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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 PCE Working Group H. Ananthakrishnan 3 Internet-Draft Packet Design 4 Intended status: Standards Track S. Sivabalan 5 Expires: March 30, 2018 Cisco 6 C. Barth 7 R. Torvi 8 Juniper Networks 9 I. Minei 10 Google, Inc 11 E. Crabbe 12 Individual Contributor 13 D. Dhody 14 Huawei Technologies 15 September 26, 2017 17 PCEP Extensions for MPSL-TE LSP Path Protection with stateful PCE 18 draft-ananthakrishnan-pce-stateful-path-protection-04 20 Abstract 22 A stateful Path Computation Element (PCE) is capable of computing as 23 well as controlling via Path Computation Element Protocol (PCEP) 24 Multiprotocol Label Switching Traffic Engineering Label Switched 25 Paths (MPLS LSP). Furthermore, it is also possible for a stateful 26 PCE to create, maintain, and delete LSPs. This document describes 27 PCEP extension to associate two or more LSPs to provide end-to-end 28 path protection. 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 30, 2018. 47 Copyright Notice 49 Copyright (c) 2017 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. Requirements Language . . . . . . . . . . . . . . . . . . 4 66 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 67 3. PCEP Extensions . . . . . . . . . . . . . . . . . . . . . . . 4 68 3.1. Path Protection Association Type . . . . . . . . . . . . 5 69 3.2. Path Protection Association TLV . . . . . . . . . . . . . 6 70 4. Operation . . . . . . . . . . . . . . . . . . . . . . . . . . 7 71 4.1. PCC Initiated LSPs . . . . . . . . . . . . . . . . . . . 7 72 4.2. PCE Initiated LSPs . . . . . . . . . . . . . . . . . . . 7 73 4.3. State Synchronization . . . . . . . . . . . . . . . . . . 8 74 4.4. Session Termination . . . . . . . . . . . . . . . . . . . 8 75 4.5. Error Handling . . . . . . . . . . . . . . . . . . . . . 8 76 5. Other considerations . . . . . . . . . . . . . . . . . . . . 8 77 6. IANA considerations . . . . . . . . . . . . . . . . . . . . . 9 78 6.1. Association Type . . . . . . . . . . . . . . . . . . . . 9 79 6.2. PPAG TLV . . . . . . . . . . . . . . . . . . . . . . . . 9 80 6.3. PCEP Errors . . . . . . . . . . . . . . . . . . . . . . . 10 81 7. Security Considerations . . . . . . . . . . . . . . . . . . . 10 82 8. Manageability Considerations . . . . . . . . . . . . . . . . 11 83 8.1. Control of Function and Policy . . . . . . . . . . . . . 11 84 8.2. Information and Data Models . . . . . . . . . . . . . . . 11 85 8.3. Liveness Detection and Monitoring . . . . . . . . . . . . 11 86 8.4. Verify Correct Operations . . . . . . . . . . . . . . . . 11 87 8.5. Requirements On Other Protocols . . . . . . . . . . . . . 11 88 8.6. Impact On Network Operations . . . . . . . . . . . . . . 11 89 9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 11 90 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 11 91 10.1. Normative References . . . . . . . . . . . . . . . . . . 12 92 10.2. Information References . . . . . . . . . . . . . . . . . 13 93 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 14 95 1. Introduction 97 [RFC5440] describes PCEP for communication between a Path Computation 98 Client (PCC) and a PCE or between one a pair of PCEs as per 99 [RFC4655]. A PCE computes paths for MPLS-TE LSPs based on various 100 constraints and optimization criteria. 102 Stateful pce [RFC8231] specifies a set of extensions to PCEP to 103 enable stateful control of paths such as MPLS TE LSPs between and 104 across PCEP sessions in compliance with [RFC4657]. It includes 105 mechanisms to effect LSP state synchronization between PCCs and PCEs, 106 delegation of control of LSPs to PCEs, and PCE control of timing and 107 sequence of path computations within and across PCEP sessions and 108 focuses on a model where LSPs are configured on the PCC and control 109 over them is delegated to the PCE. Furthermore, a mechanism to 110 dynamically instantiate LSPs on a PCC based on the requests from a 111 stateful PCE or a controller using stateful PCE, is specified in 112 [I-D.ietf-pce-pce-initiated-lsp]. 