idnits 2.17.1 draft-ietf-lsr-isis-srv6-extensions-13.txt: Checking boilerplate required by RFC 5378 and the IETF Trust (see https://trustee.ietf.org/license-info): ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/1id-guidelines.txt: ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/checklist : ---------------------------------------------------------------------------- ** There is 1 instance of too long lines in the document, the longest one being 1 character in excess of 72. Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year -- The document date (April 12, 2021) is 1100 days in the past. Is this intentional? Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Outdated reference: A later version (-13) exists of draft-ietf-6man-spring-srv6-oam-08 == Outdated reference: A later version (-26) exists of draft-ietf-lsr-flex-algo-13 -- Possible downref: Non-RFC (?) normative reference: ref. 'ISO10589' Summary: 1 error (**), 0 flaws (~~), 3 warnings (==), 2 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Networking Working Group P. Psenak, Ed. 3 Internet-Draft C. Filsfils 4 Updates: 7370 (if approved) Cisco Systems 5 Intended status: Standards Track A. Bashandy 6 Expires: October 14, 2021 Individual 7 B. Decraene 8 Orange 9 Z. Hu 10 Huawei Technologies 11 April 12, 2021 13 IS-IS Extension to Support Segment Routing over IPv6 Dataplane 14 draft-ietf-lsr-isis-srv6-extensions-13 16 Abstract 18 The Segment Routing (SR) allows for a flexible definition of end-to- 19 end paths by encoding paths as sequences of topological sub-paths, 20 called "segments". Segment routing architecture can be implemented 21 over an MPLS data plane as well as an IPv6 data plane. This document 22 describes the IS-IS extensions required to support Segment Routing 23 over an IPv6 data plane. 25 This documents updates RFC 7370 by modifying an existing registry. 27 Requirements Language 29 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 30 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 31 "OPTIONAL" in this document are to be interpreted as described in BCP 32 14 [RFC2119] [RFC8174] when, and only when, they appear in all 33 capitals, as shown here. 35 Status of This Memo 37 This Internet-Draft is submitted in full conformance with the 38 provisions of BCP 78 and BCP 79. 40 Internet-Drafts are working documents of the Internet Engineering 41 Task Force (IETF). Note that other groups may also distribute 42 working documents as Internet-Drafts. The list of current Internet- 43 Drafts is at https://datatracker.ietf.org/drafts/current/. 45 Internet-Drafts are draft documents valid for a maximum of six months 46 and may be updated, replaced, or obsoleted by other documents at any 47 time. It is inappropriate to use Internet-Drafts as reference 48 material or to cite them other than as "work in progress." 49 This Internet-Draft will expire on October 14, 2021. 51 Copyright Notice 53 Copyright (c) 2021 IETF Trust and the persons identified as the 54 document authors. All rights reserved. 56 This document is subject to BCP 78 and the IETF Trust's Legal 57 Provisions Relating to IETF Documents 58 (https://trustee.ietf.org/license-info) in effect on the date of 59 publication of this document. Please review these documents 60 carefully, as they describe your rights and restrictions with respect 61 to this document. Code Components extracted from this document must 62 include Simplified BSD License text as described in Section 4.e of 63 the Trust Legal Provisions and are provided without warranty as 64 described in the Simplified BSD License. 66 Table of Contents 68 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 69 2. SRv6 Capabilities sub-TLV . . . . . . . . . . . . . . . . . . 3 70 3. Advertising Supported Algorithms . . . . . . . . . . . . . . 4 71 4. Advertising Maximum SRv6 SID Depths . . . . . . . . . . . . . 4 72 4.1. Maximum Segments Left MSD Type . . . . . . . . . . . . . 5 73 4.2. Maximum End Pop MSD Type . . . . . . . . . . . . . . . . 5 74 4.3. Maximum H.Encaps MSD Type . . . . . . . . . . . . . . . . 5 75 4.4. Maximum End D MSD Type . . . . . . . . . . . . . . . . . 5 76 5. SRv6 SIDs and Reachability . . . . . . . . . . . . . . . . . 6 77 6. Advertising Anycast Property . . . . . . . . . . . . . . . . 7 78 7. Advertising Locators and End SIDs . . . . . . . . . . . . . . 8 79 7.1. SRv6 Locator TLV Format . . . . . . . . . . . . . . . . . 8 80 7.2. SRv6 End SID sub-TLV . . . . . . . . . . . . . . . . . . 10 81 8. Advertising SRv6 Adjacency SIDs . . . . . . . . . . . . . . . 12 82 8.1. SRv6 End.X SID sub-TLV . . . . . . . . . . . . . . . . . 12 83 8.2. SRv6 LAN End.X SID sub-TLV . . . . . . . . . . . . . . . 14 84 9. SRv6 SID Structure Sub-Sub-TLV . . . . . . . . . . . . . . . 16 85 10. Advertising Endpoint Behaviors . . . . . . . . . . . . . . . 17 86 11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17 87 11.1. SRv6 Locator TLV . . . . . . . . . . . . . . . . . . . . 17 88 11.1.1. SRv6 End SID sub-TLV . . . . . . . . . . . . . . . . 18 89 11.1.2. Revised sub-TLV table . . . . . . . . . . . . . . . 18 90 11.2. SRv6 Capabilities sub-TLV . . . . . . . . . . . . . . . 19 91 11.3. SRv6 End.X SID and SRv6 LAN End.X SID sub-TLVs . . . . . 19 92 11.4. MSD Types . . . . . . . . . . . . . . . . . . . . . . . 