER-Hop, the node selects a next hop that is along the 1203 path to the abstract node described by the first ER-Hop. If there 1204 is no first ER-Hop, the message is also in error and the system 1205 should return a "Bad Explicit Routing TLV� error using a 1206 Notification Message sent upstream. 1208 2. If there is no second ER-Hop, this indicates the end of the 1209 explicit route. The explicit route TLV should be removed from the 1210 Label Request Message. This node may or may not be the end of 1211 the LSP. Processing continues with section 4.8.2, where a new 1212 explicit route TLV may be added to the Label Request Message. 1214 3. If the node is also a part of the abstract node described by 1215 the second ER-Hop, then the node deletes the first ER-Hop and 1216 continues processing with step 2, above. Note that this makes 1217 the second ER-Hop into the first ER-Hop of the next iteration. 1219 4. The node determines if it is topologically adjacent to the 1220 abstract node described by the second ER-Hop. If so, the node 1221 selects a particular next hop which is a member of the abstract 1222 node. The node then deletes the first ER-Hop and continues 1223 processing with section 4.8.2. 1225 5. Next, the node selects a next hop within the abstract node of 1226 the first ER-Hop that is along the path to the abstract node of 1227 the second ER-Hop. If no such path exists then there are two 1228 cases: 1230 5.a If the second ER-Hop is a strict ER-Hop, then there is 1231 an error and the node should return a "Bad Strict Node� 1232 error. 1234 5.b Otherwise, if the second ER-Hop is a loose ER-Hop, then 1235 the node selects any next hop that is along the path to the 1236 next abstract node. If no path exists within the MPLS 1237 domain, then there is an error, and the node should return a 1238 "Bad loose node� error. 1240 6. Finally, the node replaces the first ER-Hop with any ER-Hop 1241 that denotes an abstract node containing the next hop. This is 1243 Jamoussi, et. al. draft-ietf-mpls-crldp-05.txt 24 1244 necessary so that when the explicit route is received by the next 1245 hop, it will be accepted. 1247 7. Progress the Label Request Message to the next hop. 1249 4.8.2. Adding ER-Hops to the explicit route TLV 1251 After selecting a next hop, the node may alter the explicit route in 1252 the following ways. 1254 If, as part of executing the algorithm in section 4.8.1, the 1255 explicit route TLV is removed, the node may add a new explicit route 1256 TLV. 1258 Otherwise, if the node is a member of the abstract node for the 1259 first ER-Hop, then a series of ER-Hops may be inserted before the 1260 first ER-Hop or may replace the first ER-Hop. Each ER-Hop in this 1261 series must denote an abstract node that is a subset of the current 1262 abstract node. 1264 Alternately, if the first ER-Hop is a loose ER-Hop, an arbitrary 1265 series of ER-Hops may be inserted prior to the first ER-Hop. 1267 4.9 Route Pinning TLV 1269 Section 2.4 describes the use of route pinning. The encoding of the 1270 Route Pinning TLV is as follows: 1272 0 1 2 3 1273 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 1274 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1275 |0|0| Type = 0x0823 | Length = 4 | 1276 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1277 |P| Reserved | 1278 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1280 Type 1281 A fourteen-bit field carrying the value of the Pinning-TLV 1282 Type = 0x0823 1284 Length 1285 Specifies the length of the value field in bytes = 4. 1287 P Bit 1288 The P bit is set to 1 to indicate that route pinning is 1289 requested. 1290 The P bit is set to 0 to indicate that route pinning is not 1291 requested 1293 Reserved 1294 Zero on transmission. Ignored on receipt. 