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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(See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Outdated reference: A later version (-23) exists of draft-ietf-pce-pcep-yang-09 Summary: 0 errors (**), 0 flaws (~~), 2 warnings (==), 1 comment (--).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: March 8, 2019 M. Negi 6 Huawei Technologies 7 V. Lopez 8 O. Gonzalez de Dios 9 Telefonica I+D 10 March 8, 2019 12 PCEP Extensions for Receiving SRLG Information 13 draft-dhody-pce-recv-srlg-08 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 The document is currently dead as there is little interest in this as 28 of now. 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 8, 2019. 47 Copyright Notice 49 Copyright (c) 2019 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 . . . . . . . . . . . . . . . . . . 3 66 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 67 3. Usage of SRLG . . . . . . . . . . . . . . . . . . . . . . . . 4 68 4. PCEP Requirements . . . . . . . . . . . . . . . . . . . . . . 4 69 5. Extension to PCEP . . . . . . . . . . . . . . . . . . . . . . 5 70 5.1. SRLG Information TLV . . . . . . . . . . . . . . . . . . 5 71 5.2. SRLG Subobject in ERO . . . . . . . . . . . . . . . . . . 6 72 6. Other Considerations . . . . . . . . . . . . . . . . . . . . 6 73 6.1. Other Path Setup Types . . . . . . . . . . . . . . . . . 6 74 6.2. Backward Compatibility . . . . . . . . . . . . . . . . . 7 75 6.3. Confidentiality via PathKey . . . . . . . . . . . . . . . 7 76 6.4. Coherent SRLG IDs . . . . . . . . . . . . . . . . . . . . 7 77 7. Security Considerations . . . . . . . . . . . . . . . . . . . 8 78 8. Manageability Considerations . . . . . . . . . . . . . . . . 8 79 8.1. Control of Function and Policy . . . . . . . . . . . . . 8 80 8.2. Information and Data Models . . . . . . . . . . . . . . . 8 81 8.3. Liveness Detection and Monitoring . . . . . . . . . . . . 8 82 8.4. Verify Correct Operations . . . . . . . . . . . . . . . . 8 83 8.5. Requirements On Other Protocols . . . . . . . . . . . . . 8 84 8.6. Impact On Network Operations . . . . . . . . . . . . . . 9 85 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 86 9.1. New TLV . . . . . . . . . . . . . . . . . . . . . . . . . 9 87 9.2. New Subobjects for the ERO Object . . . . . . . . . . . . 9 88 10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 10 89 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 10 90 11.1. Normative References . . . . . . . . . . . . . . . . . . 10 91 11.2. Informative References . . . . . . . . . . . . . . . . . 11 92 Appendix A. Contributor Addresses . . . . . . . . . . . . . . . 14 93 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 14 95 1. Introduction 97 As per [RFC4655], PCE based path computation model is deployed in 98 large, multi-domain, multi-region, or multi-layer networks. In such 99 case PCEs may cooperate with each other to provide end to end optimal 100 path. 102 It is important to understand which TE links in the network might be 103 at risk from the same failures. In this sense, a set of links can 104 constitute a 'shared risk link group' (SRLG) if they share a resource 105 whose failure can affect all links in the set [RFC4202]. H-LSP 106 (Hierarchical LSP) or S-LSP (Stitched LSP) can be used for carrying 107 one or more other LSPs as described in [RFC4206] and [RFC6107]. 108 H-LSP and S-LSP may be computed by PCE(s) and further form as a TE 109 link. The SRLG information of such LSPs can be obtained during path 110 computation itself and encoded in the PCEP Path Computation Reply 111 (PCRep) message. [I-D.zhang-ccamp-gmpls-uni-app] describes the use 112 of a PCE for end to end User-Network Interface (UNI) path 113 computation. 