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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Inter-Domain Routing G. Dawra, Ed. 3 Internet-Draft LinkedIn 4 Intended status: Standards Track C. Filsfils 5 Expires: January 8, 2020 K. Talaulikar, Ed. 6 Cisco Systems 7 M. Chen 8 Huawei 9 D. Bernier 10 Bell Canada 11 B. Decraene 12 Orange 13 July 7, 2019 15 BGP Link State Extensions for SRv6 16 draft-ietf-idr-bgpls-srv6-ext-01 18 Abstract 20 Segment Routing IPv6 (SRv6) allows for a flexible definition of end- 21 to-end paths within various topologies by encoding paths as sequences 22 of topological or functional sub-paths, called "segments". These 23 segments are advertised by the various protocols such as BGP, ISIS 24 and OSPFv3. 26 BGP Link-state (BGP-LS) address-family solution for SRv6 is similar 27 to BGP-LS for SR for MPLS dataplane. This draft defines extensions 28 to the BGP-LS to advertise SRv6 Segments along with their functions 29 and other attributes via BGP. 31 Requirements Language 33 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 34 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 35 "OPTIONAL" in this document are to be interpreted as described in BCP 36 14 [RFC2119] [RFC8174] when, and only when, they appear in all 37 capitals, as shown here. 39 Status of This Memo 41 This Internet-Draft is submitted in full conformance with the 42 provisions of BCP 78 and BCP 79. 44 Internet-Drafts are working documents of the Internet Engineering 45 Task Force (IETF). Note that other groups may also distribute 46 working documents as Internet-Drafts. The list of current Internet- 47 Drafts is at https://datatracker.ietf.org/drafts/current/. 49 Internet-Drafts are draft documents valid for a maximum of six months 50 and may be updated, replaced, or obsoleted by other documents at any 51 time. It is inappropriate to use Internet-Drafts as reference 52 material or to cite them other than as "work in progress." 54 This Internet-Draft will expire on January 8, 2020. 56 Copyright Notice 58 Copyright (c) 2019 IETF Trust and the persons identified as the 59 document authors. All rights reserved. 61 This document is subject to BCP 78 and the IETF Trust's Legal 62 Provisions Relating to IETF Documents 63 (https://trustee.ietf.org/license-info) in effect on the date of 64 publication of this document. Please review these documents 65 carefully, as they describe your rights and restrictions with respect 66 to this document. Code Components extracted from this document must 67 include Simplified BSD License text as described in Section 4.e of 68 the Trust Legal Provisions and are provided without warranty as 69 described in the Simplified BSD License. 71 Table of Contents 73 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 74 2. BGP-LS Extensions for SRv6 . . . . . . . . . . . . . . . . . 4 75 3. SRv6 Node Attributes . . . . . . . . . . . . . . . . . . . . 5 76 3.1. SRv6 Capabilities TLV . . . . . . . . . . . . . . . . . . 5 77 3.2. SRv6 Node MSD Types . . . . . . . . . . . . . . . . . . . 6 78 4. SRv6 Link Attributes . . . . . . . . . . . . . . . . . . . . 7 79 4.1. SRv6 End.X SID TLV . . . . . . . . . . . . . . . . . . . 7 80 4.2. SRv6 LAN End.X SID TLV . . . . . . . . . . . . . . . . . 9 81 4.3. SRv6 Link MSD Types . . . . . . . . . . . . . . . . . . . 11 82 5. SRv6 Prefix Attributes . . . . . . . . . . . . . . . . . . . 11 83 5.1. SRv6 Locator TLV . . . . . . . . . . . . . . . . . . . . 11 84 6. SRv6 SID NLRI . . . . . . . . . . . . . . . . . . . . . . . . 13 85 6.1. SRv6 SID Information TLV . . . . . . . . . . . . . . . . 15 86 7. SRv6 SID Attributes . . . . . . . . . . . . . . . . . . . . . 15 87 7.1. SRv6 Endpoint Function TLV . . . . . . . . . . . . . . . 15 88 7.2. SRv6 BGP Peer Node SID TLV . . . . . . . . . . . . . . . 16 89 7.3. SRv6 SID Structure TLV . . . . . . . . . . . . . . . . . 18 90 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 19 91 8.1. BGP-LS NLRI-Types . . . . . . . . . . . . . . . . . . . . 19 92 8.2. BGP-LS TLVs . . . . . . . . . . . . . . . . . . . . . . . 19 93 9. Manageability Considerations . . . . . . . . . . . . . . . . 19 94 10. Operational Considerations . . . . . . . . . . . . . . . . . 20 95 10.1. Operations . . . . . . . . . . . . . . . . . . . . . . . 20 96 11. Security Considerations . . . . . . . . . . . . . . . . . . . 20 97 12. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 20 98 13. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 20 99 14. References . . . . . . . . . . . . . . . . . . . . . . . . . 21 100 14.1. Normative References . . . . . . . . . . . . . . . . . . 21 101 14.2. Informative References . . . . . . . . . . . . . . . . . 22 102 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 23 104 1. Introduction 106 SRv6 refers to Segment Routing instantiated on the IPv6 dataplane 107 [RFC8402]. Segment Identifier (SID) is often used as a shorter 108 reference for "SRv6 Segment". 