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Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Outdated reference: A later version (-23) exists of draft-ietf-pce-pcep-stateful-pce-gmpls-13 == Outdated reference: A later version (-23) exists of draft-ietf-pce-pcep-yang-14 == Outdated reference: A later version (-13) exists of draft-ietf-pce-sr-bidir-path-02 Summary: 0 errors (**), 0 flaws (~~), 4 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 PCE Working Group R. Gandhi, Ed. 3 Internet-Draft Cisco Systems, Inc. 4 Intended status: Standards Track C. Barth 5 Expires: March 13, 2021 Juniper Networks 6 B. Wen 7 Comcast 8 September 9, 2020 10 PCEP Extensions for Associated Bidirectional Label Switched Paths (LSPs) 11 draft-ietf-pce-association-bidir-07 13 Abstract 15 The Path Computation Element Communication Protocol (PCEP) provides 16 mechanisms for Path Computation Elements (PCEs) to perform path 17 computations in response to Path Computation Clients (PCCs) requests. 18 The Stateful PCE extensions allow stateful control of Multiprotocol 19 Label Switching (MPLS) Traffic Engineering (TE) Label Switched Paths 20 (LSPs) using PCEP. 22 This document defines PCEP extensions for grouping two unidirectional 23 MPLS TE LSPs (one in each direction in the network) into an 24 Associated Bidirectional LSP. The mechanisms defined in this 25 document can be applied using a Stateful PCE for both PCE-Initiated 26 and PCC-Initiated LSPs, as well as when using a Stateless PCE. The 27 procedures defined are applicable to the LSPs using Resource 28 Reservation Protocol (RSVP) for signaling. 30 Status of This Memo 32 This Internet-Draft is submitted in full conformance with the 33 provisions of BCP 78 and BCP 79. 35 Internet-Drafts are working documents of the Internet Engineering 36 Task Force (IETF). Note that other groups may also distribute 37 working documents as Internet-Drafts. The list of current Internet- 38 Drafts is at https://datatracker.ietf.org/drafts/current/. 40 Internet-Drafts are draft documents valid for a maximum of six months 41 and may be updated, replaced, or obsoleted by other documents at any 42 time. It is inappropriate to use Internet-Drafts as reference 43 material or to cite them other than as "work in progress." 45 This Internet-Draft will expire on March 13, 2021. 47 Copyright Notice 49 Copyright (c) 2020 IETF Trust and the persons identified as the 50 document authors. All rights reserved. 52 This document is subject to BCP 78 and the IETF Trust's Legal 53 Provisions Relating to IETF Documents 54 (https://trustee.ietf.org/license-info) in effect on the date of 55 publication of this document. Please review these documents 56 carefully, as they describe your rights and restrictions with respect 57 to this document. Code Components extracted from this document must 58 include Simplified BSD License text as described in Section 4.e of 59 the Trust Legal Provisions and are provided without warranty as 60 described in the Simplified BSD License. 62 Table of Contents 64 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 65 1.1. Summary of PCEP Extensions . . . . . . . . . . . . . . . 4 66 2. Conventions Used in This Document . . . . . . . . . . . . . . 4 67 2.1. Key Word Definitions . . . . . . . . . . . . . . . . . . 4 68 2.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 5 69 3. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 5 70 3.1. Single-sided Initiation . . . . . . . . . . . . . . . . . 5 71 3.2. Double-sided Initiation . . . . . . . . . . . . . . . . . 6 72 3.3. Co-routed Associated Bidirectional LSP . . . . . . . . . 7 73 4. Protocol Extensions . . . . . . . . . . . . . . . . . . . . . 8 74 4.1. ASSOCIATION Object . . . . . . . . . . . . . . . . . . . 8 75 4.2. Bidirectional LSP Association Group TLV . . . . . . . . . 9 76 5. PCEP Procedure . . . . . . . . . . . . . . . . . . . . . . . 10 77 5.1. PCE Initiated LSPs . . . . . . . . . . . . . . . . . . . 10 78 5.2. PCC Initiated LSPs . . . . . . . . . . . . . . . . . . . 10 79 5.3. Stateless PCE . . . . . . . . . . . . . . . . . . . . . . 11 80 5.4. Bidirectional (B) Flag . . . . . . . . . . . . . . . . . 11 81 5.5. PLSP-ID Usage . . . . . . . . . . . . . . . . . . . . . . 11 82 5.6. State Synchronization . . . . . . . . . . . . . . . . . . 12 83 5.7. Error Handling . . . . . . . . . . . . . . . . . . . . . 12 84 6. Implementation Status . . . . . . . . . . . . . . . . . . . . 13 85 6.1. Implementation . . . . . . . . . . . . . . . . . . . . . 