idnits 2.17.1 draft-ietf-lsr-isis-srv6-extensions-07.txt: Checking boilerplate required by RFC 5378 and the IETF Trust (see https://trustee.ietf.org/license-info): ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/1id-guidelines.txt: ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/checklist : ---------------------------------------------------------------------------- ** There are 23 instances of too long lines in the document, the longest one being 5 characters 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 (March 23, 2020) is 1488 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references to lower-maturity documents in RFCs) -- Looks like a reference, but probably isn't: '1' on line 1070 == Outdated reference: A later version (-13) exists of draft-ietf-6man-spring-srv6-oam-03 == Outdated reference: A later version (-28) exists of draft-ietf-spring-srv6-network-programming-14 -- Possible downref: Non-RFC (?) normative reference: ref. 'ISO10589' == Outdated reference: A later version (-26) exists of draft-ietf-lsr-flex-algo-06 Summary: 1 error (**), 0 flaws (~~), 4 warnings (==), 3 comments (--).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 Intended status: Standards Track Cisco Systems 5 Expires: September 24, 2020 A. Bashandy 6 Individual 7 B. Decraene 8 Orange 9 Z. Hu 10 Huawei Technologies 11 March 23, 2020 13 IS-IS Extension to Support Segment Routing over IPv6 Dataplane 14 draft-ietf-lsr-isis-srv6-extensions-07.txt 16 Abstract 18 Segment Routing (SR) allows for a flexible definition of end-to-end 19 paths by encoding paths as sequences of topological sub-paths, called 20 "segments". Segment routing architecture can be implemented over an 21 MPLS data plane as well as an IPv6 data plane. This draft describes 22 the IS-IS extensions required to support Segment Routing over an IPv6 23 data plane. 25 Requirements Language 27 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 28 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 29 "OPTIONAL" in this document are to be interpreted as described in BCP 30 14 [RFC2119] [RFC8174] when, and only when, they appear in all 31 capitals, as shown here. 33 Status of This Memo 35 This Internet-Draft is submitted in full conformance with the 36 provisions of BCP 78 and BCP 79. 38 Internet-Drafts are working documents of the Internet Engineering 39 Task Force (IETF). Note that other groups may also distribute 40 working documents as Internet-Drafts. The list of current Internet- 41 Drafts is at https://datatracker.ietf.org/drafts/current/. 43 Internet-Drafts are draft documents valid for a maximum of six months 44 and may be updated, replaced, or obsoleted by other documents at any 45 time. It is inappropriate to use Internet-Drafts as reference 46 material or to cite them other than as "work in progress." 48 This Internet-Draft will expire on September 24, 2020. 50 Copyright Notice 52 Copyright (c) 2020 IETF Trust and the persons identified as the 53 document authors. All rights reserved. 55 This document is subject to BCP 78 and the IETF Trust's Legal 56 Provisions Relating to IETF Documents 57 (https://trustee.ietf.org/license-info) in effect on the date of 58 publication of this document. Please review these documents 59 carefully, as they describe your rights and restrictions with respect 60 to this document. Code Components extracted from this document must 61 include Simplified BSD License text as described in Section 4.e of 62 the Trust Legal Provisions and are provided without warranty as 63 described in the Simplified BSD License. 65 Table of Contents 67 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 68 2. SRv6 Capabilities sub-TLV . . . . . . . . . . . . . . . . . . 4 69 3. Advertising Supported Algorithms . . . . . . . . . . . . . . 4 70 4. Advertising Maximum SRv6 SID Depths . . . . . . . . . . . . . 5 71 4.1. Maximum Segments Left MSD Type . . . . . . . . . . . . . 5 72 4.2. Maximum End Pop MSD Type . . . . . . . . . . . . . . . . 5 73 4.3. Maximum H.Encaps MSD Type . . . . . . . . . . . . . . . . 5 74 4.4. Maximum End D MSD Type . . . . . . . . . . . . . . . . . 6 75 5. SRv6 SIDs and Reachability . . . . . . . . . . . . . . . . . 6 76 6. Advertising Anycast Property . . . . . . . . . . . . . . . . 7 77 7. Advertising Locators and End SIDs . . . . . . . . . . . . . . 8 78 7.1. SRv6 Locator TLV Format . . . . . . . . . . . . . . . . . 9 79 7.2. SRv6 End SID sub-TLV . . . . . . . . . . . . . . . . . . 10 80 8. Advertising SRv6 Adjacency SIDs . . . . . . . . . . . . . . . 12 81 8.1. SRv6 End.X SID sub-TLV . . . . . . . . . . . . . . . . . 12 82 8.2. SRv6 LAN End.X SID sub-TLV . . . . . . . . . . . . . . . 14 83 9. SRv6 SID Structure Sub-Sub-TLV . . . . . . . . . . . . . . . 16 84 10. Advertising Endpoint Behaviors . . . . . . . . . . . . . . . 17 85 11. Implementation Status . . . . . . . . . . . . . . . . . . . . 18 86 11.1. Cisco . . . . . . . . . . . . . . . . . . . . . . . . . 18 87 11.2. Huawei . . . . . . . . . . . . . . . . . . . . . . . . . 18 88 11.3. Juniper . . . . . . . . . . . . . . . . . . . . . . . . 18 89 11.4. Interoperability Testing. . . . . . . . . . . . . . . . 