1296 Jamoussi, et. al. draft-ietf-mpls-crldp-05.txt 25 1297 4.10 CR-LSP FEC Element 1299 A new FEC element is introduced in this specification to support CR- 1300 LSPs. A FEC TLV containing a FEC of Element type CR-LSP (0x04) is a 1301 CR-LSP FEC TLV. The CR-LSP FEC Element is an opaque FEC to be used 1302 only in Messages of CR-LSPs. 1304 A single FEC element MUST be included in the Label Request Message. 1305 The FEC Element SHOULD be the CR-LSP FEC Element. However, one of 1306 the other FEC elements (Type=0x01, 0x02, 0x03) defined in [1] MAY be 1307 in CR-LDP messages instead of the CR-LSP FEC Element for certain 1308 applications. A FEC TLV containing a FEC of Element type CR-LSP 1309 (0x04) is a CR-LSP FEC TLV. 1311 FEC Element Type Value 1312 Type name 1314 CR-LSP 0x04 No value; i.e., 0 value octets; 1316 The CR-LSP FEC TLV encoding is as follows: 1318 0 1 2 3 1319 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 1320 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1321 |0|0| Type = 0x0100 | Length = 1 | 1322 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1323 | CR-LSP (4) | 1324 +-+-+-+-+-+-+-+-+ 1326 Type 1327 A fourteen-bit field carrying the value of the FEC TLV 1328 Type = 0x0100 1330 Length 1331 Specifies the length of the value field in bytes = 1. 1333 CR-LSP FEC Element Type 1335 0x04 1337 5. IANA Considerations 1339 CR-LDP defines the following name spaces, which require management: 1341 - TLV types. 1342 - FEC types. 1343 - Status codes. 1345 The following sections provide guidelines for managing these name 1346 spaces. 1348 5.1 TLV Type Name Space 1350 Jamoussi, et. al. draft-ietf-mpls-crldp-05.txt 26 1351 RFC 3036 [1] defines the LDP TLV name space. This document further 1352 subdivides the range of RFC 3036 from that TLV space for TLVs 1353 associated with the CR-LDP in the range 0x0800 - 0x08FF. 1355 Following the policies outlined in [IANA], TLV types in this range 1356 are allocated through an IETF Consensus action. 1358 Initial values for this range are specified in the following table: 1360 TLV Type 1361 -------------------------------------- ---------- 1362 Explicite Route TLV 0x0800 1363 Ipv4 Prefix ER-Hop TLV 0x0801 1364 Ipv6 Prefix ER-Hop TLV 0x0802 1365 Autonomous System Number ER-Hop TLV 0x0803 1366 LSP-ID ER-Hop TLV 0x0804 1367 Traffic Parameters TLV 0x0810 1368 Preemption TLV 0x0820 1369 LSPID TLV 0x0821 1370 Resource Class TLV 0x0822 1371 Route Pinning TLV 0x0823 1373 5.2 FEC Type Name Space 1375 RFC 3036 defines the FEC Type TLV name space. This document further 1376 subdivides the range of RFC 3036 from that TLV space for TLVs 1377 associated with the CR-LDP in the range 100 - 116. 1379 Following the policies outlined in [IANA], TLV types in this range 1380 are allocated through an IETF Consensus action. 1382 Initial values for this range are specified in the follwing table: 1384 FEC Element TLV Type 1385 -------------------------------------- ---------- 1386 CR-LSP FEC Element TLV 0x0100 1388 5.3 Status Code Space 1390 RFC 3036 defines the Status Code name space. This document further 1391 subdivides the range of RFC 3036 from that TLV space for TLVs 1392 associated with the CR-LDP in the range 0x44000000 - 0x440000FF. 1394 Following the policies outlined in [IANA], TLV types in this range 1395 are allocated through an IETF Consensus action. 1397 Initial values for this range are specified in the follwing table: 1399 Status Code Type 1400 -------------------------------------- ---------- 1401 Bad Explicit Routing TLV Error 0x44000001 1403 Jamoussi, et. al. draft-ietf-mpls-crldp-05.txt 27 1404 Bad Strict Node Error 0x44000002 1405 Bad Loose Node Error 0x44000003 1406 Bad Initial ER-Hop Error 0x44000004 1407 Resource Unavailable 0x44000005 1408 Traffic Parameters Unavailable 0x44000006 1409 LSP Preempted 0x44000007 1410 Modify Request Not Supported 0x44000008 1411 Setup Abort (Label Request Aborted in [1]) 0x04000015 1413 6. Security 1415 CR-LDP inherits the same security mechanism described in Section 4.0 1416 of [1] to protect against the introduction of spoofed TCP segments 1417 into LDP session connection streams. 