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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: March 2000 4 September 1999 6 Constraint-Based LSP Setup using LDP 8 draft-ietf-mpls-cr-ldp-03.txt 10 Status of this Memo 12 This document is an Internet-Draft and is in full conformance with 13 all provisions of Section 10 of RFC2026. 15 Internet-Drafts are working documents of the Internet Engineering 16 Task Force (IETF), its areas, and its working groups. Note that 17 other groups may also distribute working documents as Internet- 18 Drafts. 20 Internet-Drafts are draft documents valid for a maximum of six 21 months and may be updated, replaced, or obsoleted by other documents 22 at any time. It is inappropriate to use Internet-Drafts as reference 23 material or to cite them other than as _work in progress._ 25 The list of current Internet-Drafts can be accessed at 26 http://www.ietf.org/ietf/1id-abstracts.txt 28 The list of Internet-Draft Shadow Directories can be accessed at 29 http://www.ietf.org/shadow.html. 31 Abstract 33 Label Distribution Protocol (LDP) is defined in [1] for distribution 34 of labels inside one MPLS domain. One of the most important 35 services that may be offered using MPLS in general and LDP in 36 particular is support for constraint-based routing of traffic across 37 the routed network. Constraint-based routing offers the opportunity 38 to extend the information used to setup paths beyond what is 39 available for the routing protocol. For instance, an LSP can be 40 setup based on explicit route constraints, QoS constraints, and 41 other constraints. Constraint-based routing (CR) is a mechanism used 42 to meet Traffic Engineering requirements that have been proposed by 43 [2], [3] and [4]. These requirements may be met by extending LDP for 44 support of constraint-based routed label switched paths (CR-LSPs). 45 Other uses for CR-LSPs include MPLS-based VPNs. 47 This draft specifies mechanisms and TLVs for support of CR-LSPs 48 using LDP. 50 Jamoussi, et. al. draft-ietf-mpls-crldp-03.txt 1 Internet Draft Constraint-Based LSP Setup using LDP September, 1999 52 Table of Contents 54 1. Introduction....................................................3 55 2. Constraint-based Routing Overview...............................3 56 2.1 Strict and Loose Explicit Routes...............................4 57 2.2 Traffic Characteristics........................................4 58 2.3 Pre-emption....................................................5 59 2.4 Route Pinning..................................................5 60 2.5 Resource Class.................................................5 61 3. Solution Overview...............................................6 62 3.1 Required Messages and TLVs.....................................7 63 3.2 Label Request Message..........................................7 64 3.3 Label Mapping Message..........................................8 65 3.4 Notification Message...........................................8 66 3.5 Release , Withdraw, and Abort Messages.........................9 67 4. Protocol Specification..........................................9 68 4.1 Explicit Route TLV (ER-TLV)...................................10 69 4.2 Explicit Route Hop TLV (ER-Hop TLV)...........................10 70 4.3 Traffic Parameters TLV........................................11 71 4.3.1 Semantics...................................................13 72 4.3.1.1 Frequency.................................................13 73 4.3.1.2 Peak Rate.................................................13 74 4.3.1.3 Committed Rate............................................14 75 4.3.1.4 Excess Burst Size.........................................14 76 4.3.1.5 Peak Rate Token Bucket....................................14 77 4.3.1.6 Committed Data Rate Token Bucket..........................14 78 4.3.1.7 Weight....................................................15 79 4.3.2 Procedures..................................................15 80 4.3.2.1 Label Request Message.....................................15 81 4.3.2.2 Label Mapping Message.....................................16 82 4.3.2.3 Notification Message......................................16 83 4.4 Preemption TLV................................................16 84 4.5 LSPID TLV.....................................................17 85 4.6 Resource Class (Color) TLV....................................18 86 4.7 ER-Hop semantics..............................................19 87 4.7.1. ER-Hop 1: The IPv4 prefix..................................19 88 4.7.2. ER-Hop 2: The IPv6 address.................................20 89 4.7.3. ER-Hop 3: The autonomous system number....................20 90 4.7.4. ER-Hop 4: LSPID............................................21 91 4.8. Processing of the Explicit Route TLV.........................22 92 4.8.1. Selection of the next hop..................................22 93 4.8.2. Adding ER-Hops to the explicit route TLV...................23 94 4.9 Route Pinning TLV.............................................24 95 4.10 CR-LSP FEC Element...........................................24 96 4.11 Error subcodes...............................................25 97 5. Security.......................................................25 98 6. Acknowledgments................................................25 99 7. Intellectual Property Consideration............................26 100 8. References.....................................................26 101 9. Author's Addresses.............................................26 102 Appendix A: CR-LSP Establishment Examples.........................29 104 Jamoussi, et. al. draft-ietf-mpls-crldp-03.txt 2 Internet Draft Constraint-Based LSP Setup using LDP September, 1999 106 A.1 Strict Explicit Route Example.................................29 107 A.2 Node Groups and Specific Nodes Example........................30 108 Appendix B. QoS Service Examples..................................33 109 B.1 Service Examples..............................................33 110 B.2 Establishing CR-LSP Supporting Real-Time Applications.........34 111 B.3 Establishing CR-LSP Supporting Delay Insensitive Applications.35 112 Appendix C. LSP Modification Using CR-LDP.........................36 113 C.1 Introduction..................................................36 114 C.2 Basic Procedure...............................................37 115 C.3 Priority Handling.............................................38 116 C.4 Modification Failure Case Handling............................39 118 1. Introduction 120 The need for constraint-based routing (CR) in MPLS has been explored 121 elsewhere [3], [2], and [4]. Explicit routing is a subset of the 122 more general constraint-based routing function. At the MPLS WG 123 meeting held during the Washington IETF (December 1997) there was 124 consensus that LDP should support explicit routing of LSPs with 125 provision for indication of associated (forwarding) priority. In 126 the Chicago meeting (August 1998), a decision was made that support 127 for explicit path setup in LDP will be moved to a separate document. 128 This document provides that support and it has been accepted as a 129 working document in the Orlando meeting (December 1998). 131 This specification proposes an end-to-end setup mechanism of a 132 constraint-based routed LSP (CR-LSP) initiated by the ingress LSR. 133 We also specify mechanisms to provide means for reservation of 134 resources using LDP. 136 This document introduce TLVs and procedures that provide support 137 for: 138 - Strict and Loose Explicit Routing 139 - Specification of Traffic Parameters 140 - Route Pinning 141 - CR-LSP Pre-emption though setup/holding priorities 142 - Handling Failures 143 - LSPID 144 - Resource Class 146 Section 2 introduces the various constraints defined in this 147 specification. Section 3 outlines the CR-LDP solution. Section 4 148 defines the TLVs and procedures used to setup constraint-based 149 routed label switched paths. Appendix A provides several examples 150 of CR-LSP path setup. Appendix B provides Service Definition 151 Examples. 153 2. Constraint-based Routing Overview 155 Constraint-based routing is a mechanism that supports the Traffic 156 Engineering requirements defined in [4]. Explicit Routing is a 157 subset of the more general constraint-based routing where the 159 Jamoussi, et. al. draft-ietf-mpls-crldp-03.txt 3 Internet Draft Constraint-Based LSP Setup using LDP September, 1999 161 constraint is the explicit route (ER). Other constraints are defined 162 to provide a network operator with control over the path taken by an 163 LSP. This section is an overview of the various constraints 164 supported by this specification. 166 2.1 Strict and Loose Explicit Routes 168 Like any other LSP a CR-LSP is a path through an MPLS network. The 169 difference is that while other paths are setup solely based on 170 information in routing tables or from a management system, the 171 constraint-based route is calculated at one point at the edge of 172 network based on criteria, including but not limited to routing 173 information. The intention is that this functionality shall give 174 desired special characteristics to the LSP in order to better 175 support the traffic sent over the LSP. The reason for setting up CR- 176 LSPs might be that one wants to assign certain bandwidth or other 177 Service Class characteristics to the LSP, or that one wants to make 178 sure that alternative routes use physically separate paths through 179 the network. 181 An explicit route is represented in a Label Request Message as a 182 list of nodes or groups of nodes along the constraint-based route. 183 When the CR-LSP is established, all or a subset of the nodes in a 184 group may be traversed by the LSP. Certain operations to be 185 performed along the path can also be encoded in the constraint-based 186 route. 