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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 3, 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 2, 2018 17 OSPFv3 Extensions for Segment Routing 18 draft-ietf-ospf-ospfv3-segment-routing-extensions-14 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 3, 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 . . . . . . . . . . 22 86 7.3. Segment Routing for External Prefixes . . . . . . . . . . 23 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 . . . . . . . . . . . . . . . . . . . . . 24 91 8.1. OSPFv3 Extended-LSA TLV Registry . . . . . . . . . . . . 24 92 8.2. OSPFv3 Extended-LSA Sub-TLV registry . . . . . . . . . . 24 93 9. Security Considerations . . . . . . . . . . . . . . . . . . . 24 94 10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 25 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 [I-D.ietf-spring-segment-routing]. 122 This draft describes the OSPFv3 extensions required for Segment 123 Routing with MPLS data plane. 125 Segment Routing architecture is described in 126 [I-D.ietf-spring-segment-routing]. 128 Segment Routing use cases are described in [RFC7855]. 130 2. Segment Routing Identifiers 132 Segment Routing defines various types of Segment Identifiers (SIDs): 133 Prefix-SID, Adjacency-SID, LAN Adjacency SID, and Binding SID. 135 2.1. SID/Label Sub-TLV 137 The SID/Label Sub-TLV appears in multiple TLVs or Sub-TLVs defined 138 later in this document. It is used to advertise the SID or label 139 associated with a prefix or adjacency. The SID/Label Sub-TLV has 140 following format: 142 0 1 2 3 143 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 1 144 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 145 | Type | Length | 146 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 147 | SID/Label (variable) | 148 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 150 where: 152 Type: 7 154 Length: Variable, 3 or 4 octets 156 SID/Label: If length is set to 3, then the 20 rightmost bits 157 represent a label. If length is set to 4, then the value 158 represents a 32-bit SID. 160 The receiving router MUST ignore the SID/Label Sub-TLV if the 161 length is other then 3 or 4. 163 3. Segment Routing Capabilities 165 Segment Routing requires some additional router capabilities to be 166 advertised to other routers in the area. 168 These SR capabilities are advertised in the OSPFv3 Router Information 169 Opaque LSA (defined in [RFC7770]). 171 3.1. SR-Algorithm TLV 173 The SR-Algorithm TLV is a top-level TLV of the OSPFv3 Router 174 Information Opaque LSA (defined in [RFC7770]). 176 The SR-Algorithm TLV is optional. It SHOULD only be advertised once 177 in the OSPFv3 Router Information Opaque LSA. If the SR-Algorithm TLV 178 is not advertised by the node, such node is considered as not being 179 segment routing capable. 181 An SR router can use various algorithms when calculating reachability 182 to OSPFv3 routers or prefixes in an OSPFv3 area. Examples of these 183 algorithms are metric-based Shortest Path First (SPF), various 184 flavors of Constrained SPF, etc. The SR-Algorithm TLV allows a 185 router to advertise the algorithms currently used by the router to 186 other routers in an OSPFv3 area. The SR-Algorithm TLV has following 187 format: 189 0 1 2 3 190 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 1 191 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 192 | Type | Length | 193 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 194 | Algorithm 1 | Algorithm... | Algorithm n | | 195 +- -+ 196 | | 197 + + 199 where: 201 Type: 8 203 Length: Variable, in octets, dependent on number of algorithms 204 advertised. 206 Algorithm: Single octet identifying the algorithm. The following 207 values are defined by this document: 209 0: Shortest Path First (SPF) algorithm based on link metric. 210 This is the standard shortest path algorithm as computed by the 211 OSPFv3 protocol. Consistent with the deployed practice for 212 link-state protocols, Algorithm 0 permits any node to overwrite 213 the SPF path with a different path based on its local policy. 214 If the SR-Algorithm TLV is advertised, Algorithm 0 MUST be 215 included. 217 1: Strict Shortest Path First (SPF) algorithm based on link 218 metric. The algorithm is identical to Algorithm 0 but 219 Algorithm 1 requires that all nodes along the path will honor 220 the SPF routing decision. Local policy at the node claiming 221 support for Algorithm 1 MUST NOT alter the SPF paths computed 222 by Algorithm 1. 