18 90 12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 19 91 12.1. SRv6 Locator TLV . . . . . . . . . . . . . . . . . . . . 19 92 12.1.1. SRv6 End SID sub-TLV . . . . . . . . . . . . . . . . 19 93 12.1.2. Revised sub-TLV table . . . . . . . . . . . . . . . 19 94 12.2. SRv6 Capabilities sub-TLV . . . . . . . . . . . . . . . 19 95 12.3. SRv6 End.X SID and SRv6 LAN End.X SID sub-TLVs . . . . . 20 96 12.4. MSD Types . . . . . . . . . . . . . . . . . . . . . . . 20 97 12.5. Sub-Sub-TLVs for SID Sub-TLVs . . . . . . . . . . . . . 21 98 12.6. Prefix Attribute Flags Sub-TLV . . . . . . . . . . . . . 21 99 13. Security Considerations . . . . . . . . . . . . . . . . . . . 21 100 14. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 21 101 15. References . . . . . . . . . . . . . . . . . . . . . . . . . 22 102 15.1. Normative References . . . . . . . . . . . . . . . . . . 22 103 15.2. Informative References . . . . . . . . . . . . . . . . . 24 104 15.3. URIs . . . . . . . . . . . . . . . . . . . . . . . . . . 25 105 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 25 107 1. Introduction 109 With Segment Routing (SR) [I-D.ietf-spring-segment-routing], a node 110 steers a packet through an ordered list of instructions, called 111 segments. 113 Segments are identified through Segment Identifiers (SIDs). 115 Segment Routing can be directly instantiated on the IPv6 data plane 116 through the use of the Segment Routing Header defined in 117 [I-D.ietf-6man-segment-routing-header]. SRv6 refers to this SR 118 instantiation on the IPv6 dataplane. 120 The network programming paradigm 121 [I-D.ietf-spring-srv6-network-programming] is central to SRv6. It 122 describes how any behavior can be bound to a SID and how any network 123 program can be expressed as a combination of SIDs. 125 This document specifies IS-IS extensions that allow the IS-IS 126 protocol to encode some of these SIDs and their behaviors. 128 Familiarity with the network programming paradigm 129 [I-D.ietf-spring-srv6-network-programming] is necessary to understand 130 the extensions specified in this document. 132 This document defines one new top level IS-IS TLV and several new IS- 133 IS sub-TLVs. 135 The SRv6 Capabilities sub-TLV announces the ability to support SRv6. 137 Several new sub-TLVs are defined to advertise various SRv6 Maximum 138 SID Depths. 140 The new SRv6 Locator top level TLV announces SRv6 locators - a form 141 of summary address for the set of topology/algorithm specific SIDs 142 instantiated at the node. 144 The SRv6 End SID sub-TLV, the SRv6 End.X SID sub-TLV, and the SRv6 145 LAN End.X SID sub-TLV are used to advertise which SIDs are 146 instantiated at a node and what Endpoint behavior is bound to each 147 instantiated SID. 149 2. SRv6 Capabilities sub-TLV 151 A node indicates that it supports the SR Segment Endpoint Node 152 functionality as specified in [I-D.ietf-6man-segment-routing-header] 153 by advertising a new SRv6 Capabilities sub-TLV of the router 154 capabilities TLV [RFC7981]. 156 The SRv6 Capabilities sub-TLV may contain optional sub-sub-TLVs. No 157 sub-sub-TLVs are currently defined. 159 The SRv6 Capabilities sub-TLV has the following format: 161 0 1 2 3 162 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 1 163 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 164 | Type | Length | Flags | 165 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 166 | optional sub-sub-TLVs... 168 Type: Suggested value 25, to be assigned by IANA 170 Length: 2 + length of sub-sub-TLVs 172 Flags: 2 octets The following flags are defined: 174 0 1 175 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 176 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 177 | |O| | 178 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 180 where: 182 O-flag: If set, the router supports use of the O-bit 183 in the Segment Routing Header(SRH) as defined in 184 [I-D.ietf-6man-spring-srv6-oam]. 186 3. Advertising Supported Algorithms 188 SRv6 capable router indicates supported algorithm(s) by advertising 189 the SR Algorithm TLV as defined in [RFC8667]. 191 4. Advertising Maximum SRv6 SID Depths 193 [RFC8491] defines the means to advertise node/link specific values 194 for Maximum SID Depths (MSD) of various types. Node MSDs are 195 advertised in a sub-TLV of the Router Capabilities TLV [RFC7981]. 196 Link MSDs are advertised in a sub-TLV of TLVs 22, 23, 141, 222, and 197 223. 199 This document defines the relevant SRv6 MSDs and requests MSD type 200 assignments in the MSD Types registry created by [RFC8491]. 202 4.1. Maximum Segments Left MSD Type 204 The Maximum Segments Left MSD Type specifies the maximum value of the 205 "SL" field [I-D.ietf-6man-segment-routing-header] in the SRH of a 206 received packet before applying the Endpoint behavior associated with 207 a SID. 209 SRH Max SL Type: 41 (Suggested value - to be assigned by IANA) 211 If no value is advertised the supported value is assumed to be 0. 213 4.2. Maximum End Pop MSD Type 215 The Maximum End Pop MSD Type specifies the maximum number of SIDs in 216 the SRH to which the router can apply "PSP" or USP" behavior, as 217 defined in [I-D.ietf-spring-srv6-network-programming] flavors. 