1419 7. Acknowledgments 1421 The messages used to signal the CR-LSP setup are based on the work 1422 done by the [1] team. 1424 The authors would also like to acknowledge the careful review and 1425 comments of Ken Hayward, Greg Wright, Geetha Brown, Brian Williams, 1426 Paul Beaubien, Matthew Yuen, Liam Casey, Ankur Anand, Adrian Farrel. 1428 8. Intellectual Property Consideration 1430 The IETF has been notified of intellectual property rights claimed 1431 in regard to some or all of the specification contained in this 1432 document. For more information consult the online list of claimed 1433 rights. 1435 9. References 1437 1 Andersson et. al., "Label Distribution Protocol Specification" 1438 RFC 3036, January 2001. 1440 2 Rosen et. al., "Multiprotocol Label Switching Architecture", 1441 RFC 3031, January 2001. 1443 3 Awduche et. al., "Requirements for Traffic Engineering Over 1444 MPLS", RFC 2702, September 1999. 1446 4 Gleeson, et. al., "A Framework for IP Based Virtual Private 1447 Networks", RFC 2764, February 2000. 1449 5 B. Jamoussi, et. al., �Applicability Statement for CR-LDP�, work 1450 in progress, (draft-ietf-mpls-crldp-applic-01), June 2000. 1452 6 S. Bradner, "Key words for use in RFCs to Indicate Requirement 1453 Levels�, RFC 2119, March 1997. 1455 Jamoussi, et. al. draft-ietf-mpls-crldp-05.txt 28 1456 7 L. Wu, et. al., "LDP State Machine", work in progress, 1457 (draft-ietf-mpls-ldp-state-03), January 2000. 1459 8 J. Ash, et. al., "LSP Modification Using CR-LDP", work in 1460 progress, (draft-ietf-mpls-crlsp-modify-02), October 2000. 1462 10. Author�s Addresses 1464 Osama S. Aboul-Magd Loa Andersson 1465 Nortel Networks Nortel Networks 1466 P O Box 3511 Station C S:t Eriksgatan 115 1467 Ottawa, ON K1Y 4H7 PO Box 6701 1468 Canada 113 85 Stockholm 1469 Phone: +1 613 763-5827 Tel: +46 8 508 835 00 1470 Osama@nortelnetworks.com Fax: +46 8 508 835 01 1471 Loa_andersson@nortelnetworks.com 1473 Peter Ashwood-Smith Ross Callon 1474 Nortel Networks Juniper Networks 1475 P O Box 3511 Station C 1194 North Mathilda Avenue, 1476 Ottawa, ON K1Y 4H7 Sunnyvale, CA 94089 1477 Canada 978-692-6724 1478 Phone: +1 613 763-4534 rcallon@juniper.net 1479 Petera@nortelnetworks.com 1481 Ram Dantu Paul Doolan 1482 Cisco Systems Ennovate Networks 1483 17919 Waterview Parkway 330 Codman Hill Rd 1484 Dallas, 75252 Marlborough MA 01719 1485 +1 469 255 0716 Phone: 978-263-2002 1486 rdantu@cisco.com Pdoolan@ennovatenetworks.com 1488 Nancy Feldman Andre Fredette 1489 IBM Research PhotonEx Corporation 1490 30 Saw Mill River Road 135 South Road 1491 Hawthorne, NY 10532 Bedford, MA 01730 1492 Phone: 914-784-3254 email: fredette@photonex.com 1493 Nkf@us.ibm.com phone: 781-275-8500 1495 Eric Gray Joel M. Halpern 1496 600 Federal Drive Longitude Systems, Inc. 1497 Andover, MA 01810 1319 Shepard Road 1498 Phone: (978) 689-1610 Sterling, VA 20164 1499 eric.gray@sandburst.com 703-433-0808 x207 1500 joel@longsys.com 1502 Juha Heinanen Fiffi Hellstrand 1503 Telia Finland, Inc. Nortel Networks 1504 Myyrmaentie 2 S:t Eriksgatan 115 1505 01600 VANTAA PO Box 6701, 113 85 Stockholm 1506 Finland Sweden 1508 Jamoussi, et. al. draft-ietf-mpls-crldp-05.txt 29 1509 Tel: +358 41 500 4808 +46705593687 1510 Jh@telia.fi fiffi@nortelnetworks.com 1512 Bilel Jamoussi Timothy E. Kilty 1513 Nortel Networks Corp. Newbridge Networks, Inc. 1514 600 Technology Park Drive 5 Corporate Drive 1515 Billerica, MA 01821 Andover, MA 01810 1516 USA USA 1517 Phone: +1 978 288-4506 phone: 978 691-4656 1518 Jamoussi@nortelnetworks.com tkilty@northchurch.net 1520 Andrew G. Malis Muckai K Girish 1521 Vivace Networks