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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(See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Outdated reference: A later version (-19) exists of draft-ietf-lsr-isis-srv6-extensions-11 == Outdated reference: A later version (-28) exists of draft-ietf-spring-srv6-network-programming-24 == Outdated reference: A later version (-22) exists of draft-ietf-spring-segment-routing-policy-09 == Outdated reference: A later version (-14) exists of draft-ietf-idr-bgpls-srv6-ext-04 Summary: 0 errors (**), 0 flaws (~~), 5 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 PCE Working Group C. Li 3 Internet-Draft Huawei Technologies 4 Intended status: Standards Track M. Negi 5 Expires: May 6, 2021 RtBrick Inc 6 M. Koldychev 7 Cisco Systems, Inc. 8 P. Kaladharan 9 RtBrick Inc 10 Y. Zhu 11 China Telecom 12 November 2, 2020 14 PCEP Extensions for Segment Routing leveraging the IPv6 data plane 15 draft-ietf-pce-segment-routing-ipv6-07 17 Abstract 19 The Source Packet Routing in Networking (SPRING) architecture 20 describes how Segment Routing (SR) can be used to steer packets 21 through an IPv6 or MPLS network using the source routing paradigm. 22 SR enables any head-end node to select any path without relying on a 23 hop-by-hop signaling technique (e.g., LDP or RSVP-TE). 25 It depends only on "segments" that are advertised by Link- State 26 IGPs. A Segment Routed Path can be derived from a variety of 27 mechanisms, including an IGP Shortest Path Tree (SPT), explicit 28 configuration, or a Path Computation Element (PCE). 30 Since SR can be applied to both MPLS and IPv6 forwarding plane, a PCE 31 should be able to compute SR-Path for both MPLS and IPv6 forwarding 32 plane. This document describes the extensions required for SR 33 support for IPv6 data plane in Path Computation Element communication 34 Protocol (PCEP). The PCEP extension and mechanism to support SR-MPLS 35 is described in RFC 8664. This document extends it to support SRv6 36 (SR over IPv6). 38 Requirements Language 40 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 41 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 42 "OPTIONAL" in this document are to be interpreted as described in BCP 43 14 [RFC2119] [RFC8174] when, and only when, they appear in all 44 capitals, as shown here. 46 Status of This Memo 48 This Internet-Draft is submitted in full conformance with the 49 provisions of BCP 78 and BCP 79. 51 Internet-Drafts are working documents of the Internet Engineering 52 Task Force (IETF). Note that other groups may also distribute 53 working documents as Internet-Drafts. The list of current Internet- 54 Drafts is at https://datatracker.ietf.org/drafts/current/. 56 Internet-Drafts are draft documents valid for a maximum of six months 57 and may be updated, replaced, or obsoleted by other documents at any 58 time. It is inappropriate to use Internet-Drafts as reference 59 material or to cite them other than as "work in progress." 61 This Internet-Draft will expire on May 6, 2021. 63 Copyright Notice 65 Copyright (c) 2020 IETF Trust and the persons identified as the 66 document authors. All rights reserved. 68 This document is subject to BCP 78 and the IETF Trust's Legal 69 Provisions Relating to IETF Documents 70 (https://trustee.ietf.org/license-info) in effect on the date of 71 publication of this document. Please review these documents 72 carefully, as they describe your rights and restrictions with respect 73 to this document. Code Components extracted from this document must 74 include Simplified BSD License text as described in Section 4.e of 75 the Trust Legal Provisions and are provided without warranty as 76 described in the Simplified BSD License. 78 Table of Contents 80 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 81 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5 82 3. Overview of PCEP Operation in SRv6 Networks . . . . . . . . . 5 83 3.1. Operation Overview . . . . . . . . . . . . . . . . . . . 6 84 3.2. SRv6-Specific PCEP Message Extensions . . . . . . . . . . 6 85 4. Object Formats . . . . . . . . . . . . . . . . . . . . . . . 7 86 4.1. The OPEN Object . . . . . . . . . . . . . . . . . . . . . 7 87 4.1.1. The SRv6 PCE Capability sub-TLV . . . . . . . . . . . 7 88 4.2. The RP/SRP Object . . . . . . . . . . . . . . . . . . . . 8 89 4.3. ERO . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 90 4.3.1. SRv6-ERO Subobject . . . . . . . . . . . . . . . . . 9 91 4.3.1.1. SID Structure . . . . . . . . . . . . . . . . . . 11 92 4.4. RRO . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 93 4.4.1. SRv6-RRO Subobject . . . . . . . . . . . . . . . . . 12 95 5. Procedures . . . . . . . . . . . . . . . . . . . . . . . . . 13 96 5.1. Exchanging the SRv6 Capability . . . . . . . . . . . . . 13 97 5.2. ERO Processing . . . . . . . . . . . . . . . . . . . . . 15 98 5.2.1. SRv6 ERO Validation . . . . . . . . . . . . . . . . . 15 99 5.2.2. Interpreting the SRv6-ERO . . . . . . . . . . . . . . 16 100 5.3. RRO Processing . . . . . . . . . . . . . . . . . . . . . 16 101 6. Security Considerations . . . . . . . . . . . . . . . . . . . 16 102 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17 103 7.1. PCEP ERO and RRO subobjects . . . . . . . . . . . . . . . 17 104 7.2. New SRv6-ERO Flag Registry . . . . . . . . . . . . . . . 17 105 7.3. PATH-SETUP-TYPE-CAPABILITY Sub-TLV Type Indicators . . . 18 106 7.4. SRv6 PCE Capability Flags . . . . . . . . . . . . . . . . 18 107 7.5. New Path Setup Type . . . . . . . . . . . . . . . . . . . 