188 The capability to specify, in addition to specified nodes, groups of 189 nodes, of which a subset will be traversed by the CR-LSP, allows the 190 system a significant amount of local flexibility in fulfilling a 191 request for a constraint-based route. This allows the generator of 192 the constraint-based route to have some degree of imperfect 193 information about the details of the path. 195 The constraint-based route is encoded as a series of ER-Hops 196 contained in a constraint-based route TLV. Each ER-Hop may identify 197 a group of nodes in the constraint-based route. A constraint-based 198 route is then a path including all of the identified groups of nodes 199 in the order in which they appear in the TLV. 201 To simplify the discussion, we call each group of nodes an abstract 202 node. Thus, we can also say that a constraint-based route is a path 203 including all of the abstract nodes, with the specified operations 204 occurring along that path. 206 2.2 Traffic Characteristics 208 The traffic characteristics of a path are described in the Traffic 209 Parameters TLV in terms of a peak rate, committed rate, and service 210 granularity. The peak and committed rates describe the bandwidth 211 constraints of a path while the service granularity can be used to 213 Jamoussi, et. al. draft-ietf-mpls-crldp-03.txt 4 Internet Draft Constraint-Based LSP Setup using LDP September, 1999 215 specify a constraint on the delay variation that the CR-LDP MPLS 216 domain may introduce to a path's traffic. 218 2.3 Pre-emption 220 CR-LDP signals the resources required by a path on each hop of the 221 route. If a route with sufficient resources can not be found, 222 existing paths may be rerouted to reallocate resources to the new 223 path. This is the process of path pre-emption. Setup and holding 224 priorities are used to rank existing paths (holding priority) and 225 the new path (setup priority) to determine if the new path can pre- 226 empt an existing path. 228 The setupPriority of a new CR-LSP and the holdingPriority attributes 229 of the existing CR-LSP are used to specify priorities. Signaling a 230 higher holding priority express that the path, once it has been 231 established, should have a lower chance of being pre-empted. 232 Signaling a higher setup priority expresses the expectation that, in 233 the case that resource are unavailable, the path is more likely to 234 pre-empt other paths. The exact rules determining bumping are an 235 aspect of network policy. 237 The allocation of setup and holding priority values to paths is an 238 aspect of network policy. 240 The setup and holding priority values range from zero (0) to seven 241 (7). The value zero (0) is the priority assigned to the most 242 important path. It is referred to as the highest priority. Seven (7) 243 is the priority for the least important path. The use of default 244 priority values is an aspect of network policy. 246 The setupPriority of a CR-LSP should not be higher (numerically 247 less) than its holdingPriority since it might bump an LSP and be 248 bumped by the next _equivalent_ request. 250 2.4 Route Pinning 252 Route pinning is applicable to segments of an LSP that are loosely 253 routed - i.e. those segments which are specified with a next hop 254 with the `L' bit set or where the next hop is an _abstract node_. A 255 CR-LSP may be setup using route pinning if it is undesirable to 256 change the path used by an LSP even when a better next hop becomes 257 available at some LSR along the loosely routed portion of the LSP. 259 2.5 Resource Class 261 The network operator may classify network resources in various ways. 262 These classes are also known as _colors_ or _administrative groups_. 263 When a CR-LSP is being established, it's necessary to indicate which 264 resource classes the CR-LSP can draw from. 266 Jamoussi, et. al. draft-ietf-mpls-crldp-03.txt 5 Internet Draft Constraint-Based LSP Setup using LDP September, 1999 268 3. Solution Overview 270 CR-LSP over LDP Specification is designed with the following goals: 272 1. Meet the requirements outlined in [4] for performing traffic 273 engineering and provide a solid foundation for performing 274 more general constraint-based routing. 276 2. Build on already specified functionality that meets the 277 requirements whenever possible. Hence, this specification is 278 based on [1]. 280 3. Keep the solution simple. 282 In this document, support for unidirectional point-to-point CR-LSPs 283 is specified. Support for point-to-multipoint, multipoint-to-point, 284 is for further study (FFS). 286 Support for constraint-based routed LSPs in this specification 287 depends on the following minimal LDP behaviors as specified in [1]: 289 - Use of Basic and/or Extended Discovery Mechanisms. 290 - Use of the Label Request Message defined in [1] in downstream 291 on demand label advertisement mode with ordered control. 292 - Use of the Label Mapping Message defined in [1] in downstream 293 on demand mode with ordered control. 294 - Use of the Notification Message defined in [1]. 295 - Use of the Withdraw and Release Messages defined in [1]. 296 - Use of the Loop Detection (in the case of loosely routed 297 segments of a CR-LSP) mechanisms defined in [1]. 299 In addition, the following functionality is added to what's defined 300 in [1]: 302 - The Label Request Message used to setup a CR-LSP includes one 303 or more CR-TLVs defined in Section 4. For instance, the Label 304 Request Message may include the ER-TLV. 305 - An LSR implicitly infers ordered control from the existence of 306 one or more CR-TLVs in the Label Request Message. This means 307 that the LSR can still be configured for independent control 308 for LSPs established as a result of dynamic routing. However, 309 when a Label Request Message includes one or more of the CR- 310 TLVs, then ordered control is used to setup the CR-LSP. Note 311 that this is also true for the loosely routed parts of a CR- 312 LSP. 313 - New status codes are defined to handle error notification for 314 failure of established paths specified in the CR-TLVs. 316 Optional TLVs are not required in the CR-LDP messages for the 317 messages to be compliant with the protocol. Optional parameters MAY 318 be required for a particular operation to work (or work correctly), 319 however. 321 Jamoussi, et. al. draft-ietf-mpls-crldp-03.txt 6 Internet Draft Constraint-Based LSP Setup using LDP September, 1999 323 Examples of CR-LSP establishment are given in Appendix A to 324 illustrate how the mechanisms described in this draft work. 326 3.1 Required Messages and TLVs 328 Any Messages, TLVs, and procedures not defined explicitly in this 329 document are defined in the LDP Specification [1]. The state 330 transitions, which relate to CR-LDP messages, can be found in [5]. 331 The following subsections are meant as a cross-reference to the [1] 332 document and indication of additional functionality beyond what's 333 defined in [1] where necessary. 335 3.2 Label Request Message 337 The Label Request Message is as defined in 3.5.8 of [1] with the 338 following modifications (required only if any of the CR-TLVs is 339 included in the Label Request Message): 341 - Only a single FEC-TLV may be included in the Label Request 342 Message. The CR-LSP FEC TLV should be used. 344 - The Optional Parameters TLV includes the definition of any of 345 the Constraint-based TLVs specified in Section 4. 347 - The Procedures to handle the Label Request Message are 348 augmented by the procedures for processing of the CR-TLVs as 349 defined in Section 4. 351 The encoding for the CR-LDP Label Request Message is as follows: 353 0 1 2 3 354 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 1 355 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 356 |0| Label Request (0x0401) | Message Length | 357 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 358 | Message ID | 359 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 360 | FEC TLV | 361 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 362 | LSPID TLV (CR-LDP, mandatory) | 363 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 364 | ER-TLV (CR-LDP, optional) | 365 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 366 | Traffic TLV (CR-LDP, optional) | 367 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 368 | Pinning TLV (CR-LDP, optional) | 369 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 370 | Resource Class TLV (CR-LDP, optional) | 371 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 372 | Pre-emption TLV (CR-LDP, optional) | 373 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 375 Jamoussi, et. al. draft-ietf-mpls-crldp-03.txt 7 Internet Draft Constraint-Based LSP Setup using LDP September, 1999 377 3.3 Label Mapping Message 379 The Label Mapping Message is as defined in 3.5.7 of [1] with the 380 following modifications: 382 - Only a single Label-TLV may be included in the Label Mapping 383 Message. 385 - The Label Mapping Message Procedures are limited to downstream 386 on demand ordered control mode. 388 A Mapping message is transmitted by a downstream LSR to an upstream 389 LSR under one of the following conditions: 391 1. The LSR is the egress end of the CR-LSP and an upstream 392 mapping has been requested. 394 2. The LSR received a mapping from its downstream next hop LSR 395 for an CR-LSP for which an upstream request is still 396 pending. 398 The encoding for the CR-LDP Label Mapping Message is as follows: 400 0 1 2 3 401 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 1 402 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 403 |0| Label Mapping (0x0400) | Message Length | 404 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 405 | Message ID | 406 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 407 | FEC TLV | 408 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 409 | Label TLV | 410 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 411 | Label Request Message ID TLV | 412 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 413 | LSPID TLV (CR-LDP, optional) | 414 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 415 | Traffic TLV (CR-LDP, optional) | 416 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 418 3.4 Notification Message 420 The Notification Message is as defined in Section 3.5.1 of [1] and 421 the Status TLV encoding is as defined in Section 3.4.6 of [1]. 422 Establishment of an CR-LSP may fail for a variety of reasons. All 423 such failures are considered advisory conditions and they are 424 signaled by the Notification Message. 