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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(See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Outdated reference: A later version (-10) exists of draft-ietf-pce-association-group-09 -- Obsolete informational reference (is this intentional?): RFC 7525 (Obsoleted by RFC 9325) == Outdated reference: A later version (-23) exists of draft-ietf-pce-pcep-yang-11 == Outdated reference: A later version (-15) exists of draft-ietf-pce-association-diversity-06 == Outdated reference: A later version (-10) exists of draft-litkowski-pce-state-sync-05 Summary: 0 errors (**), 0 flaws (~~), 5 warnings (==), 2 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 PCE Working Group H. Ananthakrishnan 3 Internet-Draft Netflix 4 Intended status: Standards Track S. Sivabalan 5 Expires: December 19, 2019 Cisco 6 C. Barth 7 Juniper Networks 8 I. Minei 9 Google, Inc 10 M. Negi 11 Huawei Technologies 12 June 17, 2019 14 PCEP Extensions for Associating Working and Protection LSPs with 15 Stateful PCE 16 draft-ietf-pce-stateful-path-protection-07 18 Abstract 20 An active stateful Path Computation Element (PCE) is capable of 21 computing as well as controlling via Path Computation Element 22 Communication Protocol (PCEP) Multiprotocol Label Switching Traffic 23 Engineering Label Switched Paths (MPLS LSP). Furthermore, it is also 24 possible for an active stateful PCE to create, maintain, and delete 25 LSPs. This document describes PCEP extension to associate two or 26 more LSPs to provide end-to-end path protection. 28 Status of This Memo 30 This Internet-Draft is submitted in full conformance with the 31 provisions of BCP 78 and BCP 79. 33 Internet-Drafts are working documents of the Internet Engineering 34 Task Force (IETF). Note that other groups may also distribute 35 working documents as Internet-Drafts. The list of current Internet- 36 Drafts is at https://datatracker.ietf.org/drafts/current/. 38 Internet-Drafts are draft documents valid for a maximum of six months 39 and may be updated, replaced, or obsoleted by other documents at any 40 time. It is inappropriate to use Internet-Drafts as reference 41 material or to cite them other than as "work in progress." 43 This Internet-Draft will expire on December 19, 2019. 45 Copyright Notice 47 Copyright (c) 2019 IETF Trust and the persons identified as the 48 document authors. All rights reserved. 50 This document is subject to BCP 78 and the IETF Trust's Legal 51 Provisions Relating to IETF Documents 52 (https://trustee.ietf.org/license-info) in effect on the date of 53 publication of this document. Please review these documents 54 carefully, as they describe your rights and restrictions with respect 55 to this document. Code Components extracted from this document must 56 include Simplified BSD License text as described in Section 4.e of 57 the Trust Legal Provisions and are provided without warranty as 58 described in the Simplified BSD License. 60 Table of Contents 62 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 63 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 4 64 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 65 3. PCEP Extensions . . . . . . . . . . . . . . . . . . . . . . . 5 66 3.1. Path Protection Association Type . . . . . . . . . . . . 5 67 3.2. Path Protection Association TLV . . . . . . . . . . . . . 6 68 4. Operation . . . . . . . . . . . . . . . . . . . . . . . . . . 7 69 4.1. State Synchronization . . . . . . . . . . . . . . . . . . 7 70 4.2. PCC-Initiated LSPs . . . . . . . . . . . . . . . . . . . 7 71 4.3. PCE-Initiated LSPs . . . . . . . . . . . . . . . . . . . 7 72 4.4. Session Termination . . . . . . . . . . . . . . . . . . . 8 73 4.5. Error Handling . . . . . . . . . . . . . . . . . . . . . 8 74 5. Other Considerations . . . . . . . . . . . . . . . . . . . . 9 75 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 76 6.1. Association Type . . . . . . . . . . . . . . . . . . . . 9 77 6.2. PPAG TLV . . . . . . . . . . . . . . . . . . . . . . . . 9 78 6.3. PCEP Errors . . . . . . . . . . . . . . . . . . . . . . . 10 79 7. Security Considerations . . . . . . . . . . . . . . . . . . . 11 80 8. Manageability Considerations . . . . . . . . . . . . . . . . 