219 SRH Max End Pop Type: 42 (Suggested value - to be assigned by IANA) 221 If the advertised value is zero or no value is advertised 222 then it is assumed that the router cannot apply PSP or USP flavors. 224 4.3. Maximum H.Encaps MSD Type 226 The Maximum H.Encaps MSD Type specifies the maximum number of SIDs 227 that can be included as part of the "H.Encaps" behavior as defined in 228 [I-D.ietf-spring-srv6-network-programming] . 230 SRH Max H.encaps Type: 44 (Suggested value - to be assigned by IANA) 232 If the advertised value is zero then the router can apply H.Encaps 233 only by encapsulating the incoming packet in another 234 IPv6 header without SRH the same way IPinIP encapsulation is 235 performed. 237 If the advertised value is non-zero then the router supports both 238 IPinIP and SRH encapsulation subject to the SID limitation 239 specified by the advertised value. 241 4.4. Maximum End D MSD Type 243 The Maximum End D MSD Type specifies the maximum number of SIDs in an 244 SRH when performing decapsulation associated with "End.Dx" behaviors 245 (e.g., "End.DX6" and "End.DT6") as defined in 246 [I-D.ietf-spring-srv6-network-programming]. 248 SRH Max End D Type: 45 (Suggested value - to be assigned by IANA) 250 If the advertised value is zero or no value is advertised 251 then it is assumed that the router cannot apply 252 "End.DX6" or "End.DT6" behaviors if the outer IPv6 header contains an SRH. 254 5. SRv6 SIDs and Reachability 256 As discussed in [I-D.ietf-spring-srv6-network-programming], an SRv6 257 Segment Identifier (SID) is 128 bits and consists of Locator, 258 Function and Argument parts. 260 A node is provisioned with topology/algorithm specific locators for 261 each of the topology/algorithm pairs supported by that node. Each 262 locator is a covering prefix for all SIDs provisioned on that node 263 which have the matching topology/algorithm. 265 Locators MUST be advertised in the SRv6 Locator TLV (see 266 Section 7.1). Forwarding entries for the locators advertised in the 267 SRv6 Locator TLV MUST be installed in the forwarding plane of 268 receiving SRv6 capable routers when the associated topology/algorithm 269 is supported by the receiving node. 271 Locators are routable and MAY also be advertised in Prefix 272 Reachability TLVs (236 or 237). 274 Locators associated with Flexible Algorithms [I-D.ietf-lsr-flex-algo] 275 SHOULD NOT be advertised in Prefix Reachability TLVs (236 or 237). 277 Locators associated with algorithm 0 and 1 (for all supported 278 topologies) SHOULD be advertised in a Prefix Reachability TLV (236 or 279 237) so that legacy routers (i.e., routers which do NOT support SRv6) 280 will install a forwarding entry for algorithm 0 and 1 SRv6 traffic. 282 In cases where a locator advertisement is received in both a Prefix 283 Reachability TLV and an SRv6 Locator TLV, the Prefix Reachability 284 advertisement MUST be preferred when installing entries in the 285 forwarding plane. This is to prevent inconsistent forwarding entries 286 between SRv6 capable and SRv6 incapable routers. 288 SRv6 SIDs are advertised as sub-TLVs in the SRv6 Locator TLV except 289 for SRv6 End.X SIDs/LAN End.X SIDs which are associated with a 290 specific Neighbor/Link and are therefore advertised as sub-TLVs in 291 TLVs 22, 23, 222, 223, and 141. 293 SRv6 SIDs are not directly routable and MUST NOT be installed in the 294 forwarding plane. Reachability to SRv6 SIDs depends upon the 295 existence of a covering locator. 297 Adherence to the rules defined in this section will assure that SRv6 298 SIDs associated with a supported topology/algorithm pair will be 299 forwarded correctly, while SRv6 SIDs associated with an unsupported 300 topology/algorithm pair will be dropped. NOTE: The drop behavior 301 depends on the absence of a default/summary route covering a given 302 locator. 304 In order for forwarding to work correctly, the locator associated 305 with SRv6 SID advertisements MUST be the longest match prefix 306 installed in the forwarding plane for those SIDs. There are a number 307 of ways in which this requirement could be compromised. In order to 308 ensure correct forwarding, network operators should take steps to 309 make sure that this requirement is not compromised. 311 o Another locator associated with a different topology/algorithm is 312 the longest match 314 o A prefix advertisement (i.e., from TLV 236 or 237) is the longest 315 match 317 6. Advertising Anycast Property 319 Both prefixes and SRv6 Locators may be configured as anycast and as 320 such the same value can be advertised by multiple routers. It is 321 useful for other routers to know that the advertisement is for an 322 anycast identifier. 324 A new flag in "Bit Values for Prefix Attribute Flags Sub-TLV" 325 registry [RFC7794] is defined to advertise the anycast property: 327 Bit #: 4 (Suggested - to be assigned by IANA) 328 Name: Anycast Flag (A-flag) 330 When the prefix/SRv6 locator is configured as anycast, the A-flag 331 SHOULD be set. Otherwise, this flag MUST be clear. 