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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Open Shortest Path First IGP P. Psenak, Ed. 3 Internet-Draft C. Filsfils 4 Intended status: Standards Track Cisco Systems, Inc. 5 Expires: February 4, 2019 S. Previdi, Ed. 6 Individual 7 H. Gredler 8 RtBrick Inc. 9 R. Shakir 10 Google, Inc. 11 W. Henderickx 12 Nokia 13 J. Tantsura 14 Nuage Networks 15 August 3, 2018 17 OSPFv3 Extensions for Segment Routing 18 draft-ietf-ospf-ospfv3-segment-routing-extensions-15 20 Abstract 22 Segment Routing (SR) allows a flexible definition of end-to-end paths 23 within IGP topologies by encoding paths as sequences of topological 24 sub-paths, called "segments". These segments are advertised by the 25 link-state routing protocols (IS-IS and OSPF). 27 This draft describes the OSPFv3 extensions required for Segment 28 Routing. 30 Requirements Language 32 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 33 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 34 document are to be interpreted as described in [RFC2119]. 36 Status of This Memo 38 This Internet-Draft is submitted in full conformance with the 39 provisions of BCP 78 and BCP 79. 41 Internet-Drafts are working documents of the Internet Engineering 42 Task Force (IETF). Note that other groups may also distribute 43 working documents as Internet-Drafts. The list of current Internet- 44 Drafts is at https://datatracker.ietf.org/drafts/current/. 46 Internet-Drafts are draft documents valid for a maximum of six months 47 and may be updated, replaced, or obsoleted by other documents at any 48 time. It is inappropriate to use Internet-Drafts as reference 49 material or to cite them other than as "work in progress." 51 This Internet-Draft will expire on February 4, 2019. 53 Copyright Notice 55 Copyright (c) 2018 IETF Trust and the persons identified as the 56 document authors. All rights reserved. 58 This document is subject to BCP 78 and the IETF Trust's Legal 59 Provisions Relating to IETF Documents 60 (https://trustee.ietf.org/license-info) in effect on the date of 61 publication of this document. Please review these documents 62 carefully, as they describe your rights and restrictions with respect 63 to this document. Code Components extracted from this document must 64 include Simplified BSD License text as described in Section 4.e of 65 the Trust Legal Provisions and are provided without warranty as 66 described in the Simplified BSD License. 68 Table of Contents 70 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 71 2. Segment Routing Identifiers . . . . . . . . . . . . . . . . . 3 72 2.1. SID/Label Sub-TLV . . . . . . . . . . . . . . . . . . . . 3 73 3. Segment Routing Capabilities . . . . . . . . . . . . . . . . 4 74 3.1. SR-Algorithm TLV . . . . . . . . . . . . . . . . . . . . 4 75 3.2. SID/Label Range TLV . . . . . . . . . . . . . . . . . . . 6 76 3.3. SR Local Block TLV . . . . . . . . . . . . . . . . . . . 8 77 3.4. SRMS Preference TLV . . . . . . . . . . . . . . . . . . . 10 78 4. OSPFv3 Extended Prefix Range TLV . . . . . . . . . . . . . . 11 79 5. Prefix SID Sub-TLV . . . . . . . . . . . . . . . . . . . . . 14 80 6. Adjacency Segment Identifier (Adj-SID) . . . . . . . . . . . 17 81 6.1. Adj-SID Sub-TLV . . . . . . . . . . . . . . . . . . . . . 17 82 6.2. LAN Adj-SID Sub-TLV . . . . . . . . . . . . . . . . . . . 19 83 7. Elements of Procedure . . . . . . . . . . . . . . . . . . . . 20 84 7.1. Intra-area Segment routing in OSPFv3 . . . . . . . . . . 20 85 7.2. Inter-area Segment routing in OSPFv3 . . . . . . . . . . 21 86 7.3. Segment Routing for External Prefixes . . . . . . . . . . 22 87 7.4. Advertisement of Adj-SID . . . . . . . . . . . . . . . . 23 88 7.4.1. Advertisement of Adj-SID on Point-to-Point Links . . 23 89 7.4.2. Adjacency SID on Broadcast or NBMA Interfaces . . . . 23 90 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 23 91 8.1. OSPFv3 Extended-LSA TLV Registry . . . . . . . . . . . . 23 92 8.2. OSPFv3 Extended-LSA Sub-TLV registry . . . . . . . . . . 24 93 9. Security Considerations . . . . . . . . . . . . . . . . . . . 24 94 10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 24 95 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 25 96 11.1. Normative References . . . . . . . . . . . . . . . . . . 25 97 11.2. Informative References . . . . . . . . . . . . . . . . . 26 98 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 26 100 1. Introduction 102 Segment Routing (SR) allows a flexible definition of end-to-end paths 103 within IGP topologies by encoding paths as sequences of topological 104 sub-paths, called "segments". These segments are advertised by the 105 link-state routing protocols (IS-IS and OSPF). Prefix segments 106 represent an ECMP-aware shortest-path to a prefix (or a node), as per 107 the state of the IGP topology. Adjacency segments represent a hop 108 over a specific adjacency between two nodes in the IGP. A prefix 109 segment is typically a multi-hop path while an adjacency segment, in 110 most cases, is a one-hop path. SR's control-plane can be applied to 111 both IPv6 and MPLS data-planes, and does not require any additional 112 signalling (other than IGP extensions). The IPv6 data plane is out 113 of the scope of this specification - OSPFv3 extension for SR with 114 IPv6 data plane will be specified in a separate document. When used 115 in MPLS networks, SR paths do not require any LDP or RSVP-TE 116 signalling. However, SR can interoperate in the presence of LSPs 117 established with RSVP or LDP. 119 There are additional segment types, e.g., Binding SID defined in 120 [RFC8402]. 122 This draft describes the OSPFv3 extensions required for Segment 123 Routing with MPLS data plane. 125 Segment Routing architecture is described in [RFC8402]. 127 Segment Routing use cases are described in [RFC7855]. 