18 108 7.6. ERROR Objects . . . . . . . . . . . . . . . . . . . . . . 19 109 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 19 110 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 19 111 9.1. Normative References . . . . . . . . . . . . . . . . . . 19 112 9.2. Informative References . . . . . . . . . . . . . . . . . 21 113 Appendix A. Contributor . . . . . . . . . . . . . . . . . . . . 23 114 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 23 116 1. Introduction 118 As per [RFC8402], with Segment Routing (SR), a node steers a packet 119 through an ordered list of instructions, called segments. A segment 120 can represent any instruction, topological or service-based. A 121 segment can have a semantic local to an SR node or global within an 122 SR domain. SR allows to enforce a flow through any path and service 123 chain while maintaining per-flow state only at the ingress node of 124 the SR domain. Segments can be derived from different components: 125 IGP, BGP, Services, Contexts, Locater, etc. The list of segment 126 forming the path is called the Segment List and is encoded in the 127 packet header. Segment Routing can be applied to the IPv6 128 architecture with the Segment Routing Header (SRH) [RFC8754]. A 129 segment is encoded as an IPv6 address. An ordered list of segments 130 is encoded as an ordered list of IPv6 addresses in the routing 131 header. The active segment is indicated by the Destination Address 132 of the packet. Upon completion of a segment, a pointer in the new 133 routing header is incremented and indicates the next segment. 135 Segment Routing use cases are described in [RFC7855] and [RFC8354]. 136 Segment Routing protocol extensions are defined in [RFC8667], and 137 [RFC8666]. 139 As per [RFC8754], an SRv6 Segment is a 128-bit value. "SRv6 SID" or 140 simply "SID" are often used as a shorter reference for "SRv6 141 Segment". Further details are in an illustration provided in 142 [I-D.ietf-spring-srv6-network-programming]. 144 The SR architecture can be applied to the MPLS forwarding plane 145 without any change, in which case an SR path corresponds to an MPLS 146 Label Switching Path (LSP). The SR is applied to IPV6 forwarding 147 plane using SRH. A SR path can be derived from an IGP Shortest Path 148 Tree (SPT), but SR-TE paths may not follow IGP SPT. Such paths may 149 be chosen by a suitable network planning tool, or a PCE and 150 provisioned on the ingress node. 152 [RFC5440] describes Path Computation Element communication Protocol 153 (PCEP) for communication between a Path Computation Client (PCC) and 154 a Path Computation Element (PCE) or between a pair of PCEs. A PCE or 155 a PCC operating as a PCE (in hierarchical PCE environment) computes 156 paths for MPLS Traffic Engineering LSPs (MPLS-TE LSPs) based on 157 various constraints and optimization criteria. [RFC8231] specifies 158 extensions to PCEP that allow a stateful PCE to compute and recommend 159 network paths in compliance with [RFC4657] and defines objects and 160 TLVs for MPLS-TE LSPs. Stateful PCEP extensions provide 161 synchronization of LSP state between a PCC and a PCE or between a 162 pair of PCEs, delegation of LSP control, reporting of LSP state from 163 a PCC to a PCE, controlling the setup and path routing of an LSP from 164 a PCE to a PCC. Stateful PCEP extensions are intended for an 165 operational model in which LSPs are configured on the PCC, and 166 control over them is delegated to the PCE. 168 A mechanism to dynamically initiate LSPs on a PCC based on the 169 requests from a stateful PCE or a controller using stateful PCE is 170 specified in [RFC8281]. As per [RFC8664], it is possible to use a 171 stateful PCE for computing one or more SR-TE paths taking into 172 account various constraints and objective functions. Once a path is 173 chosen, the stateful PCE can initiate an SR-TE path on a PCC using 174 PCEP extensions specified in [RFC8281] using the SR specific PCEP 175 extensions specified in [RFC8664]. [RFC8664] specifies PCEP 176 extensions for supporting a SR-TE LSP for MPLS data plane. This 177 document extends [RFC8664] to support SR for IPv6 data plane. 178 Additionally, using procedures described in this document, a PCC can 179 request an SRv6 path from either stateful or a stateless PCE. This 180 specification relies on the PATH-SETUP-TYPE TLV and procedures 181 specified in [RFC8408]. 183 This specification provides a mechanism for a network controller 184 (acting as a PCE) to instantiate candidate paths for an SR Policy 185 onto a head-end node (acting as a PCC) using PCEP. For more 186 information on the SR Policy Architecture, see 187 [I-D.ietf-spring-segment-routing-policy]. 189 2. Terminology 191 This document uses the following terms defined in [RFC5440]: PCC, 192 PCE, PCEP Peer. 194 This document uses the following terms defined in [RFC8051]: Stateful 195 PCE, Delegation. 197 The message formats in this document are specified using Routing 198 Backus-Naur Format (RBNF) encoding as specified in [RFC5511]. 200 NAI: Node or Adjacency Identifier. 202 PCC: Path Computation Client. 204 PCE: Path Computation Element. 206 PCEP: Path Computation Element Protocol. 208 SR: Segment Routing. 210 SID: Segment Identifier. 212 SRv6: Segment Routing for IPv6 forwarding plane. 214 SRH: IPv6 Segment Routing Header. 