333 The A-flag MUST be preserved when leaked between levels. 335 The A-flag and the N-flag MUST NOT both be set. 337 If both N-flag and A-flag are set in the prefix/SRv6 Locator 338 advertisement, the receiving routers MUST ignore the N-flag. 340 The same prefix/SRv6 Locator can be advertised by multiple routers. 341 If at least one of them sets the A-Flag in its advertisement, the 342 prefix/SRv6 Locator SHOULD be considered as anycast. 344 Locator that is advertised by a single node and without an A-Flag 345 SHOULD be interpreted as a node specific locator. 347 All the nodes advertising the same anycast locator MUST instantiate 348 the exact same set of SIDs under such anycast locator. Failure to do 349 so may result in traffic being black-holed or mis-routed. 351 The Prefix Attribute Flags Sub-TLV can be carried in the SRv6 Locator 352 TLV as well as the Prefix Reachability TLVs. When a router 353 originates both the Prefix Reachability TLV and the SRv6 Locator TLV 354 for a given prefix, and the router is originating the Prefix 355 Attribute Flags Sub-TLV in one of the TLVs, the router SHOULD 356 advertise identical versions of the Prefix Attribute Flags Sub-TLV in 357 both TLVs. 359 7. Advertising Locators and End SIDs 361 The SRv6 Locator TLV is introduced to advertise SRv6 Locators and End 362 SIDs associated with each locator. 364 This new TLV shares the sub-TLV space defined for TLVs 135, 235, 236 365 and 237. 367 7.1. SRv6 Locator TLV Format 369 The SRv6 Locator TLV has the following format: 371 0 1 2 3 372 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 1 373 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 374 | Type | Length |R|R|R|R| MTID | 375 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 377 Type: 27 (Suggested value to be assigned by IANA) 379 Length: variable. 381 MTID: Multitopology Identifier as defined in [RFC5120]. 382 Note that the value 0 is legal. 384 Followed by one or more locator entries of the form: 386 0 1 2 3 387 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 1 388 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 389 | Metric | 390 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 391 | Flags | Algorithm | 392 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 393 | Loc Size | Locator (variable)... 394 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 395 | Sub-tlv-len | Sub-TLVs (variable) . . . | 396 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 398 Metric: 4 octets. As described in [RFC5305]. 400 Flags: 1 octet. The following flags are defined 402 0 403 0 1 2 3 4 5 6 7 404 +-+-+-+-+-+-+-+-+ 405 |D| Reserved | 406 +-+-+-+-+-+-+-+-+ 408 where: 409 D bit: When the Locator is leaked from level-2 to level-1, the D 410 bit MUST be set. Otherwise, this bit MUST be clear. Locators 411 with the D bit set MUST NOT be leaked from level-1 to level-2. 412 This is to prevent looping. 414 The remaining bits are reserved for future use. They SHOULD be 415 set to zero on transmission and MUST be ignored on receipt. 417 Algorithm: 1 octet. Associated algorithm. Algorithm values 418 are defined in the IGP Algorithm Type registry. 420 Loc-Size: 1 octet. Number of bits in the SRv6 Locator field. 421 (1 - 128) 423 Locator: 1-16 octets. This field encodes the advertised SRv6 424 Locator. The Locator is encoded in the minimal number of 425 octets for the given number of bits. Trailing bits MUST be set 426 to zero and ignored when received. 428 Sub-TLV-length: 1 octet. Number of octets used by sub-TLVs 430 Optional sub-TLVs. 432 7.2. SRv6 End SID sub-TLV 434 The SRv6 End SID sub-TLV is introduced to advertise SRv6 Segment 435 Identifiers (SID) with Endpoint behaviors which do not require a 436 particular neighbor in order to be correctly applied 437 [I-D.ietf-spring-srv6-network-programming]. SRv6 SIDs associated 438 with a neighbor are advertised using the sub-TLVs defined in 439 Section 8. 441 This new sub-TLV is advertised in the SRv6 Locator TLV defined in the 442 previous section. SRv6 End SIDs inherit the topology/algorithm from 443 the parent locator. 445 The SRv6 End SID sub-TLV has the following format: 447 0 1 2 3 448 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 1 449 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 450 | Type | Length | 451 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 452 | Flags | Endpoint Behavior | 453 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 454 | SID (128 bits) . . . | 455 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 456 | SID (cont . . .) | 457 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 458 | SID (cont . . .) | 459 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 460 | SID (cont . . .) | 461 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 462 |Sub-sub-tlv-len| sub-sub-TLVs (variable) . . . | 463 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 465 Type: 5 (Suggested value to be assigned by IANA). 467 Length: variable. 469 Flags: 1 octet. No flags are currently defined. 471 Endpoint Behavior: 2 octets, as defined in [I-D.ietf-spring-srv6- 472 network-programming]. Legal behavior values for this sub-TLV are 473 defined in Section 10 of this document. 