114 Path protection refers to a paradigm in which the working LSP is 115 protected by one or more protection LSP(s). When the working LSP 116 fails, protection LSP(s) is/are activated. When the working LSPs are 117 computed and controlled by the PCE, there is benefit in a mode of 118 operation where protection LSPs are as well. 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 is the passive 128 stateful mode [RFC8051]. 130 o A PCC initiates a protection LSP and delegates the control of the 131 LSP to a stateful PCE. The PCE may compute the path for the LSP 132 and update the PCC with the information about the path as long as 133 it controls the LSP. This is the active stateful mode [RFC8051]. 135 o A protection LSP could be initiated by a stateful PCE, which 136 retains the control of the LSP. The PCE is responsible for 137 computing the path of the LSP and updating to the PCC with the 138 information about the path. This is the PCE Initiated mode 139 [I-D.ietf-pce-pce-initiated-lsp]. 141 Note that protection LSP can be established prior to the failure (in 142 which case the LSP is said to me in standby mode) or post failure of 143 the corresponding working LSP according to the operator choice/ 144 policy. 146 [I-D.ietf-pce-association-group] introduces a generic mechanism to 147 create a grouping of LSPs which can then be used to define 148 associations between a set of LSPs that is equally applicable to 149 stateful PCE (active and passive modes) and stateless PCE. 151 This document specifies a PCEP extension to associate one working LSP 152 with one or more protection LSPs using the generic association 153 mechanism. 155 This document describes a PCEP extension to associate protection LSPs 156 by creating Path Protection Association Group (PPAG) and encoding 157 this association in PCEP messages for stateful PCEP sessions. 159 1.1. Requirements Language 161 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 162 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 163 "OPTIONAL" in this document are to be interpreted as described in BCP 164 14 [RFC2119] [RFC8174] when, and only when, they appear in all 165 capitals, as shown here. 167 2. Terminology 169 The following terminologies are used in this document: 171 ERO: Explicit Route Object. 173 LSP: Label Switched Path. 175 PCC: Path Computation Client. 177 PCE: Path Computation Element 179 PCEP: Path Computation Element Protocol. 181 PPAG: Path Protection Association Group. 183 TLV: Type, Length, and Value. 185 3. PCEP Extensions 186 3.1. Path Protection Association Type 188 LSPs are not associated by listing the other LSPs with which they 189 interact, but rather by making them belong to an association group 190 referred to as "Path Protection Association Group" (PPAG) in this 191 document. All LSPs join a PPAG individually. PPAG is based on the 192 generic Association object used to associate two or more LSPs 193 specified in [I-D.ietf-pce-association-group]. A member of a PPAG 194 can take the role of working or protection LSP. This document 195 defines a new association type called "Path Protection Association 196 Type" of value TBD1. A PPAG can have one working LSP and/or one or 197 more protection LSPs. The source, destination and Tunnel ID (as 198 carried in LSP-IDENTIFIERS TLV [RFC8231], with description as per 199 [RFC3209]) of all LSPs within a PPAG MUST be the same. As per 200 [RFC3209], TE tunnel is used to associate a set of LSPs during 201 reroute or to spread a traffic trunk over multiple paths. 203 The format of the Association object used for PPAG is specified in 204 [I-D.ietf-pce-association-group] and reproduced in this document for 205 easy reference in Figure 1 and Figure 2. 