110 The network programming paradigm 111 [I-D.ietf-spring-srv6-network-programming] is central to SRv6. It 112 describes how different functions can be bound to their SIDs and how 113 a network program can be expressed as a combination of SIDs. 115 An SRv6-capable node N maintains a "My SID Table" (refer 116 [I-D.ietf-spring-srv6-network-programming]). This table contains all 117 the SRv6 segments explicitly instantiated at node N. 119 The IS-IS [I-D.ietf-lsr-isis-srv6-extensions] and OSPFv3 120 [I-D.li-ospf-ospfv3-srv6-extensions] link-state routing protocols 121 have been extended to advertise some of these SRv6 SIDs and 122 SRv6-related information. BGP ([I-D.dawra-bess-srv6-services]) has 123 been extended to advertise some of these SRv6 SIDs for VPN services. 124 Certain other SRv6 SIDs may be instantiated on a node via other 125 mechanisms for topological or service functionalities. 127 The advertisement of SR related information along with the topology 128 for the MPLS dataplane instantiation is specified in 129 [I-D.ietf-idr-bgp-ls-segment-routing-ext] and for the BGP Egress Peer 130 Engineering (EPE) is specified in 131 [I-D.ietf-idr-bgpls-segment-routing-epe]. On the similar lines, 132 introducing the SRv6 related information in BGP-LS allows it's 133 consumer applications that require topological visibility to also 134 receive the "My SID Table" from nodes across a domain or even across 135 Autonomous Systems (AS), as required. This allows applications to 136 leverage the SRv6 capabilities for network programming. 138 The identifying key of each Link-State object, namely a node, link, 139 or prefix, is encoded in the NLRI and the properties of the object 140 are encoded in the BGP-LS Attribute [RFC7752]. 142 This document describes extensions to BGP-LS to advertise the SRv6 143 "My SID Table" and other SRv6 information from all the SRv6 capable 144 nodes in the domain when sourced from link-state routing protocols 145 and directly from individual SRv6 capable nodes when sourced from 146 BGP. 148 2. BGP-LS Extensions for SRv6 150 BGP-LS[RFC7752] defines the BGP Node, Link and Prefix attributes. 151 All non-VPN link, node, and prefix information SHALL be encoded using 152 AFI 16388 / SAFI 71. VPN link, node, and prefix information SHALL be 153 encoded using AFI 16388 / SAFI 72. 155 The SRv6 information pertaining to a node is advertised via the BGP- 156 LS Node NLRI and using the BGP-LS Attribute TLVs as follows: 158 o SRv6 Capabilities of the node is advertised via a new SRv6 159 Capabilities TLV 161 o New MSD types introduced for SRv6 are advertised as new sub-TLVs 162 of the Node MSD TLV specified in 163 [I-D.ietf-idr-bgp-ls-segment-routing-msd]. 165 o Algorithm support for SRv6 is advertised via the existing SR 166 Algorithm TLV specified in 167 [I-D.ietf-idr-bgp-ls-segment-routing-ext]. 169 The SRv6 information pertaining to a link is advertised via the BGP- 170 LS Link NLRI and using the BGP-LS Attribute TLVs as follows: 172 o SRv6 End.X SID of the link state routing adjacency or the BGP EPE 173 Peer Adjacency is advertised via a new SRv6 End.X SID TLV 175 o SRv6 LAN End.X SID of the link state routing adjacency to a non- 176 DR/DIS router is advertised via a new SRv6 LAN End.X SID TLV 178 o New MSD types introduced for SRv6 are advertised as new sub-TLVs 179 of the Link MSD TLV specified in 180 [I-D.ietf-idr-bgp-ls-segment-routing-msd]. 182 The SRv6 Locator information of a node is advertised via the BGP-LS 183 Prefix NLRI using the new SRv6 Locator TLV in the BGP-LS Attribute. 185 The SRv6 SIDs associated with the node from its "My SID Table" are 186 advertised as a newly introduce BGP-LS SRv6 SID NLRI. This enables 187 the BGP-LS encoding to scale to cover a potentially large set of SRv6 188 SIDs instantiated on a node with the granularity of individual SIDs 189 and without affecting the size and scalability of the BGP-LS updates. 190 New BGP-LS Attribute TLVs are introduced for the SRv6 SID NLRI as 191 follows: 193 o The endpoint function of the SRv6 SID is advertised via a new SRv6 194 Endpoint Function TLV 196 o The BGP EPE Peer Node and Peer Set SID context is advertised via a 197 new SRv6 BGP EPE Peer Node SID TLV 199 When the BGP-LS router is advertising topology information that it 200 sources from the underlying link-state routing protocol, then it maps 201 the corresponding SRv6 information from the SRv6 extensions for IS-IS 202 [I-D.ietf-lsr-isis-srv6-extensions] and OSPFv3 203 [I-D.li-ospf-ospfv3-srv6-extensions] protocols to their BGP-LS TLVs/ 204 sub-TLVs for all SRv6 capable nodes in that routing protocol domain. 205 When the BGP-LS router is advertising topology information from the 206 BGP routing protocol [I-D.ietf-idr-bgpls-segment-routing-epe], then 207 it advertises the SRv6 information from the local node alone (e.g. 208 BGP EPE topology information or in the case of a data center network 209 running BGP as the only routing protocol). 211 Subsequent sections of this document specify the encoding of the 212 newly defined extensions. 