224 When multiple SR-Algorithm TLVs are received from a given router, the 225 receiver MUST use the first occurrence of the TLV in the OSPFv3 226 Router Information Opaque LSA. If the SR-Algorithm TLV appears in 227 multiple OSPFv3 Router Information Opaque LSAs that have different 228 flooding scopes, the SR-Algorithm TLV in the OSPFv3 Router 229 Information Opaque LSA with the area-scoped flooding scope MUST be 230 used. If the SR-Algorithm TLV appears in multiple OSPFv3 Router 231 Information Opaque LSAs that have the same flooding scope, the SR- 232 Algorithm TLV in the OSPFv3 Router Information Opaque LSA with the 233 numerically smallest Instance ID MUST be used and subsequent 234 instances of the SR-Algorithm TLV MUST be ignored. 236 The OSPFv3 Router Information Opaque LSA can be advertised at any of 237 the defined opaque flooding scopes (link, area, or Autonomous System 238 (AS)). For the purpose of SR-Algorithm TLV advertisement, area- 239 scoped flooding is REQUIRED. 241 3.2. SID/Label Range TLV 243 Prefix SIDs MAY be advertised in a form of an index as described in 244 Section 5. Such index defines the offset in the SID/Label space 245 advertised by the router. The SID/Label Range TLV is used to 246 advertise such SID/Label space. 248 The SID/Label Range TLV is a top-level TLV of the OSPFv3 Router 249 Information Opaque LSA (defined in [RFC7770]). 251 The SID/Label Range TLV MAY appear multiple times and has the 252 following format: 254 0 1 2 3 255 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 1 256 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 257 | Type | Length | 258 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 259 | Range Size | Reserved | 260 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 261 | Sub-TLVs (variable) | 262 +- -+ 263 | | 264 + + 266 where: 268 Type: 9 270 Length: Variable, in octets, dependent on Sub-TLVs. 272 Range Size: 3-octet SID/label range size (i.e., the number of SIDs 273 or labels in the range including the first SID/label). It MUST be 274 greater than 0. 276 Reserved: SHOULD be set to 0 on transmission and MUST be ignored 277 on reception. 279 Initially, the only supported Sub-TLV is the SID/Label Sub-TLV as 280 defined in Section 2.1. The SID/Label Sub-TLV MUST be included in 281 the SID/Label Range TLV. The SID/Label advertised in the SID/Label 282 Sub-TLV represents the first SID/Label in the advertised range. 284 Only a single SID/Label Sub-TLV MAY be advertised in SID/Label Range 285 TLV. If more then one SID/Label Sub-TLVs are present, the SID/Label 286 Range TLV MUST be ignored. 288 Multiple occurrences of the SID/Label Range TLV MAY be advertised, in 289 order to advertise multiple ranges. In such case: 291 o The originating router MUST encode each range into a different 292 SID/Label Range TLV. 294 o The originating router decides the order in which the set of SID/ 295 Label Range TLVs are advertised inside the Router Information 296 Opaque LSA. The originating router MUST ensure the order is the 297 same after a graceful restart (using checkpointing, non-volatile 298 storage, or any other mechanism) in order to assure the SID/label 299 range and SID index correspondence is preserved across graceful 300 restarts. 302 o The receiving router MUST adhere to the order in which the ranges 303 are advertised when calculating a SID/label from a SID index. 305 o The originating router MUST NOT advertise overlapping ranges. 307 o When a router receives multiple overlapping ranges, it MUST 308 conform to the procedures defined in 309 [I-D.ietf-spring-segment-routing-mpls]. 311 The following example illustrates the advertisement of multiple 312 ranges: 314 The originating router advertises the following ranges: 316 Range 1: Range Size: 100 SID/Label Sub-TLV: 100 317 Range 1: Range Size: 100 SID/Label Sub-TLV: 1000 318 Range 1: Range Size: 100 SID/Label Sub-TLV: 500 320 The receiving routers concatenate the ranges and build the Segment 321 Routing Global Block (SRGB) as follows: 323 SRGB = [100, 199] 324 [1000, 1099] 325 [500, 599] 327 The indexes span multiple ranges: 329 index=0 means label 100 330 ... 331 index 99 means label 199 332 index 100 means label 1000 333 index 199 means label 1099 334 ... 335 index 200 means label 500 336 ... 338 The OSPFv3 Router Information Opaque LSA can be advertised at any of 339 the defined flooding scopes (link, area, or autonomous system (AS)). 340 For the purpose of SID/Label Range TLV advertisement, area-scoped 341 flooding is REQUIRED. 343 3.3. SR Local Block TLV 345 The SR Local Block TLV (SRLB TLV) contains the range of labels the 346 node has reserved for local SIDs. SIDs from the SRLB MAY be used for 347 Adjacency-SIDs, but also by components other than the OSPFv3 348 protocol. As an example, an application or a controller can instruct 349 the router to allocate a specific local SID. Some controllers or 350 applications can use the control plane to discover the available set 351 of local SIDs on a particular router. In such cases, the SRLB is 352 advertised in the control plane. The requirement to advertise the 353 SRLB is further described in [I-D.ietf-spring-segment-routing-mpls]. 