11 81 8.1. Control of Function and Policy . . . . . . . . . . . . . 11 82 8.2. Information and Data Models . . . . . . . . . . . . . . . 11 83 8.3. Liveness Detection and Monitoring . . . . . . . . . . . . 11 84 8.4. Verify Correct Operations . . . . . . . . . . . . . . . . 11 85 8.5. Requirements On Other Protocols . . . . . . . . . . . . . 11 86 8.6. Impact On Network Operations . . . . . . . . . . . . . . 12 87 9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 12 88 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 12 89 10.1. Normative References . . . . . . . . . . . . . . . . . . 12 90 10.2. Informative References . . . . . . . . . . . . . . . . . 13 91 Appendix A. Contributor Addresses . . . . . . . . . . . . . . . 14 92 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 15 94 1. Introduction 96 [RFC5440] describes PCEP for communication between a Path Computation 97 Client (PCC) and a PCE or between a pair of PCEs as per [RFC4655]. A 98 PCE computes paths for MPLS-TE LSPs based on various constraints and 99 optimization criteria. 101 Stateful PCE [RFC8231] specifies a set of extensions to PCEP to 102 enable stateful control of paths such as MPLS TE LSPs between and 103 across PCEP sessions in compliance with [RFC4657]. It includes 104 mechanisms to effect LSP state synchronization between PCCs and PCEs, 105 delegation of control of LSPs to PCEs, and PCE control of timing and 106 sequence of path computations within and across PCEP sessions and 107 focuses on a model where LSPs are configured on the PCC and control 108 over them is delegated to the PCE. Furthermore, a mechanism to 109 dynamically instantiate LSPs on a PCC based on the requests from a 110 stateful PCE or a controller using stateful PCE, is specified in 111 [RFC8281]. 113 Path protection [RFC4427] refers to a paradigm in which the working 114 LSP is protected by one or more protection LSP(s). When the working 115 LSP fails, protection LSP(s) is/are activated. When the working LSPs 116 are computed and controlled by the PCE, there is benefit in a mode of 117 operation where protection LSPs are as well. [RFC8051] describes 118 applicability of path protection in PCE deployments. 120 This document specifies a stateful PCEP extension to associate two or 121 more LSPs for the purpose of setting up path protection. The 122 proposed extension covers the following scenarios: 124 o A PCC initiates a protection LSP and retains the control of the 125 LSP. The PCC computes the path itself or makes a request for path 126 computation to a PCE. After the path setup, it reports the 127 information and state of the path to the PCE. This includes the 128 association group identifying the working and protection LSPs. 129 This is the passive stateful mode [RFC8051]. 131 o A PCC initiates a protection LSP and delegates the control of the 132 LSP to a stateful PCE. During delegation the association group 133 identifying the working and protection LSPs is included. The PCE 134 computes the path for the protection LSP and update the PCC with 135 the information about the path as long as it controls the LSP. 136 This is the active stateful mode [RFC8051]. 138 o A protection LSP could be initiated by a stateful PCE, which 139 retains the control of the LSP. The PCE is responsible for 140 computing the path of the LSP and updating to the PCC with the 141 information about the path. This is the PCE-Initiated mode 142 [RFC8281]. 144 Note that protection LSP can be established (signaled) prior to the 145 failure (in which case the LSP is said to be in standby mode 146 [RFC4427] or a Primary LSP [RFC4872]) or post failure of the 147 corresponding working LSP according to the operator choice/policy 148 (known as secondary LSP [RFC4872]). 150 [I-D.ietf-pce-association-group] introduces a generic mechanism to 151 create a grouping of LSPs which can then be used to define 152 associations between a set of LSPs that is equally applicable to 153 stateful PCE (active and passive modes) and stateless PCE. 155 This document specifies a PCEP extension to associate one working LSP 156 with one or more protection LSPs using the generic association 157 mechanism. 