129 2. Segment Routing Identifiers 131 Segment Routing defines various types of Segment Identifiers (SIDs): 132 Prefix-SID, Adjacency-SID, LAN Adjacency SID, and Binding SID. 134 2.1. SID/Label Sub-TLV 136 The SID/Label Sub-TLV appears in multiple TLVs or Sub-TLVs defined 137 later in this document. It is used to advertise the SID or label 138 associated with a prefix or adjacency. The SID/Label Sub-TLV has 139 following format: 141 0 1 2 3 142 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 1 143 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 144 | Type | Length | 145 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 146 | SID/Label (variable) | 147 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 149 where: 151 Type: 7 153 Length: Variable, 3 or 4 octets 155 SID/Label: If length is set to 3, then the 20 rightmost bits 156 represent a label. If length is set to 4, then the value 157 represents a 32-bit SID. 159 The receiving router MUST ignore the SID/Label Sub-TLV if the 160 length is other then 3 or 4. 162 3. Segment Routing Capabilities 164 Segment Routing requires some additional router capabilities to be 165 advertised to other routers in the area. 167 These SR capabilities are advertised in the OSPFv3 Router Information 168 Opaque LSA (defined in [RFC7770]). 170 3.1. SR-Algorithm TLV 172 The SR-Algorithm TLV is a top-level TLV of the OSPFv3 Router 173 Information Opaque LSA (defined in [RFC7770]). 175 The SR-Algorithm TLV is optional. It SHOULD only be advertised once 176 in the OSPFv3 Router Information Opaque LSA. If the SR-Algorithm TLV 177 is not advertised by the node, such node is considered as not being 178 segment routing capable. 180 An SR router can use various algorithms when calculating reachability 181 to OSPFv3 routers or prefixes in an OSPFv3 area. Examples of these 182 algorithms are metric-based Shortest Path First (SPF), various 183 flavors of Constrained SPF, etc. The SR-Algorithm TLV allows a 184 router to advertise the algorithms currently used by the router to 185 other routers in an OSPFv3 area. The SR-Algorithm TLV has following 186 format: 188 0 1 2 3 189 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 1 190 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 191 | Type | Length | 192 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 193 | Algorithm 1 | Algorithm... | Algorithm n | | 194 +- -+ 195 | | 196 + + 198 where: 200 Type: 8 202 Length: Variable, in octets, dependent on number of algorithms 203 advertised. 205 Algorithm: Single octet identifying the algorithm. The following 206 values are defined by this document: 208 0: Shortest Path First (SPF) algorithm based on link metric. 209 This is the standard shortest path algorithm as computed by the 210 OSPFv3 protocol. Consistent with the deployed practice for 211 link-state protocols, Algorithm 0 permits any node to overwrite 212 the SPF path with a different path based on its local policy. 213 If the SR-Algorithm TLV is advertised, Algorithm 0 MUST be 214 included. 216 1: Strict Shortest Path First (SPF) algorithm based on link 217 metric. The algorithm is identical to Algorithm 0 but 218 Algorithm 1 requires that all nodes along the path will honor 219 the SPF routing decision. Local policy at the node claiming 220 support for Algorithm 1 MUST NOT alter the SPF paths computed 221 by Algorithm 1. 223 When multiple SR-Algorithm TLVs are received from a given router, the 224 receiver MUST use the first occurrence of the TLV in the OSPFv3 225 Router Information Opaque LSA. If the SR-Algorithm TLV appears in 226 multiple OSPFv3 Router Information Opaque LSAs that have different 227 flooding scopes, the SR-Algorithm TLV in the OSPFv3 Router 228 Information Opaque LSA with the area-scoped flooding scope MUST be 229 used. If the SR-Algorithm TLV appears in multiple OSPFv3 Router 230 Information Opaque LSAs that have the same flooding scope, the SR- 231 Algorithm TLV in the OSPFv3 Router Information Opaque LSA with the 232 numerically smallest Instance ID MUST be used and subsequent 233 instances of the SR-Algorithm TLV MUST be ignored. 235 The OSPFv3 Router Information Opaque LSA can be advertised at any of 236 the defined opaque flooding scopes (link, area, or Autonomous System 237 (AS)). For the purpose of SR-Algorithm TLV advertisement, area- 238 scoped flooding is REQUIRED. 240 3.2. SID/Label Range TLV 242 Prefix SIDs MAY be advertised in a form of an index as described in 243 Section 5. Such index defines the offset in the SID/Label space 244 advertised by the router. The SID/Label Range TLV is used to 245 advertise such SID/Label space. 247 The SID/Label Range TLV is a top-level TLV of the OSPFv3 Router 248 Information Opaque LSA (defined in [RFC7770]). 250 The SID/Label Range TLV MAY appear multiple times and has the 251 following format: 253 0 1 2 3 254 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 1 255 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 256 | Type | Length | 257 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 258 | Range Size | Reserved | 259 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 260 | Sub-TLVs (variable) | 261 +- -+ 262 | | 263 + + 265 where: 267 Type: 9 269 Length: Variable, in octets, dependent on Sub-TLVs. 271 Range Size: 3-octet SID/label range size (i.e., the number of SIDs 272 or labels in the range including the first SID/label). It MUST be 273 greater than 0. 275 Reserved: SHOULD be set to 0 on transmission and MUST be ignored 276 on reception. 278 Initially, the only supported Sub-TLV is the SID/Label Sub-TLV as 279 defined in Section 2.1. The SID/Label Sub-TLV MUST be included in 280 the SID/Label Range TLV. The SID/Label advertised in the SID/Label 281 Sub-TLV represents the first SID/Label in the advertised range. 283 Only a single SID/Label Sub-TLV MAY be advertised in SID/Label Range 284 TLV. If more then one SID/Label Sub-TLVs are present, the SID/Label 285 Range TLV MUST be ignored. 