13 86 7. Security Considerations . . . . . . . . . . . . . . . . . . . 13 87 8. Manageability Considerations . . . . . . . . . . . . . . . . 14 88 8.1. Control of Function and Policy . . . . . . . . . . . . . 14 89 8.2. Information and Data Models . . . . . . . . . . . . . . . 14 90 8.3. Liveness Detection and Monitoring . . . . . . . . . . . . 14 91 8.4. Verify Correct Operations . . . . . . . . . . . . . . . . 14 92 8.5. Requirements On Other Protocols . . . . . . . . . . . . . 14 93 8.6. Impact On Network Operations . . . . . . . . . . . . . . 14 94 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14 95 9.1. Association Types . . . . . . . . . . . . . . . . . . . . 14 96 9.2. Bidirectional LSP Association Group TLV . . . . . . . . . 15 97 9.2.1. Flag Field in Bidirectional LSP Association Group TLV 15 98 9.3. PCEP Errors . . . . . . . . . . . . . . . . . . . . . . . 15 99 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 16 100 10.1. Normative References . . . . . . . . . . . . . . . . . . 16 101 10.2. Informative References . . . . . . . . . . . . . . . . . 17 102 Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 18 103 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 18 105 1. Introduction 107 [RFC5440] describes the Path Computation Element Protocol (PCEP) as a 108 communication mechanism between a Path Computation Client (PCC) and a 109 Path Control Element (PCE), or between PCE and PCC, that enables 110 computation of Multiprotocol Label Switching (MPLS) Traffic 111 Engineering (TE) Label Switched Paths (LSPs). 113 [RFC8231] specifies extensions to PCEP to enable stateful control of 114 MPLS TE LSPs. It describes two modes of operation - Passive Stateful 115 PCE and Active Stateful PCE. In [RFC8231], the focus is on Active 116 Stateful PCE where LSPs are provisioned on the PCC and control over 117 them is delegated to a PCE. Further, [RFC8281] describes the setup, 118 maintenance and teardown of PCE-Initiated LSPs for the Stateful PCE 119 model. 121 [RFC8697] introduces a generic mechanism to create a grouping of LSPs 122 which can then be used to define associations between a set of LSPs 123 and/or a set of attributes, for example primary and secondary LSP 124 associations, and is equally applicable to the active and passive 125 modes of a Stateful PCE [RFC8231] or a stateless PCE [RFC5440]. 127 The MPLS Transport Profile (MPLS-TP) requirements document [RFC5654] 128 specifies that MPLS-TP MUST support associated bidirectional point- 129 to-point LSPs. [RFC7551] defines RSVP signaling extensions for 130 binding two reverse unidirectional LSPs [RFC3209] into an associated 131 bidirectional LSP. The fast reroute (FRR) procedures for associated 132 bidirectional LSPs are described in [RFC8537]. 134 This document defines PCEP extensions for grouping two unidirectional 135 MPLS-TE LSPs into an Associated Bidirectional LSP for both single- 136 sided and double-sided initiation cases when using a Stateful PCE for 137 both PCE-Initiated and PCC-Initiated LSPs as well as when using a 138 Stateless PCE. The procedures defined are applicable to the TE LSPs 139 using Resource Reservation Protocol (RSVP) for signaling [RFC3209]. 140 The procedure for associating two unidirectional Segment Routing (SR) 141 Paths to form an Associated Bidirectional SR Path is defined in 143 [I-D.ietf-pce-sr-bidir-path], and is outside the scope of this 144 document. 146 1.1. Summary of PCEP Extensions 148 The PCEP extensions defined in this document cover the following 149 cases: 151 o A PCC initiates the forward and/ or reverse LSP of a single-sided 152 or double-sided bidirectional LSP and retains the control of the 153 LSP. The PCC computes the path itself or makes a request for path 154 computation to a PCE. After the path setup, it reports the 155 information and state of the path to the PCE. This includes the 156 association group identifying the bidirectional LSP. This is the 157 Passive Stateful mode defined in [RFC8051]. 159 o A PCC initiates the forward and/ or reverse LSP of a single-sided 160 or double-sided bidirectional LSP and delegates the control of the 161 LSP to a Stateful PCE. During delegation the association group 162 identifying the bidirectional LSP is included. The PCE computes 163 the path of the LSP and updates the PCC with the information about 164 the path as long as it controls the LSP. This is the Active 165 Stateful mode defined in [RFC8051]. 