159 This document describes a PCEP extension to associate protection LSPs 160 by creating Path Protection Association Group (PPAG) and encoding 161 this association in PCEP messages for stateful PCEP sessions. 163 1.1. Requirements Language 165 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 166 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 167 "OPTIONAL" in this document are to be interpreted as described in BCP 168 14 [RFC2119] [RFC8174] when, and only when, they appear in all 169 capitals, as shown here. 171 2. Terminology 173 The following terminologies are used in this document: 175 ERO: Explicit Route Object. 177 LSP: Label Switched Path. 179 PCC: Path Computation Client. 181 PCE: Path Computation Element 183 PCEP: Path Computation Element Communication Protocol. 185 PPAG: Path Protection Association Group. 187 TLV: Type, Length, and Value. 189 3. PCEP Extensions 191 3.1. Path Protection Association Type 193 LSPs are not associated by listing the other LSPs with which they 194 interact, but rather by making them belong to an association group 195 referred to as "Path Protection Association Group" (PPAG) in this 196 document. All LSPs join a PPAG individually. PPAG is based on the 197 generic Association object used to associate two or more LSPs 198 specified in [I-D.ietf-pce-association-group]. A member of a PPAG 199 can take the role of working or protection LSP. This document 200 defines a new Association type called "Path Protection Association 201 Type" of value TBD1. A PPAG can have one working LSP and/or one or 202 more protection LSPs. The source, destination and Tunnel ID (as 203 carried in LSP-IDENTIFIERS TLV [RFC8231], with description as per 204 [RFC3209]) of all LSPs within a PPAG MUST be the same. As per 205 [RFC3209], TE tunnel is used to associate a set of LSPs during 206 reroute or to spread a traffic trunk over multiple paths. 208 The format of the Association object used for PPAG is specified in 209 [I-D.ietf-pce-association-group]. 211 This document defines a new Association type, the "Path Protection 212 Association Type", value will be assigned by IANA (TBD1). 214 [I-D.ietf-pce-association-group] specifies the mechanism for the 215 capability advertisement of the Association types supported by a PCEP 216 speaker by defining a ASSOC-Type-List TLV to be carried within an 217 OPEN object. This capability exchange for the Association type 218 described in this document (i.e. Path Protection Association Type) 219 MAY be done before using the policy association, i.e., the PCEP 220 speaker MAY include the Path Protection Association Type (TBD1) in 221 the ASSOC-Type-List TLV before using the PPAG in the PCEP messages. 223 This Association type is dynamic in nature and created by the PCC or 224 PCE for the LSPs belonging to the same TE tunnel (as described in 225 [RFC3209]) originating at the same head node and terminating at the 226 same destination. These associations are conveyed via PCEP messages 227 to the PCEP peer. As per [I-D.ietf-pce-association-group], the 228 association source is set to the local PCEP speaker address that 229 created the association, unless local policy dictates otherwise. 230 Operator-configured Association Range MUST NOT be set for this 231 Association type and MUST be ignored. 233 3.2. Path Protection Association TLV 235 The Path Protection Association TLV is an optional TLV for use with 236 the Path Protection Association Type. The Path Protection 237 Association TLV MUST NOT be present more than once. If it appears 238 more than once, only the first occurrence is processed and any others 239 MUST be ignored. 241 The Path Protection Association TLV follows the PCEP TLV format of 242 [RFC5440]. 244 The type (16 bits) of the TLV is to be assigned by IANA. The length 245 field (16 bit) has a fixed value of 4. 247 The value comprises of a single field, the Path Protection 248 Association Flags (32 bits), where each bit represents a flag option. 