287 Multiple occurrences of the SID/Label Range TLV MAY be advertised, in 288 order to advertise multiple ranges. In such case: 290 o The originating router MUST encode each range into a different 291 SID/Label Range TLV. 293 o The originating router decides the order in which the set of SID/ 294 Label Range TLVs are advertised inside the Router Information 295 Opaque LSA. The originating router MUST ensure the order is the 296 same after a graceful restart (using checkpointing, non-volatile 297 storage, or any other mechanism) in order to assure the SID/label 298 range and SID index correspondence is preserved across graceful 299 restarts. 301 o The receiving router MUST adhere to the order in which the ranges 302 are advertised when calculating a SID/label from a SID index. 304 o The originating router MUST NOT advertise overlapping ranges. 306 o When a router receives multiple overlapping ranges, it MUST 307 conform to the procedures defined in 308 [I-D.ietf-spring-segment-routing-mpls]. 310 The following example illustrates the advertisement of multiple 311 ranges: 313 The originating router advertises the following ranges: 315 Range 1: Range Size: 100 SID/Label Sub-TLV: 100 316 Range 1: Range Size: 100 SID/Label Sub-TLV: 1000 317 Range 1: Range Size: 100 SID/Label Sub-TLV: 500 319 The receiving routers concatenate the ranges and build the Segment 320 Routing Global Block (SRGB) as follows: 322 SRGB = [100, 199] 323 [1000, 1099] 324 [500, 599] 326 The indexes span multiple ranges: 328 index=0 means label 100 329 ... 330 index 99 means label 199 331 index 100 means label 1000 332 index 199 means label 1099 333 ... 334 index 200 means label 500 335 ... 337 The OSPFv3 Router Information Opaque LSA can be advertised at any of 338 the defined flooding scopes (link, area, or autonomous system (AS)). 339 For the purpose of SID/Label Range TLV advertisement, area-scoped 340 flooding is REQUIRED. 342 3.3. SR Local Block TLV 344 The SR Local Block TLV (SRLB TLV) contains the range of labels the 345 node has reserved for local SIDs. SIDs from the SRLB MAY be used for 346 Adjacency-SIDs, but also by components other than the OSPFv3 347 protocol. As an example, an application or a controller can instruct 348 the router to allocate a specific local SID. Some controllers or 349 applications can use the control plane to discover the available set 350 of local SIDs on a particular router. In such cases, the SRLB is 351 advertised in the control plane. The requirement to advertise the 352 SRLB is further described in [I-D.ietf-spring-segment-routing-mpls]. 353 The SRLB TLV is used to advertise the SRLB. 355 The SRLB TLV is a top-level TLV of the OSPFv3 Router Information 356 Opaque LSA (defined in [RFC7770]). 358 The SRLB TLV MAY appear multiple times in the OSPFv3 Router 359 Information Opaque LSA and has the following format: 361 0 1 2 3 362 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 1 363 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 364 | Type | Length | 365 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 366 | Range Size | Reserved | 367 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 368 | Sub-TLVs (variable) | 369 +- -+ 370 | | 371 + + 373 where: 375 Type: 14 377 Length: Variable, in octets, dependent on Sub-TLVs. 379 Range Size: 3-octet SID/label range size (i.e., the number of SIDs 380 or labels in the range including the first SID/label). It MUST be 381 greater than 0. 383 Reserved: SHOULD be set to 0 on transmission and MUST be ignored 384 on reception. 386 Initially, the only supported Sub-TLV is the SID/Label Sub-TLV as 387 defined in Section 2.1. The SID/Label Sub-TLV MUST be included in 388 the SRLB TLV. The SID/Label advertised in the SID/Label Sub-TLV 389 represents the first SID/Label in the advertised range. 391 Only a single SID/Label Sub-TLV MAY be advertised in the SRLB TLV. 392 If more then one SID/Label Sub-TLVs are present, the SRLB TLV MUST be 393 ignored. 395 The originating router MUST NOT advertise overlapping ranges. 397 Each time a SID from the SRLB is allocated, it SHOULD also be 398 reported to all components (e.g., controller or applications) in 399 order for these components to have an up-to-date view of the current 400 SRLB allocation. This is required to avoid collisions between 401 allocation instructions. 403 Within the context of OSPFv3, the reporting of local SIDs is done 404 through OSPFv3 Sub-TLVs such as the Adjacency-SID (Section 6). 405 However, the reporting of allocated local SIDs can also be done 406 through other means and protocols which are outside the scope of this 407 document. 409 A router advertising the SRLB TLV MAY also have other label ranges, 410 outside of the SRLB, used for its local allocation purposes which are 411 not advertised in the SRLB TLV. For example, it is possible that an 412 Adjacency-SID is allocated using a local label that is not part of 413 the SRLB. 415 The OSPFv3 Router Information Opaque LSA can be advertised at any of 416 the defined flooding scopes (link, area, or autonomous system (AS)). 417 For the purpose of SRLB TLV advertisement, area-scoped flooding is 418 REQUIRED. 420 3.4. SRMS Preference TLV 422 The Segment Routing Mapping Server Preference TLV (SRMS Preference 423 TLV) is used to advertise a preference associated with a node that 424 acts as an SR Mapping Server. The role of an SRMS is described in 425 [I-D.ietf-spring-segment-routing-ldp-interop]. SRMS preference is 426 defined in [I-D.ietf-spring-segment-routing-ldp-interop]. 428 The SRMS Preference TLV is a top-level TLV of the OSPFv3 Router 429 Information Opaque LSA (defined in [RFC7770]). 