115 Note that [RFC8001] specifies a extension to Resource ReserVation 116 Protocol-Traffic Engineering (RSVP-TE) where SRLG information is 117 collected at the time of signaling. But in case a PCE or cooperating 118 PCEs are used for path computation it is recommended that SRLG 119 information is provided by the PCE(s) during the path computation 120 itself to the ingress (PCC) rather than receiving this information 121 during signaling. 123 Further, for other path setup types (PST), (such as segment routing 124 (SR), PCE as central controller (PCECC)) using a PCEP based approach 125 for SRLG information is useful. 127 [RFC7926] describes a scaling problem with SRLGs in multi-layer 128 environment and introduce a concept of Macro SRLG (MSRLG). Lower 129 layer SRLG are abstracted at the time of path computation and can be 130 the basis to generate such a Macro SRLG at the PCE. 132 The document is currently dead as there is little interest in this as 133 of now. 135 1.1. Requirements Language 137 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 138 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 139 "OPTIONAL" in this document are to be interpreted as described in BCP 140 14 [RFC2119] [RFC8174] when, and only when, they appear in all 141 capitals, as shown here. 143 2. Terminology 145 The following terminology is used in this document. 147 CPS: Confidential Path Segment. A segment of a path that contains 148 nodes and links that the policy requires not to be disclosed 149 outside the domain. 151 PCE: Path Computation Element. An entity (component, application, 152 or network node) that is capable of computing a network path or 153 route based on a network graph and applying computational 154 constraints. 156 SRLG: Shared Risk Link Group. 158 UNI: User-Network Interface. 160 3. Usage of SRLG 162 [RFC4202] states that a set of links can constitute a 'shared risk 163 link group' (SRLG) if they share a resource whose failure can affect 164 all links in the set. For example, two fibers in the same conduit 165 would be in the same SRLG. If an LSR is required to have multiple 166 diversely routed LSPs to another LSR, the path computation should 167 attempt to route the paths so that they do not have any links in 168 common, and such that the path SRLGs are disjoint. 170 In case a PCE or cooperating PCEs are used for path computation, the 171 SRLG information is provided by the PCE(s). For example, disjoint 172 paths for inter-domain or inter-layer LSPs. In order to achieve path 173 computation for a secondary (backup) path, a PCC may request the PCE 174 for a route that must be SRLG disjoint from the primary (working) 175 path. The Exclude Route Object (XRO) [RFC5521] is used to specify 176 SRLG information to be explicitly excluded. 178 4. PCEP Requirements 180 Following key requirements are identified for PCEP to receive SRLG 181 information during path computation: 183 SRLG Indication: The PCEP speaker SHOULD be capable of indicating 184 whether the SRLG information of the path is to be received during 185 the path computation procedure to PCE. 187 SRLG: If requested, the SRLG information SHOULD be received during 188 the path computation and encoded in the PCEP message from PCE. 190 Cooperating PCEs [RFC4655] with inter-PCE communication work together 191 to provide the end to end optimal path as well as the SRLG 192 information of this path. During inter-domain or inter-layer path 193 computation, the aggregating PCE (Parent PCE [RFC6805] or Ingress 194 PCE(1) [RFC5441] or Higher-Layer PCE [RFC5623]) should receive the 195 SRLG information of path segments from other PCEs and provide the end 196 to end SRLG information of the optimal path to the Path Computation 197 Client (PCC). 