475 SID: 16 octets. This field encodes the advertised SRv6 SID. 477 Sub-sub-TLV-length: 1 octet. Number of octets used by sub-sub- 478 TLVs. 480 Optional sub-sub-TLVs. 482 The SRv6 End SID MUST be a subnet of the associated Locator. SRv6 483 End SIDs which are NOT a subnet of the associated locator MUST be 484 ignored. 486 Multiple SRv6 End SIDs MAY be associated with the same locator. In 487 cases where the number of SRv6 End SID sub-TLVs exceeds the capacity 488 of a single TLV, multiple Locator TLVs for the same locator MAY be 489 advertised. For a given MTID/Locator the algorithm MUST be the same 490 in all TLVs. If this restriction is not met all TLVs for that MTID/ 491 Locator MUST be ignored. 493 8. Advertising SRv6 Adjacency SIDs 495 Certain SRv6 Endpoint behaviors 496 [I-D.ietf-spring-srv6-network-programming] must be associated with a 497 particular neighbor, and in case of multiple links to the same 498 neighbor, with a particular link in order to be correctly applied. 500 This document defines two new sub-TLVs of TLV 22, 23, 222, 223, and 501 141 - namely "SRv6 End.X SID" and "SRv6 LAN End.X SID". 503 IS-IS Neighbor advertisements are topology specific - but not 504 algorithm specific. End.X SIDs therefore inherit the topology from 505 the associated neighbor advertisement, but the algorithm is specified 506 in the individual SID. 508 All End.X SIDs MUST be a subnet of a Locator with matching topology 509 and algorithm which is advertised by the same node in an SRv6 Locator 510 TLV. End.X SIDs which do not meet this requirement MUST be ignored. 512 All End.X and LAN End.X SIDs MUST be subsumed by the subnet of a 513 Locator with the matching algorithm which is advertised by the same 514 node in an SRv6 Locator TLV. End.X SIDs which do not meet this 515 requirement MUST be ignored. This ensures that the node advertising 516 the End.X or LAN End.X SID is also advertising its corresponding 517 Locator with the algorithm that will be used for computing paths 518 destined to the SID. 520 8.1. SRv6 End.X SID sub-TLV 522 This sub-TLV is used to advertise an SRv6 SID associated with a point 523 to point adjacency. Multiple SRv6 End.X SID sub-TLVs MAY be 524 associated with the same adjacency. 526 The SRv6 End.X SID sub-TLV has the following format: 528 0 1 2 3 529 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 1 530 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 531 | Type | Length | 532 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 533 | Flags | Algorithm | Weight | 534 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 535 | Endpoint Behavior | 536 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 537 | SID (128 bits) . . . | 538 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 539 | SID (cont . . .) | 540 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 541 | SID (cont . . .) | 542 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 543 | SID (cont . . .) | 544 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 545 |Sub-sub-tlv-len| Sub-sub-TLVs (variable) . . . | 546 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 548 Type: 43 (Suggested value to be assigned by IANA). 550 Length: variable. 552 Flags: 1 octet. 554 0 1 2 3 4 5 6 7 555 +-+-+-+-+-+-+-+-+ 556 |B|S|P|Reserved | 557 +-+-+-+-+-+-+-+-+ 559 where: 561 B-Flag: Backup flag. If set, the End.X SID is eligible for 562 protection (e.g., using IPFRR) as described in [RFC8355]. 564 S-Flag. Set flag. When set, the S-Flag indicates that the 565 End.X SID refers to a set of adjacencies (and therefore MAY be 566 assigned to other adjacencies as well). 568 P-Flag. Persistent flag. When set, the P-Flag indicates that 569 the End.X SID is persistently allocated, i.e., the End.X SID 570 value remains consistent across router restart and/or interface 571 flap. 573 Other bits: MUST be zero when originated and ignored when 574 received. 576 Algorithm: 1 octet. Associated algorithm. Algorithm values are 577 defined in the IGP Algorithm Type registry. 579 Weight: 1 octet. The value represents the weight of the End.X SID 580 for the purpose of load balancing. The use of the weight is 581 defined in [I-D.ietf-spring-segment-routing]. 583 Endpoint Behavior: 2 octets. As defined in [I-D.ietf-spring-srv6- 584 network-programming] Legal behavior values for this sub-TLV are 585 defined in Section 10. 587 SID: 16 octets. This field encodes the advertised SRv6 SID. 589 Sub-sub-TLV-length: 1 octet. Number of octets used by sub-sub- 590 TLVs. 592 Note that multiple TLVs for the same neighbor may be required in 593 order to advertise all of the SRv6 End.X SIDs associated with that 594 neighbor. 596 8.2. SRv6 LAN End.X SID sub-TLV 598 This sub-TLV is used to advertise an SRv6 SID associated with a LAN 599 adjacency. Since the parent TLV is advertising an adjacency to the 600 Designated Intermediate System(DIS) for the LAN, it is necessary to 601 include the System ID of the physical neighbor on the LAN with which 602 the SRv6 SID is associated. Given that a large number of neighbors 603 may exist on a given LAN a large number of SRv6 LAN END.X SID sub- 604 TLVs may be associated with the same LAN. Note that multiple TLVs 605 for the same DIS neighbor may be required in order to advertise all 606 of the SRv6 End.X SIDs associated with that neighbor. 