167 o A PCE initiates the forward and/ or reverse LSP of a single-sided 168 or double-sided bidirectional LSP on a PCC and retains the control 169 of the LSP. The PCE is responsible for computing the path of the 170 LSP and updating the PCC with the information about the path as 171 well as the association group identifying the bidirectional LSP. 172 This is the PCE-Initiated mode defined in [RFC8281]. 174 o A PCC requests co-routed or non-co-routed paths for forward and 175 reverse LSPs of a bidirectional LSP from a Stateless PCE 176 [RFC5440]. 178 2. Conventions Used in This Document 180 2.1. Key Word Definitions 182 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 183 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 184 "OPTIONAL" in this document are to be interpreted as described in BCP 185 14 [RFC2119] [RFC8174] when, and only when, they appear in all 186 capitals, as shown here. 188 2.2. Terminology 190 The reader is assumed to be familiar with the terminology defined in 191 [RFC5440], [RFC7551], [RFC8231], and [RFC8697]. 193 3. Overview 195 As shown in Figure 1, two reverse unidirectional LSPs can be grouped 196 to form an associated bidirectional LSP. There are two methods of 197 initiating the bidirectional LSP association, single-sided and 198 double-sided, as defined in [RFC7551] and described in the following 199 sections. 201 LSP1 --> LSP1 --> LSP1 --> 202 +-----+ +-----+ +-----+ +-----+ 203 | A +-----------+ B +-----------+ C +-----------+ D | 204 +-----+ +--+--+ +--+--+ +-----+ 205 <-- LSP2 | | <-- LSP2 206 | | 207 | | 208 +--+--+ +--+--+ 209 | E +-----------+ F | 210 +-----+ +-----+ 211 <-- LSP2 213 Figure 1: Example of Associated Bidirectional LSP 215 3.1. Single-sided Initiation 217 As specified in [RFC7551], in the single-sided case, the 218 bidirectional tunnel is provisioned only on one endpoint node (PCC) 219 of the tunnel. Both forward and reverse LSPs of this tunnel are 220 initiated with the Association Type set to "Single-sided 221 Bidirectional LSP Association" on the originating endpoint node. The 222 forward and reverse LSPs are identified in the Bidirectional LSP 223 Association Group TLV of their PCEP ASSOCIATION Objects. 225 The originating endpoint node signals the properties for the revere 226 LSP in the RSVP REVERSE_LSP Object [RFC7551] of the forward LSP Path 227 message. The remote endpoint then creates the corresponding reverse 228 tunnel and signals the reverse LSP in response to the received RSVP 229 Path message. Similarly, the remote endpoint node deletes the 230 reverse LSP when it receives the RSVP Path delete message [RFC3209] 231 for the forward LSP. 233 The originating endpoint (PCC) node may report/ delegate the forward 234 and reverse direction LSPs to a PCE. The remote endpoint (PCC) node 235 may report its forward direction LSP to a PCE. 237 +-----+ 238 | PCE | 239 +-----+ 240 Initiates: | ^ Reports: 241 Tunnel 1 (F) | \ Tunnel 2 (F) 242 (LSP1 (F, P1), LSP2 (R, P2)) | \ (LSP2 (F, P3)) 243 Association #1 v \ Association #1 244 +-----+ +-----+ 245 | A | | D | 246 +-----+ +-----+ 248 Figure 2: Example of PCE-Initiated Single-sided Bidirectional LSP 250 +-----+ 251 | PCE | 252 +-----+ 253 Reports/Delegates: ^ ^ Reports: 254 Tunnel 1 (F) | \ Tunnel 2 (F) 255 (LSP1 (F, P1), LSP2 (R, P2)) | \ (LSP2 (F, P3)) 256 Association #2 | \ Association #2 257 +-----+ +-----+ 258 | A | | D | 259 +-----+ +-----+ 261 Figure 3: Example of PCC-Initiated Single-sided Bidirectional LSP 263 As shown in Figures 2 and 3, the forward tunnel and both forward LSP1 264 and reverse LSP2 are initiated on the originating endpoint node A, 265 either by the PCE or the originating PCC, respectively. The 266 originating endpoint node A signals the properties of reverse LSP2 in 267 the RSVP REVERSE_LSP Object in the Path message of the forward LSP1. 268 The creation of reverse tunnel and reverse LSP2 on the remote 269 endpoint node D is triggered by the RSVP signaled forward LSP1. 270 PLSP-IDs used are shown in the Figures as P1, P2 and P3. 272 As specified in [RFC8537], for fast reroute bypass tunnel assignment, 273 the LSP starting from the originating node is identified as the 274 forward LSP of the single-sided initiated bidirectional LSP. 276 3.2. Double-sided Initiation 278 As specified in [RFC7551], in the double-sided case, the 279 bidirectional tunnel is provisioned on both endpoint nodes (PCCs) of 280 the tunnel. The forward and reverse LSPs of this tunnel are 281 initiated with the Association Type set to "Double-sided 282 Bidirectional LSP Association" on both endpoint nodes. The forward 283 and reverse LSPs are identified in the Bidirectional LSP Association 284 Group TLV of their ASSOCIATION Objects. 