214 3. SRv6 Node Attributes 216 SRv6 attributes of a node are advertised using the new BGP-LS 217 Attribute TLVs defined in this section and associated with the BGP-LS 218 Node NLRI. 220 3.1. SRv6 Capabilities TLV 222 This BGP-LS Attribute TLV is used to announce the SRv6 capabilities 223 of the node along with the BGP-LS Node NLRI and indicates the SRv6 224 support by the node. A single instance of this TLV MUST be included 225 in the BGP-LS attribute for each SRv6 capable node. This TLV maps to 226 the SRv6 Capabilities sub-TLV and the SRv6 Capabilities TLV of the 227 IS-IS and OSPFv3 protocol SRv6 extensions respectively. 229 0 1 2 3 230 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 1 231 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 232 | Type | Length | 233 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 234 | Flags | Reserved | 235 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 237 Figure 1: SRv6 Capabilities TLV Format 239 Where: 241 o Type: 2 octet field with value TBD, see Section 8. 243 o Length : 2 octet field with value set to 4. 245 o Flags: 2 octet field. The following flags are defined: 247 0 1 248 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 249 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 250 | |O| | 251 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 253 Figure 2: SRv6 Capability TLV Flags Format 255 * O-flag: If set, then router is capable of supporting SRH O-bit 256 Flags, as specified in [I-D.ali-spring-srv6-oam]. 258 o Reserved: 2 octet that SHOULD be set to 0 and MUST be ignored on 259 receipt. 261 3.2. SRv6 Node MSD Types 263 The Node MSD TLV [I-D.ietf-idr-bgp-ls-segment-routing-msd] of the 264 BGP-LS Attribute of the Node NLRI is also used to advertise the 265 limits and the supported Segment Routing Header (SRH) 266 [I-D.ietf-6man-segment-routing-header] operations supported by the 267 SRv6 capable node. The SRv6 MSD Types specified in 268 [I-D.ietf-lsr-isis-srv6-extensions] are also used with the BGP-LS 269 Node MSD TLV as these codepoints are shared between IS-IS, OSPF and 270 BGP-LS protocols. The description and semantics of these new MSD 271 types for BGP-LS are identical as specified 272 [I-D.ietf-lsr-isis-srv6-extensions] and summarized in the table 273 below: 275 +----------+------------------------------+ 276 | MSD Type | Description | 277 +----------+------------------------------+ 278 | TBD | Maximum Segments Left | 279 | TBD | Maximum End Pop | 280 | TBD | Maximum T.Insert | 281 | TBD | Maximum T.Encaps | 282 | TBD | Maximum End D | 283 +----------+------------------------------+ 285 Figure 3: SRv6 Node MSD Types 287 Each MSD type is encoded as a one octet type followed by a one octet 288 value. 290 4. SRv6 Link Attributes 292 SRv6 attributes and SIDs associated with a link or adjacency are 293 advertised using the new BGP-LS Attribute TLVs defined in this 294 section and associated with the BGP-LS Link NLRI. 296 4.1. SRv6 End.X SID TLV 298 The SRv6 End.X SID TLV is used to advertise the SRv6 End.X SIDs that 299 correspond to a point-to-point or point-to-multipoint link or 300 adjacency of the local node for IS-IS and OSPFv3 protocols. This TLV 301 can also be used to advertise the End.X function SRv6 SID 302 corresponding to the underlying layer-2 member links for a layer-3 303 bundle interface using L2 Bundle Member Attribute TLV as specified in 304 [I-D.ietf-idr-bgp-ls-segment-routing-ext] . 306 For the nodes running BGP routing protocol, this TLV is used to 307 advertise the BGP EPE Peer Adjacency SID for SRv6 on the same lines 308 as specified for SR/MPLS in [I-D.ietf-idr-bgpls-segment-routing-epe]. 309 The SRv6 End.X SID for the BGP Peer Adjacency indicates the cross- 310 connect to a specific layer-3 link to the specific BGP session peer 311 (neighbor). 313 The TLV has the following format: 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 | Length | 319 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 320 | SRv6 Endpoint Function | Flags | Algorithm | 321 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 322 | Weight | Reserved | SID (16 octets) ... 323 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 324 SID (cont ...) 325 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 326 SID (cont ...) 327 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 328 SID (cont ...) 329 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 330 SID (cont ...) | Sub-TLVs (variable) . . . 331 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 333 Figure 4: SRv6 End.X TLV Format 335 Where: 337 Type: 2 octet field with value TBD, see Section 8. 339 Length: 2 octet field with the total length of the value portion 340 of the TLV. 342 Function Code: 2 octet field. The Endpoint Function code point 343 for this SRv6 SID as defined in 344 [I-D.ietf-spring-srv6-network-programming]. 346 Flags: 1 octet of flags with the following definition: 348 0 1 2 3 4 5 6 7 349 +-+-+-+-+-+-+-+-+ 350 |B|S|P| Rsvd | 351 +-+-+-+-+-+-+-+-+ 353 Figure 5: SRv6 End.X SID TLV Flags Format 355 * B-Flag: Backup Flag. If set, the SID is eligible for 356 protection (e.g. using IPFRR) as described in [RFC8355]. 