354 The SRLB TLV is used to advertise the SRLB. 356 The SRLB TLV is a top-level TLV of the OSPFv3 Router Information 357 Opaque LSA (defined in [RFC7770]). 359 The SRLB TLV MAY appear multiple times in the OSPFv3 Router 360 Information Opaque LSA and has the following format: 362 0 1 2 3 363 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 1 364 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 365 | Type | Length | 366 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 367 | Range Size | Reserved | 368 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 369 | Sub-TLVs (variable) | 370 +- -+ 371 | | 372 + + 374 where: 376 Type: 14 378 Length: Variable, in octets, dependent on Sub-TLVs. 380 Range Size: 3-octet SID/label range size (i.e., the number of SIDs 381 or labels in the range including the first SID/label). It MUST be 382 greater than 0. 384 Reserved: SHOULD be set to 0 on transmission and MUST be ignored 385 on reception. 387 Initially, the only supported Sub-TLV is the SID/Label Sub-TLV as 388 defined in Section 2.1. The SID/Label Sub-TLV MUST be included in 389 the SRLB TLV. The SID/Label advertised in the SID/Label Sub-TLV 390 represents the first SID/Label in the advertised range. 392 Only a single SID/Label Sub-TLV MAY be advertised in the SRLB TLV. 393 If more then one SID/Label Sub-TLVs are present, the SRLB TLV MUST be 394 ignored. 396 The originating router MUST NOT advertise overlapping ranges. 398 Each time a SID from the SRLB is allocated, it SHOULD also be 399 reported to all components (e.g., controller or applications) in 400 order for these components to have an up-to-date view of the current 401 SRLB allocation. This is required to avoid collisions between 402 allocation instructions. 404 Within the context of OSPFv3, the reporting of local SIDs is done 405 through OSPFv3 Sub-TLVs such as the Adjacency-SID (Section 6). 406 However, the reporting of allocated local SIDs can also be done 407 through other means and protocols which are outside the scope of this 408 document. 410 A router advertising the SRLB TLV MAY also have other label ranges, 411 outside of the SRLB, used for its local allocation purposes which are 412 not advertised in the SRLB TLV. For example, it is possible that an 413 Adjacency-SID is allocated using a local label that is not part of 414 the SRLB. 416 The OSPFv3 Router Information Opaque LSA can be advertised at any of 417 the defined flooding scopes (link, area, or autonomous system (AS)). 418 For the purpose of SRLB TLV advertisement, area-scoped flooding is 419 REQUIRED. 421 3.4. SRMS Preference TLV 423 The Segment Routing Mapping Server Preference TLV (SRMS Preference 424 TLV) is used to advertise a preference associated with a node that 425 acts as an SR Mapping Server. The role of an SRMS is described in 426 [I-D.ietf-spring-segment-routing-ldp-interop]. SRMS preference is 427 defined in [I-D.ietf-spring-segment-routing-ldp-interop]. 429 The SRMS Preference TLV is a top-level TLV of the OSPFv3 Router 430 Information Opaque LSA (defined in [RFC7770]). 432 The SRMS Preference TLV MAY only be advertised once in the OSPFv3 433 Router Information Opaque LSA and has the following format: 435 0 1 2 3 436 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 1 437 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 438 | Type | Length | 439 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 440 | Preference | Reserved | 441 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 443 where: 445 Type: 15 447 Length: 4 octets 449 Preference: 1 octet. SRMS preference value from 0 to 255. 451 Reserved: SHOULD be set to 0 on transmission and MUST be ignored 452 on reception. 454 When multiple SRMS Preference TLVs are received from a given router, 455 the receiver MUST use the first occurrence of the TLV in the OSPFv3 456 Router Information Opaque LSA. If the SRMS Preference TLV appears in 457 multiple OSPFv3 Router Information Opaque LSAs that have different 458 flooding scopes, the SRMS Preference TLV in the OSPFv3 Router 459 Information Opaque LSA with the narrowest flooding scope MUST be 460 used. If the SRMS Preference TLV appears in multiple OSPFv3 Router 461 Information Opaque LSAs that have the same flooding scope, the SRMS 462 Preference TLV in the OSPFv3 Router Information Opaque LSA with the 463 numerically smallest Instance ID MUST be used and subsequent 464 instances of the SRMS Preference TLV MUST be ignored. 466 The OSPFv3 Router Information Opaque LSA can be advertised at any of 467 the defined flooding scopes (link, area, or autonomous system (AS)). 