20 93 11.5. Sub-Sub-TLVs for SID Sub-TLVs . . . . . . . . . . . . . 20 94 11.6. Prefix Attribute Flags Sub-TLV . . . . . . . . . . . . . 21 95 12. Security Considerations . . . . . . . . . . . . . . . . . . . 21 96 13. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 21 97 14. References . . . . . . . . . . . . . . . . . . . . . . . . . 22 98 14.1. Normative References . . . . . . . . . . . . . . . . . . 22 99 14.2. Informative References . . . . . . . . . . . . . . . . . 25 100 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 25 102 1. Introduction 104 With Segment Routing (SR) [RFC8402], a node steers a packet through 105 an ordered list of instructions, called segments. 107 Segments are identified through Segment Identifiers (SIDs). 109 Segment Routing can be directly instantiated on the IPv6 data plane 110 through the use of the Segment Routing Header defined in [RFC8754]. 111 SRv6 refers to this SR instantiation on the IPv6 dataplane. 113 The network programming paradigm [RFC8986] is central to SRv6. It 114 describes how any behavior can be bound to a SID and how any network 115 program can be expressed as a combination of SIDs. 117 This document specifies IS-IS extensions that allow the IS-IS 118 protocol to encode some of these SIDs and their behaviors. 120 Familiarity with the network programming paradigm [RFC8986] is 121 necessary to understand the extensions specified in this document. 123 The new SRv6 Locator top level TLV announces SRv6 locators - a form 124 of summary address for the set of topology/algorithm specific SIDs 125 instantiated at the node. 127 The SRv6 Capabilities sub-TLV announces the ability to support SRv6. 129 Several new sub-TLVs are defined to advertise various SRv6 Maximum 130 SID Depths. 132 The SRv6 End SID sub-TLV, the SRv6 End.X SID sub-TLV, and the SRv6 133 LAN End.X SID sub-TLV are used to advertise which SIDs are 134 instantiated at a node and what Endpoint behavior is bound to each 135 instantiated SID. 137 This documents updates [RFC7370] by modifying an existing registry 138 (Section 11.1.2). 140 2. SRv6 Capabilities sub-TLV 142 A node indicates that it supports the SR Segment Endpoint Node 143 functionality as specified in [RFC8754] by advertising a new SRv6 144 Capabilities sub-TLV of the router capabilities TLV [RFC7981]. 146 The SRv6 Capabilities sub-TLV may contain optional sub-sub-TLVs. No 147 sub-sub-TLVs are currently defined. 149 The SRv6 Capabilities sub-TLV has the following format: 151 0 1 2 3 152 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 1 153 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 154 | Type | Length | Flags | 155 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 156 | optional sub-sub-TLVs... 158 Type: 25 160 Length: 2 + length of sub-sub-TLVs 162 Flags: 2 octets The following flags are defined: 164 0 1 165 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 166 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 167 | |O| | 168 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 170 where: 172 O-flag: If set, the router supports use of the O-bit 173 in the Segment Routing Header (SRH) as defined in 174 [I-D.ietf-6man-spring-srv6-oam]. 176 3. Advertising Supported Algorithms 178 An SRv6 capable router indicates supported algorithm(s) by 179 advertising the SR Algorithm sub-TLV as defined in [RFC8667]. 181 4. Advertising Maximum SRv6 SID Depths 183 [RFC8491] defines the means to advertise node/link specific values 184 for Maximum SID Depths (MSD) of various types. Node MSDs are 185 advertised in a sub-TLV of the Router Capabilities TLV [RFC7981]. 186 Link MSDs are advertised in a sub-TLV of TLVs 22, 23, 141, 222, and 187 223. 189 This document defines the relevant SRv6 MSDs and requests MSD type 190 assignments in the MSD Types registry created by [RFC8491]. 192 4.1. Maximum Segments Left MSD Type 194 The Maximum Segments Left MSD Type signals the maximum value of the 195 "Segments Left" field [RFC8754] in the SRH of a received packet 196 before applying the Endpoint behavior associated with a SID. 198 SRH Max Segments Left Type: 41 200 If no value is advertised the supported value is 0. 202 4.2. Maximum End Pop MSD Type 204 The Maximum End Pop MSD Type signals the maximum number of SIDs in 205 the SRH to which the router can apply "Penultimate Segment Pop of the 206 SRH" or "Ultimate Segment Pop of the SRH" behavior, as defined in 207 [RFC8986] flavors. 209 SRH Max End Pop Type: 42 211 If the advertised value is zero or no value is advertised 212 then the router cannot apply PSP or USP flavors. 214 4.3. Maximum H.Encaps MSD Type 216 The Maximum H.Encaps MSD Type signals the maximum number of SIDs that 217 can be added as part of the "H.Encaps" behavior as defined in 218 [RFC8986]. 220 SRH Max H.encaps Type: 44 222 If the advertised value is zero or no value is advertised then the 223 headend can apply an SR Policy that only contains one segment, without 224 inserting any SRH header. 226 A non-zero SRH Max H.encaps MSD indicates that the headend can insert 227 an SRH up to the advertised value. 229 4.4. Maximum End D MSD Type 231 The Maximum End D MSD Type specifies the maximum number of SIDs 232 present in an SRH when performing decapsulation. These includes, but 233 not limited to, End.DX6, End.DT4, End.DT46, End with USD, End.X with 234 USD as defined in [RFC8986]. 