431 The SRMS Preference TLV MAY only be advertised once in the OSPFv3 432 Router Information Opaque LSA and has the following format: 434 0 1 2 3 435 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 1 436 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 437 | Type | Length | 438 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 439 | Preference | Reserved | 440 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 442 where: 444 Type: 15 446 Length: 4 octets 448 Preference: 1 octet. SRMS preference value from 0 to 255. 450 Reserved: SHOULD be set to 0 on transmission and MUST be ignored 451 on reception. 453 When multiple SRMS Preference TLVs are received from a given router, 454 the receiver MUST use the first occurrence of the TLV in the OSPFv3 455 Router Information Opaque LSA. If the SRMS Preference TLV appears in 456 multiple OSPFv3 Router Information Opaque LSAs that have different 457 flooding scopes, the SRMS Preference TLV in the OSPFv3 Router 458 Information Opaque LSA with the narrowest flooding scope MUST be 459 used. If the SRMS Preference TLV appears in multiple OSPFv3 Router 460 Information Opaque LSAs that have the same flooding scope, the SRMS 461 Preference TLV in the OSPFv3 Router Information Opaque LSA with the 462 numerically smallest Instance ID MUST be used and subsequent 463 instances of the SRMS Preference TLV MUST be ignored. 465 The OSPFv3 Router Information Opaque LSA can be advertised at any of 466 the defined flooding scopes (link, area, or autonomous system (AS)). 467 For the purpose of the SRMS Preference TLV advertisement, AS-scoped 468 flooding SHOULD be used. This is because SRMS servers can be located 469 in different areas than consumers of the SRMS advertisements. If 470 SRMS advertisements from an SRMS server are only used inside the SRMS 471 server's area, area-scoped flooding MAY be used. 473 4. OSPFv3 Extended Prefix Range TLV 475 In some cases it is useful to advertise attributes for a range of 476 prefixes. The Segment Routing Mapping Server, which is described in 477 [I-D.ietf-spring-segment-routing-ldp-interop], is an example of where 478 we need a single advertisement to advertise SIDs for multiple 479 prefixes from a contiguous address range. 481 The OSPFv3 Extended Prefix Range TLV is defined for this purpose. 483 The OSPFv3 Extended Prefix Range TLV is a top-level TLV of the 484 following LSAs defined in [RFC8362]: 486 E-Intra-Area-Prefix-LSA 488 E-Inter-Area-Prefix-LSA 490 E-AS-External-LSA 492 E-Type-7-LSA 494 Multiple OSPFv3 Extended Prefix Range TLVs MAY be advertised in each 495 LSA mentioned above. The OSPFv3 Extended Prefix Range TLV has the 496 following format: 498 0 1 2 3 499 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 1 500 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 501 | Type | Length | 502 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 503 | Prefix Length | AF | Range Size | 504 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 505 | Flags | Reserved | 506 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 507 | Address Prefix (variable) | 508 | ... | 509 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 510 | Sub-TLVs (variable) | 511 +- -+ 512 | | 514 where: 516 Type: 9 518 Length: Variable, in octets, dependent on Sub-TLVs. 520 Prefix length: Length of prefix in bits. 522 AF: Address family for the prefix. 524 AF: 0 - IPv4 unicast 526 AF: 1 - IPv6 unicast 528 Range size: Represents the number of prefixes that are covered by 529 the advertisement. The Range Size MUST NOT exceed the number of 530 prefixes that could be satisfied by the prefix length without 531 including: 533 Addresses from the IPv4 multicast address range (224.0.0.0/3), 534 if the AF is IPv4 unicast 536 Addresses other than the IPv6 unicast addresses, if the AF is 537 IPv6 unicast 539 Flags: Single octet field. The following flags are defined: 541 0 1 2 3 4 5 6 7 542 +--+--+--+--+--+--+--+--+ 543 |IA| | | | | | | | 544 +--+--+--+--+--+--+--+--+ 546 where: 548 IA-Flag: Inter-Area flag. If set, advertisement is of inter- 549 area type. An Are Border Router (ABR) that is advertising the 550 OSPFv3 Extended Prefix Range TLV between areas MUST set this 551 bit. 553 This bit is used to prevent redundant flooding of Prefix Range 554 TLVs between areas as follows: 556 An ABR only propagates an inter-area Prefix Range 557 advertisement from the backbone area to connected non- 558 backbone areas if the advertisement is considered to be the 559 best one. The following rules are used to select the best 560 range from the set of advertisements for the same Prefix 561 Range: 563 An ABR always prefers intra-area Prefix Range 564 advertisements over inter-area advertisements. 566 An ABR does not consider inter-area Prefix Range 567 advertisements coming from non-backbone areas. 569 Reserved: SHOULD be set to 0 on transmission and MUST be ignored 570 on reception. 572 Address Prefix: 574 For the address family IPv4 unicast, the prefix itself is 575 encoded as a 32-bit value. The default route is represented by 576 a prefix of length 0. 578 For the address family IPv6 unicast, the prefix, encoded as an 579 even multiple of 32-bit words, padded with zeroed bits as 580 necessary. This encoding consumes ((PrefixLength + 31) / 32) 581 32-bit words. 583 Prefix encoding for other address families is beyond the scope 584 of this specification. 586 5. Prefix SID Sub-TLV 588 The Prefix SID Sub-TLV is a Sub-TLV of the following OSPFv3 TLVs as 589 defined in [RFC8362] and in Section 4: 591 Intra-Area Prefix TLV 593 Inter-Area Prefix TLV 595 External Prefix TLV 597 OSPFv3 Extended Prefix Range TLV 599 It MAY appear more than once in the parent TLV and has the following 600 format: 602 0 1 2 3 603 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 1 604 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 605 | Type | Length | 606 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 607 | Flags | Algorithm | Reserved | 608 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 609 | SID/Index/Label (variable) | 610 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 611 where: 613 Type: 4 615 Length: 7 or 8 octets, dependent on the V-flag 617 Flags: Single octet field. The following flags are defined: 619 0 1 2 3 4 5 6 7 620 +--+--+--+--+--+--+--+--+ 621 | |NP|M |E |V |L | | | 622 +--+--+--+--+--+--+--+--+ 623 where: 625 NP-Flag: No-PHP flag. If set, then the penultimate hop MUST 626 NOT pop the Prefix-SID before delivering packets to the node 627 that advertised the Prefix-SID. 629 M-Flag: Mapping Server Flag. If set, the SID was advertised by 630 a Segment Routing Mapping Server as described in 631 [I-D.ietf-spring-segment-routing-ldp-interop]. 