207 0 1 2 3 208 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 1 209 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 210 | Reserved | Flags |R| 211 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 212 | Association type = TBD1 | Association | 213 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 214 | IPv4 Association Source | 215 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 216 // Optional TLVs // 217 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 219 Figure 1: PPAG IPv4 ASSOCIATION Object format 221 0 1 2 3 222 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 1 223 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 224 | Reserved | Flags |R| 225 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 226 | Association Type = TBD1 | Association | 227 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 228 | | 229 | IPv6 Association Source | 230 | | 231 | | 232 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 233 // Optional TLVs // 234 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 236 Figure 2: PPAG IPv6 ASSOCIATION Object format 238 This document defines a new Association type, the Path Protection 239 Association type, value will be assigned by IANA (TBD1). 241 This Association-Type is dynamic in nature and created by the PCC or 242 PCE for the LSPs belonging to the same TE tunnel (as described in 243 [RFC3209]) originating at the same head node and terminating at the 244 same destination. These associations are conveyed via PCEP messages 245 to the PCEP peer. Operator-configured Association Range SHOULD NOT 246 be set for this association-type and MUST be ignored. 248 3.2. Path Protection Association TLV 250 The Path Protection Association TLV is an optional TLV for use with 251 the Path Protection Association Object Type. The Path Protection 252 Association TLV MUST NOT be present more than once. If it appears 253 more than once, only the first occurrence is processed and any others 254 MUST be ignored. 256 The Path Protection Association TLV follows the PCEP TLV format of 257 [RFC5440]. 259 The type (16 bits) of the TLV is to be assigned by IANA. The length 260 field is 16 bit-long and has a fixed value of 4. 262 The value comprises a single field, the Path Protection Association 263 Flags (32 bits), where each bit represents a flag option. 265 The format of the Path Protection Association TLV (Figure 3) is as 266 follows: 268 0 1 2 3 269 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 1 270 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 271 | Type = TBD2 | Length | 272 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 273 | Path Protection Association Flags |S|P| 274 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 276 Figure 3: Path Protection Association TLV format 278 P (PROTECTION-LSP 1 bit) - Indicates whether the LSP associated with 279 the PPAG is working or protection LSP. If this flag is set, the LSP 280 is a protection LSP. 282 S (STANDBY 1 bit)- When the P flag is set, the S flag indicates 283 whether the protection LSP associated with the PPAG is in standby 284 mode. The S flag is ignored if the P flag is not set. 286 Unassigned bits are considered reserved. They MUST be set to 0 on 287 transmission and MUST be ignored on receipt. If the Path Protection 288 Association TLV is missing, it means the LSP is the working LSP. 290 4. Operation 292 LSPs are associated with other LSPs with which they interact by 293 adding them to a common association group via ASSOCIATION object. 294 All procedures and error-handling for the ASSOCIATION object is as 295 per [I-D.ietf-pce-association-group]. 297 4.1. 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 on or more LSPs 301 under its control from the corresponding PPAG. In both cases, the 302 PCC must report the change in association to PCE(s) via PCRpt 303 message. A PCC can also delegate the working and protection LSPs to 304 a stateful PCE, where PCE would control the LSPs. The stateful PCE 305 could update the paths and attributes of the LSPs in the association 306 group via PCUpd message. A PCE could also update the association to 307 PCC via PCUpd message. The procedures are described in 308 [I-D.ietf-pce-association-group]. 