468 For the purpose of the SRMS Preference TLV advertisement, AS-scoped 469 flooding SHOULD be used. This is because SRMS servers can be located 470 in a different area then consumers of the SRMS advertisements. If 471 the SRMS advertisements from the SRMS server are only used inside the 472 SRMS server's area, area-scoped flooding MAY be used. 474 4. OSPFv3 Extended Prefix Range TLV 476 In some cases it is useful to advertise attributes for a range of 477 prefixes. The Segment Routing Mapping Server, which is described in 478 [I-D.ietf-spring-segment-routing-ldp-interop], is an example where we 479 need a single advertisement to advertise SIDs for multiple prefixes 480 from a contiguous address range. 482 The OSPFv3 Extended Prefix Range TLV is defined for this purpose. 484 The OSPFv3 Extended Prefix Range TLV is a top-level TLV of the 485 following LSAs defined in [I-D.ietf-ospf-ospfv3-lsa-extend]: 487 E-Intra-Area-Prefix-LSA 489 E-Inter-Area-Prefix-LSA 491 E-AS-External-LSA 493 E-Type-7-LSA 495 Multiple OSPFv3 Extended Prefix Range TLVs MAY be advertised in each 496 LSA mentioned above. The OSPFv3 Extended Prefix Range TLV has the 497 following format: 499 0 1 2 3 500 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 1 501 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 502 | Type | Length | 503 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 504 | Prefix Length | AF | Range Size | 505 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 506 | Flags | Reserved | 507 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 508 | Address Prefix (variable) | 509 | ... | 510 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 511 | Sub-TLVs (variable) | 512 +- -+ 513 | | 515 where: 517 Type: 9 519 Length: Variable, in octets, dependent on Sub-TLVs. 521 Prefix length: Length of prefix in bits. 523 AF: Address family for the prefix. 525 AF: 0 - IPv4 unicast 527 AF: 1 - IPv6 unicast 529 Range size: Represents the number of prefixes that are covered by 530 the advertisement. The Range Size MUST NOT exceed the number of 531 prefixes that could be satisfied by the prefix length without 532 including: 534 IPv4 multicast address range (224.0.0.0/3), if the AF is IPv4 535 unicast 537 Addresses from other than the IPv6 unicast address class, if 538 the AF is IPv6 unicast 540 Flags: Single octet field. The following flags are defined: 542 0 1 2 3 4 5 6 7 543 +--+--+--+--+--+--+--+--+ 544 |IA| | | | | | | | 545 +--+--+--+--+--+--+--+--+ 547 where: 549 IA-Flag: Inter-Area flag. If set, advertisement is of inter- 550 area type. An ABR that is advertising the OSPFv3 Extended 551 Prefix Range TLV between areas MUST set this 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 [I-D.ietf-ospf-ospfv3-lsa-extend] 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 ASBR. 688 If the NP-Flag is not set, then any upstream neighbor of the Prefix- 689 SID originator MUST pop the Prefix-SID. This is equivalent to the 690 penultimate hop popping mechanism used in the MPLS dataplane. If the 691 NP-flag is not set, then the received E-flag is ignored. 693 If the NP-flag is set then: 695 If the E-flag is not set, then any upstream neighbor of the 696 Prefix-SID originator MUST keep the Prefix-SID on top of the 697 stack. This is useful when the originator of the Prefix-SID needs 698 to stitch the incoming packet into a continuing MPLS LSP to the 699 final destination. This could occur at an Area Border Router 700 (prefix propagation from one area to another) or at an AS Boundary 701 Router (prefix propagation from one domain to another). 703 If the E-flag is set, then any upstream neighbor of the Prefix-SID 704 originator MUST replace the Prefix-SID with an Explicit-NULL 705 label. This is useful, e.g., when the originator of the Prefix- 706 SID is the final destination for the related prefix and the 707 originator wishes to receive the packet with the original EXP 708 bits. 710 When the M-Flag is set, the NP-flag and the E-flag MUST be ignored at 711 reception. 713 As the Mapping Server does not specify the originator of a prefix 714 advertisement, it is not possible to determine PHP behavior solely 715 based on the Mapping Server advertisement. However, PHP behavior 716 SHOULD be done in following cases: 718 The Prefix is intra-area type and the downstream neighbor is the 719 originator of the prefix. 721 The Prefix is inter-area type and the downstream neighbor is an 722 ABR, which is advertising prefix reachability and is setting the 723 LA-bit in the Prefix Options as described in 724 [I-D.ietf-ospf-ospfv3-lsa-extend]. 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 729 [I-D.ietf-ospf-ospfv3-lsa-extend]. 731 When a Prefix-SID is advertised in the OSPFv3 Extended Prefix Range 732 TLV, then the value advertised in the Prefix SID Sub-TLV is 733 interpreted as a starting SID/Label value. 