Atoga Systems 1522 2730 Orchard Parkway 49026 Milmont Drive 1523 San Jose, CA 95134 Fremont, CA 94538 1524 Andy.Malis@vivacenetworks.com E-mail: muckai@atoga.com 1525 Tel: +1 408 383 7223 1526 Fax: +1 408 904 4748 1528 Kenneth Sundell Pasi Vaananen 1529 Nortel Networks Nokia Telecommunications 1530 S:t Eriksgatan 115 3 Burlington Woods Drive, 1531 PO Box 6701 Burlington, MA 01803 1532 113 85 Stockholm Phone: +1-781-238-4981 1533 Tel: +46 8 508 835 00 pasi.vaananen@nokia.com 1534 Fax: +46 8 508 835 01 1535 Ksundell@nortelnetworks.com 1537 Tom Worster Liwen Wu 1538 Ennovate Networks Cisco Systems 1539 60 Codman Hill Rd 250 Apollo Drive 1540 Boxborough Chelmsford, MA. 01824 1541 MA 01719 Tel: 978-244-3087. 1542 tworster@ennovatenetworks.com liwwu@cisco.com 1544 Jamoussi, et. al. draft-ietf-mpls-cr-ldp-04.txt 30 1545 Appendix A: CR-LSP Establishment Examples 1547 A.1 Strict Explicit Route Example 1549 This appendix provides an example for the setup of a strictly routed 1550 CR-LSP. In this example, a specific node represents each abstract 1551 node. 1553 The sample network used here is a four node network with two edge 1554 LSRs and two core LSRs as follows: 1556 abc 1557 LSR1------LSR2------LSR3------LSR4 1559 LSR1 generates a Label Request Message as described in Section 3.1 1560 of this draft and sends it to LSR2. This message includes the CR- 1561 TLV. 1563 A vector of three ER-Hop TLVs composes the ER-TLV. 1564 The ER-Hop TLVs used in this example are of type 0x0801 (IPv4 1565 prefix) with a prefix length of 32. Hence, each ER-Hop TLV 1566 identifies a specific node as opposed to a group of nodes. 1567 At LSR2, the following processing of the ER-TLV per Section 4.8.1 of 1568 this draft takes place: 1570 1. The node LSR2 is part of the abstract node described by the 1571 first hop . Therefore, the first step passes the test. Go 1572 to step 2. 1574 2. There is a second ER-Hop, . Go to step 3. 1576 3. LSR2 is not part of the abstract node described by the 1577 second ER-Hop . Go to Step 4. 1579 4. LSR2 determines that it is topologically adjacent to the 1580 abstract node described by the second ER-Hop . LSR2 selects 1581 a next hop (LSR3) which is the abstract node. LSR2 deletes the 1582 first ER-Hop from the ER-TLV, which now becomes . 1583 Processing continues with Section 4.8.2. 1585 At LSR2, the following processing of Section 4.8.2 takes place: 1586 Executing algorithm 4.8.1 did not result in the removal of the ER- 1587 TLV. 1589 Also, LSR2 is not a member of the abstract node described by the 1590 first ER-Hop . 1592 Finally, the first ER-Hop is a strict hop. 1594 Therefore, processing section 4.8.2 does not result in the insertion 1595 of new ER-Hops. The selection of the next hop has been already done 1596 is step 4 of Section 4.8.1 and the processing of the ER-TLV is 1598 Jamoussi, et. al. draft-ietf-mpls-cr-ldp-04.txt 31 1599 completed at LSR2. In this case, the Label Request Message including 1600 the ER-TLV is progressed by LSR2 to LSR3. 1602 At LSR3, a similar processing to the ER-TLV takes place except that 1603 the incoming ER-TLV = and the outgoing ER-TLV is . 1605 At LSR4, the following processing of section 4.8.1 takes place: 1607 1. The node LSR4 is part of the abstract node described by the 1608 first hop . Therefore, the first step passes the test. Go to 1609 step 2. 1611 2. There is no second ER-Hop, this indicates the end of the CR- 1612 LSP. The ER-TLV is removed from the Label Request Message. 1613 Processing continues with Section 4.8.2. 1615 At LSR4, the following processing of Section 4.8.2 takes place: 1616 Executing algorithm 4.8.1 resulted in the removal of the ER-TLV. 1617 LSR4 does not add a new ER-TLV. 1619 Therefore, processing section 4.8.2 does not result in the insertion 1620 of new ER-Hops. This indicates the end of the CR-LSP and the 1621 processing of the ER-TLV is completed at LSR4. 