idnits 2.17.1 draft-dhody-pce-recv-srlg-07.txt: Checking boilerplate required by RFC 5378 and the IETF Trust (see https://trustee.ietf.org/license-info): ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/1id-guidelines.txt: ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/checklist : ---------------------------------------------------------------------------- No issues found here. Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year -- The document date (October 22, 2018) is 2006 days in the past. Is this intentional? 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(See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Outdated reference: A later version (-16) exists of draft-ietf-pce-segment-routing-14 == Outdated reference: A later version (-23) exists of draft-ietf-pce-pcep-yang-09 Summary: 0 errors (**), 0 flaws (~~), 3 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 PCE Working Group D. Dhody 3 Internet-Draft F. Zhang 4 Intended status: Standards Track X. Zhang 5 Expires: April 25, 2019 M. Negi 6 Huawei Technologies 7 V. Lopez 8 O. Gonzalez de Dios 9 Telefonica I+D 10 October 22, 2018 12 PCEP Extensions for Receiving SRLG Information 13 draft-dhody-pce-recv-srlg-07 15 Abstract 17 The Path Computation Element (PCE) provides functions of path 18 computation in support of traffic engineering (TE) in networks 19 controlled by Multi-Protocol Label Switching (MPLS) and Generalized 20 MPLS (GMPLS). 22 This document provides extensions for the Path Computation Element 23 Protocol (PCEP) to receive Shared Risk Link Group (SRLG) information 24 during path computation via encoding this information in the path 25 computation reply message. 27 Status of This Memo 29 This Internet-Draft is submitted in full conformance with the 30 provisions of BCP 78 and BCP 79. 32 Internet-Drafts are working documents of the Internet Engineering 33 Task Force (IETF). Note that other groups may also distribute 34 working documents as Internet-Drafts. The list of current Internet- 35 Drafts is at https://datatracker.ietf.org/drafts/current/. 37 Internet-Drafts are draft documents valid for a maximum of six months 38 and may be updated, replaced, or obsoleted by other documents at any 39 time. It is inappropriate to use Internet-Drafts as reference 40 material or to cite them other than as "work in progress." 42 This Internet-Draft will expire on April 25, 2019. 44 Copyright Notice 46 Copyright (c) 2018 IETF Trust and the persons identified as the 47 document authors. All rights reserved. 49 This document is subject to BCP 78 and the IETF Trust's Legal 50 Provisions Relating to IETF Documents 51 (https://trustee.ietf.org/license-info) in effect on the date of 52 publication of this document. Please review these documents 53 carefully, as they describe your rights and restrictions with respect 54 to this document. Code Components extracted from this document must 55 include Simplified BSD License text as described in Section 4.e of 56 the Trust Legal Provisions and are provided without warranty as 57 described in the Simplified BSD License. 59 Table of Contents 61 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 62 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3 63 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 64 3. Usage of SRLG . . . . . . . . . . . . . . . . . . . . . . . . 4 65 4. PCEP Requirements . . . . . . . . . . . . . . . . . . . . . . 4 66 5. Extension to PCEP . . . . . . . . . . . . . . . . . . . . . . 5 67 5.1. SRLG Information TLV . . . . . . . . . . . . . . . . . . 5 68 5.2. SRLG Subobject in ERO . . . . . . . . . . . . . . . . . . 6 69 6. Other Considerations . . . . . . . . . . . . . . . . . . . . 6 70 6.1. Other Path Setup Types . . . . . . . . . . . . . . . . . 6 71 6.2. Backward Compatibility . . . . . . . . . . . . . . . . . 7 72 6.3. Confidentiality via PathKey . . . . . . . . . . . . . . . 7 73 6.4. Coherent SRLG IDs . . . . . . . . . . . . . . . . . . . . 7 74 7. Security Considerations . . . . . . . . . . . . . . . . . . . 7 75 8. Manageability Considerations . . . . . . . . . . . . . . . . 8 76 8.1. Control of Function and Policy . . . . . . . . . . . . . 8 77 8.2. Information and Data Models . . . . . . . . . . . . . . . 8 78 8.3. Liveness Detection and Monitoring . . . . . . . . . . . . 