735 Example 1: If the following router addresses (loopback addresses) 736 need to be mapped into the corresponding Prefix SID indexes: 738 Router-A: 2001:DB8::1/128, Prefix-SID: Index 1 739 Router-B: 2001:DB8::2/128, Prefix-SID: Index 2 740 Router-C: 2001:DB8::3/128, Prefix-SID: Index 3 741 Router-D: 2001:DB8::4/128, Prefix-SID: Index 4 743 then the Address Prefix field in the OSPFv3 Extended Prefix Range TLV 744 would be set to 2001:DB8::1, the Prefix Length would be set to 128, 745 the Range Size would be set to 4, and the Index value in the Prefix- 746 SID Sub-TLV would be set to 1. 748 Example 2: If the following prefixes need to be mapped into the 749 corresponding Prefix-SID indexes: 751 2001:DB8:1::0/120, Prefix-SID: Index 51 752 2001:DB8:1::100/120, Prefix-SID: Index 52 753 2001:DB8:1::200/120, Prefix-SID: Index 53 754 2001:DB8:1::300/120, Prefix-SID: Index 54 755 2001:DB8:1::400/120, Prefix-SID: Index 55 756 2001:DB8:1::500/120, Prefix-SID: Index 56 757 2001:DB8:1::600/120, Prefix-SID: Index 57 759 then the Prefix field in the OSPFv3 Extended Prefix Range TLV would 760 be set to 2001:DB8:1::0, the Prefix Length would be set to 120, the 761 Range Size would be set to 7, and the Index value in the Prefix-SID 762 Sub-TLV would be set to 51. 764 6. Adjacency Segment Identifier (Adj-SID) 766 An Adjacency Segment Identifier (Adj-SID) represents a router 767 adjacency in Segment Routing. 769 6.1. Adj-SID Sub-TLV 771 Adj-SID is an optional Sub-TLV of the Router-Link TLV as defined in 772 [I-D.ietf-ospf-ospfv3-lsa-extend]. It MAY appear multiple times in 773 the Router-Link TLV. The Adj-SID Sub-TLV has the following format: 775 0 1 2 3 776 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 1 777 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 778 | Type | Length | 779 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 780 | Flags | Weight | Reserved | 781 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 782 | SID/Label/Index (variable) | 783 +---------------------------------------------------------------+ 785 where: 787 Type: 5 789 Length: 7 or 8 octets, dependent on the V flag. 791 Flags: Single octet field containing the following flags: 793 0 1 2 3 4 5 6 7 794 +-+-+-+-+-+-+-+-+ 795 |B|V|L|G|P| | 796 +-+-+-+-+-+-+-+-+ 798 where: 800 B-Flag: Backup Flag. If set, the Adj-SID refers to an 801 adjacency that is eligible for protection (e.g., using IPFRR or 802 MPLS-FRR) as described in section 3.5 of 803 [I-D.ietf-spring-segment-routing]. 805 The V-Flag: Value/Index Flag. If set, then the Adj-SID carries 806 an absolute value. If not set, then the Adj-SID carries an 807 index. 809 The L-Flag: Local/Global Flag. If set, then the value/index 810 carried by the Adj-SID has local significance. If not set, 811 then the value/index carried by this Sub-TLV has global 812 significance. 814 The G-Flag: Group Flag. When set, the G-Flag indicates that 815 the Adj-SID refers to a group of adjacencies (and therefore MAY 816 be assigned to other adjacencies as well). 818 P-Flag. Persistent flag. When set, the P-Flag indicates that 819 the Adj-SID is persistently allocated, i.e., the Adj-SID value 820 remains consistent across router restart and/or interface flap. 822 Other bits: Reserved. These MUST be zero when sent and are 823 ignored when received. 825 Reserved: SHOULD be set to 0 on transmission and MUST be ignored 826 on reception. 828 Weight: Weight used for load-balancing purposes. The use of the 829 weight is defined in [I-D.ietf-spring-segment-routing]. 831 SID/Index/Label: According to the V and L flags, it contains 832 either: 834 A 32-bit index defining the offset in the SID/Label space 835 advertised by this router. 837 A 24-bit label where the 20 rightmost bits are used for 838 encoding the label value. 840 An SR-capable router MAY allocate an Adj-SID for each of its 841 adjacencies and set the B-Flag when the adjacency is eligible for 842 protection by an FRR mechanism (IP or MPLS) as described in 843 [I-D.ietf-spring-segment-routing]. 845 An SR-capable router MAY allocate more than one Adj-SID to an 846 adjacency 848 An SR-capable router MAY allocate the same Adj-SID to different 849 adjacencies 851 When the P-flag is not set, the Adj-SID MAY be persistent. When the 852 P-flag is set, the Adj-SID MUST be persistent. 854 6.2. LAN Adj-SID Sub-TLV 856 LAN Adj-SID is an optional Sub-TLV of the Router-Link TLV. It MAY 857 appear multiple times in the Router-Link TLV. It is used to 858 advertise a SID/Label for an adjacency to a non-DR router on a 859 broadcast, NBMA, or hybrid [RFC6845] network. 