358 * S-Flag: Set Flag. When set, the S-Flag indicates that the SID 359 refers to a set of adjacencies (and therefore MAY be assigned 360 to other adjacencies as well). 362 * P-Flag: Persistent Flag: When set, the P-Flag indicates that 363 the SID is persistently allocated, i.e., the value remains 364 consistent across router restart and/or interface flap. 366 * Rsvd bits: Reserved for future use and MUST be zero when 367 originated and ignored when received. 369 Algorithm: 1 octet field. Algorithm associated with the SID. 370 Algorithm values are defined in the IGP Algorithm Type registry. 372 Weight: 1 octet field. The value represents the weight of the SID 373 for the purpose of load balancing. The use of the weight is 374 defined in [RFC8402]. 376 Reserved: 1 octet field that SHOULD be set to 0 and MUST be 377 ignored on receipt. 379 SID: 16 octet field. This field encodes the advertised SRv6 SID 380 as 128 bit value. 382 Sub-TLVs : currently none defined. Used to advertise sub-TLVs 383 that provide additional attributes for the given SRv6 End.X SID. 385 4.2. SRv6 LAN End.X SID TLV 387 For a LAN interface, normally a node only announces its adjacency to 388 the IS-IS pseudo-node (or the equivalent OSPF Designated Router). 389 The SRv6 LAN End.X SID TLV allows a node to announce SRv6 SID 390 corresponding to functions like END.X for its adjacencies to all 391 other (i.e. non-DIS or non-DR) nodes attached to the LAN in a single 392 instance of the BGP-LS Link NLRI. Without this TLV, the 393 corresponding BGP-LS link NLRI would need to be originated for each 394 additional adjacency in order to advertise the SRv6 End.X SID TLVs 395 for these neighbor adjacencies. 397 The IS-IS and OSPFv3 SRv6 LAN End.X SID TLVs have the following 398 format: 400 0 1 2 3 401 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 1 402 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 403 | Type | Length | 404 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 405 | SRv6 Endpoint Function | Flags | Algorithm | 406 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 407 | Weight | Reserved | ISIS System-ID (6 octets) | 408 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | 409 | or OSPFv3 Router-ID (4 octets) of the neighbor | 410 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 411 | SID (16 octets) ... 412 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 413 SID (cont ...) 414 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 415 SID (cont ...) 416 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 417 SID (cont ...) | 418 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 419 | Sub-TLVs (variable) . . . 420 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 422 Figure 6: SRv6 LAN End.X SID TLV Format 424 Where: 426 o Type: 2 octet field with value TBD in case of IS-IS and TBD in 427 case of OSPFv3, see Section 8. 429 o Length: 2 octet field with the total length of the value portion 430 of the TLV. 432 o Function Code: 2 octet field. The Endpoint Function code point 433 for this SRv6 SID as defined in 434 [I-D.ietf-spring-srv6-network-programming]. 436 o Flags: 1 octet of flags with the following definition: 438 0 1 2 3 4 5 6 7 439 +-+-+-+-+-+-+-+-+ 440 |B|S|P| Rsvd | 441 +-+-+-+-+-+-+-+-+ 443 Figure 7: SRv6 LAN End.X SID TLV Flags Format 445 * B-Flag: Backup Flag. If set, the SID is eligible for 446 protection (e.g. using IPFRR) as described in [RFC8355]. 448 * S-Flag: Set Flag. When set, the S-Flag indicates that the SID 449 refers to a set of adjacencies (and therefore MAY be assigned 450 to other adjacencies as well). 452 * P-Flag: Persistent Flag: When set, the P-Flag indicates that 453 the SID is persistently allocated, i.e., the value remains 454 consistent across router restart and/or interface flap. 456 * Rsvd bits: Reserved for future use and MUST be zero when 457 originated and ignored when received. 459 o Algorithm: 1 octet field. Algorithm associated with the SID. 460 Algorithm values are defined in the IGP Algorithm Type registry. 462 o Weight: 1 octet field. The value represents the weight of the SID 463 for the purpose of load balancing. The use of the weight is 464 defined in [RFC8402]. 466 o Reserved: 1 octet field that SHOULD be set to 0 and MUST be 467 ignored on receipt. 469 o Neighbor ID : 6 octets of ISIS System ID of the neighbor for the 470 ISIS SRv6 LAN End.X SID TLV and 4 octets of OSPFv3 Router-id of 471 the neighbor for the OSPFv3 SRv6 LAN End.X SID TLV. 473 o SID: 16 octet field. This field encodes the advertised SRv6 SID 474 as 128 bit value. 