608 The SRv6 LAN End.X SID sub-TLV has the following format: 610 0 1 2 3 611 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 1 612 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 613 | Type | Length | System ID (6 octets) | 614 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | 615 | | 616 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 617 | Flags | Algorithm | Weight | 618 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 619 | Endpoint Behavior | 620 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 621 | SID (128 bits) . . . | 622 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 623 | SID (cont . . .) | 624 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 625 | SID (cont . . .) | 626 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 627 | SID (cont . . .) | 628 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 629 |Sub-sub-tlv-len| sub-sub-TLVs (variable) . . . | 630 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 632 Type: 44 (Suggested value to be assigned by IANA). 634 Length: variable. 636 System-ID: 6 octets of IS-IS System-ID of length "ID Length" as 637 defined in [ISO10589]. 639 Flags: 1 octet. 641 0 1 2 3 4 5 6 7 642 +-+-+-+-+-+-+-+-+ 643 |B|S|P|Reserved | 644 +-+-+-+-+-+-+-+-+ 646 where B,S, and P flags are as described in Section 8.1. Other 647 bits: MUST be zero when originated and ignored when received. 649 Algorithm: 1 octet. Associated algorithm. Algorithm values are 650 defined in the IGP Algorithm Type registry. 652 Weight: 1 octet. The value represents the weight of the End.X SID 653 for the purpose of load balancing. The use of the weight is 654 defined in [I-D.ietf-spring-segment-routing]. 656 Endpoint Behavior: 2 octets. As defined in [I-D.ietf-spring-srv6- 657 network-programming] Legal behavior values for this sub-TLV are 658 defined in Section 10. 660 SID: 16 octets. This field encodes the advertised SRv6 SID. 662 Sub-sub-TLV-length: 1 octet. Number of octets used by sub-sub- 663 TLVs. 665 9. SRv6 SID Structure Sub-Sub-TLV 667 SRv6 SID Structure Sub-Sub-TLV is an optional Sub-Sub-TLV of: 669 SRv6 End SID Sub-TLV (Section 7.2) 671 SRv6 End.X SID Sub-TLV (Section 8.1) 673 SRv6 LAN End.X SID Sub-TLV (Section 8.2) 675 SRv6 SID Structure Sub-Sub-TLV is used to advertise the length of 676 each individual part of the SRv6 SID as defined in 677 [I-D.ietf-spring-srv6-network-programming]. It has the following 678 format: 680 0 1 2 3 681 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 1 682 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 683 | Type | Length | 684 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 685 | LB Length | LN Length | Fun. Length | Arg. Length | 686 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 688 where: 690 Type: 1 692 Length: 4 octets. 694 LB Length: 1 octet. SRv6 SID Locator Block length in bits. 696 LN Length: 1 octet. SRv6 SID Locator Node length in bits. 698 Fun. Length: 1 octet. SRv6 SID Function length in bits. 700 Arg. Length: 1 octet. SRv6 SID Arguments length in bits. 702 ISIS SRv6 SID Structure Sub-Sub-TLV MUST NOT appear more than once in 703 its parent Sub-TLV. If it appears more than once in its parent Sub- 704 TLV, the parent Sub-TLV MUST be ignored by the receiver. 706 The sum of all four sizes advertised in ISIS SRv6 SID Structure Sub- 707 Sub-TLV must be lower or equal to 128 bits. If the sum of all four 708 sizes advertised in the ISIS SRv6 SID Structure Sub-Sub-TLV is larger 709 than 128 bits, the parent Sub-TLV MUST be ignored by the receiver. 711 10. Advertising Endpoint Behaviors 713 Endpoint behaviors are defined in 714 [I-D.ietf-spring-srv6-network-programming] and 715 [I-D.ietf-6man-spring-srv6-oam]. The codepoints for the Endpoint 716 behaviors are defined in the "SRv6 Endpoint Behaviors" registry 717 defined in [I-D.ietf-spring-srv6-network-programming]. This section 718 lists the Endpoint behaviors which MAY be advertised by ISIS, 719 together with their codepoints. If this behavior is advertised it 720 MUST only be advertised in the TLV[s] as indicated by "Y" in the 721 table below, and MUST NOT be advertised in the TLV[s] as indicated by 722 "N" in the table below. 724 Endpoint |Endpoint | End | End.X | Lan End.X | 725 Behavior |Behavior Codepoint | SID | SID | SID | 726 -----------------------|--------------------|-------|-------|-----------| 727 End (PSP, USP, USD) | 1-4, 28-31 | Y | N | N | 728 -----------------------|--------------------|-------|-------|-----------| 729 End.X (PSP, USP, USD) | 5-8, 32-35 | N | Y | Y | 730 -----------------------|--------------------|-------|-------|-----------| 731 End.T (PSP, USP, USD) | 9-12, 36-39 | Y | N | N | 732 -----------------------|--------------------|-------|-------|-----------| 733 End.DX6 | 16 | N | Y | Y | 734 -----------------------|--------------------|-------|-------|-----------| 735 End.DX4 | 17 | N | Y | Y | 736 -----------------------|--------------------|-------|-------|-----------| 737 End.DT6 | 18 | Y | N | N | 738 -----------------------|--------------------|-------|-------|-----------| 739 End.DT4 | 19 | Y | N | N | 740 -----------------------|--------------------|-------|-------|-----------| 741 End.DT64 | 20 | Y | N | N | 742 -----------------------|--------------------|-------|-------|-----------| 743 End.OP | 40 | Y | N | N | 744 -----------------------|--------------------|-------|-------|-----------| 745 End.OTP | 41 | Y | N | N | 747 11. Implementation Status 749 This section describes the implementation status of the ISIS SRv6 750 extensions. 