426 Jamoussi, et. al. draft-ietf-mpls-crldp-03.txt 8 Internet Draft Constraint-Based LSP Setup using LDP September, 1999 428 Notification Messages carry Status TLVs to specify events being 429 signaled. New status codes are defined in Section 4.11 to signal 430 error notifications associated with the establishment of a CR-LSP 431 and the processing of the CR-TLV. 433 The Notification Message may carry the LSPID TLV of the 434 corresponding CR-LSP. 436 Notification Messages MUST be forwarded toward the LSR originating 437 the Label Request at each hop and at any time that procedures in 438 this specification - or in [1] - specify sending of a Notification 439 Message in response to a Label Request Message. 441 The encoding of the notification message is as follows: 443 0 1 2 3 444 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 1 445 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 446 |0| Notification (0x0001) | Message Length | 447 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 448 | Message ID | 449 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 450 | Status (TLV) | 451 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 452 | Optional Parameters | 453 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 455 3.5 Release , Withdraw, and Abort Messages 457 The Label Release , Label Withdraw, and Label Abort Request Messages 458 are used as specified in [1]. These messages may also carry the 459 LSPID TLV. 461 4. Protocol Specification 463 The Label Request Message defined in [1] optionally carries one or 464 more of the optional Constraint-based Routing TLVs (CR-TLVs) defined 465 in this section. If needed, other constraints can be supported later 466 through the definition of new TLVs. In this specification, the 467 following TLVs are defined: 469 - Explicit Route TLV 470 - Explicit Route Hop TLV 471 - Traffic Parameters TLV 472 - Preemption TLV 473 - LSPID TLV 474 - Route Pinning TLV 475 - Resource Class TLV 476 - CR-LSP FEC TLV 478 Jamoussi, et. al. draft-ietf-mpls-crldp-03.txt 9 Internet Draft Constraint-Based LSP Setup using LDP September, 1999 480 4.1 Explicit Route TLV (ER-TLV) 482 The ER-TLV is an object that specifies the path to be taken by the 483 LSP being established. It is composed of one or more Explicit Route 484 Hop TLVs (ER-Hop TLVs) defined in Section 4.2. 486 0 1 2 3 487 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 1 488 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 489 |0|0| ER-TLV (0x0800) | Length | 490 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 491 | ER-Hop TLV 1 | 492 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 493 | ER-Hop TLV 2 | 494 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 495 ~ ............ ~ 496 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 497 | ER-Hop TLV n | 498 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 500 Type 501 A two-byte field carrying the value of the ER-TLV type whichis 502 0x800. 504 Length 505 Specifies the length of the value field in bytes. 507 ER-Hop TLVs 508 One or more ER-Hop TLVs defined in Section 4.2. 510 4.2 Explicit Route Hop TLV (ER-Hop TLV) 512 The contents of an ER-TLV are a series of variable length ER-Hop 513 TLVs. 515 A node receiving a label request message including an ER-Hop type 516 that is not supported should not progress the label request message 517 to the downstream LSR and should send back a _No Route_ Notification 518 Message. 520 Each ER-Hop TLV has the form: 522 0 1 2 3 523 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 1 524 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 525 |0|0| ER-Hop-Type | Length | 526 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 527 |L| Content // | 528 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 530 ER-Hop Type 532 Jamoussi, et. al. draft-ietf-mpls-crldp-03.txt 10 Internet Draft Constraint-Based LSP Setup using LDP September, 1999 534 A fourteen-bit field indicating the type of contents of the ER- 535 Hop. Currently defined values are: 537 Value Type 538 ----- ------------------------ 539 0x801 IPv4 prefix 540 0x802 IPv6 prefix 541 0x803 Autonomous system number 542 0x804 LSPID 544 Length 545 Specifies the length of the value field in bytes. 547 L bit 548 The L bit in the ER-Hop is a one-bit attribute. If the L bit 549 is set, then the value of the attribute is _loose._ Otherwise, 550 the value of the attribute is _strict._ For brevity, we say 551 that if the value of the ER-Hop attribute is loose then it is a 552 _loose ER-Hop._ Otherwise, it's a _strict ER-Hop._ Further, 553 we say that the abstract node of a strict or loose ER-Hop is a 554 strict or a loose node, respectively. Loose and strict nodes 555 are always interpreted relative to their prior abstract nodes. 556 The path between a strict node and its prior node MUST include 557 only network nodes from the strict node and its prior abstract 558 node. 560 The path between a loose node and its prior node MAY include 561 other network nodes, which are not part of the strict node or 562 its prior abstract node. 564 Contents 565 A variable length field containing a node or abstract node 566 which is one of the consecutive nodes that make up the 567 explicitly routed LSP. 569 4.3 Traffic Parameters TLV 571 The following sections describe the CR-LSP Traffic Parameters. The 572 required characteristics of a CR-LSP are expressed by the Traffic 573 Parameter values. 575 A Traffic Parameters TLV, is used to signal the Traffic Parameter 576 values. The Traffic Parameters are defined in the subsequent 577 sections. 579 The Traffic Parameters TLV contains a Flags field, a Frequency, a 580 Weight, and the five Traffic Parameters PDR, PBS, CDR, CBS, EBS. 581 The Traffic Parameters TLV is shown below: 583 Jamoussi, et. al. draft-ietf-mpls-crldp-03.txt 11 Internet Draft Constraint-Based LSP Setup using LDP September, 1999 585 0 1 2 3 586 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 1 587 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 588 |0|0| Traf. Param. TLV (0x0810)| Length | 589 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 590 | Flags | Frequency | Reserved | Weight | 591 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 592 | Peak Data Rate (PDR) | 593 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 594 | Peak Burst Size (PBS) | 595 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 596 | Committed Data Rate (CDR) | 597 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 598 | Committed Burst Size (CBS) | 599 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 600 | Excess Burst Size (EBS) | 601 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 603 Type 604 A fourteen-bit field carrying the value of the ER-TLV type 605 which is 0x810. 607 Length 608 Specifies the length of the value field in bytes. 610 Flags 611 The Flags field is shown below: 613 +--+--+--+--+--+--+--+--+ 614 | Res |F6|F5|F4|F3|F2|F1| 615 +--+--+--+--+--+--+--+--+ 617 Res - These bits are reserved. 618 Zero on transmission. 619 Ignored on receipt. 620 F1 - Corresponds to the PDR. 621 F2 - Corresponds to the PBS. 622 F3 - Corresponds to the CDR. 623 F4 - Corresponds to the CBS. 624 F5 - Corresponds to the EBS. 625 F6 - Corresponds to the Weight. 627 Each flag Fi is a Negotiable Flag corresponding to a Traffic 628 Parameter. The Negotiable Flag value zero denotes NotNegotiable 629 and value one denotes Negotiable. 631 Jamoussi, et. al. draft-ietf-mpls-crldp-03.txt 12 Internet Draft Constraint-Based LSP Setup using LDP September, 1999 633 Frequency 634 The Frequency field is coded as an 8 bit unsigned integer with 635 the following code points defined: 637 0- Unspecified 638 1- Frequent 639 2- VeryFrequent 640 3-255 - Reserved 641 Reserved - Zero on transmission. Ignored on receipt. 643 Weight 644 An 8 bit unsigned integer indicating the weight of the CR-LSP. 645 Valid weight values are from 1 to 255. The value 0 means that 646 weight is not applicable for the CR-LSP. 648 Traffic Parameters 649 Each Traffic Parameter is encoded as a 32-bit IEEE single- 650 precision floating-point number. A value of positive infinity 651 is represented as an IEEE single-precision floating-point 652 number with an exponent of all ones (255) and a sign and 653 mantissa of all zeros. The values PDR and CDR are in units of 654 bytes per second. The values PBS, CBS and EBS are in units of 655 bytes. 657 The value of PDR MUST be greater than or equal to the value of 658 CDR in a correctly encoded Traffic Parameters TLV. 660 4.3.1 Semantics 662 4.3.1.1 Frequency 664 The Frequency specifies at what granularity the CDR allocated to the 665 CR-LSP is made available. The value VeryFrequent means that the 666 available rate should average at least the CDR when measured over 667 any time interval equal to or longer than the shortest packet time 668 at the CDR. The value Frequent means that the available rate should 669 average at least the CDR when measured over any time interval equal 670 to or longer than a small number of shortest packet times at the 671 CDR. 673 The value Unspecified means that the CDR MAY be provided at any 674 granularity. 676 4.3.1.2 Peak Rate 678 The Peak Rate defines the maximum rate at which traffic SHOULD be 679 sent to the CR-LSP. The Peak Rate is useful for the purpose of 680 resource allocation. If resource allocation within the MPLS domain 681 depends on the Peak Rate value then it should be enforced at the 682 ingress to the MPLS domain. 684 Jamoussi, et. al. draft-ietf-mpls-crldp-03.txt 13 Internet Draft Constraint-Based LSP Setup using LDP September, 1999 686 The Peak Rate is defined in terms of the two Traffic Parameters PDR 687 and PBS, see section 4.3.1.5 below. 689 4.3.1.3 Committed Rate 691 The Committed Rate defines the rate that the MPLS domain commits to 692 be available to the CR-LSP. 694 The Committed Rate is defined in terms of the two Traffic Parameters 695 CDR and CBS, see section 4.3.1.6 below. 697 4.3.1.4 Excess Burst Size 699 The Excess Burst Size may be used at the edge of an MPLS domain for 700 the purpose of traffic conditioning. The EBS MAY be used to measure 701 the extent by which the traffic sent on a CR-LSP exceeds the 702 committed rate. 704 The possible traffic conditioning actions, such as passing, marking 705 or dropping, are specific to the MPLS domain. 707 The Excess Burst Size is defined together with the Committed Rate, 708 see section 4.3.1.6 below. 