286 The endpoint (PCC) nodes may report/ delegate the forward and reverse 287 direction LSPs to a PCE. 289 +-----+ 290 | PCE | 291 +-----+ 292 Initiates: | \ Initiates: 293 Tunnel 1 (F) | \ Tunnel 2 (F) 294 (LSP1 (F, P1)) | \ (LSP2 (F, P2)) 295 Association #3 v v Association #3 296 +-----+ +-----+ 297 | A | | D | 298 +-----+ +-----+ 300 Figure 4: Example of PCE-Initiated Double-sided Bidirectional LSP 302 +-----+ 303 | PCE | 304 +-----+ 305 Reports/Delegates: ^ ^ Reports/Delegates: 306 Tunnel 1 (F) | \ Tunnel 2 (F) 307 (LSP1 (F, P1)) | \ (LSP2 (F, P2)) 308 Association #4 | \ Association #4 309 +-----+ +-----+ 310 | A | | D | 311 +-----+ +-----+ 313 Figure 5: Example of PCC-Initiated Double-sided Bidirectional LSP 315 As shown in Figures 4 and 5, the forward tunnel and forward LSP1 are 316 initiated on the endpoint node A and the reverse tunnel and reverse 317 LSP2 are initiated on the endpoint node D, either by the PCE or the 318 PCCs, respectively. PLSP-IDs used are shown in the Figures as P1 and 319 P2. 321 As specified in [RFC8537], for fast reroute bypass tunnel assignment, 322 the LSP with the higher Source Address [RFC3209] is identified as the 323 forward LSP of the double-sided initiated bidirectional LSP. 325 3.3. Co-routed Associated Bidirectional LSP 327 In both single-sided and double-sided initiation cases, forward and 328 reverse LSPs may be co-routed as shown in Figure 6, where both 329 forward and reverse LSPs of a bidirectional LSP follow the same 330 congruent path in the forward and reverse directions, respectively. 332 LSP3 --> LSP3 --> LSP3 --> 333 +-----+ +-----+ +-----+ +-----+ 334 | A +-----------+ B +-----------+ C +-----------+ D | 335 +-----+ +-----+ +-----+ +-----+ 336 <-- LSP4 <-- LSP4 <-- LSP4 338 Figure 6: Example of Co-routed Associated Bidirectional LSP 340 4. Protocol Extensions 342 4.1. ASSOCIATION Object 344 As per [RFC8697], LSPs are associated by adding them to a common 345 association group. This document defines two new Bidirectional LSP 346 Association Groups to be used by the associated bidirectional LSPs. 347 A member of the Bidirectional LSP Association Group can take the role 348 of a forward or reverse LSP and follows the following rules: 350 o An LSP (forward or reverse) cannot be part of more than one 351 Bidirectional LSP Association Group. More than one forward LSP 352 and/ or reverse LSP can be part of a Bidirectional LSP Association 353 Group. 355 o The Tunnel (as defined in [RFC3209]) of forward and reverse LSPs 356 of the Single-sided Bidirectional LSP Association on the 357 originating node MUST be the same. 359 This document defines two new Association Types for the ASSOCIATION 360 Object (Object-Class value 40) as follows: 362 o Association Type (TBD1) = Single-sided Bidirectional LSP 363 Association Group 365 o Association Type (TBD2) = Double-sided Bidirectional LSP 366 Association Group 368 These Association Types are operator-configured associations in 369 nature and statically created by the operator on the PCEP peers. 370 'Operator-configured Association Range' TLV (Value 29) [RFC8697] MUST 371 NOT be sent for these Association Types, and MUST be ignored, so that 372 the entire range of association ID can be used for them. 374 The Association ID, Association Source, optional Global Association 375 Source and optional Extended Association ID in the Bidirectional LSP 376 Association Group Object are initialized using the procedures defined 377 in [RFC8697] and [RFC7551]. 379 4.2. Bidirectional LSP Association Group TLV 381 The Bidirectional LSP Association Group TLV is defined for use with 382 the Single-sided and Double-sided Bidirectional LSP Association Group 383 Object Types. 385 o The Bidirectional LSP Association Group TLV follows the PCEP TLV 386 format from [RFC5440]. 388 o The Type (16 bits) of the TLV is TBD3, to be assigned by IANA. 390 o The Length is 4 Bytes. 392 o The value comprises of a single field, the Bidirectional LSP 393 Association Flag (32 bits), where each bit represents a flag 394 option. 396 o If the Bidirectional LSP Association Group TLV is missing, it 397 means the LSP is the forward LSP and it is not co-routed LSP. 399 o For co-routed LSPs, this TLV MUST be present. 401 o For reverse LSPs, this TLV MUST be present. 