752 11.1. Cisco 754 Cisco's ISIS SRv6 implementation supports following functionalities: 756 Types of SID supported: End, End.X, LAN End.X, END.OP 758 Intra/Inter area/level support: Yes 760 Anycast SID support: Yes, including A-flag (Section 6) 762 SID Structure Sub-Sub-TLV: Yes 764 11.2. Huawei 766 Huawei's ISIS SRv6 implementation supports following functionalities: 768 Types of SID supported: End, End.X, LAN End.X 770 Intra/Inter area/level support: Yes 772 Anycast SID support: Yes, no A-flag support (Section 6) 774 SID Structure Sub-Sub-TLV: No 776 11.3. Juniper 778 Juniper's ISIS SRv6 implementation supports following 779 functionalities: 781 Types of SID supported: End, End.X, LAN End.X 783 Intra/Inter area/level support: Yes 785 Anycast SID support: Yes, no A-flag support (Section 6) 787 SID Structure Sub-Sub-TLV: No 789 11.4. Interoperability Testing. 791 EANTC interoperability testing has been performed in April 2019. 792 Results can be found at EANTC site [1]. 794 12. IANA Considerations 796 This document requests allocation for the following TLVs, sub- TLVs, 797 and sub-sub-TLVs as well updating the ISIS TLV registry and defining 798 a new registry. 800 12.1. SRv6 Locator TLV 802 This document adds one new TLV to the IS-IS TLV Codepoints registry. 804 Value: 27 (suggested - to be assigned by IANA) 806 Name: SRv6 Locator 808 This TLV shares sub-TLV space with existing "Sub-TLVs for TLVs 135, 809 235, 236 and 237 registry". The name of this registry needs to be 810 changed to "Sub-TLVs for TLVs 27, 135, 235, 236 and 237 registry". 812 12.1.1. SRv6 End SID sub-TLV 814 This document adds the following new sub-TLV to the (renamed) "Sub- 815 TLVs for TLVs 27, 135, 235, 236 and 237 registry". 817 Value: 5 (suggested - to be assigned by IANA) 819 Name: SRv6 End SID 821 12.1.2. Revised sub-TLV table 823 The revised table of sub-TLVs for the (renamed) "Sub-TLVs for TLVs 824 27, 135, 235, 236 and 237 registry" is shown below: 826 Type 27 135 235 236 237 828 1 n y y y y 829 2 n y y y y 830 3 n y y y y 831 4 y y y y y 832 5 y n n n n 833 11 y y y y y 834 12 y y y y y 836 12.2. SRv6 Capabilities sub-TLV 838 This document adds the definition of a new sub-TLV in the "Sub- TLVs 839 for TLV 242 registry". 841 Type: 25 (Suggested - to be assigned by IANA) 842 Description: SRv6 Capabilities 844 This document requests the creation of a new IANA managed registry 845 for sub-sub-TLVs of the SRv6 Capability sub-TLV. The registration 846 procedure is "Expert Review" as defined in [RFC7370]. Suggested 847 registry name is "sub-sub-TLVs for SRv6 Capability sub-TLV". No sub- 848 sub-TLVs are defined by this document except for the reserved value. 850 0: Reserved 852 1-255: Unassigned 854 12.3. SRv6 End.X SID and SRv6 LAN End.X SID sub-TLVs 856 This document adds the definition of two new sub-TLVs in the "sub- 857 TLVs for TLV 22, 23, 25, 141, 222 and 223 registry". 859 Type: 43 (suggested - to be assigned by IANA) 861 Description: SRv6 End.X SID 863 Type: 44 (suggested - to be assigned by IANA) 865 Description: SRv6 LAN End.X SID 867 Type 22 23 25 141 222 223 869 43 y y y y y y 870 44 y y y y y y 872 12.4. MSD Types 874 This document defines the following new MSD types. These types are 875 to be defined in the IGP MSD Types registry defined in [RFC8491] . 877 All values are suggested values to be assigned by IANA. 879 Type Description 880 ------------------ 881 41 SRH Max SL 882 42 SRH Max End Pop 883 44 SRH Max H.encaps 884 45 SRH Max End D 886 12.5. Sub-Sub-TLVs for SID Sub-TLVs 888 This document creates the following Sub-Sub-TLV Registry within the 889 "IS-IS TLV Codepoints" registry: 891 Registry: Sub-Sub-TLVs for SID Sub-TLVs 893 Registration Procedure: Expert review 895 Reference: This document (Section 7.2, Section 8.1, Section 8.2). 897 This document defines the following Sub-Sub-TLV in the "Sub-Sub-TLVs 898 for SID Sub-TLVs" registry: 900 Type: 1 902 Description: SRv6 SID Structure Sub-Sub-TLV. 904 Reference: This document (Section 9). 906 12.6. Prefix Attribute Flags Sub-TLV 908 This document adds a new bit in the "Bit Values for Prefix Attribute 909 Flags Sub-TLV" registry: 911 Bit #: 4 913 Description: A bit 915 Reference: This document (Section 6). 917 13. Security Considerations 919 Security concerns for IS-IS are addressed in [ISO10589], [RFC5304], 920 and [RFC5310]. 