236 SRH Max End D Type: 45 238 If the advertised value is zero or no value is advertised 239 then the router cannot apply any behavior that results in 240 decapsulation and forwarding of the inner packet if the 241 other IPv6 header contains an SRH. 243 5. SRv6 SIDs and Reachability 245 As discussed in [RFC8986], an SRv6 Segment Identifier (SID) is 128 246 bits and consists of Locator, Function and Argument parts. 248 A node is provisioned with topology/algorithm specific locators for 249 each of the topology/algorithm pairs supported by that node. Each 250 locator is a covering prefix for all SIDs provisioned on that node 251 which have the matching topology/algorithm. 253 Locators MUST be advertised in the SRv6 Locator TLV (see 254 Section 7.1). Forwarding entries for the locators advertised in the 255 SRv6 Locator TLV MUST be installed in the forwarding plane of 256 receiving SRv6 capable routers when the associated topology/algorithm 257 is supported by the receiving node. The processing of the prefix 258 advertised in the SRv6 Locator TLV, the calculation of its 259 reachability and the installation in the forwarding plane follows the 260 process defined for the Prefix Reachability TLV 236 [RFC5308], or TLV 261 237 [RFC5120]. 263 Locators associated with algorithm 0 and 1 (for all supported 264 topologies) SHOULD be advertised in a Prefix Reachability TLV (236 or 265 237) so that legacy routers (i.e., routers which do not support SRv6) 266 will install a forwarding entry for algorithm 0 and 1 SRv6 traffic. 268 In cases where a locator advertisement is received in both a Prefix 269 Reachability TLV and an SRv6 Locator TLV - (e.g. prefix, prefix- 270 length, MTID all being equal and Algorithm being 0 in Locator TLV), 271 In case where the same prefix, with the same prefix-length, MTID, and 272 algorithm is received in both a Prefix Reachability TLV and an SRv6 273 Locator TLV, the Prefix Reachability advertisement MUST be preferred 274 when installing entries in the forwarding plane. This is to prevent 275 inconsistent forwarding entries between SRv6 capable and SRv6 276 incapable routers. Such preference of Prefix Reachability 277 advertisement does not have any impact on the rest of the data 278 advertised in the SRv6 Locator TLV. 280 Locators associated with Flexible Algorithms (see Section 4 of 281 [I-D.ietf-lsr-flex-algo]) SHOULD NOT be advertised in Prefix 282 Reachability TLVs (236 or 237). Advertising the Flexible Algorithm 283 locator in regular Prefix Reachability TLV (236 or 237) would make 284 the forwarding for it to follow algo 0 path. 286 SRv6 SIDs are advertised as sub-TLVs in the SRv6 Locator TLV except 287 for SRv6 SIDs which are associated with a specific Neighbor/Link and 288 are therefore advertised as sub-TLVs in TLVs 22, 23, 222, 223, and 289 141. 291 SRv6 SIDs received from other nodes are not directly routable and 292 MUST NOT be installed in the forwarding plane. Reachability to SRv6 293 SIDs depends upon the existence of a covering locator. 295 Adherence to the rules defined in this section will assure that SRv6 296 SIDs associated with a supported topology/algorithm pair will be 297 forwarded correctly, while SRv6 SIDs associated with an unsupported 298 topology/algorithm pair will be dropped. NOTE: The drop behavior 299 depends on the absence of a default/summary route covering a given 300 locator. 302 In order for forwarding to work correctly, the locator associated 303 with SRv6 SID advertisements must be the longest match prefix 304 installed in the forwarding plane for those SIDs. In order to ensure 305 correct forwarding, network operators should take steps to make sure 306 that this requirement is not compromised. For example, the following 307 situations should be avoided: 309 o Another locator associated with a different topology/algorithm is 310 the longest match 312 o Another prefix advertisement (i.e., from TLV 236 or 237) is the 313 longest match 315 6. Advertising Anycast Property 317 Both prefixes and SRv6 Locators may be configured as anycast and as 318 such the same value can be advertised by multiple routers. It is 319 useful for other routers to know that the advertisement is for an 320 anycast identifier. 322 A new flag in Prefix Attribute Flags Sub-TLV [RFC7794] is defined to 323 advertise the anycast property: 325 Bit #: 4 326 Name: Anycast Flag (A-flag) 328 When the prefix/SRv6 locator is configured as anycast, the A-flag 329 SHOULD be set. Otherwise, this flag MUST be clear. 331 The A-flag MUST be preserved when the advertisement is leaked between 332 levels. 334 The A-flag and the N-flag MUST NOT both be set. If both N-flag and 335 A-flag are set in the prefix/SRv6 Locator advertisement, the 336 receiving routers MUST ignore the N-flag. 338 The same prefix/SRv6 Locator can be advertised by multiple routers. 339 If at least one of them sets the A-Flag in its advertisement, the 340 prefix/SRv6 Locator SHOULD be considered as anycast. 342 A prefix/SRv6 Locator that is advertised by a single node and without 343 an A-Flag is considered node specific. 345 All the nodes advertising the same anycast locator MUST instantiate 346 the exact same set of SIDs under such anycast locator. Failure to do 347 so may result in traffic being black-holed or mis-routed. 