476 o Sub-TLVs : currently none defined. Used to advertise sub-TLVs 477 that provide additional attributes for the given SRv6 LAN End.X 478 SID. 480 4.3. SRv6 Link MSD Types 482 The Link MSD TLV [I-D.ietf-idr-bgp-ls-segment-routing-msd] of the 483 BGP-LS Attribute of the Link NLRI is also used to advertise the 484 limits and the supported Segment Routing Header (SRH) operations 485 supported on the specific link by the SRv6 capable node. The SRv6 486 MSD Types specified in [I-D.ietf-lsr-isis-srv6-extensions] are also 487 used with the BGP-LS Link MSD TLV as these codepoints are shared 488 between IS-IS, OSPF and BGP-LS protocols. The description and 489 semantics of these new MSD types for BGP-LS are identical as 490 specified [I-D.ietf-lsr-isis-srv6-extensions] and summarized in the 491 table below: 493 +----------+------------------------------+ 494 | MSD Type | Description | 495 +----------+------------------------------+ 496 | TBD | Maximum Segments Left | 497 | TBD | Maximum End Pop | 498 | TBD | Maximum T.Insert | 499 | TBD | Maximum T.Encaps | 500 | TBD | Maximum End D | 501 +----------+------------------------------+ 503 Figure 8: SRv6 Link MSD Types 505 Each MSD type is encoded as a one octet type followed by a one octet 506 value. 508 5. SRv6 Prefix Attributes 510 SRv6 attributes with an IPv6 prefix are advertised using the new BGP- 511 LS Attribute TLVs defined in this section and associated with the 512 BGP-LS Prefix NLRI. 514 5.1. SRv6 Locator TLV 516 As described in [I-D.ietf-spring-srv6-network-programming], an SRv6 517 SID is 128 bits and represented as 519 LOC:FUNCT 521 where LOC (the locator portion) is the L most significant bits and 522 FUNCT is the 128-L least significant bits. L is called the locator 523 length and is flexible. A node is provisioned with one or more 524 locators supported by that node. Locators are covering prefixes for 525 the set of SIDs provisioned on that node. These Locators are 526 advertised as BGP-LS Prefix NLRI objects along with the SRv6 Locator 527 TLV in its BGP-LS Attribute. 529 The IPv6 Prefix matching the Locator MAY be also advertised as a 530 prefix reachability by the underlying routing protocol. In this 531 case, the Prefix NLRI would be also associated with the Prefix Metric 532 TLV that carries the routing metric for this prefix. When the 533 Locator prefix is not being advertised as a prefix reachability, then 534 the Prefix NLRI would have the SRv6 Locator TLV associated with it 535 but no Prefix Metric TLV. In the absence of Prefix Metric TLV, the 536 consumer of the BGP-LS topology information MUST NOT interpret the 537 Locator prefix as a prefix reachability routing advertisement. 539 The SRv6 Locator TLV has the following format: 541 0 1 2 3 542 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 1 543 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 544 | Type | Length | 545 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 546 | Flags | Algorithm | Reserved | 547 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 548 | Metric | 549 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 550 | Sub-TLVs (variable) . . . 551 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 553 Figure 9: SRv6 Locator TLV Format 555 Where: 557 Type: 2 octet field with value TBD, see Section 8. 559 Length: 2 octet field with the total length of the value portion 560 of the TLV. 562 Flags: 1 octet of flags with the following definition: 564 0 1 2 3 4 5 6 7 565 +-+-+-+-+-+-+-+-+ 566 |D|A| Reserved | 567 +-+-+-+-+-+-+-+-+ 569 Figure 10: SRv6 Locator TLV Flags Format 571 * D-Flag: Indicates that the locator has been leaked into the IGP 572 domain when set. IS-IS operations for this are discussed in 573 [I-D.ietf-lsr-isis-srv6-extensions]. 575 * A-Flag: When the Locator is associated with anycast 576 destinations, the A flag SHOULD be set. Otherwise, this bit 577 MUST be clear. 579 * Reserved bits: Reserved for future use and MUST be zero when 580 originated and ignored when received. 582 Algorithm: 1 octet field. Algorithm associated with the SID. 583 Algorithm values are defined in the IGP Algorithm Type registry. 585 Reserved: 2 octet field. The value MUST be zero when originated 586 and ignored when received. 588 Metric: 4 octet field. The value of the metric for the Locator. 590 Sub-TLVs : currently none defined. Used to advertise sub-TLVs 591 that provide additional attributes for the given SRv6 Locator. 593 6. SRv6 SID NLRI 595 SRv6 SID information is advertised in BGP UPDATE messages using the 596 MP_REACH_NLRI and MP_UNREACH_NLRI attributes [RFC4760]. The "Link- 597 State NLRI" defined in [RFC7752] is extended to carry the SRv6 SID 598 information. 600 A new "Link-State NLRI Type" is defined for SRv6 SID information as 601 following: 603 o Link-State NLRI Type: SRv6 SID NLRI (value TBD see IANA 604 Considerations Section 8.1). 606 The format of this new NLRI type is as shown in the following figure: 608 0 1 2 3 609 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 1 610 +-+-+-+-+-+-+-+-+ 611 | Protocol-ID | 612 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 613 | Identifier | 614 | (64 bits) | 615 ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+| 616 | Local Node Descriptors (variable) // 617 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 618 | SRv6 SID Descriptors (variable) // 619 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 621 Figure 11: SRv6 SID NLRI Format 623 Where: 625 o Protocol-ID: 1 octet field that specifies the protocol component 626 through which BGP-LS learns the SRv6 SIDs of the node. The 627 following Protocol-IDs apply to the SRv6 SID NLRI: 629 +-------------+----------------------------------+ 630 | Protocol-ID | NLRI information source protocol | 631 +-------------+----------------------------------+ 632 | 1 | IS-IS Level 1 | 633 | 2 | IS-IS Level 2 | 634 | 4 | Direct | 635 | 5 | Static configuration | 636 | 6 | OSPFv3 | 637 | 7 | BGP | 638 +-------------+----------------------------------+ 640 Figure 12: Protocol IDs for SRv6 SID NLRI 642 o Identifier: 8 octet value as defined in [RFC7752]. 