250 The format of the Path Protection Association TLV (Figure 1) is as 251 follows: 253 0 1 2 3 254 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 1 255 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 256 | Type = TBD2 | Length | 257 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 258 | PT | Path Protection Association Flags |S|P| 259 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 261 Figure 1: Path Protection Association TLV format 263 Path Protection Association Flags (32 bits) - The following flags are 264 currently defined - 266 Protecting (P): 1 bit - This bit is as defined in Section 14.1 of 267 [RFC4872] to indicate if the LSP is working or protection LSP. 269 Secondary (S): 1 bit - This bit is as defined in Section 14.1 of 270 [RFC4872] to indicate if the LSP is primary or secondary LSP. The 271 S flag is ignored if the P flag is not set. 273 Protection Type (PT): 6 bits - This field is as defined in 274 Section 14.1 of [RFC4872] to indicate the LSP protection type in 275 use. 277 Unassigned bits are considered reserved. They MUST be set to 0 on 278 transmission and MUST be ignored on receipt. 280 If the TLV is missing, it is considered that the LSP is the working 281 LSP (i.e. as if P bit is unset). 283 4. Operation 285 An LSP is associated with other LSPs with which they interact by 286 adding them to a common association group via the ASSOCIATION object. 287 All procedures and error-handling for the ASSOCIATION object is as 288 per [I-D.ietf-pce-association-group]. 290 4.1. State Synchronization 292 During state synchronization, a PCC reports all the existing LSP 293 states as described in [RFC8231]. The association group membership 294 pertaining to an LSP is also reported as per 295 [I-D.ietf-pce-association-group]. This includes PPAGs. 297 4.2. PCC-Initiated LSPs 299 A PCC can associate a set of LSPs under its control for path 300 protection purpose. Similarly, the PCC can remove one or more LSPs 301 under its control from the corresponding PPAG. In both cases, the 302 PCC reports the change in association to PCE(s) via Path Computation 303 Report (PCRpt) message. A PCC can also delegate the working and 304 protection LSPs to an active stateful PCE, where the PCE would 305 control the LSPs. The stateful PCE could update the paths and 306 attributes of the LSPs in the association group via Path Computation 307 Update (PCUpd) message. A PCE could also update the association to 308 the PCC via PCUpd message. These procedures are described in 309 [I-D.ietf-pce-association-group]. 311 It is expected that both working and protection LSP are delegated 312 together (and to the same PCE) to avoid any race conditions. Refer 313 to [I-D.litkowski-pce-state-sync] for the problem description. 315 4.3. PCE-Initiated LSPs 317 A PCE can create/update working and protection LSPs independently. 318 As specified in [I-D.ietf-pce-association-group], Association Groups 319 can be created by both the PCE and the PCC. Further, a PCE can 320 remove a protection LSP from a PPAG as specified in 321 [I-D.ietf-pce-association-group]. The PCE uses PCUpd or Path 322 Computation Initiate (PCInitiate) messages to communicate the 323 association information to the PCC. 325 4.4. Session Termination 327 As per [I-D.ietf-pce-association-group] the association information 328 is cleared along with the LSP state information. When a PCEP session 329 is terminated, after expiry of State Timeout Interval at the PCC, the 330 LSP state associated with that PCEP session is reverted to operator- 331 defined default parameters or behaviors as per [RFC8231]. The same 332 procedure is also followed for the association information. On 333 session termination at the PCE, when the LSP state reported by PCC is 334 cleared, the association information is also cleared as per 335 [I-D.ietf-pce-association-group]. Where there are no LSPs in a 336 association group, the association is considered to be deleted. 338 4.5. Error Handling 340 As per the processing rules specified in section 5.4 of 341 [I-D.ietf-pce-association-group], if a PCEP speaker does not support 342 this Path Protection Association Type, it would return a PCErr 343 message with Error-Type 26 (Early allocation by IANA) "Association 344 Error" and Error-Value 1 "Association type is not supported". 