1623 At LSR4, processing of Section 3.2 is invoked. The first condition 1624 is satisfied (LSR4 is the egress end of the CR-LSP and upstream 1625 mapping has been requested). Therefore, a Label Mapping Message is 1626 generated by LSR4 and sent to LSR3. 1628 At LSR3, the processing of Section 3.2 is invoked. The second 1629 condition is satisfied (LSR3 received a mapping from its downstream 1630 next hop LSR4 for a CR-LSP for which an upstream request is still 1631 pending). Therefore, a Label Mapping Message is generated by LSR3 1632 and sent to LSR2. 1634 At LSR2, a similar processing to LSR 3 takes place and a Label 1635 Mapping Message is sent back to LSR1, which completes the end-to-end 1636 CR-LSP setup. 1638 A.2 Node Groups and Specific Nodes Example 1640 A request at ingress LSR to setup a CR-LSP might originate from a 1641 management system or an application, the details are implementation 1642 specific. 1644 The ingress LSR uses information provided by the management system 1645 or the application and possibly also information from the routing 1646 database to calculate the explicit route and to create the Label 1647 Request Message. 1649 The Label request message carries together with other necessary 1650 information an ER-TLV defining the explicitly routed path. In our 1652 Jamoussi, et. al. draft-ietf-mpls-cr-ldp-04.txt 32 1653 example the list of hops in the ER-Hop TLV is supposed to contain an 1654 abstract node representing a group of nodes, an abstract node 1655 representing a specific node, another abstract node representing a 1656 group of nodes, and an abstract node representing a specific egress 1657 point. 1659 In--{Group 1}--{Specific A}--{Group 2}--{Specific Out: B} 1660 The ER-TLV contains four ER-Hop TLVs: 1662 1. An ER-Hop TLV that specifies a group of LSR valid for the 1663 first abstract node representing a group of nodes (Group 1). 1665 2. An ER-Hop TLV that indicates the specific node (Node A). 1667 3. An ER-Hop TLV that specifies a group of LSRs valid for the 1668 second abstract node representing a group of nodes (Group 2). 1670 4. An ER-Hop TLV that indicates the specific egress point for 1671 the CR-LSP (Node B). 1673 All the ER-Hop TLVs are strictly routed nodes. 1674 The setup procedure for this CR-LSP works as follows: 1676 1. The ingress node sends the Label Request Message to a node 1677 that is a member the group of nodes indicated in the first ER- 1678 Hop TLV, following normal routing for the specific node (A). 1680 2. The node that receives the message identifies itself as part 1681 of the group indicated in the first ER-Hop TLV, and that it is 1682 not the specific node (A) in the second. Further it realizes 1683 that the specific node (A) is not one of its next hops. 1685 3. It keeps the ER-Hop TLVs intact and sends a Label Request 1686 Message to another node that is part of the group indicated in 1687 the first ER-Hop TLV (Group 1), following normal routing for 1688 the specific node (A). 1690 4. The node that receives the message identifies itself as part 1691 of the group indicated in the first ER-Hop TLV, and that it is 1692 not the specific node (A) in the second ER-Hop TLV. Further it 1693 realizes that the specific node (A) is one of its next hops. 1695 5. It removes the first ER-Hop TLVs and sends a Label Request 1696 Message to the specific node (A). 1698 6. The specific node (A) recognizes itself in the first ER-Hop 1699 TLV. Removes the specific ER-Hop TLV. 1701 7. It sends a Label Request Message to a node that is a member 1702 of the group (Group 2) indicated in the ER-Hop TLV. 1704 Jamoussi, et. al. draft-ietf-mpls-cr-ldp-04.txt 33 1705 8. The node that receives the message identifies itself as part 1706 of the group indicated in the first ER-Hop TLV, further it 1707 realizes that the specific egress node (B) is one of its next 1708 hops. 1710 9. It sends a Label Request Message to the specific egress node 1711 (B). 