644 o Local Node Descriptors TLV: as defined in [RFC7752] for IGPs, 645 local and static configuration and as defined in 646 [I-D.ietf-idr-bgpls-segment-routing-epe] for BGP protocol. 648 o SRv6 SID Descriptors: MUST include the SRv6 SID Information TLV 649 defined in Section 6.1 and optionally MAY include the Multi- 650 Topology Identifier TLV as defined in [RFC7752]. 652 New TLVs carried in the BGP Link State Attribute defined in [RFC7752] 653 are also defined in order to carry the attributes of a SRv6 SID in 654 Section 7. 656 6.1. SRv6 SID Information TLV 658 A SRv6 SID is a 128 bit value 659 [I-D.ietf-spring-srv6-network-programming] and is encoded using the 660 SRv6 SID Information TLV. 662 The TLV has the following format: 664 0 1 2 3 665 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 1 666 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 667 | Type | Length | 668 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 669 | SID (16 octets) ... 670 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 671 SID (cont ...) 672 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 673 SID (cont ...) 674 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 675 SID (cont ...) | 676 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 678 Figure 13: SRv6 SID Information TLV Format 680 Where: 682 Type: 2 octet field with value TBD, see Section 8. 684 Length: 2 octet field with value set to 16. 686 SID: 16 octet field. This field encodes the advertised SRv6 SID 687 as 128 bit value. 689 7. SRv6 SID Attributes 691 This section specifies the new TLVs to be carried in the BGP Link 692 State Attribute associated with the BGP-LS SRv6 SID NLRI. 694 7.1. SRv6 Endpoint Function TLV 696 Each SRv6 SID instantiated in the "My SID Table" of an SRv6 capable 697 node has a specific instruction bound to it. A set of well-known 698 functions that can be associated with a SID are defined in 699 [I-D.ietf-spring-srv6-network-programming]. 701 The SRv6 Endpoint Function TLV is a mandatory TLV that MUST be 702 included in the BGP-LS Attribute associated with the BGP-LS SRv6 SID 703 NLRI. The TLV has the following format: 705 0 1 2 3 706 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 1 707 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 708 | Type | Length | 709 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 710 | SRv6 Endpoint Function | Flags | Algorithm | 711 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 713 Figure 14: SRv6 Endpoint Function TLV 715 Where: 717 Type: 2 octet field with value TBD, see Section 8. 719 Length: 2 octet field with the value 4. 721 Function Code: 2 octet field. The Endpoint Function code point 722 for this SRv6 SID as defined in 723 [I-D.ietf-spring-srv6-network-programming]. 725 Flags: 1 octet of flags with the none defined currently. Reserved 726 for future use and MUST be zero when originated and ignored when 727 received. 729 Algorithm: 1 octet field. Algorithm associated with the SID. 730 Algorithm values are defined in the IGP Algorithm Type registry. 732 7.2. SRv6 BGP Peer Node SID TLV 734 The BGP Peer Node SID and Peer Set SID for SR with MPLS dataplane are 735 specified in [I-D.ietf-idr-bgpls-segment-routing-epe]. The similar 736 Peer Node and Peer Set SID functionality can be realized with SRv6 737 using the END.X SRv6 SID. The SRv6 BGP Peer Node SID TLV is an 738 optional TLV for use in the BGP-LS Attribute for an SRv6 SID NLRI 739 corresponding to BGP protocol. This TLV MUST be included along with 740 SRv6 End.X SID that is associated with the BGP Peer Node or Peer Set 741 functionality. 743 The TLV has the following format: 745 0 1 2 3 746 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 1 747 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 748 | Type | Length | 749 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 750 | Flags | Weight | Reserved | 751 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 752 | Peer AS Number | 753 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 754 | Peer BGP Identifier | 755 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 757 Figure 15: SRv6 BGP Peer Node SID TLV Format 759 Where: 761 o Type: 2 octet field with value TBD, see Section 8. 763 o Length: 2 octet field with the value 12. 765 o Flags: 1 octet of flags with the following definition: 767 0 1 2 3 4 5 6 7 768 +-+-+-+-+-+-+-+-+ 769 |B|S|P| Rsvd | 770 +-+-+-+-+-+-+-+-+ 772 Figure 16: SRv6 BGP Peer End.X SID TLV Flags Format 774 * B-Flag: Backup Flag. If set, the SID is eligible for 775 protection (e.g. using IPFRR) as described in [RFC8355]. 