710 4.3.1.5 Peak Rate Token Bucket 712 The Peak Rate of a CR-LSP is specified in terms of a token bucket P 713 with token rate PDR and maximum token bucket size PBS. 715 The token bucket P is initially (at time 0) full, i.e., the token 716 count Tp(0) = PBS. Thereafter, the token count Tp, if less than 717 PBS, is incremented by one PDR times per second. When a packet of 718 size B bytes arrives at time t, the following happens: 720 - If Tp(t)-B >= 0, the packet is not in excess of the peak rate 721 and Tp is decremented by B down to the minimum value of 0, else 723 - the packet is in excess of the peak rate and Tp is not 724 decremented. 726 Note that according to the above definition, a positive infinite 727 value of either PDR or PBS implies that arriving packets are never 728 in excess of the peak rate. 730 The actual implementation of an LSR doesn't need to be modeled 731 according to the above formal token bucket specification. 733 4.3.1.6 Committed Data Rate Token Bucket 735 The committed rate of a CR-LSP is specified in terms of a token 736 bucket C with rate CDR. The extent by which the offered rate 737 exceeds the committed rate MAY be measured in terms of another token 739 Jamoussi, et. al. draft-ietf-mpls-crldp-03.txt 14 Internet Draft Constraint-Based LSP Setup using LDP September, 1999 741 bucket E, which also operates at rate CDR. The maximum size of the 742 token bucket C is CBS and the maximum size of the token bucket E is 743 EBS. 745 The token buckets C and E are initially (at time 0) full, i.e., the 746 token count Tc(0) = CBS and the token count Te(0) = EBS. 747 Thereafter, the token counts Tc and Te are updated CDR times per 748 second as follows: 750 - If Tc is less than CBS, Tc is incremented by one, else 751 - if Te is less then EBS, Te is incremented by one, else 752 - neither Tc nor Te is incremented. 754 When a packet of size B bytes arrives at time t, the following 755 happens: 757 - If Tc(t)-B >= 0, the packet is not in excess of the Committed 758 Rate and Tc is decremented by B down to the minimum value of 0, 759 else 760 - if Te(t)-B >= 0, the packet is in excess of the Committed rate 761 but is not in excess of the EBS and Te is decremented by B down 762 to the minimum value of 0, else 763 - the packet is in excess of both the Committed Rate and the EBS 764 and neither Tc nor Te is decremented. 766 Note that according to the above specification, a CDR value of 767 positive infinity implies that arriving packets are never in excess 768 of either the Committed Rate or EBS. A positive infinite value of 769 either CBS or EBS implies that the respective limit cannot be 770 exceeded. 772 The actual implementation of an LSR doesn't need to be modeled 773 according to the above formal specification. 775 4.3.1.7 Weight 777 The weight determines the CR-LSP's relative share of the possible 778 excess bandwidth above its committed rate. The definition of 779 _relative share_ is MPLS domain specific. 781 4.3.2 Procedures 783 4.3.2.1 Label Request Message 785 If an LSR receives an incorrectly encoded Traffic Parameters TLV in 786 which the value of PDR is less than the value of CDR then it MUST 787 send a Notification Message including the Status code _Traffic 788 Parameters Unavailable_ to the upstream LSR from which it received 789 the erroneous message. 791 Jamoussi, et. al. draft-ietf-mpls-crldp-03.txt 15 Internet Draft Constraint-Based LSP Setup using LDP September, 1999 793 If a Traffic Parameter is indicated as Negotiable in the Label 794 Request Message by the corresponding Negotiable Flag then an LSR MAY 795 replace the Traffic Parameter value with a smaller value. 797 If the Weight is indicated as Negotiable in the Label Request 798 Message by the corresponding Negotiable Flag then an LSR may replace 799 the Weight value with a lower value (down to 0). 801 If, after possible Traffic Parameter negotiation, an LSR can support 802 the CR-LSP Traffic Parameters then the LSR MUST reserve the 803 corresponding resources for the CR-LSP. 805 If, after possible Traffic Parameter negotiation, an LSR cannot 806 support the CR-LSP Traffic Parameters then the LSR MUST send a 807 Notification Message that contains the _Resource Unavailable_ status 808 code. 810 4.3.2.2 Label Mapping Message 812 If an LSR receives an incorrectly encoded Traffic Parameters TLV in 813 which the value of PDR is less than the value of CDR then it MUST 814 send a Label Release message containing the Status code _Traffic 815 Parameters Unavailable_ to the LSR from which it received the 816 erroneous message. In addition, the LSP should send a Notification 817 Message upstream with the status code _Label Request Aborted_. 819 If the negotiation flag was set in the label request message, the 820 egress LSR MUST include the (possibly negotiated) Traffic Parameters 821 and Weight in the Label Mapping message. 823 The Traffic Parameters and the Weight in a Label Mapping message 824 MUST be forwarded unchanged. 826 An LSR SHOULD adjust the resources that it reserved for a CR-LSP 827 when it receives a Label Mapping Message if the Traffic Parameters 828 differ from those in the corresponding Label Request Message. 830 4.3.2.3 Notification Message 832 If an LSR receives a Notification Message for a CR-LSP, it SHOULD 833 release any resources that it possibly had reserved for the CR-LSP. 834 In addition, on receiving a Notification Message from a Downstream 835 LSR that is associated with a Label Request from an upstream LSR, 836 the local LSR MUST propagate the Notification message using the 837 procedures in [1]. 839 4.4 Preemption TLV 841 The defualt value of the setup and holding priorities should be in 842 the middle of the range (e.g., 4) so that this feature can be turned 843 on gradually in an operational network by increasing or decerasing 844 the priority starting at the middle of the range. 846 Jamoussi, et. al. draft-ietf-mpls-crldp-03.txt 16 Internet Draft Constraint-Based LSP Setup using LDP September, 1999 848 0 1 2 3 849 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 1 850 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 851 |0|0| Preemption-TLV (0x0820) | Length | 852 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 853 | SetPrio | HoldPrio | Reserved | 854 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 856 Type 857 A fourteen-bit field carrying the value of the Preemption-TLV 858 type which is 0x820. 860 Length 861 Specifies the length of the value field in bytes. 863 Reserved 864 Zero on transmission. Ignored on receipt. 866 SetPrio 867 A SetupPriority of value zero (0) is the priority assigned to 868 the most important path. It is referred to as the highest 869 priority. Seven (7) is the priority for the least important 870 path. The higher the setup priority, the more paths CR-LDP can 871 bump to set up the path. The default value should be 4. 873 HoldPrio 874 A HoldingPriority of value zero (0) is the priority assigned to 875 the most important path. It is referred to as the highest 876 priority. Seven (7) is the priority for the least important 877 path. The default value should be 4. 878 The higher the holding priority, the less likely it is for CR- 879 LDP to reallocate its bandwidth to a new path. 881 4.5 LSPID TLV 883 LSPID is a unique identifier of a CR-LSP within an MPLS network. 885 The LSPID is composed of the ingress LSR Router ID (or any of its 886 own Ipv4 addresses) and a Locally unique CR-LSP ID to that LSR. 888 The LSPID is useful in network management, in CR-LSP repair, and in 889 using an already established CR-LSP as a hop in an ER-TLV. 891 An _action indicator flag_ is carried in the LSPID TLV. This _action 892 indicator flag_ indicates explicitly the action that should be taken 893 if the LSP already exists on the LSR receiving the message. 895 After a CR-LSP is set up, its bandwidth reservation may need to be 896 changed by the network operator, due to the new requirements for the 897 traffic carried on that CR-LSP. The _action indicator flag_ is used 899 Jamoussi, et. al. draft-ietf-mpls-crldp-03.txt 17 Internet Draft Constraint-Based LSP Setup using LDP September, 1999 901 indicate the need to modify the bandwidth and possibly other 902 parameters of an established CR-LSP without service interruption. 903 This feature has application in dynamic network resources management 904 where traffic of different priorities and service classes is 905 involved. 907 The procedure for the code point _modify_ is defined in Appendix C. 908 The procedures for other flags are FFS. 910 0 1 2 3 911 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 1 912 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 913 |0|0| LSPID-TLV (0x0821) | Length | 914 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 915 | Reserved |ActFlg | Local CR-LSP ID | 916 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 917 | Ingress LSR Router ID | 918 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 920 Type 921 A fourteen-bit field carrying the value of the LSPID-TLV type 922 which is 0x821. 924 Length 925 Specifies the length of the value field in bytes. 927 ActFlg 928 Action Indicator Flag: A 4-bit field that indicates explicitly 929 the action that should be taken if the LSP already exists on 930 the LSR receiving the message. A set of indicator code points 931 is proposed as follows: 933 0000: indicates initial LSP setup 934 0001: indicates modify LSP 935 Reserved 936 Zero on transmission. Ignored on receipt. 938 Local CR-LSP ID 939 The Local LSP ID is an identifier of the CR-LSP locally unique 940 within the Ingress LSR originating the CR-LSP. 942 Ingress LSR Router ID 943 An LSR may use any of its own IPv4 addresses in this field. 945 4.6 Resource Class (Color) TLV 947 The Resource Class as defined in [4] is used to specify which links 948 are acceptable by this CR-LSP. This information allows for the 949 network's topology to be pruned. 951 Jamoussi, et. al. draft-ietf-mpls-crldp-03.txt 18 Internet Draft Constraint-Based LSP Setup using LDP September, 1999 953 0 1 2 3 954 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 1 955 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 956 |0|0| ResCls-TLV (0x0822) | Length | 957 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 958 | RsCls | 959 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 961 Type 962 A fourteen-bit field carrying the value of the ResCls-TLV type 963 which is 0x822. 965 Length 966 Specifies the length of the value field in bytes. 968 RsCls 969 The Resource Class bit mask indicating which of the 32 970 _administrative groups_ or _colors_ of links the CR-LSP can 971 traverse. 