349 The Prefix Attribute Flags Sub-TLV can be carried in the SRv6 Locator 350 TLV as well as the Prefix Reachability TLVs. When a router 351 originates both the Prefix Reachability TLV and the SRv6 Locator TLV 352 for a given prefix, and the router is originating the Prefix 353 Attribute Flags Sub-TLV in one of the TLVs, the router SHOULD 354 advertise the same flags in the Prefix Attribute Flags Sub-TLV in 355 both TLVs. However, unlike TLVs 236 [RFC5308] and 237 [RFC5120] the 356 X-flag in the Prefix Attributes Flags sub-TLV is valid when sent in 357 the SRv6 Locator TLV. The state of the X-flag in the Prefix 358 Attributes Flags sub-TLV when included in the Locator TLV MUST match 359 the setting of the embedded "X-bit" in any advertisement of the same 360 prefix in TLVs 236 [RFC5308] and 237 [RFC5120]. In case of any 361 inconsistency between the Prefix Attribute Flags advertised in the 362 Locator TLV and in the Prefix Reachability TLV, the ones advertised 363 in Prefix Reachability TLV MUST be preferred. 365 7. Advertising Locators and End SIDs 367 The SRv6 Locator TLV is introduced to advertise SRv6 Locators and End 368 SIDs associated with each locator. 370 This new TLV shares the sub-TLV space defined for TLVs 135, 235, 236 371 and 237. 373 7.1. SRv6 Locator TLV Format 375 The SRv6 Locator TLV has the following format: 377 0 1 2 3 378 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 1 380 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 381 | Type | Length |R|R|R|R| MT ID | 382 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 384 Type: 27 386 Length: variable. 388 R bits: reserved for future use. They MUST be 389 set to zero on transmission and MUST be ignored on receipt. 391 MT ID: Multitopology Identifier as defined in [RFC5120]. 392 Note that the value 0 is legal. 394 Followed by one or more locator entries of the form: 396 0 1 2 3 397 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 1 398 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 399 | Metric | 400 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 401 | Flags | Algorithm | 402 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 403 | Loc Size | Locator (variable)... 404 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 405 | Sub-TLV-len | Sub-TLVs (variable) . . . | 406 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 408 Metric: 4 octets. As described in [RFC5305]. 410 Flags: 1 octet. The following flags are defined 412 0 413 0 1 2 3 4 5 6 7 414 +-+-+-+-+-+-+-+-+ 415 |D| Reserved | 416 +-+-+-+-+-+-+-+-+ 418 where: 419 D bit: Same as described in section 4.1. of [RFC5305]. 421 The remaining bits are reserved for future use. They MUST be 422 set to zero on transmission and MUST be ignored on receipt. 424 Algorithm: 1 octet. As defined in [RFC8665]. 426 Loc-Size: 1 octet. Number of bits in the SRv6 Locator field. 428 MUST be from the range (1 - 128). The TLV MUST be ignored if 429 the Loc-Size is outside of this range. 431 Locator: 1-16 octets. This field encodes the advertised SRv6 432 Locator. The Locator is encoded in the minimal number of 433 octets for the given number of bits. Trailing bits MUST be set 434 to zero and ignored when received. 436 Sub-TLV-length: 1 octet. Number of octets used by sub-TLVs 438 Optional sub-TLVs: Sub-TLVs 1, 2, 4, 5, 11, 12 are allowed. 439 Any other Sub-TLVs MUST be ignored. 441 7.2. SRv6 End SID sub-TLV 443 The SRv6 End SID sub-TLV is introduced to advertise SRv6 Segment 444 Identifiers (SID) with Endpoint behaviors which do not require a 445 particular neighbor in order to be correctly applied. SRv6 SIDs 446 associated with a neighbor are advertised using the sub-TLVs defined 447 in Section 8. 449 Supported behavior values together with parent TLVs in which they 450 area advertised are specified in Section 10 of this document. Please 451 note that not all behaviors defined in [RFC8986] are defined in this 452 document, e.g. END.T is not. 454 This new sub-TLV is advertised in the SRv6 Locator TLV defined in the 455 previous section. SRv6 End SIDs inherit the topology/algorithm from 456 the parent locator. 458 The SRv6 End SID sub-TLV has the following format: 460 0 1 2 3 461 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 1 462 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 463 | Type | Length | 464 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 465 | Flags | Endpoint Behavior | 466 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 467 | SID (128 bits) . . . | 468 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 469 | SID (cont . . .) | 470 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 471 | SID (cont . . .) | 472 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 473 | SID (cont . . .) | 474 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 475 |Sub-sub-TLV-len| Sub-sub-TLVs (variable) . . . | 476 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 478 Type: 5. 480 Length: variable. 482 Flags: 1 octet. No flags are currently defined. 484 Endpoint Behavior: 2 octets, as defined in [RFC8986]. Supported 485 behavior values for this sub-TLV are defined in Section 10 of this 486 document. Unsupported or unrecognized behavior values are ignored 487 by the receiver. 