199 5. Extension to PCEP 201 This document defines a new TLV that can be carried in the LSPA (LSP 202 Attributes) object [RFC5440] so that a PCEP speaker can request SRLG 203 information along with the path from the PCE. The SRLG subobject 204 maybe carried inside the Explicit Route Object (ERO) in the PCEP 205 message from PCE. 207 5.1. SRLG Information TLV 209 This document specify a new TLV for the LSPA Object to indicate that 210 the PCE SHOULD provide the SRLG information along with the path. Its 211 format is shown in the following figure: 213 0 1 2 3 214 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 1 215 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 216 | Type | Length | 217 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 218 | Reserved | Flags |S| 219 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 221 SRLG-INFO TLV 223 The Type for the TLV is TBD. The length is fixed value of 4. The 224 value portion consist of - 226 Reserved (16-bit): MUST be set to zero while sending and ignored 227 on receipt. 229 Flags (16-bit): Currently one flag is defined - 231 S (SRLG - 1 bit): when set, in a PCReq message, this indicates 232 that the SRLG information of the path SHOULD be provided in the 233 PCRep message. Otherwise, when cleared, this indicates that 234 the SRLG information SHOULD NOT be included in the PCRep 235 message. In a PCRep message, when the S bit is set this 236 indicates that the returned path in ERO also carry the SRLG 237 information; otherwise (when the S bit is cleared), the 238 returned path does not carry SRLG information. Further incase 239 of PCRpt [RFC8231] message for delegated LSP the flag indicates 240 that when PCE computes the path, it SHOULD provide the SRLG 241 information in PCUpd [RFC8231] message. Incase of PCUpd and 242 PCInitiate [RFC8281] message, the flag indicates that the ERO 243 also carry the SRLG information. 245 5.2. SRLG Subobject in ERO 247 As per [RFC5440], ERO is used to encode the path and is carried 248 within a PCRep message to provide the computed path when computation 249 was successful. Further as per [RFC8231] and [RFC8281], the ERO is 250 also encoded in PCUpd and PCInitiate message for stateful operations. 252 The SRLG of a path is the union of the SRLGs of the links in the path 253 [RFC4202]. The SRLG subobject is defined in [RFC8001] for 254 ROUTE_RECORD object (RRO). The same subobject format (reproduced 255 below) can be used by the ERO object in the PCEP messages. 257 0 1 2 3 258 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 1 259 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 260 | Type | Length |D| Reserved | 261 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 262 | SRLG ID 1 (4 octets) | 263 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 264 ~ ...... ~ 265 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 266 | SRLG ID n (4 octets) | 267 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 269 The meaning and description of Type, Length, D-Bit and SRLG ID can be 270 found in [RFC8001]. Reserved field MUST be set to zero on 271 transmission and MUST be ignored on receipt. 273 The SRLG subobject should be encoded inside the ERO object in the 274 PCEP messages by the PCE when the S-Bit is set in the SRLG-INFO TLV 275 (inside LSPA object). Incase no SRLG information is present for the 276 path, an empty SRLG subobject with Length as 4 (and no SRLG-IDs) is 277 included. 279 6. Other Considerations 281 6.1. Other Path Setup Types 283 Initially PCEP was used for LSPs that are set up using the RSVP-TE 284 signaling protocol. However, other TE path setup methods are 285 possible within the PCE architecture such as SR 286 [I-D.ietf-pce-segment-routing]. 288 [RFC8001] describes SRLG information collection via RSVP-TE 289 extension, which can not be used for Segment Routing (SR), making PCE 290 the best source for the SRLG information for SR. 292 6.2. Backward Compatibility 294 If a PCE receives a PCEP message and the PCE does not understand the 295 new TLV in the LSPA object, then as per [RFC5440], it would ignore 296 the TLV. In which case, the PCC will receive ERO with no SRLG 297 subobject and can determine that the PCE does not support the PCEP 298 extention as defined in this document. 