973 4.7 ER-Hop semantics 975 4.7.1. ER-Hop 1: The IPv4 prefix 977 The abstract node represented by this ER-Hop is the set of nodes, 978 which have an IP address, which lies within this prefix. Note that 979 a prefix length of 32 indicates a single IPv4 node. 981 0 1 2 3 982 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 1 983 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 984 |0|0| 0x801 | Length | 985 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 986 |L| Reserved | PreLen | 987 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 988 | IPv4 Address (4 bytes) | 989 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 991 Type 992 IPv4 Address 0x801 994 Length 995 Specifies the length of the value field in bytes. 997 L Bit 998 Set to indicate Loose hop. 999 Cleared to indicate a strict hop. 1001 Reserved 1002 Zero on transmission. Ignored on receipt. 1004 PreLen 1006 Jamoussi, et. al. draft-ietf-mpls-crldp-03.txt 19 Internet Draft Constraint-Based LSP Setup using LDP September, 1999 1008 Prefix Length 1-32 1010 IP Address 1011 A four-byte field indicating the IP Address. 1013 4.7.2. ER-Hop 2: The IPv6 address 1015 0 1 2 3 1016 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 1017 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1018 |0|0| 0x802 | Length | 1019 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1020 |L| Reserved | PreLen | 1021 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1022 | IPV6 address | 1023 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1024 | IPV6 address (continued) | 1025 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1026 | IPV6 address (continued) | 1027 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1028 | IPV6 address (continued) | 1029 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1031 Type 1032 0x802 IPv6 address 1034 Length 1035 Specifies the length of the value field in bytes. 1037 L Bit 1038 Set to indicate Loose hop. 1039 Cleared to indicate a strict hop. 1041 Reserved 1042 Zero on transmission. Ignored on receipt. 1044 PreLen 1045 Prefix Length 1-128 1047 IPv6 address 1048 A 128-bit unicast host address. 1050 4.7.3. ER-Hop 3: The autonomous system number 1052 The abstract node represented by this ER-Hop is the set of nodes 1053 belonging to the autonomous system. 1055 Jamoussi, et. al. draft-ietf-mpls-crldp-03.txt 20 Internet Draft Constraint-Based LSP Setup using LDP September, 1999 1057 0 1 2 3 1058 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 1059 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1060 |0|0| 0x803 | Length | 1061 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1062 |L| Reserved | AS Number | 1063 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1065 Type 1066 AS Number 0x803 1068 Length 1069 Specifies the length of the value field in bytes. 1071 L Bit 1072 Set to indicate Loose hop. 1073 Cleared to indicate a strict hop. 1075 Reserved 1076 Zero on transmission. Ignored on receipt. 1078 AS Number 1079 Autonomous System number 1081 4.7.4. ER-Hop 4: LSPID 1083 The LSPID is used to identify the tunnel ingress point as the next 1084 hop in the ER. This ER-Hop allows for stacking new CR-LSPs within an 1085 already established CR-LSP. It also allows for splicing the CR-LSP 1086 being established with an existing CR-LSP. 1088 If an LSPID Hop is the last ER-Hop in an ER-TLV, than the LSR may 1089 splice the CR-LSP of the incoming Label Request to the CR-LSP that 1090 currently exists with this LSPID. This is useful, for example, at 1091 the point at which a Label Request used for local repair arrives at 1092 the next ER-Hop after the loosely specified CR-LSP segment. Use of 1093 the LSPID Hop in this scenario eliminates the need for ER-Hops to 1094 keep the entire remaining ER-TLV at each LSR that is at either 1095 (upstream or downstream) end of a loosely specified CR-LSP segment 1096 as part of its state information. This is due to the fact that the 1097 upstream LSR needs only to keep the next ER-Hop and the LSPID and 1098 the downstream LSR needs only to keep the LSPID in order for each 1099 end to be able to recognize that the same LSP is being identified. 1101 If the LSPID Hop is not the last hop in an ER-TLV, the LSR must 1102 forward the remaining ER-TLV in a Label Request message, using the 1103 CR-LSP specified by the LSPID, to the LSR that is the CR-LSP's 1104 egress. That LSR will continue processing of the CR-LSP Label 1105 Request Message. The result is a tunneled, or stacked, CR-LSP. 1107 Jamoussi, et. al. draft-ietf-mpls-crldp-03.txt 21 Internet Draft Constraint-Based LSP Setup using LDP September, 1999 1109 0 1 2 3 1110 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 1111 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1112 |0|0| 0x804 | Length | 1113 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1114 |L| Reserved | Local LSPID | 1115 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1116 | Ingress LSR Router ID | 1117 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1119 Type 1120 LSPID 0x804 1122 Length 1123 Specifies the length of the value field in bytes. 1125 L Bit 1126 Set to indicate Loose hop. 1127 Cleared to indicate a strict hop. 1129 Reserved 1130 Zero on transmission. Ignored on receipt. 1132 Local LSPID 1133 A 2 byte field indicating the LSPID which is unique with 1134 reference to its Ingress LSR. 1136 Ingress LSR Router ID 1137 An LSR may use any of its own IPv4 addresses in this field. 1139 4.8. Processing of the Explicit Route TLV 1141 4.8.1. Selection of the next hop 1143 A Label Request Message containing an explicit route TLV must 1144 determine the next hop for this path. Selection of this next hop 1145 may involve a selection from a set of possible alternatives. The 1146 mechanism for making a selection from this set is implementation 1147 dependent and is outside of the scope of this specification. 1148 Selection of particular paths is also outside of the scope of this 1149 specification, but it is assumed that each node will make a best 1150 effort attempt to determine a loop-free path. Note that such best 1151 efforts may be overridden by local policy. 1153 To determine the next hop for the path, a node performs the 1154 following steps: 1156 1. The node receiving the Label Request Message must first 1157 evaluate the first ER-Hop. If the L bit is not set in the 1158 first ER-Hop and if the node is not part of the abstract node 1159 described by the first ER-Hop, it has received the message in 1161 Jamoussi, et. al. draft-ietf-mpls-crldp-03.txt 22 Internet Draft Constraint-Based LSP Setup using LDP September, 1999 1163 error, and should return a _Bad Initial ER-Hop_ error. If the 1164 L bit is set and the local node is not part of the abstract 1165 node described by the first ER-Hop, the node selects a next 1166 hop that is along the path to the abstract node described by 1167 the first ER-Hop. If there is no first ER-Hop, the message is 1168 also in error and the system should return a _Bad Explicit 1169 Routing TLV_ error using a Notification Message sent upstream. 1171 2. If there is no second ER-Hop, this indicates the end of the 1172 explicit route. The explicit route TLV should be removed from 1173 the Label Request Message. This node may or may not be the 1174 end of the LSP. Processing continues with section 4.8.2, 1175 where a new explicit route TLV may be added to the Label 1176 Request Message. 1178 3. If the node is also a part of the abstract node described by 1179 the second ER-Hop, then the node deletes the first ER-Hop and 1180 continues processing with step 2, above. Note that this makes 1181 the second ER-Hop into the first ER-Hop of the next iteration. 1183 4. The node determines if it is topologically adjacent to the 1184 abstract node described by the second ER-Hop. If so, the node 1185 selects a particular next hop which is a member of the 1186 abstract node. The node then deletes the first ER-Hop and 1187 continues processing with section 4.8.2. 1189 5. Next, the node selects a next hop within the abstract node of 1190 the first ER-Hop that is along the path to the abstract node 1191 of the second ER-Hop. If no such path exists then there are 1192 two cases: 1194 5.a If the second ER-Hop is a strict ER-Hop, then there is 1195 an error and the node should return a _Bad Strict Node_ 1196 error. 1198 5.b Otherwise, if the second ER-Hop is a loose ER-Hop, then 1199 the node selects any next hop that is along the path to the 1200 next abstract node. If no path exists within the MPLS 1201 domain, then there is an error, and the node should return a 1202 _Bad loose node_ error. 1204 6. Finally, the node replaces the first ER-Hop with any ER-Hop 1205 that denotes an abstract node containing the next hop. This 1206 is necessary so that when the explicit route is received by 1207 the next hop, it will be accepted. 1209 7. Progress the Label Request Message to the next hop. 1211 4.8.2. Adding ER-Hops to the explicit route TLV 1213 After selecting a next hop, the node may alter the explicit route in 1214 the following ways. 1216 Jamoussi, et. al. draft-ietf-mpls-crldp-03.txt 23 Internet Draft Constraint-Based LSP Setup using LDP September, 1999 1218 If, as part of executing the algorithm in section 4.8.1, the 1219 explicit route TLV is removed, the node may add a new explicit route 1220 TLV. 1222 Otherwise, if the node is a member of the abstract node for the 1223 first ER-Hop, then a series of ER-Hops may be inserted before the 1224 first ER-Hop or may replace the first ER-Hop. Each ER-Hop in this 1225 series must denote an abstract node that is a subset of the current 1226 abstract node. 1228 Alternately, if the first ER-Hop is a loose ER-Hop, an arbitrary 1229 series of ER-Hops may be inserted prior to the first ER-Hop. 1231 4.9 Route Pinning TLV 1233 Section 2.4 describes the use of route pinning. The encoding of the 1234 Route Pinning TLV is as follows: 1236 0 1 2 3 1237 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 1238 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1239 |0|0| 0x823 | Length | 1240 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1241 |P| Reserved | 1242 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1244 Type 1245 Pinning-TLV type 0x823 1247 Length 1248 Specifies the length of the value field in bytes. 1250 P Bit 1251 The P bit is set to 1 to indicate that route pinning is 1252 requested. 1253 The P bit is set to 0 to indicate that route pinning is not 1254 requested 1256 Reserved 1257 Zero on transmission. Ignored on receipt. 