633 E-Flag: Explicit-Null Flag. If set, any upstream neighbor of 634 the Prefix-SID originator MUST replace the Prefix-SID with the 635 Explicit-NULL label (0 for IPv4, 2 for IPv6) before forwarding 636 the packet. 638 V-Flag: Value/Index Flag. If set, then the Prefix-SID carries 639 an absolute value. If not set, then the Prefix-SID carries an 640 index. 642 L-Flag: Local/Global Flag. If set, then the value/index 643 carried by the Prefix-SID has local significance. If not set, 644 then the value/index carried by this Sub-TLV has global 645 significance. 647 Other bits: Reserved. These MUST be zero when sent and are 648 ignored when received. 650 Reserved: SHOULD be set to 0 on transmission and MUST be ignored 651 on reception. 653 Algorithm: Single octet identifying the algorithm the Prefix-SID 654 is associated with as defined in Section 3.1. 656 A router receiving a Prefix-SID from a remote node and with an 657 algorithm value that such remote node has not advertised in the 658 SR-Algorithm Sub-TLV (Section 3.1) MUST ignore the Prefix-SID Sub- 659 TLV. 661 SID/Index/Label: According to the V and L flags, it contains 662 either: 664 A 32-bit index defining the offset in the SID/Label space 665 advertised by this router. 667 A 24-bit label where the 20 rightmost bits are used for 668 encoding the label value. 670 If an OSPFv3 router advertises multiple Prefix-SIDs for the same 671 prefix, topology, and algorithm, all of them MUST be ignored. 673 When calculating the outgoing label for the prefix, the router MUST 674 take into account, as described below, the E, NP, and M flags 675 advertised by the next-hop router if that router advertised the SID 676 for the prefix. This MUST be done regardless of whether the next-hop 677 router contributes to the best path to the prefix. 679 The NP-Flag (No-PHP) MUST be set and the E-flag MUST be clear for 680 Prefix-SIDs allocated to prefixes that are propagated between areas 681 by an ABR based on intra-area or inter-area reachability, unless the 682 advertised prefix is directly attached to such ABR. 684 The NP-Flag (No-PHP) MUST be set and the E-flag MUST be clear for 685 Prefix-SIDs allocated to redistributed prefixes, unless the 686 redistributed prefix is directly attached to the advertising 687 Autonomous System Boundary Router (ASBR). 689 If the NP-Flag is not set, then any upstream neighbor of the Prefix- 690 SID originator MUST pop the Prefix-SID. This is equivalent to the 691 penultimate hop popping mechanism used in the MPLS dataplane. If the 692 NP-flag is not set, then the received E-flag is ignored. 694 If the NP-flag is set then: 696 If the E-flag is not set, then any upstream neighbor of the 697 Prefix-SID originator MUST keep the Prefix-SID on top of the 698 stack. This is useful when the originator of the Prefix-SID needs 699 to stitch the incoming packet into a continuing MPLS LSP to the 700 final destination. This could occur at an Area Border Router 701 (prefix propagation from one area to another) or at an AS Boundary 702 Router (prefix propagation from one domain to another). 704 If the E-flag is set, then any upstream neighbor of the Prefix-SID 705 originator MUST replace the Prefix-SID with an Explicit-NULL 706 label. This is useful, e.g., when the originator of the Prefix- 707 SID is the final destination for the related prefix and the 708 originator wishes to receive the packet with the original EXP 709 bits. 711 When the M-Flag is set, the NP-flag and the E-flag MUST be ignored on 712 reception. 714 As the Mapping Server does not specify the originator of a prefix 715 advertisement, it is not possible to determine PHP behavior solely 716 based on the Mapping Server advertisement. However, PHP behavior 717 SHOULD be done in following cases: 719 The Prefix is intra-area type and the downstream neighbor is the 720 originator of the prefix. 722 The Prefix is inter-area type and the downstream neighbor is an 723 ABR, which is advertising prefix reachability and is setting the 724 LA-bit in the Prefix Options as described in [RFC8362]. 726 The Prefix is external type and the downstream neighbor is an 727 ASBR, which is advertising prefix reachability and is setting the 728 LA-bit in the Prefix Options as described in [RFC8362]. 730 When a Prefix-SID is advertised in the OSPFv3 Extended Prefix Range 731 TLV, then the value advertised in the Prefix SID Sub-TLV is 732 interpreted as a starting SID/Label value. 734 Example 1: If the following router addresses (loopback addresses) 735 need to be mapped into the corresponding Prefix SID indexes: 737 Router-A: 2001:DB8::1/128, Prefix-SID: Index 1 738 Router-B: 2001:DB8::2/128, Prefix-SID: Index 2 739 Router-C: 2001:DB8::3/128, Prefix-SID: Index 3 740 Router-D: 2001:DB8::4/128, Prefix-SID: Index 4 742 then the Address Prefix field in the OSPFv3 Extended Prefix Range TLV 743 would be set to 2001:DB8::1, the Prefix Length would be set to 128, 744 the Range Size would be set to 4, and the Index value in the Prefix- 745 SID Sub-TLV would be set to 1. 