310 4.2. PCE Initiated LSPs 312 A PCE can create/update working and protection LSPs independently. 313 As specified in [I-D.ietf-pce-association-group], Association Groups 314 can be created by both PCE and PCC. 316 Further, a PCE can remove a protection LSP from a PPAG as specified 317 in [I-D.ietf-pce-association-group]. 319 4.3. State Synchronization 321 During state synchronization, a PCC MUST report all the existing path 322 protection association groups as well as any path protection flags to 323 PCE(s). Following the state synchronization, the PCE would remove 324 all stale information as per [I-D.ietf-pce-association-group]. 326 4.4. Session Termination 328 As per [I-D.ietf-pce-association-group] the association information 329 is cleared along with the LSP state information. When a PCEP session 330 is terminated, after expiry of State Timeout Interval at PCC, the LSP 331 state associated with that PCEP session is reverted to operator- 332 defined default parameters or behaviors as per [RFC8231]. Same 333 procedure is also followed for the association information. On 334 session termination at the PCE, when the LSP state reported by PCC is 335 cleared, the association information is also cleared. Where there 336 are no LSPs in a association group, the association is considered to 337 be deleted.. 339 4.5. Error Handling 341 All LSPs (working or protection) within a PPAG MUST belong to the 342 same TE Tunnel (as described in [RFC3209]) and have the same source 343 and destination. If a PCE attempts to add an LSP to a PPAG and the 344 Tunnel ID (as carried in LSP-IDENTIFIERS TLV [RFC8231], with 345 description as per [RFC3209]) or source or destination of the LSP is 346 different from the LSP(s) in the PPAG, the PCC MUST send PCErr with 347 Error-Type= TBD (Association Error) [I-D.ietf-pce-association-group] 348 and Error-Value = TBD3 (Tunnel ID or End points mismatch for Path 349 Protection Association). 351 There MUST be only one working LSP within a PPAG. If a PCEP Speaker 352 attempts to add another working LSP, the PCEP peer MUST send PCErr 353 with Error-Type=TBD (Association Error) 354 [I-D.ietf-pce-association-group] and Error-Value = TBD4 (Attempt to 355 add another working LSP for Path Protection Association). 357 5. Other considerations 359 The diversity requirement for a group of LSPs is handled via another 360 association type called "Disjointness Association", as described in 361 [I-D.ietf-pce-association-diversity]. The diversity requirements for 362 the the protection LSP are also handled by including both ASSOCIATION 363 object for the group of LSPs. 365 6. IANA considerations 367 6.1. Association Type 369 This document defines a new association type, originally defined in 370 [I-D.ietf-pce-association-group], for path protection. IANA is 371 requested to make the assignment of a new value for the sub-registry 372 "ASSOCIATION Type Field" (request to be created in 373 [I-D.ietf-pce-association-group]), as follows: 375 +----------------------+-------------------------+------------------+ 376 | Association Type | Association Name | Reference | 377 | Value | | | 378 +----------------------+-------------------------+------------------+ 379 | TBD1 | Path Protection | This | 380 | | Association | document | 381 +----------------------+-------------------------+------------------+ 383 6.2. PPAG TLV 385 This document defines a new TLV for carrying additional information 386 of LSPs within a path protection association group. IANA is 387 requested to make the assignment of a new value for the existing 388 "PCEP TLV Type Indicators" registry as follows: 390 +---------------+-----------------------------------+---------------+ 391 | TLV Type | TLV Name | Reference | 392 | Value | | | 393 +---------------+-----------------------------------+---------------+ 394 | TBD2 | Path Protection Association Group | This document | 395 | | TLV | | 396 +---------------+-----------------------------------+---------------+ 398 This document requests that a new sub-registry, named "Path 399 protection Association