216 SR Path: IPv6 Segment List (List of IPv6 SIDs representing a path in 217 IPv6 SR domain) 219 Further, note that the term LSP used in the PCEP specifications, 220 would be equivalent to a SRv6 Path (represented as a list of SRv6 221 segments) in the context of supporting SRv6 in PCEP. 223 3. Overview of PCEP Operation in SRv6 Networks 225 Basic operations for PCEP speakers is as per [RFC8664]. SRv6 Paths 226 computed by a PCE can be represented as an ordered list of SRv6 227 segments of 128-bit value. "SRv6 SID" or simply "SID" are often used 228 as a shorter reference for "SRv6 Segment" in this document. 230 [RFC8664] defined a new Explicit Route Object (ERO) subobject denoted 231 by "SR-ERO subobject" capable of carrying a SID as well as the 232 identity of the node/adjacency represented by the SID. SR-capable 233 PCEP speakers should be able to generate and/or process such ERO 234 subobject. An ERO containing SR-ERO subobjects can be included in 235 the PCEP Path Computation Reply (PCRep) message defined in [RFC5440], 236 the PCEP LSP Initiate Request message (PCInitiate) defined in 238 [RFC8281], as well as in the PCEP LSP Update Request (PCUpd) and PCEP 239 LSP State Report (PCRpt) messages defined in defined in [RFC8231]. 241 This document define new subobjects "SRv6-ERO" and "SRv6-RRO" in ERO 242 and RRO respectively to carry SRv6 SID (IPv6 Address). SRv6-capable 243 PCEP speakers MUST be able to generate and/or process this. 245 When a PCEP session between a PCC and a PCE is established, both PCEP 246 speakers exchange their capabilities to indicate their ability to 247 support SRv6 specific functionality. 249 In summary, this document: 251 o Defines a new PCEP capability for SRv6. 253 o Defines a new subobject SRv6-ERO in ERO. 255 o Defines a new subobject SRv6-RRO in RRO. 257 o Defines a new path setup type carried in the PATH-SETUP-TYPE TLV 258 and the PATH-SETUP-TYPE-CAPABILITY TLV. 260 3.1. Operation Overview 262 In SR networks, an ingress node of an SR path appends all outgoing 263 packets with an SR header consisting of a list of SIDs (IPv6 Prefix 264 in case of SRv6). The header has all necessary information to guide 265 the packets from the ingress node to the egress node of the path, and 266 hence there is no need for any signaling protocol. 268 For IPv6 in control plane with MPLS data-plane, mechanism remains 269 same as [RFC8664] 271 This document describes extensions to SR path for IPv6 data plane. 272 SRv6 Path (i.e. ERO) consists of an ordered set of SRv6 SIDs(see 273 details in Figure 2). 275 A PCC or PCE indicates its ability to support SRv6 during the PCEP 276 session Initialization Phase via a new SRv6-PCE-CAPABILITY sub-TLV 277 (see details in Section 4.1.1). 279 3.2. SRv6-Specific PCEP Message Extensions 281 As defined in [RFC5440], a PCEP message consists of a common header 282 followed by a variable length body made up of mandatory and/or 283 optional objects. This document does not require any changes in the 284 format of PCReq and PCRep messages specified in [RFC5440], PCInitiate 285 message specified in [RFC8281], and PCRpt and PCUpd messages 286 specified in [RFC8231]. However, PCEP messages pertaining to SRv6 287 MUST include PATH-SETUP-TYPE TLV in the RP or SRP object to clearly 288 identify that SRv6 is intended. 290 4. Object Formats 292 4.1. The OPEN Object 294 4.1.1. The SRv6 PCE Capability sub-TLV 296 This document defines a new Path Setup Type (PST) [RFC8408] for SRv6, 297 as follows: 299 o PST = TBD2: Path is setup using SRv6. 301 A PCEP speaker MUST indicate its support of the function described in 302 this document by sending a PATH-SETUP-TYPE-CAPABILITY TLV in the OPEN 303 object with this new PST included in the PST list. 305 This document also defines the SRv6-PCE-CAPABILITY sub-TLV. PCEP 306 speakers use this sub-TLV to exchange information about their SRv6 307 capability. If a PCEP speaker includes PST=TBD2 in the PST List of 308 the PATH-SETUP-TYPE-CAPABILITY TLV then it MUST also include the 309 SRv6-PCE-CAPABILITY sub-TLV inside the PATH-SETUP-TYPE-CAPABILITY 310 TLV. 312 The format of the SRv6-PCE-CAPABILITY sub-TLV is shown in the 313 following figure: 315 0 1 2 3 316 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 1 317 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 318 | Type=TBD1 | Length | 319 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 320 | Reserved | Flags |N|X| 321 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 322 | MSD-Type | MSD-Value | MSD-Type | MSD-Value | 323 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 324 // ... // 325 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 326 | MSD-Type | MSD-Value | Padding | 327 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 329 Figure 1: SRv6-PCE-CAPABILITY sub-TLV format 331 The code point for the TLV type (TBD1) is to be defined by IANA. The 332 TLV length is variable. 334 The value comprises of - 336 Reserved: 2 octet, this field MUST be set to 0 on transmission, 337 and ignored on receipt. 339 Flags: 2 octet, two bits are currently assigned in this document. 341 N bit: A PCC sets this flag bit to 1 to indicate that it is 342 capable of resolving a Node or Adjacency Identifier (NAI) to a 343 SRv6-SID. 345 X bit: A PCC sets this bit to 1 to indicate that it does not 346 impose any limit on MSD (irrespective of the MSD-Type). 348 Unassigned bits MUST be set to 0 and ignored on receipt. 350 A pair of (MSD-Type, MSD-Value): Where MSD-Type (1 octet) is as 351 per the IGP MSD Type registry created by [RFC8491] and populated 352 with SRv6 MSD types as per [I-D.ietf-lsr-isis-srv6-extensions]; 353 MSD-Value (1 octet) is as per [RFC8491]. 