1259 4.10 CR-LSP FEC Element 1261 A new FEC element is introduced in this specification to support CR- 1262 LSPs. This new FEC element does not preclude the use of other FECs 1263 elements (Type=0x01, 0x02, 0x03) defined in the LDP spec in CR-LDP 1264 messages. The CR-LDP FEC Element is an opaque FEC to be used only in 1265 Messages of CR-LSPs. 1267 Jamoussi, et. al. draft-ietf-mpls-crldp-03.txt 24 Internet Draft Constraint-Based LSP Setup using LDP September, 1999 1269 FEC Element Type Value 1270 Type name 1272 CR-LSP 0x04 No value; i.e., 0 value octets; 1274 The CR-LSP FEC TLV encoding is as follows: 1276 0 1 2 3 1277 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 1278 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1279 |0|0| FEC(0x0100) | Length | 1280 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1281 | CR-LSP (4) | 1282 +-+-+-+-+-+-+-+-+ 1284 Type 1285 FEC TLV type 0x0100 1287 Length 1288 Specifies the length of the value field in bytes. 1290 CR-LSP FEC Element Type 1291 0x04 1293 4.11 Error subcodes 1295 In the processing described above, certain errors need to be 1296 reported as part of the Notification Message. This section defines 1297 the status codes for the errors described in this specification. 1299 Status Code Type 1300 -------------------------------------- ---------- 1301 Bad Explicit Routing TLV Error 0x44000001 1302 Bad Strict Node Error 0x44000002 1303 Bad Loose Node Error 0x44000003 1304 Bad Initial ER-Hop Error 0x44000004 1305 Resource Unavailable 0x44000005 1306 Traffic Parameters Unavailable 0x44000006 1307 Setup Abort (Label Request Aborted in [1]) 0x04000015 1308 Modify Request Not Supported 0x44000008 1310 5. Security 1312 Pre-emption has to be controlled by the MPLS domain. 1314 Resource reservation requires the LSRs to have an LSP admission 1315 control function. 1317 Traffic Engineered LSPs can bypass normal routing. 1319 6. Acknowledgments 1321 Jamoussi, et. al. draft-ietf-mpls-crldp-03.txt 25 Internet Draft Constraint-Based LSP Setup using LDP September, 1999 1323 The messages used to signal the CR-LSP setup are based on the work 1324 done by the [1] team. 1326 The authors would also like to acknowledge the careful review and 1327 comments of Ken Hayward, Greg Wright, Geetha Brown, Brian Williams, 1328 Paul Beaubien, Matthew Yuen, Liam Casey, Ankur Anand, Adrian Farrel. 1330 7. Intellectual Property Consideration 1332 The IETF has been notified of intellectual property rights claimed 1333 in regard to some or all of the specification contained in this 1334 document. For more information consult the online list of claimed 1335 rights. 1337 8. References 1339 1 Andersson et al, "Label Distribution Protocol Specification" 1340 work in progress (draft-ietf-mpls-ldp-05), June 1999. 1342 2 Callon et al, "Framework for Multiprotocol Label Switching", 1343 work in progress (draft-ietf-mpls-framework-05), September 1999. 1345 3 Rosen et al, "Multiprotocol Label Switching Architecture", 1346 work in progress (draft-ietf-mpls-arch-06), September 1999. 1348 4 Awduche et al, "Requirements for Traffic Engineering Over 1349 MPLS", RFC 2702, September 1999. 1351 5 L. Wu, et. al., "LDP State Machine" work in progress 1352 (draft-ietf-mpls-ldp-state-00), Feb 1999. 1354 9. Author's Addresses 1356 Osama S. Aboul-Magd Loa Andersson 1357 Nortel Networks Nortel Networks 1358 P O Box 3511 Station C S:t Eriksgatan 115 1359 Ottawa, ON K1Y 4H7 PO Box 6701 1360 Canada 113 85 Stockholm 1361 Phone: +1 613 763-5827 Tel: +46 8 508 835 00 1362 Osama@nortelnetworks.com Fax: +46 8 508 835 01 1363 Loa_andersson@nortelnetworks.com 1365 Peter Ashwood-Smith Ross Callon 1366 Nortel Networks IronBridge Networks 1367 P O Box 3511 Station C 55 Hayden Avenue, 1368 Ottawa, ON K1Y 4H7 Lexington, MA 02173 1369 Canada Phone: +1-781-402-8017 1370 Phone: +1 613 763-4534 Rcallon@ironbridgenetworks.com 1371 Petera@nortelnetworks.com 1373 Ram Dantu Paul Doolan 1374 Alcatel USA Inc. Ennovate Networks 1376 Jamoussi, et. al. draft-ietf-mpls-crldp-03.txt 26 Internet Draft Constraint-Based LSP Setup using LDP August, 1999 1378 IP Competence Center 330 Codman Hill Rd 1379 1201 E. Campbell Road.,446-315 Marlborough MA 01719 1380 Richadson, TX USA., 75081-2206 Phone: 978-263-2002 1381 Phone: 972 996 2938 Pdoolan@ennovatenetworks.com 1382 Fax: 972 996 5902 1383 Ram.dantu@alcatel.com 1385 Nancy Feldman Andre Fredette 1386 IBM Corp. Nortel Networks 1387 17 Skyline Drive 600 Technology Park Drive 1388 Hawthorne NY 10532 Billerica, MA 01821 1389 Phone: 914-784-3254 978-288-8524 1390 Nkf@us.ibm.com Fredette@nortelnetworks.com 1392 Eric Gray Joel M. Halpern 1393 Lucent Technologies, Inc Institutional Venture Partners 1394 1600 Osgood St. 650-926-5633 1395 North Andover, MA 01847 Joel@mcquillan.com 1396 Phone: 603-659-3386 1397 Ewgray@lucent.com 1399 Juha Heinanen Fiffi Hellstrand 1400 Telia Finland, Inc. Ericsson Telecom AB 1401 Myyrmaentie 2 S-126 25 STOCKHOLM 1402 01600 VANTAA Sweden 1403 Finland Tel: +46 8 719 4933 1404 Tel: +358 41 500 4808 Etxfiff@etxb.ericsson.se 1405 Jh@telia.fi 1407 Bilel Jamoussi Timothy E. Kilty 1408 Nortel Networks Corp. Northchurch Communications 1409 600 Technology Park Drive 5 Corporate Drive, 1410 Billerica, MA 01821 Andover, MA 018110 1411 USA phone: 978 691-4656 1412 Phone: +1 978 288-4506 Tkilty@northc.com 1413 Jamoussi@nortelnetworks.com 1415 Andrew G. Malis Muckai K Girish 1416 Ascend Communications, Inc. SBC Technology Resources, 1417 1 Robbins Road 4698 Willow Road 1418 Westford, MA 01886 Pleasanton, CA 94588 1419 Phone: 978 952-7414 Phone: (925) 598-1263 1420 fax: 978 392-2074 Fax: (925) 598-1321 1421 Malis@ascend.com Mgirish@tri.sbc.com 1423 Kenneth Sundell Pasi Vaananen 1424 Nortel Networks Nokia Telecommunications 1425 S:t Eriksgatan 115 3 Burlington Woods Drive, 1426 PO Box 6701 Burlington, MA 01803 1427 113 85 Stockholm Phone: +1-781-238-4981 1428 Tel: +46 8 508 835 00 Pasi.vaanenen@ntc.nokia.com 1429 Fax: +46 8 508 835 01 1431 Jamoussi, et. al. draft-ietf-mpls-cr-ldp-03.txt 27 Internet Draft Constraint-Based LSP Setup using LDP August, 1999 1433 Ksundell@nortelnetworks.com 1435 Tom Worster Liwen Wu 1436 Nokia Alcatel U.S.A 1437 3 Burlington Woods Dr. 44983 Knoll Square 1438 Suite 250 Ashburn, Va. 20147 1439 Burlington MA 01803 USA Phone: (703) 724-2619 1440 +1 617 247 2624 FAX: (703) 724-2005 1441 Tom.worster@nokia.com Liwen.wu@and.alcatel.com 1443 Jamoussi, et. al. draft-ietf-mpls-cr-ldp-03.txt 28 Internet Draft Constraint-Based LSP Setup using LDP August, 1999 1445 Appendix A: CR-LSP Establishment Examples 1447 A.1 Strict Explicit Route Example 1449 This appendix provides an example for the setup of a strictly routed 1450 CR-LSP. In this example, a specific node represents each abstract 1451 node. 1453 The sample network used here is a four node network with two edge 1454 LSRs and two core LSRs as follows: 1456 abc 1457 LSR1------LSR2------LSR3------LSR4 1459 LSR1 generates a Label Request Message as described in Section 3.1 1460 of this draft and sends it to LSR2. This message includes the CR- 1461 TLV. 1463 A vector of three ER-Hop TLVs composes the ER-TLV. 1464 The ER-Hop TLVs used in this example are of type 0x0801 (IPv4 1465 prefix) with a prefix length of 32. Hence, each ER-Hop TLV 1466 identifies a specific node as opposed to a group of nodes. 1467 At LSR2, the following processing of the ER-TLV per Section 4.8.1 of 1468 this draft takes place: 1470 1) The node LSR2 is part of the abstract node described by the 1471 first hop . Therefore, the first step passes the test. 1472 Go to step 2. 1474 2) There is a second ER-Hop, . Go to step 3. 1476 3) LSR2 is not part of the abstract node described by the 1477 second ER-Hop . Go to Step 4. 1479 4) LSR2 determines that it is topologically adjacent to the 1480 abstract node described by the second ER-Hop . LSR2 1481 selects a next hop (LSR3) which is the abstract node. LSR2 1482 deletes the first ER-Hop from the ER-TLV, which now 1483 becomes . Processing continues with Section 4.8.2. 1485 At LSR2, the following processing of Section 4.8.2 takes place: 1486 Executing algorithm 4.8.1 did not result in the removal of the ER- 1487 TLV. 1489 Also, LSR2 is not a member of the abstract node described by the 1490 first ER-Hop . 1492 Finally, the first ER-Hop is a strict hop. 1494 Therefore, processing section 4.8.2 does not result in the insertion 1495 of new ER-Hops. The selection of the next hop has been already done 1496 is step 4 of Section 4.8.1 and the processing of the ER-TLV is 1498 Jamoussi, et. al. draft-ietf-mpls-cr-ldp-03.txt 29 Internet Draft Constraint-Based LSP Setup using LDP August, 1999 1500 completed at LSR2. In this case, the Label Request Message including 1501 the ER-TLV is progressed by LSR2 to LSR3. 1503 At LSR3, a similar processing to the ER-TLV takes place except that 1504 the incoming ER-TLV = and the outgoing ER-TLV is . 1506 At LSR4, the following processing of section 4.8.1 takes place: 1508 1) The node LSR4 is part of the abstract node described by the 1509 first hop . Therefore, the first step passes the test. Go 1510 to step 2. 1511 2) There is no second ER-Hop, this indicates the end of the CR- 1512 LSP. The ER-TLV is removed from the Label Request Message. 1513 Processing continues with Section 4.8.2. 1515 At LSR4, the following processing of Section 4.8.2 takes place: 1516 Executing algorithm 4.8.1 resulted in the removal of the ER-TLV. 1517 LSR4 does not add a new ER-TLV. 1519 Therefore, processing section 4.8.2 does not result in the insertion 1520 of new ER-Hops. This indicates the end of the CR-LSP and the 1521 processing of the ER-TLV is completed at LSR4. 1523 At LSR4, processing of Section 3.2 is invoked. The first condition 1524 is satisfied (LSR4 is the egress end of the CR-LSP and upstream 1525 mapping has been requested). Therefore, a Label Mapping Message is 1526 generated by LSR4 and sent to LSR3. 1528 At LSR3, the processing of Section 3.2 is invoked. The second 1529 condition is satisfied (LSR3 received a mapping from its downstream 1530 next hop LSR4 for a CR-LSP for which an upstream request is still 1531 pending). Therefore, a Label Mapping Message is generated by LSR3 1532 and sent to LSR2. 1534 At LSR2, a similar processing to LSR 3 takes place and a Label 1535 Mapping Message is sent back to LSR1, which completes the end-to-end 1536 CR-LSP setup. 