922 14. Contributors 924 The following people gave a substantial contribution to the content 925 of this document and should be considered as co-authors: 927 Stefano Previdi 928 Huawei Technologies 929 Email: stefano@previdi.net 931 Paul Wells 932 Cisco Systems 933 Saint Paul, 934 Minnesota 935 United States 936 Email: pauwells@cisco.com 938 Daniel Voyer 939 Email: daniel.voyer@bell.ca 941 Satoru Matsushima 942 Email: satoru.matsushima@g.softbank.co.jp 944 Bart Peirens 945 Email: bart.peirens@proximus.com 947 Hani Elmalky 948 Email: hani.elmalky@ericsson.com 950 Prem Jonnalagadda 951 Email: prem@barefootnetworks.com 953 Milad Sharif 954 Email: msharif@barefootnetworks.com> 956 Robert Hanzl 957 Cisco Systems 958 Millenium Plaza Building, V Celnici 10, Prague 1, 959 Prague, Czech Republic 960 Email rhanzl@cisco.com 962 Ketan Talaulikar 963 Cisco Systems, Inc. 964 Email: ketant@cisco.com 966 15. References 968 15.1. Normative References 970 [I-D.ietf-6man-segment-routing-header] 971 Filsfils, C., Dukes, D., Previdi, S., Leddy, J., 972 Matsushima, S., and D. Voyer, "IPv6 Segment Routing Header 973 (SRH)", draft-ietf-6man-segment-routing-header-26 (work in 974 progress), October 2019. 976 [I-D.ietf-6man-spring-srv6-oam] 977 Ali, Z., Filsfils, C., Matsushima, S., Voyer, D., and M. 978 Chen, "Operations, Administration, and Maintenance (OAM) 979 in Segment Routing Networks with IPv6 Data plane (SRv6)", 980 draft-ietf-6man-spring-srv6-oam-03 (work in progress), 981 December 2019. 983 [I-D.ietf-spring-srv6-network-programming] 984 Filsfils, C., Camarillo, P., Leddy, J., Voyer, D., 985 Matsushima, S., and Z. Li, "SRv6 Network Programming", 986 draft-ietf-spring-srv6-network-programming-14 (work in 987 progress), March 2020. 989 [ISO10589] 990 Standardization", I. ". O. F., "Intermediate system to 991 Intermediate system intra-domain routeing information 992 exchange protocol for use in conjunction with the protocol 993 for providing the connectionless-mode Network Service (ISO 994 8473), ISO/IEC 10589:2002, Second Edition.", Nov 2002. 996 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 997 Requirement Levels", BCP 14, RFC 2119, 998 DOI 10.17487/RFC2119, March 1997, 999 . 1001 [RFC5120] Przygienda, T., Shen, N., and N. Sheth, "M-ISIS: Multi 1002 Topology (MT) Routing in Intermediate System to 1003 Intermediate Systems (IS-ISs)", RFC 5120, 1004 DOI 10.17487/RFC5120, February 2008, 1005 . 1007 [RFC5304] Li, T. and R. Atkinson, "IS-IS Cryptographic 1008 Authentication", RFC 5304, DOI 10.17487/RFC5304, October 1009 2008, . 1011 [RFC5305] Li, T. and H. Smit, "IS-IS Extensions for Traffic 1012 Engineering", RFC 5305, DOI 10.17487/RFC5305, October 1013 2008, . 1015 [RFC5310] Bhatia, M., Manral, V., Li, T., Atkinson, R., White, R., 1016 and M. Fanto, "IS-IS Generic Cryptographic 1017 Authentication", RFC 5310, DOI 10.17487/RFC5310, February 1018 2009, . 1020 [RFC7370] Ginsberg, L., "Updates to the IS-IS TLV Codepoints 1021 Registry", RFC 7370, DOI 10.17487/RFC7370, September 2014, 1022 . 1024 [RFC7794] Ginsberg, L., Ed., Decraene, B., Previdi, S., Xu, X., and 1025 U. Chunduri, "IS-IS Prefix Attributes for Extended IPv4 1026 and IPv6 Reachability", RFC 7794, DOI 10.17487/RFC7794, 1027 March 2016, . 1029 [RFC7981] Ginsberg, L., Previdi, S., and M. Chen, "IS-IS Extensions 1030 for Advertising Router Information", RFC 7981, 1031 DOI 10.17487/RFC7981, October 2016, 1032 . 1034 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 1035 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 1036 May 2017, . 1038 [RFC8491] Tantsura, J., Chunduri, U., Aldrin, S., and L. Ginsberg, 1039 "Signaling Maximum SID Depth (MSD) Using IS-IS", RFC 8491, 1040 DOI 10.17487/RFC8491, November 2018, 1041 . 1043 [RFC8667] Previdi, S., Ed., Ginsberg, L., Ed., Filsfils, C., 1044 Bashandy, A., Gredler, H., and B. Decraene, "IS-IS 1045 Extensions for Segment Routing", RFC 8667, 1046 DOI 10.17487/RFC8667, December 2019, 1047 . 1049 15.2. Informative References 1051 [I-D.ietf-lsr-flex-algo] 1052 Psenak, P., Hegde, S., Filsfils, C., Talaulikar, K., and 1053 A. Gulko, "IGP Flexible Algorithm", draft-ietf-lsr-flex- 1054 algo-06 (work in progress), February 2020. 1056 [I-D.ietf-spring-segment-routing] 1057 Filsfils, C., Previdi, S., Ginsberg, L., Decraene, B., 1058 Litkowski, S., and R. Shakir, "Segment Routing 1059 Architecture", draft-ietf-spring-segment-routing-15 (work 1060 in progress), January 2018. 1062 [RFC8355] Filsfils, C., Ed., Previdi, S., Ed., Decraene, B., and R. 1063 Shakir, "Resiliency Use Cases in Source Packet Routing in 1064 Networking (SPRING) Networks", RFC 8355, 1065 DOI 10.17487/RFC8355, March 2018, 1066 . 1068 15.3. URIs 1070 [1] http://www.eantc.de/fileadmin/eantc/downloads/events/2017- 1071 2020/MPLS2019/Segment_Routing_IPv6__SRv6_.pdf 1073 Authors' Addresses 1075 Peter Psenak (editor) 1076 Cisco Systems 1077 Pribinova Street 10 1078 Bratislava 81109 1079 Slovakia 1081 Email: ppsenak@cisco.com 1083 Clarence Filsfils 1084 Cisco Systems 1085 Brussels 1086 Belgium 1088 Email: cfilsfil@cisco.com 1090 Ahmed Bashandy 1091 Individual 1093 Email: abashandy.ietf@gmail.com 1095 Bruno Decraene 1096 Orange 1097 Issy-les-Moulineaux 1098 France 1100 Email: bruno.decraene@orange.com 1102 Zhibo Hu 1103 Huawei Technologies 1105 Email: huzhibo@huawei.com