300 If PCEP speaker receives a PCEP message with SRLG subobject that it 301 does not support or recognize, it would act according to the existing 302 processing rules of the ERO as per [RFC5440]. 304 6.3. Confidentiality via PathKey 306 [RFC5520] defines a mechanism to hide the contents of a segment of a 307 path, called the Confidential Path Segment (CPS). The CPS may be 308 replaced by a path-key that can be conveyed in the PCEP and signaled 309 within in a RSVP-TE ERO. 311 When path-key confidentiality is used, encoding SRLG information in 312 PCRep along with the path-key could be useful to compute a SRLG 313 disjoint backup path at the later instance. 315 The path segment that needs to be hidden (that is, CPS) MAY be 316 replaced in the ERO with a PKS. The PCE MAY use the SRLG Sub-objects 317 in the ERO along with the PKS sub-object. 319 6.4. Coherent SRLG IDs 321 In a multi-layer multi-domain scenario, SRLG ids may be configured by 322 different management entities in each layer/domain. In such 323 scenarios, maintaining a coherent set of SRLG IDs is a key 324 requirement in order to be able to use the SRLG information properly. 325 Thus, SRLG IDs must be unique. Note that current procedure is 326 targeted towards a scenario where the different layers and domains 327 belong to the same operator, or to several coordinated administrative 328 groups. Ensuring the aforementioned coherence of SRLG IDs is beyond 329 the scope of this document. Further scenarios, where coherence in 330 the SRLG IDs cannot be guaranteed are out of the scope of the present 331 document and are left for further study. 333 7. Security Considerations 335 The procedures defined in this document permit the transfer of SRLG 336 data between layers or domains during the path computation of LSPs, 337 subject to policy at the PCE. It is recommended that PCE policies 338 take the implications of releasing SRLG information into 339 consideration and behave accordingly during path computation. Other 340 security concerns are discussed in [RFC5440]. An analysis of the 341 security issues for routing protocols that use TCP (including PCEP) 342 is provided in [RFC6952], while [RFC8253] discusses a TLS based 343 approach to provide secure transport for PCEP. 345 8. Manageability Considerations 347 8.1. Control of Function and Policy 349 A PCE involved in inter-domain or inter-layer path computation should 350 be capable of being configured with a SRLG processing policy to 351 specify if the SRLG IDs of the domain or specific layer network can 352 be exposed to the PCEP peer outside the domain or layer network, or 353 whether they should be summarized, mapped to values that are 354 comprehensible to PCC outside the domain or layer network, or removed 355 entirely. 357 8.2. Information and Data Models 359 [RFC7420] describes the PCEP MIB and [I-D.ietf-pce-pcep-yang] specify 360 PCEP YANG, there are no new MIB Objects or YANG changes for this 361 document. 363 8.3. Liveness Detection and Monitoring 365 Mechanisms defined in this document do not imply any new liveness 366 detection and monitoring requirements in addition to those already 367 listed in [RFC5440]. 369 8.4. Verify Correct Operations 371 Mechanisms defined in this document do not imply any new operation 372 verification requirements in addition to those already listed in 373 [RFC5440] and [RFC8231]. 375 8.5. Requirements On Other Protocols 377 Mechanisms defined in this document do not imply any new requirements 378 on other protocols. Note that, [RFC8001] provide similar 379 requirements for signaling protocol. 381 8.6. Impact On Network Operations 383 Mechanisms defined in this document do not have any impact on network 384 operations in addition to those already listed in [RFC5440] and 385 [RFC8231]. 387 9. IANA Considerations 389 IANA assigns values to PCEP parameters in registries defined in 390 [RFC5440]. IANA is requested to make the following additional 391 assignments. 