489 SID: 16 octets. This field encodes the advertised SRv6 SID. 491 Sub-sub-TLV-length: 1 octet. Number of octets used by sub-sub- 492 TLVs. 494 Optional Sub-sub-TLVs. 496 The SRv6 End SID MUST be a subnet of the associated Locator. SRv6 497 End SIDs which are not a subnet of the associated locator MUST be 498 ignored. 500 Multiple SRv6 End SIDs MAY be associated with the same locator. In 501 cases where the number of SRv6 End SID sub-TLVs exceeds the capacity 502 of a single TLV, multiple Locator TLVs for the same locator MAY be 503 advertised. For a given MTID/Locator the algorithm MUST be the same 504 in all TLVs. If this restriction is not met all TLVs for that MTID/ 505 Locator MUST be ignored. 507 8. Advertising SRv6 Adjacency SIDs 509 Certain SRv6 Endpoint behaviors [RFC8986] are associated with a 510 particular adjacency. 512 This document defines two new sub-TLVs of TLV 22, 23, 222, 223, and 513 141 - namely "SRv6 End.X SID sub-TLVs" and "SRv6 LAN End.X SID sub- 514 TLVs". 516 IS-IS Neighbor advertisements are topology specific - but not 517 algorithm specific. SIDs advertised in SRv6 End.X SID and SRv6 LAN 518 End.X SID sub-TLVs therefore inherit the topology from the associated 519 neighbor advertisement, but the algorithm is specified in the 520 individual SID. 522 All SIDs advertised in SRv6 End.X SID and SRv6 LAN End.X SID sub-TLVs 523 MUST be a subnet of a Locator with matching topology and algorithm 524 which is advertised by the same node in an SRv6 Locator TLV. SIDs 525 that do not meet this requirement MUST be ignored. This ensures that 526 the node advertising these SIDs is also advertising its corresponding 527 Locator with the algorithm that will be used for computing paths 528 destined to the SID. 530 8.1. SRv6 End.X SID sub-TLV 532 This sub-TLV is used to advertise an SRv6 SID associated with a point 533 to point adjacency. Multiple SRv6 End.X SID sub-TLVs MAY be 534 associated with the same adjacency. 536 The SRv6 End.X SID sub-TLV has the following format: 538 0 1 2 3 539 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 1 540 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 541 | Type | Length | 542 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 543 | Flags | Algorithm | Weight | 544 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 545 | Endpoint Behavior | 546 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 547 | SID (128 bits) . . . | 548 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 549 | SID (cont . . .) | 550 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 551 | SID (cont . . .) | 552 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 553 | SID (cont . . .) | 554 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 555 |Sub-sub-tlv-len| Sub-sub-TLVs (variable) . . . | 556 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 558 Type: 43 560 Length: variable. 562 Flags: 1 octet. 564 0 1 2 3 4 5 6 7 565 +-+-+-+-+-+-+-+-+ 566 |B|S|P|Reserved | 567 +-+-+-+-+-+-+-+-+ 569 where: 571 B-Flag: Backup flag. If set, the SID is eligible for 572 protection (e.g., using IPFRR) as described in [RFC8355]. 574 S-Flag. Set flag. When set, the S-Flag indicates that the SID 575 refers to a set of adjacencies (and therefore MAY be assigned 576 to other adjacencies as well). 578 P-Flag. Persistent flag. When set, the P-Flag indicates that 579 the SID is persistently allocated, i.e., the SID value remains 580 consistent across router restart and/or interface flap. 582 Reserved bits: MUST be zero when originated and ignored when 583 received. 585 Algorithm: 1 octet. As defined in [RFC8665]. 587 Weight: 1 octet. The value represents the weight of the SID for 588 the purpose of load balancing. The use of the weight is defined 589 in [RFC8402]. 591 Endpoint Behavior: 2 octets. As defined in [RFC8986]. Supported 592 behavior values for this sub-TLV are defined in Section 10 of this 593 document. Unsupported or unrecognized behavior values are ignored 594 by the receiver. 596 SID: 16 octets. This field encodes the advertised SRv6 SID. 598 Sub-sub-TLV-length: 1 octet. Number of octets used by sub-sub- 599 TLVs. 601 Note that multiple TLVs for the same neighbor may be required in 602 order to advertise all of the SRv6 SIDs associated with that 603 neighbor. 605 8.2. SRv6 LAN End.X SID sub-TLV 607 This sub-TLV is used to advertise an SRv6 SID associated with a LAN 608 adjacency. Since the parent TLV is advertising an adjacency to the 609 Designated Intermediate System (DIS) for the LAN, it is necessary to 610 include the System ID of the physical neighbor on the LAN with which 611 the SRv6 SID is associated. Given that a large number of neighbors 612 may exist on a given LAN a large number of SRv6 LAN END.X SID sub- 613 TLVs may be associated with the same LAN. Note that multiple TLVs 614 for the same DIS neighbor may be required in order to advertise all 615 of the SRv6 SIDs associated with that neighbor. 