1713 10. The specific egress node (B) recognizes itself as the 1714 egress for the CR-LSP, it returns a Label Mapping Message, that 1715 will traverse the same path as the Label Request Message in the 1716 opposite direction. 1718 Jamoussi, et. al. draft-ietf-mpls-cr-ldp-04.txt 34 1719 Appendix B. QoS Service Examples 1721 B.1 Service Examples 1723 Construction of an end-to-end service is the result of the rules 1724 enforced at the edge and the treatment that packets receive at the 1725 network nodes. The rules define the traffic conditioning actions 1726 that are implemented at the edge and they include policing with 1727 pass, mark, and drop capabilities. The edge rules are expected tobe 1728 defined by the mutual agreements between the service providers and 1729 their customers and they will constitute an essential part of the 1730 SLA. Therefore edge rules are not included in the signaling 1731 protocol. 1733 Packet treatment at a network node is usually referred to as the 1734 local behavior. Local behavior could be specified in many ways. One 1735 example for local behavior specification is the service frequency 1736 introduced in section 4.3.2.1, together with the resource 1737 reservation rules implemented at the nodes. 1739 Edge rules and local behaviors can be viewed as the main building 1740 blocks for the end-to-end service construction. The following table 1741 illustrates the applicability of the building block approach for 1742 constructing different services including those defined for ATM. 1744 Service PDR PBS CDR CBS EBS Service Conditioning 1745 Examples Frequency Action 1747 DS S S =PDR =PBS 0 Frequent drop>PDR 1749 TS S S S S 0 Unspecified drop>PDR,PBS 1750 mark>CDR,CBS 1752 BE inf inf inf inf 0 Unspecified - 1754 FRS S S CIR ~B_C ~B_E Unspecified drop>PDR,PBS 1755 mark>CDR,CBS,EBS 1757 ATM-CBR PCR CDVT =PCR =CDVT 0 VeryFrequent drop>PCR 1759 ATM-VBR.3(rt) PCR CDVT SCR MBS 0 Frequent drop>PCR 1760 mark>SCR,MBS 1762 ATM-VBR.3(nrt) PCR CDVT SCR MBS 0 Unspecified drop>PCR 1763 mark>SCR,MBS 1765 ATM-UBR PCR CDVT - - 0 Unspecified drop>PCR 1767 ATM-GFR.1 PCR CDVT MCR MBS 0 Unspecified drop>PCR 1769 ATM-GFR.2 PCR CDVT MCR MBS 0 Unspecified drop>PCR 1770 mark>MCR,MFS 1772 Jamoussi, et. al. draft-ietf-mpls-cr-ldp-04.txt 35 1773 int-serv-CL p m r b 0 Frequent drop>p 1774 drop>r,b 1776 S= User specified 1778 In the above table, the DS refers to a delay sensitive service where 1779 the network commits to deliver with high probability user datagrams 1780 at a rate of PDR with minimum delay and delay requirements. 1781 Datagrams in excess of PDR will be discarded. 1783 The TS refers to a generic throughput sensitive service where the 1784 network commits to deliver with high probability user datagrams at a 1785 rate of at least CDR. The user may transmit at a rate higher than 1786 CDR but datagrams in excess of CDR would have a lower probability of 1787 being delivered. 1789 The BE is the best effort service and it implies that there are no 1790 expected service guarantees from the network. 1792 B.2 Establishing CR-LSP Supporting Real-Time Applications 1794 In this scenario the customer needs to establish an LSP for 1795 supporting real-time applications such as voice and video. The 1796 Delay-sensitive (DS) service is requested in this case. 1798 The first step is the specification of the traffic parameters in the 1799 signaling message. The two parameters of interest to the DS service 1800 are the PDR and the PBS and the user based on his requirements 1801 specifies their values. Since all the traffic parameters are 1802 included in the signaling message, appropriate values must be 1803 assigned to all of them. For DS service, the CDR and the CBS values 1804 are set equal to the PDR and the PBS respectively. An indication of 1805 whether the parameter values are subject to negotiation is flagged. 