393 9.1. New TLV 395 IANA maintains the "Path Computation Element Protocol (PCEP) Numbers" 396 registry and the "PCEP TLV Type Indicators" sub-registry. IANA is 397 requested to allocate a codepoint for - 399 Type Meaning Reference 400 TBD SRLG-INFO This document 402 This document requests that a new sub-registry, named "SRLG-INFO TLV 403 Flag Field", is created within the "Path Computation Element Protocol 404 (PCEP) Numbers" registry to manage the Flag field of the this TLV. 405 New values are to be assigned by Standards Action [RFC8126]. Each 406 bit should be tracked with the following qualities: 408 o Bit number (counting from bit 0 as the most significant bit) 410 o Capability description 412 o Defining RFC 414 The following values are defined in this document: 416 Bit Description Reference 417 31 SRLG (S-bit) This document 419 9.2. New Subobjects for the ERO Object 421 PCEP uses the ERO registry maintained for RSVP at 422 http://www.iana.org/assignments/rsvp-parameters/rsvp- 423 parameters.xhtml. Within this registry IANA maintains sub-registry 424 for ERO subobject at http://www.iana.org/assignments/rsvp-parameters/ 425 rsvp-parameters.xhtml#rsvp-parameters-25 426 Upon approval of this document, IANA is requested to make identical 427 additions to the registry as follows (which is un-assigned right 428 now): 430 Subobject Type Reference 431 34 SRLG sub-object [This I.D.] 433 Note that, an allocation for SRLG sub-object for RRO in RSVP-TE is 434 made for [RFC8001]. 436 10. Acknowledgments 438 Special thanks to the authors of [RFC8001]. This document borrows 439 some of text from it. 441 11. References 443 11.1. Normative References 445 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 446 Requirement Levels", BCP 14, RFC 2119, 447 DOI 10.17487/RFC2119, March 1997, 448 . 450 [RFC5440] Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation 451 Element (PCE) Communication Protocol (PCEP)", RFC 5440, 452 DOI 10.17487/RFC5440, March 2009, 453 . 455 [RFC8001] Zhang, F., Ed., Gonzalez de Dios, O., Ed., Margaria, C., 456 Hartley, M., and Z. Ali, "RSVP-TE Extensions for 457 Collecting Shared Risk Link Group (SRLG) Information", 458 RFC 8001, DOI 10.17487/RFC8001, January 2017, 459 . 461 [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for 462 Writing an IANA Considerations Section in RFCs", BCP 26, 463 RFC 8126, DOI 10.17487/RFC8126, June 2017, 464 . 466 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 467 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 468 May 2017, . 470 [RFC8231] Crabbe, E., Minei, I., Medved, J., and R. Varga, "Path 471 Computation Element Communication Protocol (PCEP) 472 Extensions for Stateful PCE", RFC 8231, 473 DOI 10.17487/RFC8231, September 2017, 474 . 476 [RFC8281] Crabbe, E., Minei, I., Sivabalan, S., and R. Varga, "Path 477 Computation Element Communication Protocol (PCEP) 478 Extensions for PCE-Initiated LSP Setup in a Stateful PCE 479 Model", RFC 8281, DOI 10.17487/RFC8281, December 2017, 480 . 482 11.2. Informative References 484 [RFC4202] Kompella, K., Ed. and Y. Rekhter, Ed., "Routing Extensions 485 in Support of Generalized Multi-Protocol Label Switching 486 (GMPLS)", RFC 4202, DOI 10.17487/RFC4202, October 2005, 487 . 489 [RFC4206] Kompella, K. and Y. Rekhter, "Label Switched Paths (LSP) 490 Hierarchy with Generalized Multi-Protocol Label Switching 491 (GMPLS) Traffic Engineering (TE)", RFC 4206, 492 DOI 10.17487/RFC4206, October 2005, 493 . 495 [RFC4655] Farrel, A., Vasseur, J., and J. Ash, "A Path Computation 496 Element (PCE)-Based Architecture", RFC 4655, 497 DOI 10.17487/RFC4655, August 2006, 498 . 500 [RFC5441] Vasseur, JP., Ed., Zhang, R., Bitar, N., and JL. Le Roux, 501 "A Backward-Recursive PCE-Based Computation (BRPC) 502 Procedure to Compute Shortest Constrained Inter-Domain 503 Traffic Engineering Label Switched Paths", RFC 5441, 504 DOI 10.17487/RFC5441, April 2009, 505 . 