355 This sub-TLV format is compliant with the PCEP TLV format defined in 356 [RFC5440]. That is, the sub-TLV is composed of 2 octets for the 357 type, 2 octets specifying the length, and a Value field. The Type 358 field when set to TBD1 identifies the SRv6-PCE-CAPABILITY sub-TLV and 359 the presence of the sub-TLV indicates the support for the SRv6 paths 360 in PCEP. The Length field defines the length of the value portion in 361 octets. The TLV is padded to 4-octet alignment, and padding is not 362 included in the Length field. The number of (MSD-Type,MSD-Value) 363 pairs can be determined from the Length field of the TLV. 365 4.2. The RP/SRP Object 367 In order to indicate the SRv6 path, RP or SRP object MUST include the 368 PATH-SETUP-TYPE TLV specified in [RFC8408]. This document defines a 369 new Path Setup Type (PST=TBD2) for SRv6. 371 The LSP-IDENTIFIERS TLV MAY be present for the above PST type. 373 4.3. ERO 375 In order to support SRv6, new subobject "SRv6-ERO" is defined in ERO. 377 4.3.1. SRv6-ERO Subobject 379 An SRv6-ERO subobject is formatted as shown in the following figure. 381 0 1 2 3 382 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 1 383 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 384 |L| Type=TBD3 | Length | NT | Flags |V|T|F|S| 385 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 386 | Reserved | Endpoint Behavior | 387 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 388 | | 389 | SRv6 SID (optional) | 390 | (128-bit) | 391 | | 392 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 393 // NAI (variable, optional) // 394 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 395 | SID Structure (optional) | 396 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 398 Figure 2: SRv6-ERO Subobject Format 400 The fields in the SRv6-ERO Subobject are as follows: 402 The 'L' Flag: Indicates whether the subobject represents a loose-hop 403 (see [RFC3209]). If this flag is set to zero, a PCC MUST NOT 404 overwrite the SID value present in the SRv6-ERO subobject. 405 Otherwise, a PCC MAY expand or replace one or more SID values in the 406 received SRv6-ERO based on its local policy. 408 Type: indicates the content of the subobject, i.e. when the field is 409 set to TBD3, the suboject is a SRv6-ERO subobject representing a SRv6 410 SID. 412 Length: Contains the total length of the subobject in octets. The 413 Length MUST be at least 24, and MUST be a multiple of 4. An SRv6-ERO 414 subobject MUST contain at least one of a SRv6-SID or an NAI. The S 415 and F bit in the Flags field indicates whether the SRv6-SID or NAI 416 fields are absent. 418 NAI Type (NT): Indicates the type and format of the NAI contained in 419 the object body, if any is present. If the F bit is set to zero (see 420 below) then the NT field has no meaning and MUST be ignored by the 421 receiver. This document reuses NT types defined in [RFC8664]: 423 If NT value is 0, the NAI MUST NOT be included. 425 When NT value is 2, the NAI is as per the 'IPv6 Node ID' format 426 defined in [RFC8664], which specifies an IPv6 address. This is 427 used to identify the owner of the SRv6 Identifier. This is 428 optional, as the LOC (the locater portion) of the SRv6 SID serves 429 a similar purpose (when present). 431 When NT value is 4, the NAI is as per the 'IPv6 Adjacency' format 432 defined in [RFC8664], which specify a pair of IPv6 addresses. 433 This is used to identify the IPv6 Adjacency and used with the SRv6 434 Adj-SID. 436 When NT value is 6, the NAI is as per the 'link-local IPv6 437 addresses' format defined in [RFC8664], which specify a pair of 438 (global IPv6 address, interface ID) tuples. It is used to 439 identify the IPv6 Adjacency and used with the SRv6 Adj-SID. 441 SR-MPLS specific NT types are not valid in SRv6-ERO. 443 Flags: Used to carry additional information pertaining to the 444 SRv6-SID. This document defines the following flag bits. The other 445 bits MUST be set to zero by the sender and MUST be ignored by the 446 receiver. 448 o S: When this bit is set to 1, the SRv6-SID value in the subobject 449 body is absent. In this case, the PCC is responsible for choosing 450 the SRv6-SID value, e.g., by looking up in the SR-DB using the NAI 451 which, in this case, MUST be present in the subobject. If the S 452 bit is set to 1 then F bit MUST be set to zero. 454 o F: When this bit is set to 1, the NAI value in the subobject body 455 is absent. The F bit MUST be set to 1 if NT=0, and otherwise MUST 456 be set to zero. The S and F bits MUST NOT both be set to 1. 458 o T: When this bit is set to 1, the SID Structure value in the 459 subobject body is present. The T bit MUST be set to 0 when S bit 460 is set to 1. If the T bit is set when the S bit is set, the T bit 461 MUST be ignored. Thus, the T bit indicates the presence of an 462 optional 8-byte SID Structure when SRv6 SID is included. The SID 463 Structure is defined in Section 4.3.1.1. 465 o V: The "SID verification" bit usage is as per Section 5.1 of 466 [I-D.ietf-spring-segment-routing-policy]. 468 [Editor's Note: Need to check if another flag - A flag for the SR 469 Algorithm is required.] 470 Reserved: MUST be set to zero while sending and ignored on receipt. 472 Endpoint Behavior: A 16 bit field representing the behavior 473 associated with the SRv6 SIDs. This information is optional and 474 plays no role in the fields in SRH imposed on the packet. It could 475 be used for maintainability and diagnostic purpose. If behavior is 476 not known, 0 is used. The list of Endpoint behavior are defined in 477 [I-D.ietf-spring-srv6-network-programming]. 479 SRv6 SID: SRv6 Identifier is the 128 bit IPv6 addresses representing 480 the SRv6 segment. 