8 79 8.4. Verify Correct Operations . . . . . . . . . . . . . . . . 8 80 8.5. Requirements On Other Protocols . . . . . . . . . . . . . 8 81 8.6. Impact On Network Operations . . . . . . . . . . . . . . 8 82 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 83 9.1. New TLV . . . . . . . . . . . . . . . . . . . . . . . . . 9 84 9.2. New Subobjects for the ERO Object . . . . . . . . . . . . 9 85 10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 10 86 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 10 87 11.1. Normative References . . . . . . . . . . . . . . . . . . 10 88 11.2. Informative References . . . . . . . . . . . . . . . . . 11 89 Appendix A. Contributor Addresses . . . . . . . . . . . . . . . 14 90 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 14 92 1. Introduction 94 As per [RFC4655], PCE based path computation model is deployed in 95 large, multi-domain, multi-region, or multi-layer networks. In such 96 case PCEs may cooperate with each other to provide end to end optimal 97 path. 99 It is important to understand which TE links in the network might be 100 at risk from the same failures. In this sense, a set of links can 101 constitute a 'shared risk link group' (SRLG) if they share a resource 102 whose failure can affect all links in the set [RFC4202]. H-LSP 103 (Hierarchical LSP) or S-LSP (Stitched LSP) can be used for carrying 104 one or more other LSPs as described in [RFC4206] and [RFC6107]. 105 H-LSP and S-LSP may be computed by PCE(s) and further form as a TE 106 link. The SRLG information of such LSPs can be obtained during path 107 computation itself and encoded in the PCEP Path Computation Reply 108 (PCRep) message. [I-D.zhang-ccamp-gmpls-uni-app] describes the use 109 of a PCE for end to end User-Network Interface (UNI) path 110 computation. 112 Note that [RFC8001] specifies a extension to Resource ReserVation 113 Protocol-Traffic Engineering (RSVP-TE) where SRLG information is 114 collected at the time of signaling. But in case a PCE or cooperating 115 PCEs are used for path computation it is recommended that SRLG 116 information is provided by the PCE(s) during the path computation 117 itself to the ingress (PCC) rather than receiving this information 118 during signaling. 120 Further, for other path setup types (PST), (such as segment routing 121 (SR), PCE as central controller (PCECC)) using a PCEP based approach 122 for SRLG information is useful. 124 [RFC7926] describes a scaling problem with SRLGs in multi-layer 125 environment and introduce a concept of Macro SRLG (MSRLG). Lower 126 layer SRLG are abstracted at the time of path computation and can be 127 the basis to generate such a Macro SRLG at the PCE. 129 1.1. Requirements Language 131 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 132 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 133 "OPTIONAL" in this document are to be interpreted as described in BCP 134 14 [RFC2119] [RFC8174] when, and only when, they appear in all 135 capitals, as shown here. 137 2. Terminology 139 The following terminology is used in this document. 141 CPS: Confidential Path Segment. A segment of a path that contains 142 nodes and links that the policy requires not to be disclosed 143 outside the domain. 145 PCE: Path Computation Element. An entity (component, application, 146 or network node) that is capable of computing a network path or 147 route based on a network graph and applying computational 148 constraints. 150 SRLG: Shared Risk Link Group. 152 UNI: User-Network Interface. 154 3. Usage of SRLG 156 [RFC4202] states that a set of links can constitute a 'shared risk 157 link group' (SRLG) if they share a resource whose failure can affect 158 all links in the set. For example, two fibers in the same conduit 159 would be in the same SRLG. If an LSR is required to have multiple 160 diversely routed LSPs to another LSR, the path computation should 161 attempt to route the paths so that they do not have any links in 162 common, and such that the path SRLGs are disjoint. 164 In case a PCE or cooperating PCEs are used for path computation, the 165 SRLG information is provided by the PCE(s). For example, disjoint 166 paths for inter-domain or inter-layer LSPs. In order to achieve path 167 computation for a secondary (backup) path, a PCC may request the PCE 168 for a route that must be SRLG disjoint from the primary (working) 169 path. The Exclude Route Object (XRO) [RFC5521] is used to specify 170 SRLG information to be explicitly excluded. 