346 All LSPs (working or protection) within a PPAG MUST belong to the 347 same TE Tunnel (as described in [RFC3209]) and have the same source 348 and destination. If a PCEP speaker attempts to add an LSP to a PPAG 349 and the Tunnel ID (as carried in LSP-IDENTIFIERS TLV [RFC8231], with 350 description as per [RFC3209]) or source or destination of the LSP is 351 different from the LSP(s) in the PPAG, the PCC MUST send PCErr with 352 Error-Type 26 (Early allocation by IANA) (Association Error) 353 [I-D.ietf-pce-association-group] and Error-Value TBD3 (Tunnel ID or 354 End points mismatch for Path Protection Association). In case of 355 Path Protection, LSP-IDENTIFIERS TLV SHOULD be included for all LSPs 356 (including Segment Routing (SR) [I-D.ietf-pce-segment-routing]). 358 When the protection type is set to 1+1 or 1:N with N=1, there MUST be 359 only one working LSP and one protection LSP within a PPAG. If a PCEP 360 speaker attempts to add another working/protection LSP, the PCEP peer 361 MUST send PCErr with Error-Type 26 (Early allocation by IANA) 362 (Association Error) [I-D.ietf-pce-association-group] and Error-Value 363 TBD4 (Attempt to add another working/protection LSP for Path 364 Protection Association). 366 All processing as per section 5.4 of [I-D.ietf-pce-association-group] 367 continues to apply. 369 5. Other Considerations 371 The working and protection LSPs are typically resource disjoint 372 (e.g., node, SRLG disjoint). This ensures that a single failure will 373 not affect both the working and protection LSPs. The disjoint 374 requirement for a group of LSPs is handled via another Association 375 type called "Disjointness Association", as described in 376 [I-D.ietf-pce-association-diversity]. The diversity requirements for 377 the protection LSP are also handled by including both ASSOCIATION 378 objects identifying both the protection association group and the 379 disjoint association group for the group of LSPs. 381 [RFC4872] introduces the concept and mechanisms to support the 382 association of one LSP to another LSP across different RSVP - Traffic 383 Engineering (RSVP-TE) sessions using ASSOCIATION and PROTECTION 384 object. The information in the PPAG TLV in PCEP as received from the 385 PCE, is used to trigger the signalling of working LSP and protection 386 LSP, with the Path Protection Association Flags mapped to the 387 corresponding fields in the PROTECTION Object in RSVP-TE. 389 6. IANA Considerations 391 6.1. Association Type 393 This document defines a new Association type, originally defined in 394 [I-D.ietf-pce-association-group], for path protection. IANA is 395 requested to make the assignment of a new value for the sub-registry 396 "ASSOCIATION Type Field" (request to be created in 397 [I-D.ietf-pce-association-group]), as follows: 399 +----------------------+-------------------------+------------------+ 400 | Association type | Association Name | Reference | 401 | Value | | | 402 +----------------------+-------------------------+------------------+ 403 | TBD1 | Path Protection | This | 404 | | Association | document | 405 +----------------------+-------------------------+------------------+ 407 6.2. PPAG TLV 409 This document defines a new TLV for carrying additional information 410 of LSPs within a path protection association group. IANA is 411 requested to make the assignment of a new value for the existing 412 "PCEP TLV Type Indicators" registry as follows: 414 +---------------+-----------------------------------+---------------+ 415 | TLV Type | TLV Name | Reference | 416 | Value | | | 417 +---------------+-----------------------------------+---------------+ 418 | TBD2 | Path Protection Association Group | This document | 419 | | TLV | | 420 +---------------+-----------------------------------+---------------+ 422 This document requests that a new sub-registry, named "Path 423 protection Association Group TLV Flag Field", is created within the 424 "Path Computation Element Protocol (PCEP) Numbers" registry to manage 425 the Flag field in the Path Protection Association Group TLV. New 426 values are to be assigned by Standards Action [RFC8126]. Each bit 427 should be tracked with the following qualities: 429 o Bit number (count from 0 as the most significant bit) 431 o Name flag 433 o Reference 435 +------------+-----------------------+----------------+ 436 | Bit Number | Name | Reference | 437 +------------+-----------------------+----------------+ 