747 Example 2: If the following prefixes need to be mapped into the 748 corresponding Prefix-SID indexes: 750 2001:DB8:1::0/120, Prefix-SID: Index 51 751 2001:DB8:1::100/120, Prefix-SID: Index 52 752 2001:DB8:1::200/120, Prefix-SID: Index 53 753 2001:DB8:1::300/120, Prefix-SID: Index 54 754 2001:DB8:1::400/120, Prefix-SID: Index 55 755 2001:DB8:1::500/120, Prefix-SID: Index 56 756 2001:DB8:1::600/120, Prefix-SID: Index 57 758 then the Prefix field in the OSPFv3 Extended Prefix Range TLV would 759 be set to 2001:DB8:1::0, the Prefix Length would be set to 120, the 760 Range Size would be set to 7, and the Index value in the Prefix-SID 761 Sub-TLV would be set to 51. 763 6. Adjacency Segment Identifier (Adj-SID) 765 An Adjacency Segment Identifier (Adj-SID) represents a router 766 adjacency in Segment Routing. 768 6.1. Adj-SID Sub-TLV 770 The Adj-SID Sub-TLV is an optional Sub-TLV of the Router-Link TLV as 771 defined in [RFC8362]. It MAY appear multiple times in the Router- 772 Link TLV. The Adj-SID Sub-TLV has the following format: 774 0 1 2 3 775 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 1 776 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 777 | Type | Length | 778 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 779 | Flags | Weight | Reserved | 780 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 781 | SID/Label/Index (variable) | 782 +---------------------------------------------------------------+ 784 where: 786 Type: 5 788 Length: 7 or 8 octets, dependent on the V flag. 790 Flags: Single octet field containing the following flags: 792 0 1 2 3 4 5 6 7 793 +-+-+-+-+-+-+-+-+ 794 |B|V|L|G|P| | 795 +-+-+-+-+-+-+-+-+ 797 where: 799 B-Flag: Backup Flag. If set, the Adj-SID refers to an 800 adjacency that is eligible for protection (e.g., using IPFRR or 801 MPLS-FRR) as described in section 3.5 of [RFC8402]. 803 The V-Flag: Value/Index Flag. If set, then the Adj-SID carries 804 an absolute value. If not set, then the Adj-SID carries an 805 index. 807 The L-Flag: Local/Global Flag. If set, then the value/index 808 carried by the Adj-SID has local significance. If not set, 809 then the value/index carried by this Sub-TLV has global 810 significance. 812 The G-Flag: Group Flag. When set, the G-Flag indicates that 813 the Adj-SID refers to a group of adjacencies (and therefore MAY 814 be assigned to other adjacencies as well). 816 P-Flag. Persistent flag. When set, the P-Flag indicates that 817 the Adj-SID is persistently allocated, i.e., the Adj-SID value 818 remains the same across router restart and/or interface flap. 820 Other bits: Reserved. These MUST be zero when sent and are 821 ignored when received. 823 Reserved: SHOULD be set to 0 on transmission and MUST be ignored 824 on reception. 826 Weight: Weight used for load-balancing purposes. The use of the 827 weight is defined in [RFC8402]. 829 SID/Index/Label: According to the V and L flags, it contains 830 either: 832 A 32-bit index defining the offset in the SID/Label space 833 advertised by this router. 835 A 24-bit label where the 20 rightmost bits are used for 836 encoding the label value. 838 An SR-capable router MAY allocate an Adj-SID for each of its 839 adjacencies and set the B-Flag when the adjacency is eligible for 840 protection by an FRR mechanism (IP or MPLS) as described in 841 [RFC8402]. 843 An SR-capable router MAY allocate more than one Adj-SID to an 844 adjacency. 846 An SR-capable router MAY allocate the same Adj-SID to different 847 adjacencies. 849 When the P-flag is not set, the Adj-SID MAY be persistent. When the 850 P-flag is set, the Adj-SID MUST be persistent. 852 6.2. LAN Adj-SID Sub-TLV 854 The LAN Adj-SID Sub-TLV is an optional Sub-TLV of the Router-Link 855 TLV. It MAY appear multiple times in the Router-Link TLV. It is 856 used to advertise a SID/Label for an adjacency to a non-DR router on 857 a broadcast, NBMA, or hybrid [RFC6845] network. 859 0 1 2 3 860 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 1 861 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 862 | Type | Length | 863 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 864 | Flags | Weight | Reserved | 865 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 866 | Neighbor ID | 867 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 868 | SID/Label/Index (variable) | 869 +---------------------------------------------------------------+ 871 where: 873 Type: 6 875 Length: 11 or 12 octets, dependent on V-flag. 877 Flags: same as in Section 6.1 879 Weight: Weight used for load-balancing purposes. The use of the 880 weight is defined in [RFC8402]. 882 Reserved: SHOULD be set to 0 on transmission and MUST be ignored 883 on reception. 885 Neighbor ID: The Router ID of the neighbor for which the LAN-Adj- 886 SID is advertised. 888 SID/Index/Label: According to the V and L flags, it contains 889 either: 891 A 32-bit index defining the offset in the SID/Label space 892 advertised by this router. 894 A 24-bit label where the 20 rightmost bits are used for 895 encoding the label value. 897 When the P-flag is not set, the Adj-SID MAY be persistent. When 898 the P-flag is set, the Adj-SID MUST be persistent. 900 7. Elements of Procedure 902 7.1. Intra-area Segment routing in OSPFv3 904 An OSPFv3 router that supports segment routing MAY advertise Prefix- 905 SIDs for any prefix to which it is advertising reachability (e.g., a 906 loopback IP address as described in Section 5). 