403 o The Bidirectional LSP Association Group TLV MUST NOT be present 404 more than once. If it appears more than once, only the first 405 occurrence is processed and any others MUST be ignored. 407 The format of the Bidirectional LSP Association Group TLV is shown in 408 Figure 7: 410 0 1 2 3 411 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 1 412 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 413 | Type = TBD3 | Length | 414 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 415 | Reserved |C|R|F| 416 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 418 Figure 7: Bidirectional LSP Association Group TLV format 420 Flags for Bidirectional LSP Association Group TLV are defined as 421 following. 423 F (Forward LSP, 1 bit) - Indicates whether the LSP associated is the 424 forward LSP of the bidirectional LSP. If this flag is set, the LSP 425 is a forward LSP. 427 R (Reverse LSP, 1 bit) - Indicates whether the LSP associated is the 428 reverse LSP of the bidirectional LSP. If this flag is set, the LSP 429 is a reverse LSP. 431 C (Co-routed Path, 1 bit) - Indicates whether the bidirectional LSP 432 is co-routed. This flag MUST be set for both the forward and reverse 433 LSPs of a co-routed bidirectional LSP. 435 The C flag is used by the PCE (for both Stateful and Stateless) to 436 compute bidirectional paths of the forward and reverse LSPs of a co- 437 routed bidirectional LSP. 439 The Reserved flags MUST be set to 0 when sent and MUST be ignored 440 when received. 442 5. PCEP Procedure 444 5.1. PCE Initiated LSPs 446 As specified in [RFC8697], the Bidirectional LSP Association Groups 447 can be created by a Stateful PCE. 449 o Stateful PCE can create and update the forward and reverse LSPs 450 independently for both Single-sided and Double-sided Bidirectional 451 LSP Association Groups. 453 o Stateful PCE can establish and remove the association relationship 454 on a per LSP basis. 456 o Stateful PCE can create and update the LSP and the association on 457 a PCC via PCInitiate and PCUpd messages, respectively, using the 458 procedures described in [RFC8697]. 460 5.2. PCC Initiated LSPs 462 As specified in [RFC8697], Bidirectional LSP Association Groups can 463 also be created by a PCC. 465 o PCC can create and update the forward and reverse LSPs 466 independently for both Single-sided and Double-sided Bidirectional 467 LSP Association Groups. 469 o PCC can establish and remove the association relationship on a per 470 LSP basis. 472 o PCC MUST report the change in the association group of an LSP to 473 PCE(s) via PCRpt message. 475 o PCC can report the forward and reverse LSPs independently to 476 PCE(s) via PCRpt message. 478 o PCC can delegate the forward and reverse LSPs independently to a 479 Stateful PCE, where PCE would control the LSPs. For single-sided 480 case, originating (PCC) node can delegate both forward and reverse 481 LSPs of a tunnel together to a Stateful PCE in order to avoid any 482 race condition. 484 o Stateful PCE can update the LSPs in the Bidirectional LSP 485 Association Group via PCUpd message, using the procedures 486 described in [RFC8697]. 488 5.3. Stateless PCE 490 For a stateless PCE, it might be useful to associate a path 491 computation request to an association group, thus enabling it to 492 associate a common set of configuration parameters or behaviors with 493 the request. A PCC can request co-routed or non-co-routed forward 494 and reverse direction paths from a stateless PCE for a Bidirectional 495 LSP Association Group. 497 5.4. Bidirectional (B) Flag 499 As defined in [RFC5440], the Bidirectional (B) flag in the Request 500 Parameters (RP) object is set when the PCC specifies that the path 501 computation request is for a bidirectional TE LSP with the same TE 502 requirements in each direction. For an associated bidirectional LSP, 503 the B-flag is also set when the PCC makes the path computation 504 request for the same TE requirements for the forward and reverse 505 direction LSPs. 507 Note that the B-flag defined in Stateful PCE Request Parameter (SRP) 508 object [I-D.ietf-pce-pcep-stateful-pce-gmpls] to indicate 509 'bidirectional co-routed LSP' is used for GMPLS signaled 510 bidirectional LSPs and is not applicable to the associated 511 bidirectional LSPs. 513 5.5. PLSP-ID Usage 515 As defined in [RFC8231], a PCEP-specific LSP Identifier (PLSP-ID) is 516 created by a PCC to uniquely identify an LSP and it remains the same 517 for the lifetime of a PCEP session. 