777 * S-Flag: Set Flag. When set, the S-Flag indicates that the SID 778 refers to a set of BGP peering sessions (i.e. BGP Peer Set SID 779 functionality) and therefore MAY be assigned to one or more 780 End.X SIDs associated with BGP peer sessions. 782 * P-Flag: Persistent Flag: When set, the P-Flag indicates that 783 the SID is persistently allocated, i.e., the value remains 784 consistent across router restart and/or session flap. 786 * Rsvd bits: Reserved for future use and MUST be zero when 787 originated and ignored when received. 789 o Weight: 1 octet field. The value represents the weight of the SID 790 for the purpose of load balancing. The use of the weight is 791 defined in [RFC8402]. 793 o Peer AS Number : 4 octets of BGP AS number of the peer router. 795 o Peer BGP Identifier : 4 octets of the BGP Identifier (BGP Router- 796 ID) of the peer router. 798 For a SRv6 BGP EPE Peer Node SID, one instance of this TLV is 799 associated with the SRv6 SID. For SRv6 BGP EPE Peer Set SID, 800 multiple instances of this TLV (one for each peer in the "peer set") 801 are associated with the SRv6 SID and the S (set/group) flag is SET. 803 7.3. SRv6 SID Structure TLV 805 SRv6 SID Structure TLV is used to advertise the length of each 806 individual part of the SRv6 SID as defined in 807 [I-D.ietf-spring-srv6-network-programming]. It is an optional TLV 808 for use in the BGP-LS Attribute for an SRv6 SID NLRI. The TLV has 809 the following format: 811 0 1 2 3 812 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 1 813 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 814 | Type | Length | 815 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 816 | LB Length | LN Length | Fun. Length | Arg. Length | 817 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 819 Figure 17: SRv6 SID Structure TLV 821 Where: 823 Type: 2 octet field with value TBD, see Section 8. 825 Length: 2 octet field with the value 4. 827 LB Length: 1 octet field. SRv6 SID Locator Block length in bits. 829 LN Length: 1 octet field. SRv6 SID Locator Node length in bits. 831 Function Length: 1 octet field. SRv6 SID Function length in bits. 833 Argument Length: 1 octet field. SRv6 SID Argument length in bits. 835 8. IANA Considerations 837 This document requests assigning code-points from the IANA "Border 838 Gateway Protocol - Link State (BGP-LS) Parameters" registry as 839 described in the sub-sections below. 841 8.1. BGP-LS NLRI-Types 843 The following codepoints is suggested (to be assigned by IANA) from 844 within the sub-registry called "BGP-LS NLRI-Types": 846 +------+----------------------------+---------------+ 847 | Type | NLRI Type | Reference | 848 +------+----------------------------+---------------+ 849 | TBD | SRv6 SID | this document | 850 +------+----------------------------+---------------+ 852 Figure 18: SRv6 SID NLRI Type Codepoint 854 8.2. BGP-LS TLVs 856 The following TLV codepoints are suggested (to be assigned by IANA) 857 from within the sub-registry called "BGP-LS Node Descriptor, Link 858 Descriptor, Prefix Descriptor, and Attribute TLVs": 860 +----------+----------------------------------------+---------------+ 861 | TLV Code | Description | Value defined | 862 | Point | | in | 863 +----------+----------------------------------------+---------------+ 864 | TBD | SRv6 Capabilities TLV | this document | 865 | TBD | SRv6 End.X SID TLV | this document | 866 | TBD | IS-IS SRv6 LAN End.X SID TLV | this document | 867 | TBD | OSPFv3 SRv6 LAN End.X SID TLV | this document | 868 | TBD | SRv6 Locator TLV | this document | 869 | TBD | SRv6 SID Information TLV | this document | 870 | TBD | SRv6 Endpoint Function TLV | this document | 871 | TBD | SRv6 BGP Peer Node SID TLV | this document | 872 | TBD | SRv6 SID Structure TLV | this document | 873 +----------+----------------------------------------+---------------+ 875 Figure 19: SRv6 BGP-LS Attribute TLV Codepoints 877 9. Manageability Considerations 879 This section is structured as recommended in[RFC5706] 881 10. Operational Considerations 883 10.1. Operations 885 Existing BGP and BGP-LS operational procedures apply. No additional 886 operation procedures are defined in this document. 888 11. Security Considerations 890 Procedures and protocol extensions defined in this document do not 891 affect the BGP security model. See the 'Security Considerations' 892 section of [RFC4271] for a discussion of BGP security. Also refer 893 to[RFC4272] and [RFC6952] for analysis of security issues for BGP. 895 12. Contributors 897 James Uttaro 898 AT&T 899 USA 900 Email: ju1738@att.com 902 Hani Elmalky 903 Ericsson 904 USA 905 Email: hani.elmalky@gmail.com 907 Arjun Sreekantiah 908 Individual 909 USA 910 Email: arjunhrs@gmail.com 912 Les Ginsberg 913 Cisco Systems 914 USA 915 Email: ginsberg@cisco.com 917 Shunwan Zhuang 918 Huawei 919 China 920 Email: zhuangshunwan@huawei.com 922 13. Acknowledgements 924 The authors would like to thank Peter Psenak and Arun Babu for their 925 review of this document and their comments. 