617 The SRv6 LAN End.X SID sub-TLV has the following format: 619 0 1 2 3 620 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 1 621 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 622 | Type | Length | | 623 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | 624 | Neighbor System-ID (ID length octets) | 625 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 626 | Flags | Algorithm | Weight | 627 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 628 | Endpoint Behavior | 629 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 630 | SID (128 bits) . . . | 631 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 632 | SID (cont . . .) | 633 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 634 | SID (cont . . .) | 635 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 636 | SID (cont . . .) | 637 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 638 |Sub-sub-TLV-len| sub-sub-TLVs (variable) . . . | 639 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 641 Type: 44 643 Length: variable. 645 Neighbor System-ID: IS-IS System-ID of length "ID Length" as 646 defined in [ISO10589]. 648 Flags: 1 octet. 650 0 1 2 3 4 5 6 7 651 +-+-+-+-+-+-+-+-+ 652 |B|S|P|Reserved | 653 +-+-+-+-+-+-+-+-+ 655 where B,S, and P flags are as described in Section 8.1. 656 Reserved bits MUST be zero when originated and MUST be ignored 657 when received. 659 Algorithm: 1 octet. As defined in [RFC8665]. 661 Weight: 1 octet. The value represents the weight of the SID for 662 the purpose of load balancing. The use of the weight is defined 663 in [RFC8402]. 665 Endpoint Behavior: 2 octets. As defined in [RFC8986]. Supported 666 behavior values for this sub-TLV are defined in Section 10 of this 667 document. Unsupported or unrecognized behavior values are ignored 668 by the receiver. 670 SID: 16 octets. This field encodes the advertised SRv6 SID. 672 Sub-sub-TLV-length: 1 octet. Number of octets used by sub-sub- 673 TLVs. 675 9. SRv6 SID Structure Sub-Sub-TLV 677 SRv6 SID Structure Sub-Sub-TLV is an optional Sub-Sub-TLV of: 679 SRv6 End SID Sub-TLV (Section 7.2) 681 SRv6 End.X SID Sub-TLV (Section 8.1) 683 SRv6 LAN End.X SID Sub-TLV (Section 8.2) 685 SRv6 SID Structure Sub-Sub-TLV is used to advertise the as defined in 686 [RFC8986]. It has the following format: 688 0 1 2 3 689 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 1 690 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 691 | Type | Length | 692 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 693 | LB Length | LN Length | Fun. Length | Arg. Length | 694 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 696 where: 698 Type: 1 700 Length: 4 octets. 702 LB Length: 1 octet. SRv6 SID Locator Block length in bits. 704 LN Length: 1 octet. SRv6 SID Locator Node length in bits. 706 Fun. Length: 1 octet. SRv6 SID Function length in bits. 708 Arg. Length: 1 octet. SRv6 SID Arguments length in bits. 710 ISIS SRv6 SID Structure Sub-Sub-TLV MUST NOT appear more than once in 711 its parent Sub-TLV. If it appears more than once in its parent Sub- 712 TLV, the parent Sub-TLV MUST be ignored by the receiver. 714 The sum of all four sizes advertised in ISIS SRv6 SID Structure Sub- 715 Sub-TLV MUST be lower or equal to 128 bits. If the sum of all four 716 sizes advertised in the ISIS SRv6 SID Structure Sub-Sub-TLV is larger 717 than 128 bits, the parent Sub-TLV MUST be ignored by the receiver. 719 The SRv6 SID Structure Sub-Sub-TLV indicates the structure of the SID 720 associated with it. It's usage is outside of the scope of this 721 document. 723 10. Advertising Endpoint Behaviors 725 Endpoint behaviors are defined in [RFC8986]. The codepoints for the 726 Endpoint behaviors are defined in the "SRv6 Endpoint Behaviors" 727 registry defined in [RFC8986]. If this behavior is advertised it 728 MUST only be advertised in the TLV[s] as indicated by "Y" in the 729 table below, and MUST NOT be advertised in the TLV[s] as indicated by 730 "N" in the table below. 732 Endpoint |Endpoint | End | End.X | Lan End.X | 733 Behavior |Behavior Codepoint| SID | SID | SID | 734 ----------------------|------------------|-----|-------|-----------| 735 End (PSP, USP, USD)| 1-4, 28-31 | Y | N | N | 736 ----------------------|------------------|-----|-------|-----------| 737 End.X (PSP, USP, USD)| 5-8, 32-35 | N | Y | Y | 738 ----------------------|------------------|-----|-------|-----------| 739 End.DX6 | 16 | N | Y | Y | 740 ----------------------|------------------|-----|-------|-----------| 741 End.DX4 | 17 | N | Y | Y | 742 ----------------------|------------------|-----|-------|-----------| 743 End.DT6 | 18 | Y | N | N | 744 ----------------------|------------------|-----|-------|-----------| 745 End.DT4 | 19 | Y | N | N | 746 ----------------------|------------------|-----|-------|-----------| 747 End.DT46 | 20 | Y | N | N | 749 11. IANA Considerations 751 This document requests allocation for the following TLVs, sub-TLVs, 752 and sub-sub-TLVs as well updating the ISIS TLV registry and defining 753 a new registry. 755 11.1. SRv6 Locator TLV 757 This document makes the following registrations in the the IS-IS TLV 758 Codepoints registry. 760 Type Description IIH LSP SNP Purge 761 ---- --------------------- --- --- --- ----- 762 27 SRv6 Locator TLV n y n n 764 11.1.1. SRv6 End SID sub-TLV 766 The SRv6 Locator TLV shares sub-TLV space with TLVs 135, 235, 236 and 767 237. This document updates the "Sub-TLVs for TLVs 135, 235, 236, and 768 237 (Extended IP reachability, MT IP. Reach, IPv6 IP. Reach, and MT 769 IPv6 IP. Reach TLVs)" registry defined in [RFC7370]. IANA is 770 requested to update the name of the "Sub-TLVs for TLVs 135, 235, 236, 771 and 237 (Extended IP reachability, MT IP. Reach, IPv6 IP. Reach, 772 and MT IPv6 IP. Reach TLVs)" registry to "Sub-TLVs for TLVs 27, 135, 773 235, 236, and 237 (SRv6 Locator, Extended IP reachability, MT IP. 774 Reach, IPv6 IP. Reach, and MT IPv6 IP. Reach TLVs)". 