438 | 31 | P - PROTECTION-LSP | This document | 439 | 30 | S - STANDBY | This document | 440 | 0-5 | Protection Type Flags | This document | 441 +------------+-----------------------+----------------+ 443 Table 1: PPAG TLV 445 6.3. PCEP Errors 447 This document defines new Error-Values related to path protection 448 association for Error-type 26 "Association Error" defined in 449 [I-D.ietf-pce-association-group]. IANA is requested to allocate new 450 error values within the "PCEP-ERROR Object Error Types and Values" 451 sub-registry of the PCEP Numbers registry, as follows: 453 +-------------+-----------------------------------------+-----------+ 454 | Error-value | Meaning | Reference | 455 +-------------+-----------------------------------------+-----------+ 456 | TBD3 | Tunnel ID or End points mismatch for | This | 457 | | Path Protection Association | document | 458 | TBD4 | Attempt to add another | This | 459 | | working/protection LSP for Path | document | 460 | | Protection Association | | 461 +-------------+-----------------------------------------+-----------+ 463 7. Security Considerations 465 The security considerations described in [RFC8231], [RFC8281], and 466 [RFC5440] apply to the extensions described in this document as well. 467 Additional considerations related to associations where a malicious 468 PCEP speaker could be spoofed and could be used as an attack vector 469 by creating associations is described in 470 [I-D.ietf-pce-association-group]. Thus securing the PCEP session 471 using Transport Layer Security (TLS) [RFC8253], as per the 472 recommendations and best current practices in [RFC7525], is 473 RECOMMENDED. 475 8. Manageability Considerations 477 8.1. Control of Function and Policy 479 Mechanisms defined in this document do not imply any control or 480 policy requirements in addition to those already listed in [RFC5440], 481 [RFC8231], and [RFC8281]. 483 8.2. Information and Data Models 485 [RFC7420] describes the PCEP MIB, there are no new MIB Objects for 486 this document. 488 The PCEP YANG module [I-D.ietf-pce-pcep-yang] supports associations. 490 8.3. Liveness Detection and Monitoring 492 Mechanisms defined in this document do not imply any new liveness 493 detection and monitoring requirements in addition to those already 494 listed in [RFC5440], [RFC8231], and [RFC8281]. 496 8.4. Verify Correct Operations 498 Mechanisms defined in this document do not imply any new operation 499 verification requirements in addition to those already listed in 500 [RFC5440], [RFC8231], and [RFC8281]. 502 8.5. Requirements On Other Protocols 504 Mechanisms defined in this document do not imply any new requirements 505 on other protocols. 507 8.6. Impact On Network Operations 509 Mechanisms defined in this document do not have any impact on network 510 operations in addition to those already listed in [RFC5440], 511 [RFC8231], and [RFC8281]. 513 9. Acknowledgments 515 We would like to thank Jeff Tantsura, Xian Zhang and Greg Mirsky for 516 their contributions to this document. 518 10. References 520 10.1. Normative References 522 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 523 Requirement Levels", BCP 14, RFC 2119, 524 DOI 10.17487/RFC2119, March 1997, 525 . 527 [RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V., 528 and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP 529 Tunnels", RFC 3209, DOI 10.17487/RFC3209, December 2001, 530 . 532 [RFC4872] Lang, J., Ed., Rekhter, Y., Ed., and D. Papadimitriou, 533 Ed., "RSVP-TE Extensions in Support of End-to-End 534 Generalized Multi-Protocol Label Switching (GMPLS) 535 Recovery", RFC 4872, DOI 10.17487/RFC4872, May 2007, 536 . 538 [RFC5440] Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation 539 Element (PCE) Communication Protocol (PCEP)", RFC 5440, 540 DOI 10.17487/RFC5440, March 2009, 541 . 543 [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for 544 Writing an IANA Considerations Section in RFCs", BCP 26, 545 RFC 8126, DOI 10.17487/RFC8126, June 2017, 546 . 548 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 549 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 550 May 2017, . 