1807 The transport characteristics of the DS service require Frequent 1808 frequency to be requested to reflect the real-time delay 1809 requirements of the service. 1811 In addition to the transport characteristics, both the network 1812 provider and the customer need to agree on the actions enforced at 1813 the edge. The specification of those actions is expected to be a 1814 part of the service level agreement (SLA) negotiation and is not 1815 included in the signaling protocol. For DS service, the edge action 1816 is to drop packets that exceed the PDR and the PBS specifications. 1817 The signaling message will be sent in the direction of the ER path 1818 and the LSP is established following the normal LDP procedures. Each 1819 LSR applies its admission control rules. If sufficient resources are 1820 not available and the parameter values are subject to negotiation, 1821 then the LSR could negotiate down the PDR, the PBS, or both. 1823 Jamoussi, et. al. draft-ietf-mpls-cr-ldp-04.txt 36 1824 The new parameter values are echoed back in the Label Mapping 1825 Message. LSRs might need to re-adjust their resource reservations 1826 based on the new traffic parameter values. 1828 B.3 Establishing CR-LSP Supporting Delay Insensitive Applications 1830 In this example we assume that a throughput sensitive (TS) service 1831 is requested. For resource allocation the user assigns values for 1832 PDR, PBS, CDR, and CBS. The negotiation flag is set if the traffic 1833 parameters are subject to negotiation. 1834 Since the service is delay insensitive by definition, the 1835 Unspecified frequency is signaled to indicate that the service 1836 frequency is not an issue. 1838 Similar to the previous example, the edge actions are not subject 1839 for signaling and are specified in the service level agreement 1840 between the user and the network provider. 1842 For TS service, the edge rules might include marking to indicate 1843 high discard precedence values for all packets that exceed CDR and 1844 the CBS. The edge rules will also include dropping of packets that 1845 conform to neither PDR nor PBS. 1847 Each LSR of the LSP is expected to run its admission control rules 1848 and negotiate traffic parameters down if sufficient resources do not 1849 exist. The new parameter values are echoed back in the Label Mapping 1850 Message. LSRs might need to re-adjust their resources based on the 1851 new traffic parameter values. 1853 Jamoussi, et. al. draft-ietf-mpls-cr-ldp-04.txt 37 1854 Full Copyright Statement 1855 "Copyright � The Internet Society (date). All Rights Reserved. This 1856 document and translations of it may be copied and furnished to 1857 others, and derivative works that comment on or otherwise explain it 1858 or assist in its implementation may be prepared, copied, published 1859 and distributed, in whole or in part, without restriction of any 1860 kind, provided that the above copyright notice and this paragraph 1861 are included on all such copies and derivative works. However, this 1862 document itself may not be modified in any way, such as by removing 1863 the copyright notice or references to the Internet Society or other 1864 Internet organizations, except as needed for the purpose of 1865 developing Internet standards in which case the procedures for 1866 copyrights defined in the Internet Standards process must be 1867 followed, or as required to translate it into languages other than 1868 English. 1870 The limited permissions granted above are perpetual and will not be 1871 revoked by the Internet Society or its successors or assigns. 1873 Jamoussi, et. al. draft-ietf-mpls-cr-ldp-04.txt 38