482 NAI: The NAI associated with the SRv6-SID. The NAI's format depends 483 on the value in the NT field, and is described in [RFC8664]. 485 At least one of the SRv6-SID or the NAI MUST be included in the 486 SRv6-ERO subobject, and both MAY be included. 488 4.3.1.1. SID Structure 490 The SID Structure is an optional part of the SR-ERO subobject, as 491 described in Section 4.3.1. It is formatted as shown in the 492 following figure. 494 0 1 2 3 495 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 1 496 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 497 | LB Length | LN Length | Fun. Length | Arg. Length | 498 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 499 | Reserved | Flags | 500 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 502 Figure 3: SID Structure Format 504 where: 506 LB Length: 1 octet. SRv6 SID Locator Block length in bits. 508 LN Length: 1 octet. SRv6 SID Locator Node length in bits. 510 Fun. Length: 1 octet. SRv6 SID Function length in bits. 512 Arg. Length: 1 octet. SRv6 SID Arguments length in bits. 514 The sum of all four sizes in the SID Structure must be lower or equal 515 to 128 bits. If the sum of all four sizes advertised in the SID 516 Structure is larger than 128 bits, the corresponding SRv6 SID MUST be 517 considered as an Error. A PCErr message with Error-Type = 10 518 ("Reception of an invalid object") and Error-Value = TBD ("Invalid 519 SRv6 SID Structure"). 521 Reserved: MUST be set to zero while sending and ignored on receipt. 523 Flags: Currentky no flags are defined. Unassigned bits must be set 524 to zero while sending and ignored on receipt. 526 The SRv6 SID Structure TLV provides the detailed encoding information 527 of an SRv6 SID, which is useful in the use cases that require to know 528 the SRv6 SID structure. When a PCEP speaker receives the SRv6 SID 529 and its structure information, the SRv6 SID can be parsed based on 530 the SRv6 SID Structure TLV and/or possible local policies. The 531 cunsumers of SRv6 SID structure MAY be other use cases, and the 532 processing and usage of SRv6 SID structure TLV are different based on 533 use cases. This is out of the scope of this document, and will be 534 described in other documents. 536 4.4. RRO 538 In order to support SRv6, new subobject "SRv6-RRO" is defined in RRO. 540 4.4.1. SRv6-RRO Subobject 542 A PCC reports an SRv6 path to a PCE by sending a PCRpt message, per 543 [RFC8231]. The RRO on this message represents the SID list that was 544 applied by the PCC, that is, the actual path taken. The procedures 545 of [RFC8664] with respect to the RRO apply equally to this 546 specification without change. 548 An RRO contains one or more subobjects called "SRv6-RRO subobjects" 549 whose format is shown below: 551 0 1 2 3 552 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 1 553 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 554 | Type=TBD4 | Length | NT | Flags |V|T|F|S| 555 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 556 | Reserved | Endpoint Behavior | 557 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 558 | | 559 | SRv6 SID | 560 | (128-bit) | 561 | | 562 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 563 // NAI (variable) // 564 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 565 | SID Structure (optional) | 566 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 568 Figure 4: SRv6-RRO Subobject Format 570 The format of the SRv6-RRO subobject is the same as that of the 571 SRv6-ERO subobject, but without the L flag. 573 The V flag has no meaning in the SRv6-RRO and is ignored on receipt 574 at the PCE. 576 Ordering of SRv6-RRO subobjects by PCC in PCRpt message remains as 577 per [RFC8664]. 579 5. Procedures 581 5.1. Exchanging the SRv6 Capability 583 A PCC indicates that it is capable of supporting the head-end 584 functions for SRv6 by including the SRv6-PCE-CAPABILITY sub-TLV in 585 the Open message that it sends to a PCE. A PCE indicates that it is 586 capable of computing SRv6 paths by including the SRv6-PCE-CAPABILITY 587 sub-TLV in the Open message that it sends to a PCC. 589 If a PCEP speaker receives a PATH-SETUP-TYPE-CAPABILITY TLV with a 590 PST list containing PST=TBD2, but the SRv6-PCE-CAPABILITY sub-TLV is 591 absent, then the PCEP speaker MUST send a PCErr message with Error- 592 Type 10 (Reception of an invalid object) and Error-Value TBD5 (to be 593 assigned by IANA) (Missing PCE-SRv6-CAPABILITY sub-TLV) and MUST then 594 close the PCEP session. If a PCEP speaker receives a PATH-SETUP- 595 TYPE-CAPABILITY TLV with a SRv6-PCE-CAPABILITY sub-TLV, but the PST 596 list does not contain PST=TBD2, then the PCEP speaker MUST ignore the 597 SRv6-PCE-CAPABILITY sub-TLV. 599 The number of SRv6 SIDs that can be imposed on a packet depends on 600 the PCC's IPv6 data plane's capability. If a PCC sets the X flag to 601 1 then the MSD is not used and MUST NOT be included. If a PCE 602 receives an SRv6-PCE-CAPABILITY sub-TLV with the X flag set to 1 then 603 it MUST ignore any MSD-Type, MSD-Value fields and MUST assume that 604 the sender can impose any length of SRH. If a PCC sets the X flag to 605 zero, then it sets the SRv6 MSD-Type, MSD-Value fields that it can 606 impose on a packet. If a PCE receives an SRv6-PCE-CAPABILITY sub-TLV 607 with the X flag and SRv6 MSD-Type, MSD-Value fields both set to zero 608 then it is considered as an error and the PCE MUST respond with a 609 PCErr message (Error-Type=1 "PCEP session establishment failure" and 610 Error-Value=1 "reception of an invalid Open message or a non Open 611 message."). In case the MSD-Type in SRv6-PCE-CAPABILITY sub-TLV 612 received by the PCE does not correspond to one of the SRv6 MSD types, 613 the PCE MUST respond with a PCErr message (Error-Type=1 "PCEP session 614 establishment failure" and Error-Value=1 "reception of an invalid 615 Open message or a non Open message."). 