172 4. PCEP Requirements 174 Following key requirements are identified for PCEP to receive SRLG 175 information during path computation: 177 SRLG Indication: The PCEP speaker SHOULD be capable of indicating 178 whether the SRLG information of the path is to be received during 179 the path computation procedure to PCE. 181 SRLG: If requested, the SRLG information SHOULD be received during 182 the path computation and encoded in the PCEP message from PCE. 184 Cooperating PCEs [RFC4655] with inter-PCE communication work together 185 to provide the end to end optimal path as well as the SRLG 186 information of this path. During inter-domain or inter-layer path 187 computation, the aggregating PCE (Parent PCE [RFC6805] or Ingress 188 PCE(1) [RFC5441] or Higher-Layer PCE [RFC5623]) should receive the 189 SRLG information of path segments from other PCEs and provide the end 190 to end SRLG information of the optimal path to the Path Computation 191 Client (PCC). 193 5. Extension to PCEP 195 This document defines a new TLV that can be carried in the LSPA (LSP 196 Attributes) object [RFC5440] so that a PCEP speaker can request SRLG 197 information along with the path from the PCE. The SRLG subobject 198 maybe carried inside the Explicit Route Object (ERO) in the PCEP 199 message from PCE. 201 5.1. SRLG Information TLV 203 This document specify a new TLV for the LSPA Object to indicate that 204 the PCE SHOULD provide the SRLG information along with the path. Its 205 format is shown in the following figure: 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 | Type | Length | 211 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 212 | Reserved | Flags |S| 213 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 215 SRLG-INFO TLV 217 The Type for the TLV is TBD. The length is fixed value of 4. The 218 value portion consist of - 220 Reserved (16-bit): MUST be set to zero while sending and ignored 221 on receipt. 223 Flags (16-bit): Currently one flag is defined - 225 S (SRLG - 1 bit): when set, in a PCReq message, this indicates 226 that the SRLG information of the path SHOULD be provided in the 227 PCRep message. Otherwise, when cleared, this indicates that 228 the SRLG information SHOULD NOT be included in the PCRep 229 message. In a PCRep message, when the S bit is set this 230 indicates that the returned path in ERO also carry the SRLG 231 information; otherwise (when the S bit is cleared), the 232 returned path does not carry SRLG information. Further incase 233 of PCRpt [RFC8231] message for delegated LSP the flag indicates 234 that when PCE computes the path, it SHOULD provide the SRLG 235 information in PCUpd [RFC8231] message. Incase of PCUpd and 236 PCInitiate [RFC8281] message, the flag indicates that the ERO 237 also carry the SRLG information. 239 5.2. SRLG Subobject in ERO 241 As per [RFC5440], ERO is used to encode the path and is carried 242 within a PCRep message to provide the computed path when computation 243 was successful. Further as per [RFC8231] and [RFC8281], the ERO is 244 also encoded in PCUpd and PCInitiate message for stateful operations. 246 The SRLG of a path is the union of the SRLGs of the links in the path 247 [RFC4202]. The SRLG subobject is defined in [RFC8001] for 248 ROUTE_RECORD object (RRO). The same subobject format (reproduced 249 below) can be used by the ERO object in the PCEP messages. 251 0 1 2 3 252 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 1 253 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 254 | Type | Length |D| Reserved | 255 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 256 | SRLG ID 1 (4 octets) | 257 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 258 ~ ...... ~ 259 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 260 | SRLG ID n (4 octets) | 261 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 263 The meaning and description of Type, Length, D-Bit and SRLG ID can be 264 found in [RFC8001]. Reserved field MUST be set to zero on 265 transmission and MUST be ignored on receipt. 