552 [RFC8231] Crabbe, E., Minei, I., Medved, J., and R. Varga, "Path 553 Computation Element Communication Protocol (PCEP) 554 Extensions for Stateful PCE", RFC 8231, 555 DOI 10.17487/RFC8231, September 2017, 556 . 558 [RFC8281] Crabbe, E., Minei, I., Sivabalan, S., and R. Varga, "Path 559 Computation Element Communication Protocol (PCEP) 560 Extensions for PCE-Initiated LSP Setup in a Stateful PCE 561 Model", RFC 8281, DOI 10.17487/RFC8281, December 2017, 562 . 564 [I-D.ietf-pce-association-group] 565 Minei, I., Crabbe, E., Sivabalan, S., Ananthakrishnan, H., 566 Dhody, D., and Y. Tanaka, "PCEP Extensions for 567 Establishing Relationships Between Sets of LSPs", draft- 568 ietf-pce-association-group-09 (work in progress), April 569 2019. 571 10.2. Informative References 573 [RFC4427] Mannie, E., Ed. and D. Papadimitriou, Ed., "Recovery 574 (Protection and Restoration) Terminology for Generalized 575 Multi-Protocol Label Switching (GMPLS)", RFC 4427, 576 DOI 10.17487/RFC4427, March 2006, 577 . 579 [RFC4655] Farrel, A., Vasseur, J., and J. Ash, "A Path Computation 580 Element (PCE)-Based Architecture", RFC 4655, 581 DOI 10.17487/RFC4655, August 2006, 582 . 584 [RFC4657] Ash, J., Ed. and J. Le Roux, Ed., "Path Computation 585 Element (PCE) Communication Protocol Generic 586 Requirements", RFC 4657, DOI 10.17487/RFC4657, September 587 2006, . 589 [RFC7420] Koushik, A., Stephan, E., Zhao, Q., King, D., and J. 590 Hardwick, "Path Computation Element Communication Protocol 591 (PCEP) Management Information Base (MIB) Module", 592 RFC 7420, DOI 10.17487/RFC7420, December 2014, 593 . 595 [RFC7525] Sheffer, Y., Holz, R., and P. Saint-Andre, 596 "Recommendations for Secure Use of Transport Layer 597 Security (TLS) and Datagram Transport Layer Security 598 (DTLS)", BCP 195, RFC 7525, DOI 10.17487/RFC7525, May 599 2015, . 601 [RFC8051] Zhang, X., Ed. and I. Minei, Ed., "Applicability of a 602 Stateful Path Computation Element (PCE)", RFC 8051, 603 DOI 10.17487/RFC8051, January 2017, 604 . 606 [RFC8253] Lopez, D., Gonzalez de Dios, O., Wu, Q., and D. Dhody, 607 "PCEPS: Usage of TLS to Provide a Secure Transport for the 608 Path Computation Element Communication Protocol (PCEP)", 609 RFC 8253, DOI 10.17487/RFC8253, October 2017, 610 . 612 [I-D.ietf-pce-pcep-yang] 613 Dhody, D., Hardwick, J., Beeram, V., and J. Tantsura, "A 614 YANG Data Model for Path Computation Element 615 Communications Protocol (PCEP)", draft-ietf-pce-pcep- 616 yang-11 (work in progress), March 2019. 618 [I-D.ietf-pce-association-diversity] 619 Litkowski, S., Sivabalan, S., Barth, C., and M. Negi, 620 "Path Computation Element communication Protocol (PCEP) 621 extension for signaling LSP diversity constraint", draft- 622 ietf-pce-association-diversity-06 (work in progress), 623 February 2019. 625 [I-D.ietf-pce-segment-routing] 626 Sivabalan, S., Filsfils, C., Tantsura, J., Henderickx, W., 627 and J. Hardwick, "PCEP Extensions for Segment Routing", 628 draft-ietf-pce-segment-routing-16 (work in progress), 629 March 2019. 631 [I-D.litkowski-pce-state-sync] 632 Litkowski, S., Sivabalan, S., Li, C., and H. Zheng, "Inter 633 Stateful Path Computation Element (PCE) Communication 634 Procedures.", draft-litkowski-pce-state-sync-05 (work in 635 progress), March 2019. 637 Appendix A. Contributor Addresses 639 Dhruv Dhody 640 Huawei Technologies 641 Divyashree Techno Park, Whitefield 642 Bangalore, Karnataka 560066 643 India 645 EMail: dhruv.ietf@gmail.com 646 Raveendra Torvi 647 Juniper Networks 648 1194 N Mathilda Ave, 649 Sunnyvale, CA, 94086 650 USA 652 EMail: rtorvi@juniper.net 654 Edward Crabbe 655 Individual Contributor 657 EMail: edward.crabbe@gmail.com 659 Authors' Addresses 661 Hariharan Ananthakrishnan 662 Netflix 663 USA 665 Email: hari@netflix.com 667 Siva Sivabalan 668 Cisco 669 2000 Innovation Drive 670 Kananta, Ontaria K2K 3E8 671 Canada 673 Email: msiva@cisco.com 675 Colby Barth 676 Juniper Networks 677 1194 N Mathilda Ave, 678 Sunnyvale, CA, 94086 679 USA 681 Email: cbarth@juniper.net 683 Ina Minei 684 Google, Inc 685 1600 Amphitheatre Parkway 686 Mountain View, CA, 94043 687 USA 689 Email: inaminei@google.com 690 Mahendra Singh Negi 691 Huawei Technologies 692 Divyashree Techno Park, Whitefield 693 Bangalore, Karnataka 560066 694 India 696 Email: mahendrasingh@huawei.com