507 [RFC5520] Bradford, R., Ed., Vasseur, JP., and A. Farrel, 508 "Preserving Topology Confidentiality in Inter-Domain Path 509 Computation Using a Path-Key-Based Mechanism", RFC 5520, 510 DOI 10.17487/RFC5520, April 2009, 511 . 513 [RFC5521] Oki, E., Takeda, T., and A. Farrel, "Extensions to the 514 Path Computation Element Communication Protocol (PCEP) for 515 Route Exclusions", RFC 5521, DOI 10.17487/RFC5521, April 516 2009, . 518 [RFC5623] Oki, E., Takeda, T., Le Roux, JL., and A. Farrel, 519 "Framework for PCE-Based Inter-Layer MPLS and GMPLS 520 Traffic Engineering", RFC 5623, DOI 10.17487/RFC5623, 521 September 2009, . 523 [RFC6107] Shiomoto, K., Ed. and A. Farrel, Ed., "Procedures for 524 Dynamically Signaled Hierarchical Label Switched Paths", 525 RFC 6107, DOI 10.17487/RFC6107, February 2011, 526 . 528 [RFC6805] King, D., Ed. and A. Farrel, Ed., "The Application of the 529 Path Computation Element Architecture to the Determination 530 of a Sequence of Domains in MPLS and GMPLS", RFC 6805, 531 DOI 10.17487/RFC6805, November 2012, 532 . 534 [RFC6952] Jethanandani, M., Patel, K., and L. Zheng, "Analysis of 535 BGP, LDP, PCEP, and MSDP Issues According to the Keying 536 and Authentication for Routing Protocols (KARP) Design 537 Guide", RFC 6952, DOI 10.17487/RFC6952, May 2013, 538 . 540 [RFC7420] Koushik, A., Stephan, E., Zhao, Q., King, D., and J. 541 Hardwick, "Path Computation Element Communication Protocol 542 (PCEP) Management Information Base (MIB) Module", 543 RFC 7420, DOI 10.17487/RFC7420, December 2014, 544 . 546 [RFC7926] Farrel, A., Ed., Drake, J., Bitar, N., Swallow, G., 547 Ceccarelli, D., and X. Zhang, "Problem Statement and 548 Architecture for Information Exchange between 549 Interconnected Traffic-Engineered Networks", BCP 206, 550 RFC 7926, DOI 10.17487/RFC7926, July 2016, 551 . 553 [RFC8253] Lopez, D., Gonzalez de Dios, O., Wu, Q., and D. Dhody, 554 "PCEPS: Usage of TLS to Provide a Secure Transport for the 555 Path Computation Element Communication Protocol (PCEP)", 556 RFC 8253, DOI 10.17487/RFC8253, October 2017, 557 . 559 [I-D.ietf-pce-segment-routing] 560 Sivabalan, S., Filsfils, C., Tantsura, J., Henderickx, W., 561 and J. Hardwick, "PCEP Extensions for Segment Routing", 562 draft-ietf-pce-segment-routing-16 (work in progress), 563 March 2019. 565 [I-D.ietf-pce-pcep-yang] 566 Dhody, D., Hardwick, J., Beeram, V., and J. Tantsura, "A 567 YANG Data Model for Path Computation Element 568 Communications Protocol (PCEP)", draft-ietf-pce-pcep- 569 yang-09 (work in progress), October 2018. 571 [I-D.zhang-ccamp-gmpls-uni-app] 572 Zhang, F., Dios, O., Farrel, A., Zhang, X., and D. 573 Ceccarelli, "Applicability of Generalized Multiprotocol 574 Label Switching (GMPLS) User-Network Interface (UNI)", 575 draft-zhang-ccamp-gmpls-uni-app-05 (work in progress), 576 February 2014. 578 Appendix A. Contributor Addresses 580 Udayasree Palle 582 EMail: udayasreereddy@gmail.com 584 Avantika 585 India 587 EMail: s.avantika.avantika@gmail.com 589 Authors' Addresses 591 Dhruv Dhody 592 Huawei Technologies 593 Divyashree Techno Park, Whitefield 594 Bangalore, Karnataka 560066 595 India 597 EMail: dhruv.ietf@gmail.com 599 Fatai Zhang 600 Huawei Technologies 601 Bantian, Longgang District 602 Shenzhen, Guangdong 518129 603 P.R.China 605 EMail: zhangfatai@huawei.com 607 Xian Zhang 608 Huawei Technologies 609 Bantian, Longgang District 610 Shenzhen, Guangdong 518129 611 P.R.China 613 EMail: zhang.xian@huawei.com 615 Mahendra Singh Negi 616 Huawei Technologies 617 Divyashree Techno Park, Whitefield 618 Bangalore, Karnataka 560066 619 India 621 EMail: mahend.ietf@gmail.com 622 Victor Lopez 623 Telefonica I+D 624 Distrito Telefonica 625 Edificio Sur 3, 3rd floor 626 Madrid 28050 627 Spain 629 EMail: victor.lopezalvarez@telefonica.com 631 Oscar Gonzalez de Dios 632 Telefonica I+D 633 Distrito Telefonica 634 Edificio Sur 3, 3rd floor 635 Madrid 28050 636 Spain 638 EMail: oscar.gonzalezdedios@telefonica.com