861 0 1 2 3 862 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 1 863 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 864 | Type | Length | 865 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 866 | Flags | Weight | Reserved | 867 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 868 | Neighbor ID | 869 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 870 | SID/Label/Index (variable) | 871 +---------------------------------------------------------------+ 873 where: 875 Type: 6 877 Length: 11 or 12 octets, dependent on V-flag. 879 Flags: same as in Section 6.1 881 Weight: Weight used for load-balancing purposes. The use of the 882 weight is defined in [I-D.ietf-spring-segment-routing]. 884 Reserved: SHOULD be set to 0 on transmission and MUST be ignored 885 on reception. 887 Neighbor ID: The Router ID of the neighbor for which the LAN-Adj- 888 SID is advertised. 890 SID/Index/Label: According to the V and L flags, it contains 891 either: 893 A 32-bit index defining the offset in the SID/Label space 894 advertised by this router. 896 A 24-bit label where the 20 rightmost bits are used for 897 encoding the label value. 899 When the P-flag is not set, the Adj-SID MAY be persistent. When 900 the P-flag is set, the Adj-SID MUST be persistent. 902 7. Elements of Procedure 904 7.1. Intra-area Segment routing in OSPFv3 906 An OSPFv3 router that supports segment routing MAY advertise Prefix- 907 SIDs for any prefix to which it is advertising reachability (e.g., a 908 loopback IP address as described in Section 5). 910 A Prefix-SID can also be advertised by SR Mapping Servers (as 911 described in [I-D.ietf-spring-segment-routing-ldp-interop]). A 912 Mapping Server advertises Prefix-SIDs for remote prefixes that exist 913 in the OSPFv3 routing domain. Multiple Mapping Servers can advertise 914 Prefix-SIDs for the same prefix, in which case the same Prefix-SID 915 MUST be advertised by all of them. The SR Mapping Server could use 916 either area flooding scope or autonomous system flooding scope when 917 advertising Prefix SID for prefixes, based on the configuration of 918 the SR Mapping Server. Depending on the flooding scope used, the SR 919 Mapping Server chooses the OSPFv3 LSA type that will be used. If the 920 area flooding scope is needed, an E-Intra-Area-Prefix-LSA 921 ([I-D.ietf-ospf-ospfv3-lsa-extend]) is used. If autonomous system 922 flooding scope is needed, an E-AS-External-LSA 923 ([I-D.ietf-ospf-ospfv3-lsa-extend]) is used. 925 When a Prefix-SID is advertised by the Mapping Server, which is 926 indicated by the M-flag in the Prefix-SID Sub-TLV (Section 5), the 927 route type as implied by the LSA type is ignored and the Prefix-SID 928 is bound to the corresponding prefix independent of the route type. 930 Advertisement of the Prefix-SID by the Mapping Server using an Inter- 931 Area Prefix TLV, External-Prefix TLV, or Intra-Area-Prefix TLV 932 ([I-D.ietf-ospf-ospfv3-lsa-extend]) does not itself contribute to the 933 prefix reachability. The NU-bit MUST be set in the PrefixOptions 934 field of the LSA which is used by the Mapping Server to advertise SID 935 or SID Range, which prevents the advertisement from contributing to 936 prefix reachability. 938 An SR Mapping Server MUST use the OSPFv3 Extended Prefix Range TLVs 939 when advertising SIDs for prefixes. Prefixes of different route- 940 types can be combined in a single OSPFv3 Extended Prefix Range TLV 941 advertised by an SR Mapping Server. 943 Area-scoped OSPFv3 Extended Prefix Range TLVs are propagated between 944 areas. Similar to propagation of prefixes between areas, an ABR only 945 propagates the OSPFv3 Extended Prefix Range TLV that it considers to 946 be the best from the set it received. The rules used to pick the 947 best OSPFv3 Extended Prefix Range TLV are described in Section 4. 949 When propagating an OSPFv3 Extended Prefix Range TLV between areas, 950 ABRs MUST set the IA-Flag, that is used to prevent redundant flooding 951 of the OSPFv3 Extended Prefix Range TLV between areas as described in 952 Section 4. 954 7.2. Inter-area Segment routing in OSPFv3 956 In order to support SR in a multi-area environment, OSPFv3 MUST 957 propagate Prefix-SID information between areas. The following 958 procedure is used to propagate Prefix SIDs between areas. 960 When an OSPFv3 ABR advertises an Inter-Area-Prefix-LSA from an intra- 961 area prefix to all its connected areas, it will also include Prefix- 962 SID Sub-TLV, as described in Section 5. The Prefix-SID value will be 963 set as follows: 965 The ABR will look at its best path to the prefix in the source 966 area and find the advertising router associated with the best path 967 to that prefix. 969 The ABR will then determine if such router advertised a Prefix-SID 970 for the prefix and use it when advertising the Prefix-SID to other 971 connected areas. 