776 IANA is asked to add this document as a reference to (renamed) "Sub- 777 TLVs for TLVs 27, 135, 235, 236, and 237 (SRv6 Locator, Extended IP 778 reachability, MT IP. Reach, IPv6 IP. Reach, and MT IPv6 IP. Reach 779 TLVs)" registry. 781 This document makes the following registrations in the (renamed) 782 "Sub-TLVs for TLVs 27, 135, 235, 236, and 237 (SRv6 Locator, Extended 783 IP reachability, MT IP. Reach, IPv6 IP. Reach, and MT IPv6 IP. 784 Reach TLVs)" registry: 786 Type: 5 788 Description: SRv6 End SID sub-TLV. 790 Reference: This document (Section 7.2). 792 11.1.2. Revised sub-TLV table 794 The revised table of sub-TLVs for the (renamed) "Sub-TLVs for TLVs 795 27, 135, 235, 236, and 237 (SRv6 Locator, Extended IP reachability, 796 MT IP. Reach, IPv6 IP. Reach, and MT IPv6 IP. Reach TLVs)" 797 registry is shown below: 799 Type 27 135 235 236 237 801 1 y y y y y 802 2 y y y y y 803 3 n y y y y 804 4 y y y y y 805 5 y n n n n 806 6 n y y y y 807 11 y y y y y 808 12 y y y y y 809 32 n y y y y 811 11.2. SRv6 Capabilities sub-TLV 813 This document makes the following registrations in the "Sub-TLVs for 814 TLV 242 (IS-IS Router CAPABILITY TLV)": 816 Type: 25 818 Description: SRv6 Capabilities sub-TLV. 820 Reference: This document (Section 2). 822 This document requests the creation of a new IANA managed registry, 823 under "IS-IS TLV Codepoints" registry - sub-sub-TLVs of the SRv6 824 Capability sub-TLV. The registration procedure is "Expert Review" as 825 defined in [RFC8126]. Guidance for the Designated Experts is 826 provided in the [RFC7370]. Suggested registry name is "sub-sub-TLVs 827 for SRv6 Capability sub-TLV". No sub-sub-TLVs are defined by this 828 document except for the reserved value. 830 0: Reserved 832 1-255: Unassigned 834 11.3. SRv6 End.X SID and SRv6 LAN End.X SID sub-TLVs 836 This document makes the following registrations in the "Sub-TLVs for 837 TLVs 22, 23, 25, 141, 222, and 223 (Extended IS reachability, IS 838 Neighbor Attribute, L2 Bundle Member Attributes, inter-AS 839 reachability information, MT-ISN, and MT IS Neighbor Attribute TLVs)" 840 registry: 842 Type: 43 844 Description: SRv6 End.X SID sub-TLV. 846 Reference: This document (Section 8.1). 848 Type: 44 850 Description: SRv6 LAN End.X SID sub-TLV. 852 Reference: This document (Section 8.2). 854 Type 22 23 25 141 222 223 856 43 y y y y y y 857 44 y y y y y y 859 11.4. MSD Types 861 This document makes the following registrations in the IGP MSD-Types 862 registry: 864 Value Name Reference 865 ------------------ 866 41 SRH Max SL [This Document] 867 42 SRH Max End Pop [This Document] 868 44 SRH Max H.encaps [This Document] 869 45 SRH Max End D [This Document] 871 11.5. Sub-Sub-TLVs for SID Sub-TLVs 873 This document requests a new IANA registry be created under the IS-IS 874 TLV Codepoints Registry to control the assignment of sub-TLV types 875 for the SID Sub-TLVs specified in this document - Section 7.2, 876 Section 8.1, Section 8.2. The suggested name of the new registry is 877 "sub-sub-TLVs for SRv6 End SID (5) (sub-TLV of TLVs 27, 135, 235, 236 878 and 237) and SRv6 End.X SID (43)/SRv6 LAN End.X SID (44) (Sub-TLVs 879 for TLVs 22, 23, 25, 141, 222, and 223)". The registration procedure 880 is "Expert Review" as defined in [RFC8126]. Guidance for the 881 Designated Experts is provided in [RFC7370]. The following 882 assignments are made by this document: 884 Type Description Encoding 885 Reference 886 --------------------------------------------------------- 887 0 Reserved 888 1 SRv6 SID Structure Sub-Sub-TLV [This Document] 889 2-255 Unassigned 891 Type 5 43 44 893 1 y y y 895 11.6. Prefix Attribute Flags Sub-TLV 897 This document adds a new bit in the "Bit Values for Prefix Attribute 898 Flags Sub-TLV" registry: 900 Bit #: 4 902 Description: Anycast Flag (A-flag) 904 Reference: This document (Section 6). 906 12. Security Considerations 908 Security concerns for IS-IS are addressed in [ISO10589], [RFC5304], 909 and [RFC5310]. While IS-IS is deployed under a single administrative 910 domain, there can be deployments where potential attackers have 911 access to one or more networks in the IS-IS routing domain. In these 912 deployments, the stronger authentication mechanisms defined in the 913 aforementioned documents SHOULD be used. 915 This document describes the IS-IS extensions required to support 916 Segment Routing over an IPv6 data plane. The security considerations 917 for Segment Routing are discussed in [RFC8402]. [RFC8986] defines 918 the SRv6 Network Programming concept and specifies the main Segment 919 Routing behaviors to enable the creation of interoperable overlays; 920 the security considerations from that document apply too. 922 The advertisement of an incorrect MSD value may have negative 923 consequences, see [RFC8491] for additional considerations. 