617 Note that the MSD-Type, MSD-Value exchanged via the SRv6-PCE- 618 CAPABILITY sub-TLV indicates the SRv6 SID imposition limit for the 619 PCC node. However, if a PCE learns these via different means, e.g 620 routing protocols, as specified in: 621 [I-D.li-ospf-ospfv3-srv6-extensions]; 622 [I-D.ietf-lsr-isis-srv6-extensions]; [I-D.ietf-idr-bgpls-srv6-ext], 623 then it ignores the values in the SRv6-PCE-CAPABILITY sub-TLV. 624 Furthermore, whenever a PCE learns the other advanced SRv6 MSD via 625 different means, it MUST use that value regardless of the values 626 exchanged in the SRv6-PCE-CAPABILITY sub-TLV. 628 Once an SRv6-capable PCEP session is established with a non-zero SRv6 629 MSD value, the corresponding PCE MUST NOT send SRv6 paths with a 630 number of SIDs exceeding that SRv6 MSD value (based on the SRv6 MSD 631 Type). If a PCC needs to modify the SRv6 MSD value, it MUST close 632 the PCEP session and re-establish it with the new value. If a PCEP 633 session is established with a non-zero SRv6 MSD value, and the PCC 634 receives an SRv6 path containing more SIDs than specified in the SRv6 635 MSD value (based on the SRv6 MSD type), the PCC MUST send a PCErr 636 message with Error-Type 10 (Reception of an invalid object) and 637 Error-Value 3 (Unsupported number of Segment ERO subobjects). If a 638 PCEP session is established with an SRv6 MSD value of zero, then the 639 PCC MAY specify an SRv6 MSD for each path computation request that it 640 sends to the PCE, by including a "maximum SID depth" metric object on 641 the request similar to [RFC8664]. 643 The N flag, X flag and (MSD-Type,MSD-Value) pair inside the SRv6-PCE- 644 CAPABILITY sub-TLV are meaningful only in the Open message sent from 645 a PCC to a PCE. As such, a PCE MUST set the flags to zero and not 646 include any (MSD-Type,MSD-Value) pair in the SRv6-PCE-CAPABILITY sub- 647 TLV in an outbound message to a PCC. Similarly, a PCC MUST ignore 648 N,X flag and any (MSD-Type,MSD-Value) pair received from a PCE. If a 649 PCE receives multiple SRv6-PCE-CAPABILITY sub-TLVs in an Open 650 message, it processes only the first sub-TLV received. 652 5.2. ERO Processing 654 The ERO processing remains as per [RFC5440] and [RFC8664]. 656 5.2.1. SRv6 ERO Validation 658 If a PCC does not support the SRv6 PCE Capability and thus cannot 659 recognize the SRv6-ERO or SRv6-RRO subobjects, it will respond 660 according to the rules for a malformed object per [RFC5440]. 662 On receiving an SRv6-ERO, a PCC MUST validate that the Length field, 663 the S bit, the F bit, the T bit, and the NT field are consistent, as 664 follows. 666 o If NT=0, the F bit MUST be 1, the S bit MUST be zero and the 667 Length MUST be 24. 669 o If NT=2, the F bit MUST be zero. If the S bit is 1, the Length 670 MUST be 24, otherwise the Length MUST be 40. 672 o If NT=4, the F bit MUST be zero. If the S bit is 1, the Length 673 MUST be 40, otherwise the Length MUST be 56. 675 o If NT=6, the F bit MUST be zero. If the S bit is 1, the Length 676 MUST be 48, otherwise the Length MUST be 64. 678 o NT types (1,3, and 5) are not valid for SRv6. 680 o If T bit is 1, then S bit MUST be zero. 682 If a PCC finds that the NT field, Length field, S bit, F bit, and T 683 bit are not consistent, it MUST consider the entire ERO invalid and 684 MUST send a PCErr message with Error-Type = 10 ("Reception of an 685 invalid object") and Error-Value = 11 ("Malformed object"). 687 If a PCEP speaker that does not recognize the NT value received in 688 SRv6-ERO subobject, it would behave as per [RFC8664]. 690 In case a PCEP speaker receives the SRv6-ERO subobject, when the PST 691 is not set to TBD2 or SRv6-PCE-CAPABILITY sub-TLV was not exchanged, 692 it MUST send a PCErr message with Error-Type = 19 ("Invalid 693 Operation") and Error-Value = TBD5 ("Attempted SRv6 when the 694 capability was not advertised"). 696 If a PCC receives a list of SRv6 segments, and the number of SRv6 697 segments exceeds the SRv6 MSD that the PCC can impose on the packet 698 (SRH), it MUST send a PCErr message with Error-Type = 10 ("Reception 699 of an invalid object") and Error-Value = TBD ("Unsupported number of 700 Segment ERO subobjects") as per [RFC8664]. 702 When a PCEP speaker detects that all subobjects of ERO are not of 703 type TBD3, and if it does not handle such ERO, it MUST send a PCErr 704 message with Error-Type = 10 ("Reception of an invalid object") and 705 Error-Value = TBD ("Non-identical ERO subobjects")as per [RFC8664]. 707 5.2.2. Interpreting the SRv6-ERO 709 The SRv6-ERO contains a sequence of subobjects. According to 710 [I-D.ietf-spring-segment-routing-policy], each SRv6-ERO subobject in 711 the sequence identifies a segment that the traffic will be directed 712 to, in the order given. That is, the first subobject identifies the 713 first segment the traffic will be directed to, the second SRv6-ERO 714 subobject represents the second segment, and so on. 716 The PCC interprets the SRv6-ERO by converting it to an SRv6 SRH plus 717 a next hop. The PCC sends packets along the segment routed path by 718 prepending the SRH onto the packets and sending the resulting, 719 modified packet to the next hop. 721 5.3. RRO Processing 723 The syntax checking rules that apply to the SRv6-RRO subobject are 724 identical to those of the SRv6-ERO subobject, except as noted below. 