267 The SRLG subobject should be encoded inside the ERO object in the 268 PCEP messages by the PCE when the S-Bit is set in the SRLG-INFO TLV 269 (inside LSPA object). Incase no SRLG information is present for the 270 path, an empty SRLG subobject with Length as 4 (and no SRLG-IDs) is 271 included. 273 6. Other Considerations 275 6.1. Other Path Setup Types 277 Initially PCEP was used for LSPs that are set up using the RSVP-TE 278 signaling protocol. However, other TE path setup methods are 279 possible within the PCE architecture such as SR 280 [I-D.ietf-pce-segment-routing]. 282 [RFC8001] describes SRLG information collection via RSVP-TE 283 extension, which can not be used for Segment Routing (SR), making PCE 284 the best source for the SRLG information for SR. 286 6.2. Backward Compatibility 288 If a PCE receives a PCEP message and the PCE does not understand the 289 new TLV in the LSPA object, then as per [RFC5440], it would ignore 290 the TLV. In which case, the PCC will receive ERO with no SRLG 291 subobject and can determine that the PCE does not support the PCEP 292 extention as defined in this document. 294 If PCEP speaker receives a PCEP message with SRLG subobject that it 295 does not support or recognize, it would act according to the existing 296 processing rules of the ERO as per [RFC5440]. 298 6.3. Confidentiality via PathKey 300 [RFC5520] defines a mechanism to hide the contents of a segment of a 301 path, called the Confidential Path Segment (CPS). The CPS may be 302 replaced by a path-key that can be conveyed in the PCEP and signaled 303 within in a RSVP-TE ERO. 305 When path-key confidentiality is used, encoding SRLG information in 306 PCRep along with the path-key could be useful to compute a SRLG 307 disjoint backup path at the later instance. 309 The path segment that needs to be hidden (that is, CPS) MAY be 310 replaced in the ERO with a PKS. The PCE MAY use the SRLG Sub-objects 311 in the ERO along with the PKS sub-object. 313 6.4. Coherent SRLG IDs 315 In a multi-layer multi-domain scenario, SRLG ids may be configured by 316 different management entities in each layer/domain. In such 317 scenarios, maintaining a coherent set of SRLG IDs is a key 318 requirement in order to be able to use the SRLG information properly. 319 Thus, SRLG IDs must be unique. Note that current procedure is 320 targeted towards a scenario where the different layers and domains 321 belong to the same operator, or to several coordinated administrative 322 groups. Ensuring the aforementioned coherence of SRLG IDs is beyond 323 the scope of this document. Further scenarios, where coherence in 324 the SRLG IDs cannot be guaranteed are out of the scope of the present 325 document and are left for further study. 327 7. Security Considerations 329 The procedures defined in this document permit the transfer of SRLG 330 data between layers or domains during the path computation of LSPs, 331 subject to policy at the PCE. It is recommended that PCE policies 332 take the implications of releasing SRLG information into 333 consideration and behave accordingly during path computation. Other 334 security concerns are discussed in [RFC5440]. An analysis of the 335 security issues for routing protocols that use TCP (including PCEP) 336 is provided in [RFC6952], while [RFC8253] discusses a TLS based 337 approach to provide secure transport for PCEP. 339 8. Manageability Considerations 341 8.1. Control of Function and Policy 343 A PCE involved in inter-domain or inter-layer path computation should 344 be capable of being configured with a SRLG processing policy to 345 specify if the SRLG IDs of the domain or specific layer network can 346 be exposed to the PCEP peer outside the domain or layer network, or 347 whether they should be summarized, mapped to values that are 348 comprehensible to PCC outside the domain or layer network, or removed 349 entirely. 351 8.2. Information and Data Models 353 [RFC7420] describes the PCEP MIB and [I-D.ietf-pce-pcep-yang] specify 354 PCEP YANG, there are no new MIB Objects or YANG changes for this 355 document. 357 8.3. Liveness Detection and Monitoring 359 Mechanisms defined in this document do not imply any new liveness 360 detection and monitoring requirements in addition to those already 361 listed in [RFC5440]. 