973 If no Prefix-SID was advertised for the prefix in the source area 974 by the router that contributes to the best path to the prefix, the 975 originating ABR will use the Prefix-SID advertised by any other 976 router when propagating the Prefix-SID for the prefix to other 977 areas. 979 When an OSPFv3 ABR advertises Inter-Area-Prefix-LSA LSAs from an 980 inter-area route to all its connected areas, it will also include 981 Prefix-SID Sub-TLV, as described in Section 5. The Prefix-SID value 982 will be set as follows: 984 The ABR will look at its best path to the prefix in the backbone 985 area and find the advertising router associated with the best path 986 to that prefix. 988 The ABR will then determine if such router advertised a Prefix-SID 989 for the prefix and use it when advertising the Prefix-SID to other 990 connected areas. 992 If no Prefix-SID was advertised for the prefix in the backbone 993 area by the ABR that contributes to the best path to the prefix, 994 the originating ABR will use the Prefix-SID advertised by any 995 other router when propagating the Prefix-SID for the prefix to 996 other areas. 998 7.3. Segment Routing for External Prefixes 1000 AS-External-LSAs are flooded domain wide. When an ASBR, which 1001 supports SR, originates an E-AS-External-LSA, it SHOULD also include 1002 a Prefix-SID Sub-TLV, as described in Section 5. The Prefix-SID 1003 value will be set to the SID that has been reserved for that prefix. 1005 When an NSSA [RFC3101] ABR translates an E-NSSA-LSA into an E-AS- 1006 External-LSA, it SHOULD also advertise the Prefix-SID for the prefix. 1007 The NSSA ABR determines its best path to the prefix advertised in the 1008 translated E-NSSA-LSA and finds the advertising router associated 1009 with that path. If the advertising router has advertised a Prefix- 1010 SID for the prefix, then the NSSA ABR uses it when advertising the 1011 Prefix-SID for the E-AS-External-LSA. Otherwise, the Prefix-SID 1012 advertised by any other router will be used. 1014 7.4. Advertisement of Adj-SID 1016 The Adjacency Segment Routing Identifier (Adj-SID) is advertised 1017 using the Adj-SID Sub-TLV as described in Section 6. 1019 7.4.1. Advertisement of Adj-SID on Point-to-Point Links 1021 An Adj-SID MAY be advertised for any adjacency on a P2P link that is 1022 in neighbor state 2-Way or higher. If the adjacency on a P2P link 1023 transitions from the FULL state, then the Adj-SID for that adjacency 1024 MAY be removed from the area. If the adjacency transitions to a 1025 state lower then 2-Way, then the Adj-SID advertisement MUST be 1026 withdrawn from the area. 1028 7.4.2. Adjacency SID on Broadcast or NBMA Interfaces 1030 Broadcast, NBMA, or hybrid [RFC6845] networks in OSPFv3 are 1031 represented by a star topology where the Designated Router (DR) is 1032 the central point to which all other routers on the broadcast, NBMA, 1033 or hybrid network connect. As a result, routers on the broadcast, 1034 NBMA, or hybrid network advertise only their adjacency to the DR. 1035 Routers that do not act as DR do not form or advertise adjacencies 1036 with each other. They do, however, maintain 2-Way adjacency state 1037 with each other and are directly reachable. 1039 When Segment Routing is used, each router on the broadcast, NBMA, or 1040 hybrid network MAY advertise the Adj-SID for its adjacency to the DR 1041 using the Adj-SID Sub-TLV as described in Section 6.1. 1043 SR-capable routers MAY also advertise a LAN-Adj-SID for other 1044 neighbors (e.g., BDR, DR-OTHER) on the broadcast, NBMA, or hybrid 1045 network using the LAN-Adj-SID Sub-TLV as described in Section 6.2. 1047 8. IANA Considerations 1049 This specification updates several existing OSPFv3 registries. 1051 8.1. OSPFv3 Extended-LSA TLV Registry 1053 Following values are allocated: 1055 o suggested value 9 - OSPFv3 Extended Prefix Range TLV 1057 8.2. OSPFv3 Extended-LSA Sub-TLV registry 1059 o 4 - Prefix SID Sub-TLV 1061 o 5 - Adj-SID Sub-TLV 1063 o 6 - LAN Adj-SID Sub-TLV 1065 o 7 - SID/Label Sub-TLV 1067 9. Security Considerations 1069 With the OSPFv3 segment routing extensions defined herein, OSPFv3 1070 will now program the MPLS data plane [RFC3031] in addition to the IP 1071 data plane. Previously, LDP [RFC5036] or another label distribution 1072 mechanism was required to advertise MPLS labels and program the MPLS 1073 data plane. 1075 In general, the same types of attacks that can be carried out on the 1076 IP control plane can be carried out on the MPLS control plane 1077 resulting in traffic being misrouted in the respective data planes. 1078 However, the latter can be more difficult to detect and isolate. 