726 If a PCEP speaker receives an SRv6-RRO subobject in which both SRv6 727 SID and NAI are absent, it MUST consider the entire RRO invalid and 728 send a PCErr message with Error-Type = 10 ("Reception of an invalid 729 object") and Error-Value = TBD6 ("Both SID and NAI are absent in 730 SRv6-RRO subobject"). 732 If a PCE detects that the subobjects of an RRO are a mixture of 733 SRv6-RRO subobjects and subobjects of other types, then it MUST send 734 a PCErr message with Error-Type = 10 ("Reception of an invalid 735 object") and Error-Value = TBD7 ("RRO mixes SRv6-RRO subobjects with 736 other subobject types"). 738 6. Security Considerations 740 The security considerations described in [RFC5440], [RFC8231] and 741 [RFC8281], [RFC8664], are applicable to this specification. No 742 additional security measure is required. 744 7. IANA Considerations 746 7.1. PCEP ERO and RRO subobjects 748 This document defines a new subobject type for the PCEP explicit 749 route object (ERO), and a new subobject type for the PCEP record 750 route object (RRO). The code points for subobject types of these 751 objects is maintained in the RSVP parameters registry, under the 752 EXPLICIT_ROUTE and ROUTE_RECORD objects. IANA is requested to 753 allocate code-points in the RSVP Parameters registry for each of the 754 new subobject types defined in this document. 756 Object Subobject Subobject Type 757 --------------------- -------------------------- ------------------ 758 EXPLICIT_ROUTE SRv6-ERO (PCEP-specific) TBD3 759 ROUTE_RECORD SRv6-RRO (PCEP-specific) TBD4 761 7.2. New SRv6-ERO Flag Registry 763 IANA is requested to create a new sub-registry, named "SRv6-ERO Flag 764 Field", within the "Path Computation Element Protocol (PCEP) Numbers" 765 registry to manage the Flag field of the SRv6-ERO subobject. New 766 values are to be assigned by Standards Action [RFC8126]. Each bit 767 should be tracked with the following qualities: 769 o Bit number (counting from bit 0 as the most significant bit) 771 o Capability description 773 o Defining RFC 775 The following values are defined in this document: 777 Bit Description Reference 778 ----- ------------------ -------------- 779 0-7 Unassigned 780 8 SID Verification (V) This document 781 9 SID Structure is This document 782 present (T) 783 10 NAI is absent (F) This document 784 11 SID is absent (S) This document 786 7.3. PATH-SETUP-TYPE-CAPABILITY Sub-TLV Type Indicators 788 IANA maintains a sub-registry, named "PATH-SETUP-TYPE-CAPABILITY Sub- 789 TLV Type Indicators", within the "Path Computation Element Protocol 790 (PCEP) Numbers" registry to manage the type indicator space for sub- 791 TLVs of the PATH-SETUP-TYPE-CAPABILITY TLV. IANA is requested to 792 make the following assignment: 794 Value Meaning Reference 795 ----- ------- --------- 796 TBD1 SRv6-PCE-CAPABILITY This Document 798 7.4. SRv6 PCE Capability Flags 800 IANA is requested to create a new sub-registry, named "SRv6 801 Capability Flag Field", within the "Path Computation Element Protocol 802 (PCEP) Numbers" registry to manage the Flag field of the SRv6-PCE- 803 CAPABILITY sub-TLV. New values are to be assigned by Standards 804 Action [RFC8126]. Each bit should be tracked with the following 805 qualities: 807 o Bit number (counting from bit 0 as the most significant bit) 809 o Capability description 811 o Defining RFC 813 The following values are defined in this document: 815 Bit Description Reference 817 0-13 Unassigned 818 14 Node or Adjacency This document 819 Identifier (NAI) is 820 supported (N) 821 15 Unlimited Maximum SID This document 822 Depth (X) 824 7.5. New Path Setup Type 826 [RFC8408] created a sub-registry within the "Path Computation Element 827 Protocol (PCEP) Numbers" registry called "PCEP Path Setup Types". 828 IANA is requested to allocate a new code point within this registry, 829 as follows: 831 Value Description Reference 832 ----- ----------- --------- 833 TBD2 Traffic engineering path is This Document 834 setup using SRv6. 836 7.6. ERROR Objects 838 IANA is requested to allocate code-points in the PCEP-ERROR Object 839 Error Types and Values registry for the following new error-values: 841 Error-Type Meaning 842 ---------- ------- 843 10 Reception of an invalid object 844 Error-value = TBD5 (Missing 845 PCE-SRv6-CAPABILITY sub-TLV) 846 Error-value = TBD6 (Both SID and NAI are absent 847 in SRv6-RRO subobject) 848 Error-value = TBD7 (RRO mixes SRv6-RRO subobjects 849 with other subobject types) 850 Error-value = TBD8 (Invalid SRv6 SID Structure) 851 19 Invalid Operation 852 Error-value = TBD5 (Attempted SRv6 when the 853 capability was not advertised) 855 8. Acknowledgements 857 The authors would like to thank Jeff Tentsura, Adrian Farrel, Aijun 858 Wang and Khasanov Boris for valuable suggestions. 860 9. References 862 9.1. Normative References 864 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 865 Requirement Levels", BCP 14, RFC 2119, 866 DOI 10.17487/RFC2119, March 1997, 867 . 869 [RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V., 870 and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP 871 Tunnels", RFC 3209, DOI 10.17487/RFC3209, December 2001, 872 . 874 [RFC5440] Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation 875 Element (PCE) Communication Protocol (PCEP)", RFC 5440, 876 DOI 10.17487/RFC5440, March 2009, 877 . 