1538 A.2 Node Groups and Specific Nodes Example 1540 A request at ingress LSR to setup a CR-LSP might originate from a 1541 management system or an application, the details are implementation 1542 specific. 1544 The ingress LSR uses information provided by the management system 1545 or the application and possibly also information from the routing 1546 database to calculate the explicit route and to create the Label 1547 Request Message. 1549 The Label request message carries together with other necessary 1550 information an ER-TLV defining the explicitly routed path. In our 1551 example the list of hops in the ER-Hop TLV is supposed to contain an 1553 Jamoussi, et. al. draft-ietf-mpls-cr-ldp-03.txt 30 Internet Draft Constraint-Based LSP Setup using LDP August, 1999 1555 abstract node representing a group of nodes, an abstract node 1556 representing a specific node, another abstract node representing a 1557 group of nodes, and an abstract node representing a specific egress 1558 point. 1560 In--{Group 1}--{Specific A}--{Group 2}--{Specific Out: B} 1561 The ER-TLV contains four ER-Hop TLVs: 1563 1. An ER-Hop TLV that specifies a group of LSR valid for the 1564 first abstract node representing a group of nodes (Group 1). 1566 2. An ER-Hop TLV that indicates the specific node (Node A). 1568 3. An ER-Hop TLV that specifies a group of LSRs valid for the 1569 second abstract node representing a group of nodes (Group 1570 2). 1572 4. An ER-Hop TLV that indicates the specific egress point for 1573 the CR-LSP (Node B). 1575 All the ER-Hop TLVs are strictly routed nodes. 1576 The setup procedure for this CR-LSP works as follows: 1578 1. The ingress node sends the Label Request Message to a node 1579 that is a member the group of nodes indicated in the first 1580 ER-Hop TLV, following normal routing for the specific node 1581 (A). 1583 2. The node that receives the message identifies itself as part 1584 of the group indicated in the first ER-Hop TLV, and that it 1585 is not the specific node (A) in the second. Further it 1586 realizes that the specific node (A) is not one of its next 1587 hops. 1589 3. It keeps the ER-Hop TLVs intact and sends a Label Request 1590 Message to another node that is part of the group indicated 1591 in the first ER-Hop TLV (Group 1), following normal routing 1592 for the specific node (A). 1594 4. The node that receives the message identifies itself as part 1595 of the group indicated in the first ER-Hop TLV, and that it 1596 is not the specific node (A) in the second ER-Hop TLV. 1597 Further it realizes that the specific node (A) is one of its 1598 next hops. 1600 5. It removes the first ER-Hop TLVs and sends a Label Request 1601 Message to the specific node (A). 1603 6. The specific node (A) recognizes itself in the first ER-Hop 1604 TLV. Removes the specific ER-Hop TLV. 1606 Jamoussi, et. al. draft-ietf-mpls-cr-ldp-03.txt 31 Internet Draft Constraint-Based LSP Setup using LDP August, 1999 1608 7. It sends a Label Request Message to a node that is a member 1609 of the group (Group 2) indicated in the ER-Hop TLV. 1611 8. The node that receives the message identifies itself as part 1612 of the group indicated in the first ER-Hop TLV, further it 1613 realizes that the specific egress node (B) is one of its 1614 next hops. 1616 9. It sends a Label Request Message to the specific egress node 1617 (B). 1619 10.The specific egress node (B) recognizes itself as the egress 1621 for the CR-LSP, it returns a Label Mapping Message, that 1622 will traverse the same path as the Label Request Message in 1623 the opposite direction. 1625 Jamoussi, et. al. draft-ietf-mpls-cr-ldp-03.txt 32 Internet Draft Constraint-Based LSP Setup using LDP August, 1999 1627 Appendix B. QoS Service Examples 1629 B.1 Service Examples 1631 Construction of an end-to-end service is the result of the rules 1632 enforced at the edge and the treatment that packets receive at the 1633 network nodes. The rules define the traffic conditioning actions 1634 that are implemented at the edge and they include policing with 1635 pass, mark, and drop capabilities. The edge rules are expected tobe 1636 defined by the mutual agreements between the service providers and 1637 their customers and they will constitute an essential part of the 1638 SLA. Therefore edge rules are not included in the signaling 1639 protocol. 1641 Packet treatment at a network node is usually referred to as the 1642 local behavior. Local behavior could be specified in many ways. One 1643 example for local behavior specification is the service frequency 1644 introduced in section 4.3.2.1, together with the resource 1645 reservation rules implemented at the nodes. 1647 Edge rules and local behaviors can be viewed as the main building 1648 blocks for the end-to-end service construction. The following table 1649 illustrates the applicability of the building block approach for 1650 constructing different services including those defined for ATM. 1652 Service PDR PBS CDR CBS EBS Service Conditioning 1653 Examples Frequency Action 1655 DS S S =PDR =PBS 0 Frequent drop>PDR 1657 TS S S S S 0 Unspecified drop>PDR,PBS 1658 mark>CDR,CBS 1660 BE inf inf inf inf 0 Unspecified - 1662 FRS S S CIR ~B_C ~B_E Unspecified drop>PDR,PBS 1663 mark>CDR,CBS,EBS 1665 ATM-CBR PCR CDVT =PCR =CDVT 0 VeryFrequent drop>PCR 1667 ATM-VBR.3(rt) PCR CDVT SCR MBS 0 Frequent drop>PCR 1668 mark>SCR,MBS 1670 ATM-VBR.3(nrt) PCR CDVT SCR MBS 0 Unspecified drop>PCR 1671 mark>SCR,MBS 1673 ATM-UBR PCR CDVT - - 0 Unspecified drop>PCR 1675 ATM-GFR.1 PCR CDVT MCR MBS 0 Unspecified drop>PCR 1677 ATM-GFR.2 PCR CDVT MCR MBS 0 Unspecified drop>PCR 1678 mark>MCR,MFS 1680 Jamoussi, et. al. draft-ietf-mpls-cr-ldp-03.txt 33 Internet Draft Constraint-Based LSP Setup using LDP August, 1999 1682 int-serv-CL p m r b 0 Frequent drop>p 1683 drop>r,b 1685 S= User specified 1687 In the above table, the DS refers to a delay sensitive service where 1688 the network commits to deliver with high probability user datagrams 1689 at a rate of PDR with minimum delay and delay requirements. 1690 Datagrams in excess of PDR will be discarded. 1692 The TS refers to a generic throughput sensitive service where the 1693 network commits to deliver with high probability user datagrams at a 1694 rate of at least CDR. The user may transmit at a rate higher than 1695 CDR but datagrams in excess of CDR would have a lower probability of 1696 being delivered. 1698 The BE is the best effort service and it implies that there are no 1699 expected service guarantees from the network. 1701 B.2 Establishing CR-LSP Supporting Real-Time Applications 1703 In this scenario the customer needs to establish an LSP for 1704 supporting real-time applications such as voice and video. The 1705 Delay-sensitive (DS) service is requested in this case. 1707 The first step is the specification of the traffic parameters in the 1708 signaling message. The two parameters of interest to the DS service 1709 are the PDR and the PBS and the user based on his requirements 1710 specifies their values. Since all the traffic parameters are 1711 included in the signaling message, appropriate values must be 1712 assigned to all of them. For DS service, the CDR and the CBS values 1713 are set equal to the PDR and the PBS respectively. An indication of 1714 whether the parameter values are subject to negotiation is flagged. 1716 The transport characteristics of the DS service require Frequent 1717 frequency to be requested to reflect the real-time delay 1718 requirements of the service. 1720 In addition to the transport characteristics, both the network 1721 provider and the customer need to agree on the actions enforced at 1722 the edge. The specification of those actions is expected to be a 1723 part of the service level agreement (SLA) negotiation and is not 1724 included in the signaling protocol. For DS service, the edge action 1725 is to drop packets that exceed the PDR and the PBS specifications. 1726 The signaling message will be sent in the direction of the ER path 1727 and the LSP is established following the normal LDP procedures. Each 1728 LSR applies its admission control rules. If sufficient resources are 1729 not available and the parameter values are subject to negotiation, 1730 then the LSR could negotiate down the PDR, the PBS, or both. 1732 Jamoussi, et. al. draft-ietf-mpls-cr-ldp-03.txt 34 Internet Draft Constraint-Based LSP Setup using LDP August, 1999 1734 The new parameter values are echoed back in the Label Mapping 1735 Message. LSRs might need to re-adjust their resource reservations 1736 based on the new traffic parameter values. 1738 B.3 Establishing CR-LSP Supporting Delay Insensitive Applications 1740 In this example we assume that a throughput sensitive (TS) service 1741 is requested. For resource allocation the user assigns values for 1742 PDR, PBS, CDR, and CBS. The negotiation flag is set if the traffic 1743 parameters are subject to negotiation. 1744 Since the service is delay insensitive by definition, the 1745 Unspecified frequency is signaled to indicate that the service 1746 frequency is not an issue. 1748 Similar to the previous example, the edge actions are not subject 1749 for signaling and are specified in the service level agreement 1750 between the user and the network provider. 1752 For TS service, the edge rules might include marking to indicate 1753 high discard precedence values for all packets that exceed CDR and 1754 the CBS. The edge rules will also include dropping of packets that 1755 conform to neither PDR nor PBS. 1757 Each LSR of the LSP is expected to run its admission control rules 1758 and negotiate traffic parameters down if sufficient resources do not 1759 exist. The new parameter values are echoed back in the Label Mapping 1760 Message. LSRs might need to re-adjust their resources based on the 1761 new traffic parameter values. 1763 Jamoussi, et. al. draft-ietf-mpls-cr-ldp-03.txt 35 Internet Draft Constraint-Based LSP Setup using LDP August, 1999 1765 Appendix C. LSP Modification Using CR-LDP 1767 After a CR-LSP is set up, its bandwidth reservation may need to be 1768 changed by the network operator, due to the new requirements for the 1769 traffic carried on that CR-LSP. This contribution presents an 1770 approach to modify the bandwidth and possibly other parameters of an 1771 established CR-LSP using CR-LDP without service interruption. The 1772 LSP modification feature can be supported by CR-LDP with a minor 1773 extension of an _action indicator flag_. This feature has 1774 application in dynamic network resources management where traffic of 1775 different priorities and service classes is involved. 