363 8.4. Verify Correct Operations 365 Mechanisms defined in this document do not imply any new operation 366 verification requirements in addition to those already listed in 367 [RFC5440] and [RFC8231]. 369 8.5. Requirements On Other Protocols 371 Mechanisms defined in this document do not imply any new requirements 372 on other protocols. Note that, [RFC8001] provide similar 373 requirements for signaling protocol. 375 8.6. Impact On Network Operations 377 Mechanisms defined in this document do not have any impact on network 378 operations in addition to those already listed in [RFC5440] and 379 [RFC8231]. 381 9. IANA Considerations 383 IANA assigns values to PCEP parameters in registries defined in 384 [RFC5440]. IANA is requested to make the following additional 385 assignments. 387 9.1. New TLV 389 IANA maintains the "Path Computation Element Protocol (PCEP) Numbers" 390 registry and the "PCEP TLV Type Indicators" sub-registry. IANA is 391 requested to allocate a codepoint for - 393 Type Meaning Reference 394 TBD SRLG-INFO This document 396 This document requests that a new sub-registry, named "SRLG-INFO TLV 397 Flag Field", is created within the "Path Computation Element Protocol 398 (PCEP) Numbers" registry to manage the Flag field of the this TLV. 399 New values are to be assigned by Standards Action [RFC8126]. Each 400 bit should be tracked with the following qualities: 402 o Bit number (counting from bit 0 as the most significant bit) 404 o Capability description 406 o Defining RFC 408 The following values are defined in this document: 410 Bit Description Reference 411 31 SRLG (S-bit) This document 413 9.2. New Subobjects for the ERO Object 415 PCEP uses the ERO registry maintained for RSVP at 416 http://www.iana.org/assignments/rsvp-parameters/rsvp- 417 parameters.xhtml. Within this registry IANA maintains sub-registry 418 for ERO subobject at http://www.iana.org/assignments/rsvp-parameters/ 419 rsvp-parameters.xhtml#rsvp-parameters-25 421 Upon approval of this document, IANA is requested to make identical 422 additions to the registry as follows (which is un-assigned right 423 now): 425 Subobject Type Reference 426 34 SRLG sub-object [This I.D.] 428 Note that, an allocation for SRLG sub-object for RRO in RSVP-TE is 429 made for [RFC8001]. 431 10. Acknowledgments 433 Special thanks to the authors of [RFC8001]. This document borrows 434 some of text from it. 436 11. References 438 11.1. Normative References 440 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 441 Requirement Levels", BCP 14, RFC 2119, 442 DOI 10.17487/RFC2119, March 1997, 443 . 445 [RFC5440] Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation 446 Element (PCE) Communication Protocol (PCEP)", RFC 5440, 447 DOI 10.17487/RFC5440, March 2009, 448 . 450 [RFC8001] Zhang, F., Ed., Gonzalez de Dios, O., Ed., Margaria, C., 451 Hartley, M., and Z. Ali, "RSVP-TE Extensions for 452 Collecting Shared Risk Link Group (SRLG) Information", 453 RFC 8001, DOI 10.17487/RFC8001, January 2017, 454 . 456 [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for 457 Writing an IANA Considerations Section in RFCs", BCP 26, 458 RFC 8126, DOI 10.17487/RFC8126, June 2017, 459 . 461 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 462 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 463 May 2017, . 465 [RFC8231] Crabbe, E., Minei, I., Medved, J., and R. Varga, "Path 466 Computation Element Communication Protocol (PCEP) 467 Extensions for Stateful PCE", RFC 8231, 468 DOI 10.17487/RFC8231, September 2017, 469 . 471 [RFC8281] Crabbe, E., Minei, I., Sivabalan, S., and R. Varga, "Path 472 Computation Element Communication Protocol (PCEP) 473 Extensions for PCE-Initiated LSP Setup in a Stateful PCE 474 Model", RFC 8281, DOI 10.17487/RFC8281, December 2017, 475 . 477 11.2. Informative References 479 [RFC4202] Kompella, K., Ed. and Y. Rekhter, Ed., "Routing Extensions 480 in Support of Generalized Multi-Protocol Label Switching 481 (GMPLS)", RFC 4202, DOI 10.17487/RFC4202, October 2005, 482 . 484 [RFC4206] Kompella, K. and Y. Rekhter, "Label Switched Paths (LSP) 485 Hierarchy with Generalized Multi-Protocol Label Switching 486 (GMPLS) Traffic Engineering (TE)", RFC 4206, 487 DOI 10.17487/RFC4206, October 2005, 488 . 490 [RFC4655] Farrel, A., Vasseur, J., and J. Ash, "A Path Computation 491 Element (PCE)-Based Architecture", RFC 4655, 492 DOI 10.17487/RFC4655, August 2006, 493 . 