927 14. References 929 14.1. Normative References 931 [I-D.ali-spring-srv6-oam] 932 Ali, Z., Filsfils, C., Kumar, N., Pignataro, C., 933 faiqbal@cisco.com, f., Gandhi, R., Leddy, J., Matsushima, 934 S., Raszuk, R., daniel.voyer@bell.ca, d., Dawra, G., 935 Peirens, B., Chen, M., and G. Naik, "Operations, 936 Administration, and Maintenance (OAM) in Segment Routing 937 Networks with IPv6 Data plane (SRv6)", draft-ali-spring- 938 srv6-oam-02 (work in progress), October 2018. 940 [I-D.dawra-bess-srv6-services] 941 Dawra, G., Filsfils, C., Brissette, P., Agrawal, S., 942 Leddy, J., daniel.voyer@bell.ca, d., 943 daniel.bernier@bell.ca, d., Steinberg, D., Raszuk, R., 944 Decraene, B., Matsushima, S., Zhuang, S., and J. Rabadan, 945 "SRv6 BGP based Overlay services", draft-dawra-bess- 946 srv6-services-01 (work in progress), July 2019. 948 [I-D.ietf-6man-segment-routing-header] 949 Filsfils, C., Dukes, D., Previdi, S., Leddy, J., 950 Matsushima, S., and d. daniel.voyer@bell.ca, "IPv6 Segment 951 Routing Header (SRH)", draft-ietf-6man-segment-routing- 952 header-21 (work in progress), June 2019. 954 [I-D.ietf-idr-bgp-ls-segment-routing-ext] 955 Previdi, S., Talaulikar, K., Filsfils, C., Gredler, H., 956 and M. Chen, "BGP Link-State extensions for Segment 957 Routing", draft-ietf-idr-bgp-ls-segment-routing-ext-16 958 (work in progress), June 2019. 960 [I-D.ietf-idr-bgp-ls-segment-routing-msd] 961 Tantsura, J., Chunduri, U., Talaulikar, K., Mirsky, G., 962 and N. Triantafillis, "Signaling MSD (Maximum SID Depth) 963 using Border Gateway Protocol Link-State", draft-ietf-idr- 964 bgp-ls-segment-routing-msd-05 (work in progress), June 965 2019. 967 [I-D.ietf-idr-bgpls-segment-routing-epe] 968 Previdi, S., Talaulikar, K., Filsfils, C., Patel, K., Ray, 969 S., and J. Dong, "BGP-LS extensions for Segment Routing 970 BGP Egress Peer Engineering", draft-ietf-idr-bgpls- 971 segment-routing-epe-19 (work in progress), May 2019. 973 [I-D.ietf-lsr-isis-srv6-extensions] 974 Psenak, P., Filsfils, C., Bashandy, A., Decraene, B., and 975 Z. Hu, "IS-IS Extension to Support Segment Routing over 976 IPv6 Dataplane", draft-ietf-lsr-isis-srv6-extensions-02 977 (work in progress), July 2019. 979 [I-D.ietf-spring-srv6-network-programming] 980 Filsfils, C., Camarillo, P., Leddy, J., 981 daniel.voyer@bell.ca, d., Matsushima, S., and Z. Li, "SRv6 982 Network Programming", draft-ietf-spring-srv6-network- 983 programming-01 (work in progress), July 2019. 985 [I-D.li-ospf-ospfv3-srv6-extensions] 986 Li, Z., Hu, Z., Cheng, D., Talaulikar, K., and P. Psenak, 987 "OSPFv3 Extensions for SRv6", draft-li-ospf- 988 ospfv3-srv6-extensions-03 (work in progress), March 2019. 990 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 991 Requirement Levels", BCP 14, RFC 2119, 992 DOI 10.17487/RFC2119, March 1997, 993 . 995 [RFC7752] Gredler, H., Ed., Medved, J., Previdi, S., Farrel, A., and 996 S. Ray, "North-Bound Distribution of Link-State and 997 Traffic Engineering (TE) Information Using BGP", RFC 7752, 998 DOI 10.17487/RFC7752, March 2016, 999 . 1001 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 1002 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 1003 May 2017, . 1005 [RFC8402] Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L., 1006 Decraene, B., Litkowski, S., and R. Shakir, "Segment 1007 Routing Architecture", RFC 8402, DOI 10.17487/RFC8402, 1008 July 2018, . 1010 14.2. Informative References 1012 [RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A 1013 Border Gateway Protocol 4 (BGP-4)", RFC 4271, 1014 DOI 10.17487/RFC4271, January 2006, 1015 . 1017 [RFC4272] Murphy, S., "BGP Security Vulnerabilities Analysis", 1018 RFC 4272, DOI 10.17487/RFC4272, January 2006, 1019 . 1021 [RFC4760] Bates, T., Chandra, R., Katz, D., and Y. Rekhter, 1022 "Multiprotocol Extensions for BGP-4", RFC 4760, 1023 DOI 10.17487/RFC4760, January 2007, 1024 . 1026 [RFC5706] Harrington, D., "Guidelines for Considering Operations and 1027 Management of New Protocols and Protocol Extensions", 1028 RFC 5706, DOI 10.17487/RFC5706, November 2009, 1029 . 1031 [RFC6952] Jethanandani, M., Patel, K., and L. Zheng, "Analysis of 1032 BGP, LDP, PCEP, and MSDP Issues According to the Keying 1033 and Authentication for Routing Protocols (KARP) Design 1034 Guide", RFC 6952, DOI 10.17487/RFC6952, May 2013, 1035 . 1037 [RFC8355] Filsfils, C., Ed., Previdi, S., Ed., Decraene, B., and R. 1038 Shakir, "Resiliency Use Cases in Source Packet Routing in 1039 Networking (SPRING) Networks", RFC 8355, 1040 DOI 10.17487/RFC8355, March 2018, 1041 . 1043 Authors' Addresses 1045 Gaurav Dawra (editor) 1046 LinkedIn 1047 USA 1049 Email: gdawra.ietf@gmail.com 1051 Clarence Filsfils 1052 Cisco Systems 1053 Belgium 1055 Email: cfilsfil@cisco.com 1057 Ketan Talaulikar (editor) 1058 Cisco Systems 1059 India 1061 Email: ketant@cisco.com 1062 Mach Chen 1063 Huawei 1064 China 1066 Email: mach.chen@huawei.com 1068 Daniel Bernier 1069 Bell Canada 1070 Canada 1072 Email: daniel.bernier@bell.ca 1074 Bruno Decraene 1075 Orange 1076 France 1078 Email: bruno.decraene@orange.com