908 A Prefix-SID can also be advertised by SR Mapping Servers (as 909 described in [I-D.ietf-spring-segment-routing-ldp-interop]). A 910 Mapping Server advertises Prefix-SIDs for remote prefixes that exist 911 in the OSPFv3 routing domain. Multiple Mapping Servers can advertise 912 Prefix-SIDs for the same prefix, in which case the same Prefix-SID 913 MUST be advertised by all of them. The SR Mapping Server could use 914 either area flooding scope or autonomous system flooding scope when 915 advertising Prefix SIDs for prefixes, based on the configuration of 916 the SR Mapping Server. Depending on the flooding scope used, the SR 917 Mapping Server chooses the OSPFv3 LSA type that will be used. If the 918 area flooding scope is needed, an E-Intra-Area-Prefix-LSA [RFC8362] 919 is used. If autonomous system flooding scope is needed, an E-AS- 920 External-LSA [RFC8362] is used. 922 When a Prefix-SID is advertised by the Mapping Server, which is 923 indicated by the M-flag in the Prefix-SID Sub-TLV (Section 5), the 924 route type as implied by the LSA type is ignored and the Prefix-SID 925 is bound to the corresponding prefix independent of the route type. 927 Advertisement of the Prefix-SID by the Mapping Server using an Inter- 928 Area Prefix TLV, External-Prefix TLV, or Intra-Area-Prefix TLV 929 [RFC8362] does not itself contribute to the prefix reachability. The 930 NU-bit MUST be set in the PrefixOptions field of the LSA which is 931 used by the Mapping Server to advertise SID or SID Range, which 932 prevents the advertisement from contributing to prefix reachability. 934 An SR Mapping Server MUST use the OSPFv3 Extended Prefix Range TLVs 935 when advertising SIDs for prefixes. Prefixes of different route- 936 types can be combined in a single OSPFv3 Extended Prefix Range TLV 937 advertised by an SR Mapping Server. 939 Area-scoped OSPFv3 Extended Prefix Range TLVs are propagated between 940 areas. Similar to propagation of prefixes between areas, an ABR only 941 propagates the OSPFv3 Extended Prefix Range TLV that it considers to 942 be the best from the set it received. The rules used to pick the 943 best OSPFv3 Extended Prefix Range TLV are described in Section 4. 945 When propagating an OSPFv3 Extended Prefix Range TLV between areas, 946 ABRs MUST set the IA-Flag, that is used to prevent redundant flooding 947 of the OSPFv3 Extended Prefix Range TLV between areas as described in 948 Section 4. 950 7.2. Inter-area Segment routing in OSPFv3 952 In order to support SR in a multi-area environment, OSPFv3 MUST 953 propagate Prefix-SID information between areas. The following 954 procedure is used to propagate Prefix SIDs between areas. 956 When an OSPFv3 ABR advertises an Inter-Area-Prefix-LSA from an intra- 957 area prefix to all its connected areas, it will also include the 958 Prefix-SID Sub-TLV, as described in Section 5. The Prefix-SID value 959 will be set as follows: 961 The ABR will look at its best path to the prefix in the source 962 area and find the advertising router associated with the best path 963 to that prefix. 965 The ABR will then determine if such router advertised a Prefix-SID 966 for the prefix and use it when advertising the Prefix-SID to other 967 connected areas. 969 If no Prefix-SID was advertised for the prefix in the source area 970 by the router that contributes to the best path to the prefix, the 971 originating ABR will use the Prefix-SID advertised by any other 972 router when propagating the Prefix-SID for the prefix to other 973 areas. 975 When an OSPFv3 ABR advertises Inter-Area-Prefix-LSA LSAs from an 976 inter-area route to all its connected areas, it will also include the 977 Prefix-SID Sub-TLV, as described in Section 5. The Prefix-SID value 978 will be set as follows: 980 The ABR will look at its best path to the prefix in the backbone 981 area and find the advertising router associated with the best path 982 to that prefix. 984 The ABR will then determine if such router advertised a Prefix-SID 985 for the prefix and use it when advertising the Prefix-SID to other 986 connected areas. 988 If no Prefix-SID was advertised for the prefix in the backbone 989 area by the ABR that contributes to the best path to the prefix, 990 the originating ABR will use the Prefix-SID advertised by any 991 other router when propagating the Prefix-SID for the prefix to 992 other areas. 994 7.3. Segment Routing for External Prefixes 996 AS-External-LSAs are flooded domain wide. When an ASBR, which 997 supports SR, originates an E-AS-External-LSA, it SHOULD also include 998 a Prefix-SID Sub-TLV, as described in Section 5. The Prefix-SID 999 value will be set to the SID that has been reserved for that prefix. 1001 When an NSSA [RFC3101] ABR translates an E-NSSA-LSA into an E-AS- 1002 External-LSA, it SHOULD also advertise the Prefix-SID for the prefix. 1003 The NSSA ABR determines its best path to the prefix advertised in the 1004 translated E-NSSA-LSA and finds the advertising router associated 1005 with that path. If the advertising router has advertised a Prefix- 1006 SID for the prefix, then the NSSA ABR uses it when advertising the 1007 Prefix-SID for the E-AS-External-LSA. Otherwise, the Prefix-SID 1008 advertised by any other router will be used. 1010 7.4. Advertisement of Adj-SID 1012 The Adjacency Segment Routing Identifier (Adj-SID) is advertised 1013 using the Adj-SID Sub-TLV as described in Section 6. 1015 7.4.1. Advertisement of Adj-SID on Point-to-Point Links 1017 An Adj-SID MAY be advertised for any adjacency on a P2P link that is 1018 in neighbor state 2-Way or higher. If the adjacency on a P2P link 1019 transitions from the FULL state, then the Adj-SID for that adjacency 1020 MAY be removed from the area. If the adjacency transitions to a 1021 state lower then 2-Way, then the Adj-SID advertisement MUST be 1022 withdrawn from the area. 1024 7.4.2. Adjacency SID on Broadcast or NBMA Interfaces 1026 Broadcast, NBMA, or hybrid [RFC6845] networks in OSPFv3 are 1027 represented by a star topology where the Designated Router (DR) is 1028 the central point to which all other routers on the broadcast, NBMA, 1029 or hybrid network connect. As a result, routers on the broadcast, 1030 NBMA, or hybrid network advertise only their adjacency to the DR. 1031 Routers that do not act as DR do not form or advertise adjacencies 1032 with each other. They do, however, maintain 2-Way adjacency state 1033 with each other and are directly reachable. 1035 When Segment Routing is used, each router on the broadcast, NBMA, or 1036 hybrid network MAY advertise the Adj-SID for its adjacency to the DR 1037 using the Adj-SID Sub-TLV as described in Section 6.1. 