495 [RFC5441] Vasseur, JP., Ed., Zhang, R., Bitar, N., and JL. Le Roux, 496 "A Backward-Recursive PCE-Based Computation (BRPC) 497 Procedure to Compute Shortest Constrained Inter-Domain 498 Traffic Engineering Label Switched Paths", RFC 5441, 499 DOI 10.17487/RFC5441, April 2009, 500 . 502 [RFC5520] Bradford, R., Ed., Vasseur, JP., and A. Farrel, 503 "Preserving Topology Confidentiality in Inter-Domain Path 504 Computation Using a Path-Key-Based Mechanism", RFC 5520, 505 DOI 10.17487/RFC5520, April 2009, 506 . 508 [RFC5521] Oki, E., Takeda, T., and A. Farrel, "Extensions to the 509 Path Computation Element Communication Protocol (PCEP) for 510 Route Exclusions", RFC 5521, DOI 10.17487/RFC5521, April 511 2009, . 513 [RFC5623] Oki, E., Takeda, T., Le Roux, JL., and A. Farrel, 514 "Framework for PCE-Based Inter-Layer MPLS and GMPLS 515 Traffic Engineering", RFC 5623, DOI 10.17487/RFC5623, 516 September 2009, . 518 [RFC6107] Shiomoto, K., Ed. and A. Farrel, Ed., "Procedures for 519 Dynamically Signaled Hierarchical Label Switched Paths", 520 RFC 6107, DOI 10.17487/RFC6107, February 2011, 521 . 523 [RFC6805] King, D., Ed. and A. Farrel, Ed., "The Application of the 524 Path Computation Element Architecture to the Determination 525 of a Sequence of Domains in MPLS and GMPLS", RFC 6805, 526 DOI 10.17487/RFC6805, November 2012, 527 . 529 [RFC6952] Jethanandani, M., Patel, K., and L. Zheng, "Analysis of 530 BGP, LDP, PCEP, and MSDP Issues According to the Keying 531 and Authentication for Routing Protocols (KARP) Design 532 Guide", RFC 6952, DOI 10.17487/RFC6952, May 2013, 533 . 535 [RFC7420] Koushik, A., Stephan, E., Zhao, Q., King, D., and J. 536 Hardwick, "Path Computation Element Communication Protocol 537 (PCEP) Management Information Base (MIB) Module", 538 RFC 7420, DOI 10.17487/RFC7420, December 2014, 539 . 541 [RFC7926] Farrel, A., Ed., Drake, J., Bitar, N., Swallow, G., 542 Ceccarelli, D., and X. Zhang, "Problem Statement and 543 Architecture for Information Exchange between 544 Interconnected Traffic-Engineered Networks", BCP 206, 545 RFC 7926, DOI 10.17487/RFC7926, July 2016, 546 . 548 [RFC8253] Lopez, D., Gonzalez de Dios, O., Wu, Q., and D. Dhody, 549 "PCEPS: Usage of TLS to Provide a Secure Transport for the 550 Path Computation Element Communication Protocol (PCEP)", 551 RFC 8253, DOI 10.17487/RFC8253, October 2017, 552 . 554 [I-D.ietf-pce-segment-routing] 555 Sivabalan, S., Filsfils, C., Tantsura, J., Henderickx, W., 556 and J. Hardwick, "PCEP Extensions for Segment Routing", 557 draft-ietf-pce-segment-routing-14 (work in progress), 558 October 2018. 560 [I-D.ietf-pce-pcep-yang] 561 Dhody, D., Hardwick, J., Beeram, V., and J. Tantsura, "A 562 YANG Data Model for Path Computation Element 563 Communications Protocol (PCEP)", draft-ietf-pce-pcep- 564 yang-09 (work in progress), October 2018. 566 [I-D.zhang-ccamp-gmpls-uni-app] 567 Zhang, F., Dios, O., Farrel, A., Zhang, X., and D. 568 Ceccarelli, "Applicability of Generalized Multiprotocol 569 Label Switching (GMPLS) User-Network Interface (UNI)", 570 draft-zhang-ccamp-gmpls-uni-app-05 (work in progress), 571 February 2014. 573 Appendix A. Contributor Addresses 575 Udayasree Palle 577 EMail: udayasreereddy@gmail.com 579 Avantika 580 India 582 EMail: s.avantika.avantika@gmail.com 584 Authors' Addresses 586 Dhruv Dhody 587 Huawei Technologies 588 Divyashree Techno Park, Whitefield 589 Bangalore, Karnataka 560066 590 India 592 EMail: dhruv.ietf@gmail.com 594 Fatai Zhang 595 Huawei Technologies 596 Bantian, Longgang District 597 Shenzhen, Guangdong 518129 598 P.R.China 600 EMail: zhangfatai@huawei.com 602 Xian Zhang 603 Huawei Technologies 604 Bantian, Longgang District 605 Shenzhen, Guangdong 518129 606 P.R.China 608 EMail: zhang.xian@huawei.com 610 Mahendra Singh Negi 611 Huawei Technologies 612 Divyashree Techno Park, Whitefield 613 Bangalore, Karnataka 560066 614 India 616 EMail: mahend.ietf@gmail.com 617 Victor Lopez 618 Telefonica I+D 619 Distrito Telefonica 620 Edificio Sur 3, 3rd floor 621 Madrid 28050 622 Spain 624 EMail: victor.lopezalvarez@telefonica.com 626 Oscar Gonzalez de Dios 627 Telefonica I+D 628 Distrito Telefonica 629 Edificio Sur 3, 3rd floor 630 Madrid 28050 631 Spain 633 EMail: oscar.gonzalezdedios@telefonica.com