519 In case of Single-sided Bidirectional LSP Association, the reverse 520 LSP of a bidirectional LSP created on the originating node is 521 identified by the PCE using 2 different PLSP-IDs based on the PCEP 522 session on the ingress or egress nodes for the LSP. In other words, 523 the reverse LSP on the originating node will have a PLSP-ID P1 at the 524 ingress node while it will have a PLSP-ID P3 at the egress node. 525 This is not the case for the forward LSP of the Single-sided 526 Bidirectional LSP on the originating node and there is no change in 527 the PLSP-ID allocation procedure for it. In case of Double-sided 528 Bidirectional LSP Association, there is no change in the PLSP-ID 529 allocation procedure. 531 For an Associated Bidirectional LSP, LSP-IDENTIFIERS TLV [RFC8231] 532 MUST be included in all forward and reverse LSPs. 534 5.6. State Synchronization 536 During state synchronization, a PCC MUST report all the existing 537 Bidirectional LSP Association Groups to the Stateful PCE as per 538 [RFC8697]. After the state synchronization, the PCE MUST remove all 539 stale Bidirectional LSP Associations. 541 5.7. Error Handling 543 An LSP (forward or reverse) cannot be part of more than one 544 Bidirectional LSP Association Group. If a PCE attempts to add an LSP 545 not complying to this rule, the PCC MUST send PCErr with Error-Type = 546 26 (Association Error) and Error-Value = TBD4 (Bidirectional LSP 547 Association - Group Mismatch). Similarly, if a PCC attempts to add 548 an LSP at PCE not complying to this rule, the PCE MUST send this 549 PCErr. 551 The LSPs (forward or reverse) in a Single-sided Bidirectional 552 Association Group MUST belong to the same TE Tunnel (as defined in 553 [RFC3209]). If a PCE attempts to add an LSP in a Single-sided 554 Bidirectional LSP Association Group for a different Tunnel, the PCC 555 MUST send PCErr with Error-Type = 26 (Association Error) and Error- 556 Value = TBD5 (Bidirectional Association - Tunnel Mismatch). 557 Similarly, if a PCC attempts to add an LSP to a Single-sided 558 Bidirectional LSP Association Group at PCE not complying to this 559 rule, the PCE MUST send this PCErr. 561 The PCEP Path Setup Type (PST) for RSVP is set to 'Path is set up 562 using the RSVP-TE signaling protocol' (Value 0) [RFC8408]. If a PCEP 563 speaker receives a different PST value for the Bidirectional LSP 564 Association Groups defined in this document and it does not support; 565 it MUST return a PCErr message with Error-Type = 26 (Association 566 Error) and Error-Value = TBD6 (Bidirectional LSP Association - Path 567 Setup Type Not Supported). 569 The processing rules as specified in Section 6.4 of [RFC8697] 570 continue to apply to the Association Types defined in this document. 572 6. Implementation Status 574 [Note to the RFC Editor - remove this section before publication, as 575 well as remove the reference to RFC 7942.] 577 This section records the status of known implementations of the 578 protocol defined by this specification at the time of posting of this 579 Internet-Draft, and is based on a proposal described in [RFC7942]. 580 The description of implementations in this section is intended to 581 assist the IETF in its decision processes in progressing drafts to 582 RFCs. Please note that the listing of any individual implementation 583 here does not imply endorsement by the IETF. Furthermore, no effort 584 has been spent to verify the information presented here that was 585 supplied by IETF contributors. This is not intended as, and must not 586 be construed to be, a catalog of available implementations or their 587 features. Readers are advised to note that other implementations may 588 exist. 590 According to [RFC7942], "this will allow reviewers and working groups 591 to assign due consideration to documents that have the benefit of 592 running code, which may serve as evidence of valuable experimentation 593 and feedback that have made the implemented protocols more mature. 594 It is up to the individual working groups to use this information as 595 they see fit". 