1039 SR-capable routers MAY also advertise a LAN-Adj-SID for other 1040 neighbors (e.g., BDR, DR-OTHER) on the broadcast, NBMA, or hybrid 1041 network using the LAN-Adj-SID Sub-TLV as described in Section 6.2. 1043 8. IANA Considerations 1045 This specification updates several existing OSPFv3 registries. 1047 8.1. OSPFv3 Extended-LSA TLV Registry 1049 Following values are allocated: 1051 o suggested value 9 - OSPFv3 Extended Prefix Range TLV 1053 8.2. OSPFv3 Extended-LSA Sub-TLV registry 1055 o 4 - Prefix SID Sub-TLV 1057 o 5 - Adj-SID Sub-TLV 1059 o 6 - LAN Adj-SID Sub-TLV 1061 o 7 - SID/Label Sub-TLV 1063 9. Security Considerations 1065 With the OSPFv3 segment routing extensions defined herein, OSPFv3 1066 will now program the MPLS data plane [RFC3031] in addition to the IP 1067 data plane. Previously, LDP [RFC5036] or another label distribution 1068 mechanism was required to advertise MPLS labels and program the MPLS 1069 data plane. 1071 In general, the same types of attacks that can be carried out on the 1072 IP control plane can be carried out on the MPLS control plane 1073 resulting in traffic being misrouted in the respective data planes. 1074 However, the latter can be more difficult to detect and isolate. 1076 Existing security extensions as described in [RFC5340] and [RFC8362] 1077 apply to these segment routing extensions. While OSPFv3 is under a 1078 single administrative domain, there can be deployments where 1079 potential attackers have access to one or more networks in the OSPFv3 1080 routing domain. In these deployments, stronger authentication 1081 mechanisms such as those specified in [RFC4552] or [RFC7166] SHOULD 1082 be used. 1084 Implementations MUST assure that malformed TLV and Sub-TLV defined in 1085 this document are detected and do not provide a vulnerability for 1086 attackers to crash the OSPFv3 router or routing process. Reception 1087 of a malformed TLV or Sub-TLV SHOULD be counted and/or logged for 1088 further analysis. Logging of malformed TLVs and Sub-TLVs SHOULD be 1089 rate-limited to prevent a Denial of Service (DoS) attack (distributed 1090 or otherwise) from overloading the OSPFv3 control plane. 1092 10. Acknowledgements 1094 Thanks to Acee Lindem for his substantial contribution to the content 1095 of this document. 1097 We would like to thank Anton Smirnov for his contribution as well. 1099 11. References 1101 11.1. Normative References 1103 [I-D.ietf-spring-segment-routing-ldp-interop] 1104 Bashandy, A., Filsfils, C., Previdi, S., Decraene, B., and 1105 S. Litkowski, "Segment Routing interworking with LDP", 1106 draft-ietf-spring-segment-routing-ldp-interop-14 (work in 1107 progress), July 2018. 1109 [I-D.ietf-spring-segment-routing-mpls] 1110 Bashandy, A., Filsfils, C., Previdi, S., Decraene, B., 1111 Litkowski, S., and R. Shakir, "Segment Routing with MPLS 1112 data plane", draft-ietf-spring-segment-routing-mpls-14 1113 (work in progress), June 2018. 1115 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 1116 Requirement Levels", BCP 14, RFC 2119, 1117 DOI 10.17487/RFC2119, March 1997, 1118 . 1120 [RFC3031] Rosen, E., Viswanathan, A., and R. Callon, "Multiprotocol 1121 Label Switching Architecture", RFC 3031, 1122 DOI 10.17487/RFC3031, January 2001, 1123 . 1125 [RFC3101] Murphy, P., "The OSPF Not-So-Stubby Area (NSSA) Option", 1126 RFC 3101, DOI 10.17487/RFC3101, January 2003, 1127 . 1129 [RFC5036] Andersson, L., Ed., Minei, I., Ed., and B. Thomas, Ed., 1130 "LDP Specification", RFC 5036, DOI 10.17487/RFC5036, 1131 October 2007, . 1133 [RFC5340] Coltun, R., Ferguson, D., Moy, J., and A. Lindem, "OSPF 1134 for IPv6", RFC 5340, DOI 10.17487/RFC5340, July 2008, 1135 . 1137 [RFC6845] Sheth, N., Wang, L., and J. Zhang, "OSPF Hybrid Broadcast 1138 and Point-to-Multipoint Interface Type", RFC 6845, 1139 DOI 10.17487/RFC6845, January 2013, 1140 . 1142 [RFC7770] Lindem, A., Ed., Shen, N., Vasseur, JP., Aggarwal, R., and 1143 S. Shaffer, "Extensions to OSPF for Advertising Optional 1144 Router Capabilities", RFC 7770, DOI 10.17487/RFC7770, 1145 February 2016, . 1147 [RFC8362] Lindem, A., Roy, A., Goethals, D., Reddy Vallem, V., and 1148 F. Baker, "OSPFv3 Link State Advertisement (LSA) 1149 Extensibility", RFC 8362, DOI 10.17487/RFC8362, April 1150 2018, . 1152 [RFC8402] Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L., 1153 Decraene, B., Litkowski, S., and R. Shakir, "Segment 1154 Routing Architecture", RFC 8402, DOI 10.17487/RFC8402, 1155 July 2018, . 1157 11.2. Informative References 1159 [RFC4552] Gupta, M. and N. Melam, "Authentication/Confidentiality 1160 for OSPFv3", RFC 4552, DOI 10.17487/RFC4552, June 2006, 1161 . 1163 [RFC7166] Bhatia, M., Manral, V., and A. Lindem, "Supporting 1164 Authentication Trailer for OSPFv3", RFC 7166, 1165 DOI 10.17487/RFC7166, March 2014, 1166 . 1168 [RFC7855] Previdi, S., Ed., Filsfils, C., Ed., Decraene, B., 1169 Litkowski, S., Horneffer, M., and R. Shakir, "Source 1170 Packet Routing in Networking (SPRING) Problem Statement 1171 and Requirements", RFC 7855, DOI 10.17487/RFC7855, May 1172 2016, . 1174 Authors' Addresses 1176 Peter Psenak (editor) 1177 Cisco Systems, Inc. 1178 Eurovea Centre, Central 3 1179 Pribinova Street 10 1180 Bratislava 81109 1181 Slovakia 1183 Email: ppsenak@cisco.com 1185 Clarence Filsfils 1186 Cisco Systems, Inc. 1187 Brussels 1188 Belgium 1190 Email: cfilsfil@cisco.com 1191 Stefano Previdi (editor) 1192 Individual 1194 Email: stefano.previdi@net 1196 Hannes Gredler 1197 RtBrick Inc. 1198 Austria 1200 Email: hannes@rtbrick.com 1202 Rob Shakir 1203 Google, Inc. 1204 1600 Amphitheatre Parkway 1205 Mountain View, CA 94043 1206 US 1208 Email: robjs@google.com 1210 Wim Henderickx 1211 Nokia 1212 Copernicuslaan 50 1213 Antwerp 2018 1214 BE 1216 Email: wim.henderickx@nokia.com 1218 Jeff Tantsura 1219 Nuage Networks 1220 US 1222 Email: jefftant.ietf@gmail.com