925 13. Contributors 927 The following people gave a substantial contribution to the content 928 of this document and should be considered as co-authors: 930 Stefano Previdi 931 Huawei Technologies 932 Email: stefano@previdi.net 934 Paul Wells 935 Cisco Systems 936 Saint Paul, 937 Minnesota 938 United States 939 Email: pauwells@cisco.com 941 Daniel Voyer 942 Email: daniel.voyer@bell.ca 944 Satoru Matsushima 945 Email: satoru.matsushima@g.softbank.co.jp 947 Bart Peirens 948 Email: bart.peirens@proximus.com 950 Hani Elmalky 951 Email: hani.elmalky@ericsson.com 953 Prem Jonnalagadda 954 Email: prem@barefootnetworks.com 956 Milad Sharif 957 Email: msharif@barefootnetworks.com> 959 Robert Hanzl 960 Cisco Systems 961 Millenium Plaza Building, V Celnici 10, Prague 1, 962 Prague, Czech Republic 963 Email rhanzl@cisco.com 965 Ketan Talaulikar 966 Cisco Systems, Inc. 967 Email: ketant@cisco.com 969 14. References 971 14.1. Normative References 973 [I-D.ietf-6man-spring-srv6-oam] 974 Ali, Z., Filsfils, C., Matsushima, S., Voyer, D., and M. 975 Chen, "Operations, Administration, and Maintenance (OAM) 976 in Segment Routing Networks with IPv6 Data plane (SRv6)", 977 draft-ietf-6man-spring-srv6-oam-08 (work in progress), 978 October 2020. 980 [I-D.ietf-lsr-flex-algo] 981 Psenak, P., Hegde, S., Filsfils, C., Talaulikar, K., and 982 A. Gulko, "IGP Flexible Algorithm", draft-ietf-lsr-flex- 983 algo-13 (work in progress), October 2020. 985 [ISO10589] 986 International Organization for Standardization, 987 "Intermediate system to Intermediate system intra-domain 988 routeing information exchange protocol for use in 989 conjunction with the protocol for providing the 990 connectionless-mode Network Service (ISO 8473)", Nov 2002. 992 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 993 Requirement Levels", BCP 14, RFC 2119, 994 DOI 10.17487/RFC2119, March 1997, 995 . 997 [RFC5120] Przygienda, T., Shen, N., and N. Sheth, "M-ISIS: Multi 998 Topology (MT) Routing in Intermediate System to 999 Intermediate Systems (IS-ISs)", RFC 5120, 1000 DOI 10.17487/RFC5120, February 2008, 1001 . 1003 [RFC5305] Li, T. and H. Smit, "IS-IS Extensions for Traffic 1004 Engineering", RFC 5305, DOI 10.17487/RFC5305, October 1005 2008, . 1007 [RFC5308] Hopps, C., "Routing IPv6 with IS-IS", RFC 5308, 1008 DOI 10.17487/RFC5308, October 2008, 1009 . 1011 [RFC7370] Ginsberg, L., "Updates to the IS-IS TLV Codepoints 1012 Registry", RFC 7370, DOI 10.17487/RFC7370, September 2014, 1013 . 1015 [RFC7794] Ginsberg, L., Ed., Decraene, B., Previdi, S., Xu, X., and 1016 U. Chunduri, "IS-IS Prefix Attributes for Extended IPv4 1017 and IPv6 Reachability", RFC 7794, DOI 10.17487/RFC7794, 1018 March 2016, . 1020 [RFC7981] Ginsberg, L., Previdi, S., and M. Chen, "IS-IS Extensions 1021 for Advertising Router Information", RFC 7981, 1022 DOI 10.17487/RFC7981, October 2016, 1023 . 1025 [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for 1026 Writing an IANA Considerations Section in RFCs", BCP 26, 1027 RFC 8126, DOI 10.17487/RFC8126, June 2017, 1028 . 1030 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 1031 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 1032 May 2017, . 1034 [RFC8402] Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L., 1035 Decraene, B., Litkowski, S., and R. Shakir, "Segment 1036 Routing Architecture", RFC 8402, DOI 10.17487/RFC8402, 1037 July 2018, . 1039 [RFC8491] Tantsura, J., Chunduri, U., Aldrin, S., and L. Ginsberg, 1040 "Signaling Maximum SID Depth (MSD) Using IS-IS", RFC 8491, 1041 DOI 10.17487/RFC8491, November 2018, 1042 . 1044 [RFC8665] Psenak, P., Ed., Previdi, S., Ed., Filsfils, C., Gredler, 1045 H., Shakir, R., Henderickx, W., and J. Tantsura, "OSPF 1046 Extensions for Segment Routing", RFC 8665, 1047 DOI 10.17487/RFC8665, December 2019, 1048 . 1050 [RFC8667] Previdi, S., Ed., Ginsberg, L., Ed., Filsfils, C., 1051 Bashandy, A., Gredler, H., and B. Decraene, "IS-IS 1052 Extensions for Segment Routing", RFC 8667, 1053 DOI 10.17487/RFC8667, December 2019, 1054 . 1056 [RFC8754] Filsfils, C., Ed., Dukes, D., Ed., Previdi, S., Leddy, J., 1057 Matsushima, S., and D. Voyer, "IPv6 Segment Routing Header 1058 (SRH)", RFC 8754, DOI 10.17487/RFC8754, March 2020, 1059 . 1061 [RFC8986] Filsfils, C., Ed., Camarillo, P., Ed., Leddy, J., Voyer, 1062 D., Matsushima, S., and Z. Li, "Segment Routing over IPv6 1063 (SRv6) Network Programming", RFC 8986, 1064 DOI 10.17487/RFC8986, February 2021, 1065 . 1067 14.2. Informative References 1069 [RFC5304] Li, T. and R. Atkinson, "IS-IS Cryptographic 1070 Authentication", RFC 5304, DOI 10.17487/RFC5304, October 1071 2008, . 1073 [RFC5310] Bhatia, M., Manral, V., Li, T., Atkinson, R., White, R., 1074 and M. Fanto, "IS-IS Generic Cryptographic 1075 Authentication", RFC 5310, DOI 10.17487/RFC5310, February 1076 2009, . 1078 [RFC8355] Filsfils, C., Ed., Previdi, S., Ed., Decraene, B., and R. 1079 Shakir, "Resiliency Use Cases in Source Packet Routing in 1080 Networking (SPRING) Networks", RFC 8355, 1081 DOI 10.17487/RFC8355, March 2018, 1082 . 1084 Authors' Addresses 1086 Peter Psenak (editor) 1087 Cisco Systems 1088 Pribinova Street 10 1089 Bratislava 81109 1090 Slovakia 1092 Email: ppsenak@cisco.com 1094 Clarence Filsfils 1095 Cisco Systems 1096 Brussels 1097 Belgium 1099 Email: cfilsfil@cisco.com 1101 Ahmed Bashandy 1102 Individual 1104 Email: abashandy.ietf@gmail.com 1106 Bruno Decraene 1107 Orange 1108 Issy-les-Moulineaux 1109 France 1111 Email: bruno.decraene@orange.com 1112 Zhibo Hu 1113 Huawei Technologies 1115 Email: huzhibo@huawei.com