597 6.1. Implementation 599 The PCEP extensions defined in this document has been implemented by 600 a vendor on their product. No further information is available at 601 this time. 603 7. Security Considerations 605 The security considerations described in [RFC5440], [RFC8231], and 606 [RFC8281] apply to the extensions defined in this document as well. 608 Two new Association Types for the ASSOCIATION Object, Single-sided 609 Bidirectional LSP Association Group and Double-sided Bidirectional 610 LSP Association Group are introduced in this document. Additional 611 security considerations related to LSP associations due to a 612 malicious PCEP speaker is described in [RFC8697] and apply to these 613 Association Types. Hence, securing the PCEP session using Transport 614 Layer Security (TLS) [RFC8253] is recommended. 616 8. Manageability Considerations 618 8.1. Control of Function and Policy 620 The mechanisms defined in this document do not imply any control or 621 policy requirements in addition to those already listed in [RFC5440], 622 [RFC8231], and [RFC8281]. 624 8.2. Information and Data Models 626 [RFC7420] describes the PCEP MIB, there are no new MIB Objects 627 defined for LSP associations. 629 The PCEP YANG module [I-D.ietf-pce-pcep-yang] defines data model for 630 LSP associations. 632 8.3. Liveness Detection and Monitoring 634 The mechanisms defined in this document do not imply any new liveness 635 detection and monitoring requirements in addition to those already 636 listed in [RFC5440], [RFC8231], and [RFC8281]. 638 8.4. Verify Correct Operations 640 The mechanisms defined in this document do not imply any new 641 operation verification requirements in addition to those already 642 listed in [RFC5440], [RFC8231], and [RFC8281]. 644 8.5. Requirements On Other Protocols 646 The mechanisms defined in this document do not add any new 647 requirements on other protocols. 649 8.6. Impact On Network Operations 651 The mechanisms defined in this document do not have any impact on 652 network operations in addition to those already listed in [RFC5440], 653 [RFC8231], and [RFC8281]. 655 9. IANA Considerations 657 9.1. Association Types 659 This document adds new Association Types for the ASSOCIATION Object 660 (Object-class value 40) defined [RFC8697]. IANA is requested to make 661 the assignment of values for the sub-registry "ASSOCIATION Type" 662 [RFC8697], as follows: 664 Type Name Reference 665 --------------------------------------------------------------------- 666 TBD1 Single-sided Bidirectional LSP Association Group [This document] 667 TBD2 Double-sided Bidirectional LSP Association Group [This document] 669 9.2. Bidirectional LSP Association Group TLV 671 This document defines a new TLV for carrying additional information 672 of LSPs within a Bidirectional LSP Association Group. IANA is 673 requested to add the assignment of a new value in the existing "PCEP 674 TLV Type Indicators" registry as follows: 676 Value Meaning Reference 677 ------------------------------------------------------------------- 678 TBD3 Bidirectional LSP Association Group TLV [This document] 680 9.2.1. Flag Field in Bidirectional LSP Association Group TLV 682 This document requests that a new sub-registry, named "Bidirectional 683 LSP Association Group TLV Flag Field", is created within the "Path 684 Computation Element Protocol (PCEP) Numbers" registry to manage the 685 Flag field in the Bidirectional LSP Association Group TLV. New 686 values are to be assigned by Standards Action [RFC8126]. Each bit 687 should be tracked with the following qualities: 689 o Bit number (count from 0 as the most significant bit) 691 o Description 693 o Reference 695 The following values are defined in this document for the Flag field. 697 Bit No. Description Reference 698 --------------------------------------------------------- 699 31 F - Forward LSP [This document] 700 30 R - Reverse LSP [This document] 701 29 C - Co-routed Path [This document] 703 9.3. PCEP Errors 705 This document defines new Error value for Error Type 26 (Association 706 Error). IANA is requested to allocate new Error value within the 707 "PCEP-ERROR Object Error Types and Values" sub-registry of the PCEP 708 Numbers registry, as follows: 710 Error Type Description Reference 711 --------------------------------------------------------- 712 26 Association Error 714 Error value: TBD4 [This document] 715 Bidirectional LSP Association - Group Mismatch 717 Error value: TBD5 [This document] 718 Bidirectional LSP Association - Tunnel Mismatch 720 Error value: TBD6 [This document] 721 Bidirectional LSP Association - Path Setup Type 722 Not Supported 724 10. References 726 10.1. Normative References 728 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 729 Requirement Levels", BCP 14, RFC 2119, 730 DOI 10.17487/RFC2119, March 1997, 731 . 