Group TLV Flag Field", is created within the 400 "Path Computation Element Protocol (PCEP) Numbers" registry to manage 401 the Flag field in the Path Protection Association Group TLV. New 402 values are to be assigned by Standards Action [RFC8126]. Each bit 403 should be tracked with the following qualities: 405 Each bit should be tracked with the following qualities: 407 o Bit number (count from 0 as the most significant bit) 409 o Name flag 411 o Reference 412 +------------+--------------------+----------------+ 413 | Bit Number | Name | Reference | 414 +------------+--------------------+----------------+ 415 | 31 | P - PROTECTION-LSP | This document | 416 | 30 | S - STANDBY | This document | 417 +------------+--------------------+----------------+ 419 Table 1: PPAG TLV 421 6.3. PCEP Errors 423 This document defines new Error-Type and Error-Value related to path 424 protection association. IANA is requested to allocate new error 425 values within the "PCEP-ERROR Object Error Types and Values" sub- 426 registry of the PCEP Numbers registry, as follows: 428 +------------+-------------------+----------------------------------+ 429 | Error-Type | Meaning | Reference | 430 +------------+-------------------+----------------------------------+ 431 | TBD | Association error | [I-D.ietf-pce-association-group] | 432 | | Error-value=TBD3: | This document | 433 | | Tunnel ID or End | | 434 | | points mismatch | | 435 | | for Path | | 436 | | Protection | | 437 | | Association | | 438 | | Error-value=TBD4: | This document | 439 | | Attempt to add | | 440 | | another working | | 441 | | LSP for Path | | 442 | | Protection | | 443 | | Association | | 444 +------------+-------------------+----------------------------------+ 446 7. Security Considerations 448 The security considerations described in [RFC8231], 449 [I-D.ietf-pce-pce-initiated-lsp], and [RFC5440] apply to the 450 extensions described in this document as well. Additional 451 considerations related to associations where a malicious PCEP speaker 452 could be spoofed and could be used as an attack vector by creating 453 associations is described in [I-D.ietf-pce-association-group]. Thus 454 securing the PCEP session using Transport Layer Security (TLS) 455 [I-D.ietf-pce-pceps], as per the recommendations and best current 456 practices in [RFC7525], is RECOMMENDED. 458 8. Manageability Considerations 460 8.1. Control of Function and Policy 462 Mechanisms defined in this document do not imply any control or 463 policy requirements in addition to those already listed in [RFC5440], 464 [RFC8231], and [I-D.ietf-pce-pce-initiated-lsp]. 466 8.2. Information and Data Models 468 [RFC7420] describes the PCEP MIB, there are no new MIB Objects for 469 this document. 471 The PCEP YANG module [I-D.ietf-pce-pcep-yang] supports associations. 473 8.3. Liveness Detection and Monitoring 475 Mechanisms defined in this document do not imply any new liveness 476 detection and monitoring requirements in addition to those already 477 listed in [RFC5440], [RFC8231], and [I-D.ietf-pce-pce-initiated-lsp]. 479 8.4. Verify Correct Operations 481 Mechanisms defined in this document do not imply any new operation 482 verification requirements in addition to those already listed in 483 [RFC5440], [RFC8231], and [I-D.ietf-pce-pce-initiated-lsp]. 485 8.5. Requirements On Other Protocols 487 Mechanisms defined in this document do not imply any new requirements 488 on other protocols. 490 8.6. Impact On Network Operations 492 Mechanisms defined in this document do not have any impact on network 493 operations in addition to those already listed in [RFC5440], 494 [RFC8231], and [I-D.ietf-pce-pce-initiated-lsp]. 496 9. Acknowledgments 498 We would like to thank Jeff Tantsura and Xian Zhang for their 499 contributions to this document. 501 10. References 502 10.1. Normative References 504 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 505 Requirement Levels", BCP 14, RFC 2119, 506 DOI 10.17487/RFC2119, March 1997, 507 . 