1080 Existing security extensions as described in [RFC5340] and 1081 [I-D.ietf-ospf-ospfv3-lsa-extend] apply to these segment routing 1082 extensions. While OSPFv3 is under a single administrative domain, 1083 there can be deployments where potential attackers have access to one 1084 or more networks in the OSPFv3 routing domain. In these deployments, 1085 stronger authentication mechanisms such as those specified in 1086 [RFC4552] or [RFC7166] SHOULD be used. 1088 Implementations MUST assure that malformed TLV and Sub-TLV defined in 1089 this document are detected and do not provide a vulnerability for 1090 attackers to crash the OSPFv3 router or routing process. Reception 1091 of a malformed TLV or Sub-TLV SHOULD be counted and/or logged for 1092 further analysis. Logging of malformed TLVs and Sub-TLVs SHOULD be 1093 rate-limited to prevent a Denial of Service (DoS) attack (distributed 1094 or otherwise) from overloading the OSPFv3 control plane. 1096 10. Acknowledgements 1098 Thanks to Acee Lindem for his substantial contribution to the content 1099 of this document. 1101 We would like to thank Anton Smirnov for his contribution as well. 1103 11. References 1105 11.1. Normative References 1107 [I-D.ietf-ospf-ospfv3-lsa-extend] 1108 Lindem, A., Roy, A., Goethals, D., Vallem, V., and F. 1109 Baker, "OSPFv3 LSA Extendibility", draft-ietf-ospf-ospfv3- 1110 lsa-extend-23 (work in progress), January 2018. 1112 [I-D.ietf-spring-segment-routing] 1113 Filsfils, C., Previdi, S., Ginsberg, L., Decraene, B., 1114 Litkowski, S., and R. Shakir, "Segment Routing 1115 Architecture", draft-ietf-spring-segment-routing-15 (work 1116 in progress), January 2018. 1118 [I-D.ietf-spring-segment-routing-ldp-interop] 1119 Bashandy, A., Filsfils, C., Previdi, S., Decraene, B., and 1120 S. Litkowski, "Segment Routing interworking with LDP", 1121 draft-ietf-spring-segment-routing-ldp-interop-14 (work in 1122 progress), July 2018. 1124 [I-D.ietf-spring-segment-routing-mpls] 1125 Bashandy, A., Filsfils, C., Previdi, S., Decraene, B., 1126 Litkowski, S., and R. Shakir, "Segment Routing with MPLS 1127 data plane", draft-ietf-spring-segment-routing-mpls-14 1128 (work in progress), June 2018. 1130 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 1131 Requirement Levels", BCP 14, RFC 2119, 1132 DOI 10.17487/RFC2119, March 1997, 1133 . 1135 [RFC3031] Rosen, E., Viswanathan, A., and R. Callon, "Multiprotocol 1136 Label Switching Architecture", RFC 3031, 1137 DOI 10.17487/RFC3031, January 2001, 1138 . 1140 [RFC3101] Murphy, P., "The OSPF Not-So-Stubby Area (NSSA) Option", 1141 RFC 3101, DOI 10.17487/RFC3101, January 2003, 1142 . 1144 [RFC5036] Andersson, L., Ed., Minei, I., Ed., and B. Thomas, Ed., 1145 "LDP Specification", RFC 5036, DOI 10.17487/RFC5036, 1146 October 2007, . 1148 [RFC5340] Coltun, R., Ferguson, D., Moy, J., and A. Lindem, "OSPF 1149 for IPv6", RFC 5340, DOI 10.17487/RFC5340, July 2008, 1150 . 1152 [RFC6845] Sheth, N., Wang, L., and J. Zhang, "OSPF Hybrid Broadcast 1153 and Point-to-Multipoint Interface Type", RFC 6845, 1154 DOI 10.17487/RFC6845, January 2013, 1155 . 1157 [RFC7770] Lindem, A., Ed., Shen, N., Vasseur, JP., Aggarwal, R., and 1158 S. Shaffer, "Extensions to OSPF for Advertising Optional 1159 Router Capabilities", RFC 7770, DOI 10.17487/RFC7770, 1160 February 2016, . 1162 [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for 1163 Writing an IANA Considerations Section in RFCs", BCP 26, 1164 RFC 8126, DOI 10.17487/RFC8126, June 2017, 1165 . 1167 11.2. Informative References 1169 [RFC4552] Gupta, M. and N. Melam, "Authentication/Confidentiality 1170 for OSPFv3", RFC 4552, DOI 10.17487/RFC4552, June 2006, 1171 . 1173 [RFC7166] Bhatia, M., Manral, V., and A. Lindem, "Supporting 1174 Authentication Trailer for OSPFv3", RFC 7166, 1175 DOI 10.17487/RFC7166, March 2014, 1176 . 1178 [RFC7855] Previdi, S., Ed., Filsfils, C., Ed., Decraene, B., 1179 Litkowski, S., Horneffer, M., and R. Shakir, "Source 1180 Packet Routing in Networking (SPRING) Problem Statement 1181 and Requirements", RFC 7855, DOI 10.17487/RFC7855, May 1182 2016, . 1184 Authors' Addresses 1185 Peter Psenak (editor) 1186 Cisco Systems, Inc. 1187 Eurovea Centre, Central 3 1188 Pribinova Street 10 1189 Bratislava 81109 1190 Slovakia 1192 Email: ppsenak@cisco.com 1194 Clarence Filsfils 1195 Cisco Systems, Inc. 1196 Brussels 1197 Belgium 1199 Email: cfilsfil@cisco.com 1201 Stefano Previdi (editor) 1202 Individual 1204 Email: stefano.previdi@net 1206 Hannes Gredler 1207 RtBrick Inc. 1208 Austria 1210 Email: hannes@rtbrick.com 1212 Rob Shakir 1213 Google, Inc. 1214 1600 Amphitheatre Parkway 1215 Mountain View, CA 94043 1216 US 1218 Email: robjs@google.com 1220 Wim Henderickx 1221 Nokia 1222 Copernicuslaan 50 1223 Antwerp 2018 1224 BE 1226 Email: wim.henderickx@nokia.com 1227 Jeff Tantsura 1228 Nuage Networks 1229 US 1231 Email: jefftant.ietf@gmail.com