1777 Conventions used in this Appendix: 1779 L: LSP (Label Switched Path) 1780 Lid: LSPID (LSP Identifier) 1781 T: Traffic Parameters 1782 R: LSR (Label Switching Router) 1783 FTN: FEC To NHLFE 1784 FEC: Forwarding Equivalence Class 1785 NHLFE: Next Hop Label Forwarding Entity 1786 TLV: Type Length Value 1788 C.1 Introduction 1790 Consider an LSP L1 that has been established with its set of traffic 1791 parameters T0. A certain amount of bandwidth is reserved along the 1792 path of L1. Consider then that some changes are required on L1. For 1793 example, the bandwidth of L1 needs to be increased to accommodate 1794 the increased traffic on L1. Or the SLA associated with L1 needs to 1795 be modified because a different service class is desired. The 1796 network operator, in these cases, would like to modify the 1797 characteristics of L1, for example, to change its traffic parameter 1798 set from T0 to T1, without releasing the LSP L1 to interrupt the 1799 service. In some other cases, network operators may want to reroute 1800 a CR-LSP to a different path for either improved performance or 1801 better network resource utilization. In all these cases, LSP 1802 modification is required. In section C.2 below, a method to modify 1803 an active LSP using CR-LDP is presented. The concept of LSPID in CR- 1804 LDP is used to achieve the LSP modification, without releasing the 1805 LSP and interrupting the service and, without double booking the 1806 bandwidth. Only a minimum extension on CR-LDP, an action indication 1807 flag of _modify_ is needed in order to explicitly specify the 1808 behavior, and allow the existing LSPID to support other networking 1809 capabilities in the future. Section 4.5 specifies the action 1810 indication flag of _modify_ for CR-LDP. An example is described to 1811 demonstrate an application of the presented method in dynamically 1812 managing network bandwidth requirements without interrupting 1813 service. 1815 Jamoussi, et. al. draft-ietf-mpls-cr-ldp-03.txt 36 Internet Draft Constraint-Based LSP Setup using LDP August, 1999 1817 C.2 Basic Procedure 1819 LSP modification can only be allowed when the LSP is already set up 1820 and active. That is, modification is not defined nor allowed during 1821 the LSP establishment or label release/withdraw phases. Only 1822 modification requested by the ingress LSR of the LSP is considered 1823 in this draft for CR-LSP. Ingress LSR cannot modify an LSP before a 1824 previous modification procedure is completed. 1826 Assume that CR-LSP L1 is set up with LSPID L-id1, which is unique in 1827 the MPLS network. The ingress LSR R1 of L1 has in its FTN (FEC To 1828 NHLFE) table FEC1 -> Label A mapping where A is the outgoing label 1829 for LSP L1. To modify the characteristics of L1, R1 sends a Label 1830 Request Message. In the messages, the TLVs will have the new 1831 requested values, and the LSPID TLV is included which indicates the 1832 value of L-id1. The Traffic Parameters TLV, the ER-TLV, the Resource 1833 Class (color) TLV and the Preemption TLV can have values different 1834 from those in the original Label Request Message, which has been 1835 used to set up L1 earlier. Thus, L1 can be changed in its bandwidth 1836 request (traffic parameter TLV), its traffic service class (traffic 1837 parameter TLV), the route it traverses (ER TLV) and its setup and 1838 holding (Preemption TLV) priorities. The ingress LSR R1 now still 1839 has the entry in FTN as FEC1 -> Label A. R1 is waiting to establish 1840 another entry for FEC1. 1842 When an LSR Ri along the path of L1 receives the Label Request 1843 message, its behavior is the same as that of receiving any Label 1844 request message. The only extension is that Ri examines the LSPID 1845 carried in the Label Request Message, L-id1 and identifies if it 1846 already has L-id1. If Ri does not have L-id1, Ri behaves the same as 1847 receiving a new Label Request message. If Ri already has L-id1, Ri 1848 takes the newly received Traffic Parameter TLV and computes the new 1849 bandwidth required and derives the new service class. Compared with 1850 the already reserved bandwidth for L-id1, Ri now reserves only the 1851 difference of the bandwidth requirements. This prevents Ri from 1852 doing bandwidth double booking. If a new service class is requested, 1853 Ri also prepares to receive the traffic on L1 in, perhaps a 1854 different type of queue, just the same as handling it for a Label 1855 Request Message. Ri assigns a new label for the Label Request 1856 Message. 1858 When the Label Mapping message is received, two sets of labels exist 1859 for the same LSPID. Then the ingress LSR R1 will have two outgoing 1860 labels, A and B, associated with the same FEC, where B is the new 1861 outgoing label received for LSP L1. The ingress LSR R1 can now 1862 activate the new entry in FTN, FEC1 - > Label B. This means that R1 1863 swaps traffic on L1 to the new label _B_ (_new_ path) for L1. The 1864 packets can now be sent with the new label B, with the new set of 1865 traffic parameters if any, on a new path, that is, if a new path is 1866 requested in the Label Request Message for the modification. All the 1867 other LSRs along the path will start to receive the incoming packets 1868 with the new label. For the incoming new label, the LSR has already 1870 Jamoussi, et. al. draft-ietf-mpls-cr-ldp-03.txt 37 Internet Draft Constraint-Based LSP Setup using LDP August, 1999 1872 established its mapping to the new outgoing label. Thus, the packets 1873 will be sent out with the new outgoing label. The LSRs do not have 1874 to implement new procedures to track the new and old 1875 characteristics of the LSP. 1877 The ingress LSR R1 then starts to release the original label A for 1878 LSP L1. The Label Release Message is sent by R1 towards the down 1879 stream LSRs. The Release message carries the LSPID of L-id1 and the 1880 Label TLV to indicate which label is to be released. The Release 1881 Message is propagated to the egress LSR to release the original 1882 labels previously used for L1. Upon receiving the Label Release 1883 Message, LSR R1 examines the LSPID, L-id1 and finds out that the L- 1884 id1 has still another set of label (incoming/outgoing) under it. 1885 Thus, the old label is released without releasing the resource in 1886 use. That is, if the bandwidth has been decreased for L1, the delta 1887 bandwidth is released. Otherwise, no bandwidth is released. This 1888 modification procedure can not only be applied to modify the traffic 1889 parameters and/or service class of an active LSP, but also to 1890 reroute an existing LSP, and/or change its setup/holding priority if 1891 desired. After the release procedure, the modification of the LSP is 1892 completed. 1894 The method described above follows the normal behavior of Label 1895 Request / Mapping / Notification / Release /Withdraw procedure of a 1896 CR-LDP operated LSR with a specific action taken on LSPID. If Label 1897 Withdraw Message is used to withdraw a label associated with an 1898 LSPID, the Label TLV should be included to specify which label to 1899 withdraw. Since the LSPID can also be used for other feature 1900 support, an action indication flag of _modify_ assigned to the LSPID 1901 would explicitly explain the action/semantics that should be 1902 associated with the messaging procedure. The details of this flag 1903 are addressed in Section 4.5. 1905 C.3 Priority Handling 1907 When sending a Label Request Message for an active LSP L1 to request 1908 changes, the setup priority used in the label Request Message can be 1909 different from the one used in the previous Label Request Message, 1910 effectively indicating the priority of this _modification_ request. 1911 Network operators can use this feature to decide what priority is to 1912 be assigned to a modification request, based on their 1913 policies/algorithms and other traffic situations in the network. For 1914 example, the priority for modification can be determined by the 1915 priority of the customer/LSP. If a customer has exceeded the 1916 reserved bandwidth of its VPN LSP tunnel by too much, the 1917 modification request's priority may be given higher. 1918 The Label Request message for the modification of an active LSP can 1919 also be sent with a holding priority different from its previous 1920 one. This effectively changes the holding priority of the LSP. Upon 1921 receiving a Label Request Message that requests a new holding 1922 priority, the LSR assigns the new holding priority to the bandwidth. 1923 That is, the new holding priority is assigned to both the existing 1925 Jamoussi, et. al. draft-ietf-mpls-cr-ldp-03.txt 38 Internet Draft Constraint-Based LSP Setup using LDP August, 1999 1927 incoming / outgoing labels and the new labels to be established for 1928 the LSPID in question. In this way self-bumping is prevented. 1930 C.4 Modification Failure Case Handling 1932 A modification attempt may fail due to insufficient resource or 1933 other situations. A Notification message is sent back to the ingress 1934 LSR R1 to indicate the failure of Label Request Message that 1935 intended to modify the LSP. Retry may be attempted if desired by the 1936 network operator. 1938 If the LSP on the original path failed when a modification attempt 1939 is in progress, the attempt should be aborted by using the Label 1940 Abort Request message as specified in LDP draft. 1942 Full Copyright Statement 1943 _Copyright c The Internet Society (date). All Rights Reserved. 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However, this 1950 document itself may not be modified in any way, such as by removing 1951 the copyright notice or references to the Internet Society or other 1952 Internet organizations, except as needed for the purpose of 1953 developing Internet standards in which case the procedures for 1954 copyrights defined in the Internet Standards process must be 1955 followed, or as required to translate it into languages other than 1956 English. 1958 The limited permissions granted above are perpetual and will not be 1959 revoked by the Internet Society or its successors or assigns. 1961 Jamoussi, et. al. draft-ietf-mpls-cr-ldp-03.txt 39