509 [RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V., 510 and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP 511 Tunnels", RFC 3209, DOI 10.17487/RFC3209, December 2001, 512 . 514 [RFC5440] Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation 515 Element (PCE) Communication Protocol (PCEP)", RFC 5440, 516 DOI 10.17487/RFC5440, March 2009, 517 . 519 [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for 520 Writing an IANA Considerations Section in RFCs", BCP 26, 521 RFC 8126, DOI 10.17487/RFC8126, June 2017, 522 . 524 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 525 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 526 May 2017, . 528 [RFC8231] Crabbe, E., Minei, I., Medved, J., and R. Varga, "Path 529 Computation Element Communication Protocol (PCEP) 530 Extensions for Stateful PCE", RFC 8231, 531 DOI 10.17487/RFC8231, September 2017, 532 . 534 [I-D.ietf-pce-pce-initiated-lsp] 535 Crabbe, E., Minei, I., Sivabalan, S., and R. Varga, "PCEP 536 Extensions for PCE-initiated LSP Setup in a Stateful PCE 537 Model", draft-ietf-pce-pce-initiated-lsp-10 (work in 538 progress), June 2017. 540 [I-D.ietf-pce-association-group] 541 Minei, I., Crabbe, E., Sivabalan, S., Ananthakrishnan, H., 542 Dhody, D., and Y. Tanaka, "PCEP Extensions for 543 Establishing Relationships Between Sets of LSPs", draft- 544 ietf-pce-association-group-04 (work in progress), August 545 2017. 547 10.2. Information References 549 [RFC4655] Farrel, A., Vasseur, J., and J. Ash, "A Path Computation 550 Element (PCE)-Based Architecture", RFC 4655, 551 DOI 10.17487/RFC4655, August 2006, 552 . 554 [RFC4657] Ash, J., Ed. and J. Le Roux, Ed., "Path Computation 555 Element (PCE) Communication Protocol Generic 556 Requirements", RFC 4657, DOI 10.17487/RFC4657, September 557 2006, . 559 [RFC7420] Koushik, A., Stephan, E., Zhao, Q., King, D., and J. 560 Hardwick, "Path Computation Element Communication Protocol 561 (PCEP) Management Information Base (MIB) Module", 562 RFC 7420, DOI 10.17487/RFC7420, December 2014, 563 . 565 [RFC7525] Sheffer, Y., Holz, R., and P. Saint-Andre, 566 "Recommendations for Secure Use of Transport Layer 567 Security (TLS) and Datagram Transport Layer Security 568 (DTLS)", BCP 195, RFC 7525, DOI 10.17487/RFC7525, May 569 2015, . 571 [RFC8051] Zhang, X., Ed. and I. Minei, Ed., "Applicability of a 572 Stateful Path Computation Element (PCE)", RFC 8051, 573 DOI 10.17487/RFC8051, January 2017, 574 . 576 [I-D.ietf-pce-pceps] 577 Lopez, D., Dios, O., Wu, Q., and D. Dhody, "Secure 578 Transport for PCEP", draft-ietf-pce-pceps-18 (work in 579 progress), September 2017. 581 [I-D.ietf-pce-pcep-yang] 582 Dhody, D., Hardwick, J., Beeram, V., and j. 583 jefftant@gmail.com, "A YANG Data Model for Path 584 Computation Element Communications Protocol (PCEP)", 585 draft-ietf-pce-pcep-yang-05 (work in progress), June 2017. 587 [I-D.ietf-pce-association-diversity] 588 Litkowski, S., Sivabalan, S., Barth, C., and D. Dhody, 589 "Path Computation Element communication Protocol extension 590 for signaling LSP diversity constraint", draft-ietf-pce- 591 association-diversity-02 (work in progress), September 592 2017. 594 Authors' Addresses 596 Hariharan Ananthakrishnan 597 Packet Design 598 1 South Almaden Blvd, #1150, 599 San Jose, CA, 95113 600 USA 602 EMail: hari@packetdesign.com 604 Siva Sivabalan 605 Cisco 606 2000 Innovation Drive 607 Kananta, Ontaria K2K 3E8 608 Canada 610 EMail: msiva@cisco.com 612 Colby Barth 613 Juniper Networks 614 1194 N Mathilda Ave, 615 Sunnyvale, CA, 94086 616 USA 618 EMail: cbarth@juniper.net 620 Raveendra Torvi 621 Juniper Networks 622 1194 N Mathilda Ave, 623 Sunnyvale, CA, 94086 624 USA 626 EMail: rtorvi@juniper.net 628 Ina Minei 629 Google, Inc 630 1600 Amphitheatre Parkway 631 Mountain View, CA, 94043 632 USA 634 EMail: inaminei@google.com 635 Edward Crabbe 636 Individual Contributor 638 EMail: edward.crabbe@gmail.com 640 Dhruv Dhody 641 Huawei Technologies 642 Divyashree Techno Park, Whitefield 643 Bangalore, Karnataka 560066 644 India 646 EMail: dhruv.ietf@gmail.com