733 [RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V., 734 and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP 735 Tunnels", RFC 3209, DOI 10.17487/RFC3209, December 2001, 736 . 738 [RFC5440] Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation 739 Element (PCE) Communication Protocol (PCEP)", RFC 5440, 740 DOI 10.17487/RFC5440, March 2009, 741 . 743 [RFC7551] Zhang, F., Ed., Jing, R., and R. Gandhi, Ed., "RSVP-TE 744 Extensions for Associated Bidirectional Label Switched 745 Paths (LSPs)", RFC 7551, DOI 10.17487/RFC7551, May 2015, 746 . 748 [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for 749 Writing an IANA Considerations Section in RFCs", BCP 26, 750 RFC 8126, DOI 10.17487/RFC8126, June 2017, 751 . 753 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 754 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 755 May 2017, . 757 [RFC8231] Crabbe, E., Minei, I., Medved, J., and R. Varga, "Path 758 Computation Element Communication Protocol (PCEP) 759 Extensions for Stateful PCE", RFC 8231, 760 DOI 10.17487/RFC8231, September 2017, 761 . 763 [RFC8281] Crabbe, E., Minei, I., Sivabalan, S., and R. Varga, "Path 764 Computation Element Communication Protocol (PCEP) 765 Extensions for PCE-Initiated LSP Setup in a Stateful PCE 766 Model", RFC 8281, DOI 10.17487/RFC8281, December 2017, 767 . 769 [RFC8537] Gandhi, R., Ed., Shah, H., and J. Whittaker, "Updates to 770 the Fast Reroute Procedures for Co-routed Associated 771 Bidirectional Label Switched Paths (LSPs)", RFC 8537, 772 DOI 10.17487/RFC8537, February 2019, 773 . 775 [RFC8697] Minei, I., Crabbe, E., Sivabalan, S., Ananthakrishnan, H., 776 Dhody, D., and Y. Tanaka, "Path Computation Element 777 Communication Protocol (PCEP) Extensions for Establishing 778 Relationships between Sets of Label Switched Paths 779 (LSPs)", RFC 8697, DOI 10.17487/RFC8697, January 2020, 780 . 782 10.2. Informative References 784 [I-D.ietf-pce-pcep-stateful-pce-gmpls] 785 Lee, Y., Zheng, H., Dios, O., Lopezalvarez, V., and Z. 786 Ali, "Path Computation Element (PCE) Protocol Extensions 787 for Stateful PCE Usage in GMPLS-controlled Networks", 788 draft-ietf-pce-pcep-stateful-pce-gmpls-13 (work in 789 progress), April 2020. 791 [I-D.ietf-pce-pcep-yang] 792 Dhody, D., Hardwick, J., Beeram, V., and J. Tantsura, "A 793 YANG Data Model for Path Computation Element 794 Communications Protocol (PCEP)", draft-ietf-pce-pcep- 795 yang-14 (work in progress), July 2020. 797 [I-D.ietf-pce-sr-bidir-path] 798 Li, C., Chen, M., Cheng, W., Gandhi, R., and Q. Xiong, 799 "PCEP Extensions for Associated Bidirectional Segment 800 Routing (SR) Paths", draft-ietf-pce-sr-bidir-path-02 (work 801 in progress), March 2020. 803 [RFC5654] Niven-Jenkins, B., Ed., Brungard, D., Ed., Betts, M., Ed., 804 Sprecher, N., and S. Ueno, "Requirements of an MPLS 805 Transport Profile", RFC 5654, DOI 10.17487/RFC5654, 806 September 2009, . 808 [RFC7420] Koushik, A., Stephan, E., Zhao, Q., King, D., and J. 809 Hardwick, "Path Computation Element Communication Protocol 810 (PCEP) Management Information Base (MIB) Module", 811 RFC 7420, DOI 10.17487/RFC7420, December 2014, 812 . 814 [RFC7942] Sheffer, Y. and A. Farrel, "Improving Awareness of Running 815 Code: The Implementation Status Section", BCP 205, 816 RFC 7942, DOI 10.17487/RFC7942, July 2016, 817 . 819 [RFC8051] Zhang, X., Ed. and I. Minei, Ed., "Applicability of a 820 Stateful Path Computation Element (PCE)", RFC 8051, 821 DOI 10.17487/RFC8051, January 2017, 822 . 824 [RFC8253] Lopez, D., Gonzalez de Dios, O., Wu, Q., and D. Dhody, 825 "PCEPS: Usage of TLS to Provide a Secure Transport for the 826 Path Computation Element Communication Protocol (PCEP)", 827 RFC 8253, DOI 10.17487/RFC8253, October 2017, 828 . 830 [RFC8408] Sivabalan, S., Tantsura, J., Minei, I., Varga, R., and J. 831 Hardwick, "Conveying Path Setup Type in PCE Communication 832 Protocol (PCEP) Messages", RFC 8408, DOI 10.17487/RFC8408, 833 July 2018, . 835 Acknowledgments 837 The authors would like to thank Dhruv Dhody for various discussions 838 on association groups and inputs to this document. The authors would 839 also like to thank Dhruv Dhody, Mike Taillon, and Marina Fizgeer for 840 reviewing this document and providing valuable comments. 842 Authors' Addresses 844 Rakesh Gandhi (editor) 845 Cisco Systems, Inc. 846 Canada 848 Email: rgandhi@cisco.com 849 Colby Barth 850 Juniper Networks 852 Email: cbarth@juniper.net 854 Bin Wen 855 Comcast 857 Email: Bin_Wen@cable.comcast.com