879 [RFC5511] Farrel, A., "Routing Backus-Naur Form (RBNF): A Syntax 880 Used to Form Encoding Rules in Various Routing Protocol 881 Specifications", RFC 5511, DOI 10.17487/RFC5511, April 882 2009, . 884 [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for 885 Writing an IANA Considerations Section in RFCs", BCP 26, 886 RFC 8126, DOI 10.17487/RFC8126, June 2017, 887 . 889 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 890 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 891 May 2017, . 893 [RFC8231] Crabbe, E., Minei, I., Medved, J., and R. Varga, "Path 894 Computation Element Communication Protocol (PCEP) 895 Extensions for Stateful PCE", RFC 8231, 896 DOI 10.17487/RFC8231, September 2017, 897 . 899 [RFC8281] Crabbe, E., Minei, I., Sivabalan, S., and R. Varga, "Path 900 Computation Element Communication Protocol (PCEP) 901 Extensions for PCE-Initiated LSP Setup in a Stateful PCE 902 Model", RFC 8281, DOI 10.17487/RFC8281, December 2017, 903 . 905 [RFC8402] Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L., 906 Decraene, B., Litkowski, S., and R. Shakir, "Segment 907 Routing Architecture", RFC 8402, DOI 10.17487/RFC8402, 908 July 2018, . 910 [RFC8408] Sivabalan, S., Tantsura, J., Minei, I., Varga, R., and J. 911 Hardwick, "Conveying Path Setup Type in PCE Communication 912 Protocol (PCEP) Messages", RFC 8408, DOI 10.17487/RFC8408, 913 July 2018, . 915 [RFC8491] Tantsura, J., Chunduri, U., Aldrin, S., and L. Ginsberg, 916 "Signaling Maximum SID Depth (MSD) Using IS-IS", RFC 8491, 917 DOI 10.17487/RFC8491, November 2018, 918 . 920 [RFC8664] Sivabalan, S., Filsfils, C., Tantsura, J., Henderickx, W., 921 and J. Hardwick, "Path Computation Element Communication 922 Protocol (PCEP) Extensions for Segment Routing", RFC 8664, 923 DOI 10.17487/RFC8664, December 2019, 924 . 926 [I-D.ietf-lsr-isis-srv6-extensions] 927 Psenak, P., Filsfils, C., Bashandy, A., Decraene, B., and 928 Z. Hu, "IS-IS Extension to Support Segment Routing over 929 IPv6 Dataplane", draft-ietf-lsr-isis-srv6-extensions-11 930 (work in progress), October 2020. 932 [I-D.ietf-spring-srv6-network-programming] 933 Filsfils, C., Camarillo, P., Leddy, J., Voyer, D., 934 Matsushima, S., and Z. Li, "SRv6 Network Programming", 935 draft-ietf-spring-srv6-network-programming-24 (work in 936 progress), October 2020. 938 9.2. Informative References 940 [RFC4657] Ash, J., Ed. and J. Le Roux, Ed., "Path Computation 941 Element (PCE) Communication Protocol Generic 942 Requirements", RFC 4657, DOI 10.17487/RFC4657, September 943 2006, . 945 [RFC7855] Previdi, S., Ed., Filsfils, C., Ed., Decraene, B., 946 Litkowski, S., Horneffer, M., and R. Shakir, "Source 947 Packet Routing in Networking (SPRING) Problem Statement 948 and Requirements", RFC 7855, DOI 10.17487/RFC7855, May 949 2016, . 951 [RFC8051] Zhang, X., Ed. and I. Minei, Ed., "Applicability of a 952 Stateful Path Computation Element (PCE)", RFC 8051, 953 DOI 10.17487/RFC8051, January 2017, 954 . 956 [RFC8354] Brzozowski, J., Leddy, J., Filsfils, C., Maglione, R., 957 Ed., and M. Townsley, "Use Cases for IPv6 Source Packet 958 Routing in Networking (SPRING)", RFC 8354, 959 DOI 10.17487/RFC8354, March 2018, 960 . 962 [RFC8666] Psenak, P., Ed. and S. Previdi, Ed., "OSPFv3 Extensions 963 for Segment Routing", RFC 8666, DOI 10.17487/RFC8666, 964 December 2019, . 966 [RFC8667] Previdi, S., Ed., Ginsberg, L., Ed., Filsfils, C., 967 Bashandy, A., Gredler, H., and B. Decraene, "IS-IS 968 Extensions for Segment Routing", RFC 8667, 969 DOI 10.17487/RFC8667, December 2019, 970 . 972 [RFC8754] Filsfils, C., Ed., Dukes, D., Ed., Previdi, S., Leddy, J., 973 Matsushima, S., and D. Voyer, "IPv6 Segment Routing Header 974 (SRH)", RFC 8754, DOI 10.17487/RFC8754, March 2020, 975 . 977 [I-D.ietf-spring-segment-routing-policy] 978 Filsfils, C., Talaulikar, K., Voyer, D., Bogdanov, A., and 979 P. Mattes, "Segment Routing Policy Architecture", draft- 980 ietf-spring-segment-routing-policy-09 (work in progress), 981 November 2020. 983 [I-D.li-ospf-ospfv3-srv6-extensions] 984 Li, Z., Hu, Z., Cheng, D., Talaulikar, K., and P. Psenak, 985 "OSPFv3 Extensions for SRv6", draft-li-ospf- 986 ospfv3-srv6-extensions-07 (work in progress), November 987 2019. 989 [I-D.ietf-idr-bgpls-srv6-ext] 990 Dawra, G., Filsfils, C., Talaulikar, K., Chen, M., 991 daniel.bernier@bell.ca, d., and B. Decraene, "BGP Link 992 State Extensions for SRv6", draft-ietf-idr-bgpls- 993 srv6-ext-04 (work in progress), November 2020. 995 Appendix A. Contributor 997 The following persons contributed to this document: 999 Dhruv Dhody 1000 Huawei Technologies 1001 Divyashree Techno Park, Whitefield 1002 Bangalore, Karnataka 560066 1003 India 1005 EMail: dhruv.ietf@gmail.com 1007 Huang Wumin 1008 Huawei Technologies 1009 Huawei Building, No. 156 Beiqing Rd. 1010 Beijing 100095 1011 China 1013 Email: huangwumin@huawei.com 1015 Shuping Peng 1016 Huawei Technologies 1017 Huawei Building, No. 156 Beiqing Rd. 1018 Beijing 100095 1019 China 1021 Email: pengshuping@huawei.com 1023 Authors' Addresses 1025 Cheng Li(Editor) 1026 Huawei Technologies 1027 Huawei Campus, No. 156 Beiqing Rd. 1028 Beijing 100095 1029 China 1031 EMail: c.l@huawei.com 1033 Mahendra Singh Negi 1034 RtBrick Inc 1035 Bangalore, Karnataka 1036 India 1038 EMail: mahend.ietf@gmail.com 1039 Mike Koldychev 1040 Cisco Systems, Inc. 1041 Canada 1043 EMail: mkoldych@cisco.com 1045 Prejeeth Kaladharan 1046 RtBrick Inc 1047 Bangalore, Karnataka 1048 India 1050 EMail: prejeeth@rtbrick.com 1052 Yongqing Zhu 1053 China Telecom 1054 109 West Zhongshan Ave, Tianhe District 1055 Bangalore, Guangzhou 1056 P.R. China 1058 EMail: zhuyq8@chinatelecom.cn