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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: November 24, 2018 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 May 23, 2018 17 OSPFv3 Extensions for Segment Routing 18 draft-ietf-ospf-ospfv3-segment-routing-extensions-13 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 November 24, 2018. 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. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 25 95 11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 25 96 12. References . . . . . . . . . . . . . . . . . . . . . . . . . 25 97 12.1. Normative References . . . . . . . . . . . . . . . . . . 25 98 12.2. Informative References . . . . . . . . . . . . . . . . . 26 99 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 27 101 1. Introduction 103 Segment Routing (SR) allows a flexible definition of end-to-end paths 104 within IGP topologies by encoding paths as sequences of topological 105 sub-paths, called "segments". These segments are advertised by the 106 link-state routing protocols (IS-IS and OSPF). Prefix segments 107 represent an ECMP-aware shortest-path to a prefix (or a node), as per 108 the state of the IGP topology. Adjacency segments represent a hop 109 over a specific adjacency between two nodes in the IGP. A prefix 110 segment is typically a multi-hop path while an adjacency segment, in 111 most cases, is a one-hop path. SR's control-plane can be applied to 112 both IPv6 and MPLS data-planes, and does not require any additional 113 signalling (other than IGP extensions). The IPv6 data plane is out 114 of the scope of this specification - OSPFv3 extension for SR with 115 IPv6 data plane will be specified in a separate document. When used 116 in MPLS networks, SR paths do not require any LDP or RSVP-TE 117 signalling. However, SR can interoperate in the presence of LSPs 118 established with RSVP or LDP. 120 There are additional segment types, e.g., Binding SID defined in 121 [I-D.ietf-spring-segment-routing]. 123 This draft describes the OSPFv3 extensions required for Segment 124 Routing with MPLS data plane. 126 Segment Routing architecture is described in 127 [I-D.ietf-spring-segment-routing]. 129 Segment Routing use cases are described in [RFC7855]. 131 2. Segment Routing Identifiers 133 Segment Routing defines various types of Segment Identifiers (SIDs): 134 Prefix-SID, Adjacency-SID, LAN Adjacency SID, and Binding SID. 136 2.1. SID/Label Sub-TLV 138 The SID/Label Sub-TLV appears in multiple TLVs or Sub-TLVs defined 139 later in this document. It is used to advertise the SID or label 140 associated with a prefix or adjacency. The SID/Label Sub-TLV has 141 following format: 143 0 1 2 3 144 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 1 145 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 146 | Type | Length | 147 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 148 | SID/Label (variable) | 149 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 151 where: 153 Type: 7 155 Length: Variable, 3 or 4 octets 157 SID/Label: If length is set to 3, then the 20 rightmost bits 158 represent a label. If length is set to 4, then the value 159 represents a 32-bit SID. 161 The receiving router MUST ignore the SID/Label Sub-TLV if the 162 length is other then 3 or 4. 164 3. Segment Routing Capabilities 166 Segment Routing requires some additional router capabilities to be 167 advertised to other routers in the area. 169 These SR capabilities are advertised in the OSPFv3 Router Information 170 Opaque LSA (defined in [RFC7770]). 172 3.1. SR-Algorithm TLV 174 The SR-Algorithm TLV is a top-level TLV of the OSPFv3 Router 175 Information Opaque LSA (defined in [RFC7770]). 177 The SR-Algorithm TLV is optional. It SHOULD only be advertised once 178 in the OSPFv3 Router Information Opaque LSA. If the SR-Algorithm TLV 179 is not advertised by the node, such node is considered as not being 180 segment routing capable. 182 An SR router can use various algorithms when calculating reachability 183 to OSPFv3 routers or prefixes in an OSPFv3 area. Examples of these 184 algorithms are metric-based Shortest Path First (SPF), various 185 flavors of Constrained SPF, etc. The SR-Algorithm TLV allows a 186 router to advertise the algorithms currently used by the router to 187 other routers in an OSPFv3 area. The SR-Algorithm TLV has following 188 format: 190 0 1 2 3 191 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 1 192 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 193 | Type | Length | 194 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 195 | Algorithm 1 | Algorithm... | Algorithm n | | 196 +- -+ 197 | | 198 + + 200 where: 202 Type: 8 204 Length: Variable, in octets, dependent on number of algorithms 205 advertised. 207 Algorithm: Single octet identifying the algorithm. The following 208 values are defined by this document: 210 0: Shortest Path First (SPF) algorithm based on link metric. 211 This is the standard shortest path algorithm as computed by the 212 OSPFv3 protocol. Consistent with the deployed practice for 213 link-state protocols, Algorithm 0 permits any node to overwrite 214 the SPF path with a different path based on its local policy. 215 If the SR-Algorithm TLV is advertised, Algorithm 0 MUST be 216 included. 218 1: Strict Shortest Path First (SPF) algorithm based on link 219 metric. The algorithm is identical to Algorithm 0 but 220 Algorithm 1 requires that all nodes along the path will honor 221 the SPF routing decision. Local policy at the node claiming 222 support for Algorithm 1 MUST NOT alter the SPF paths computed 223 by Algorithm 1. 225 When multiple SR-Algorithm TLVs are received from a given router, the 226 receiver MUST use the first occurrence of the TLV in the OSPFv3 227 Router Information Opaque LSA. If the SR-Algorithm TLV appears in 228 multiple OSPFv3 Router Information Opaque LSAs that have different 229 flooding scopes, the SR-Algorithm TLV in the OSPFv3 Router 230 Information Opaque LSA with the area-scoped flooding scope MUST be 231 used. If the SR-Algorithm TLV appears in multiple OSPFv3 Router 232 Information Opaque LSAs that have the same flooding scope, the SR- 233 Algorithm TLV in the OSPFv3 Router Information Opaque LSA with the 234 numerically smallest Instance ID MUST be used and subsequent 235 instances of the SR-Algorithm TLV MUST be ignored. 237 The OSPFv3 Router Information Opaque LSA can be advertised at any of 238 the defined opaque flooding scopes (link, area, or Autonomous System 239 (AS)). For the purpose of SR-Algorithm TLV advertisement, area- 240 scoped flooding is REQUIRED. 242 3.2. SID/Label Range TLV 244 Prefix SIDs MAY be advertised in a form of an index as described in 245 Section 5. Such index defines the offset in the SID/Label space 246 advertised by the router. The SID/Label Range TLV is used to 247 advertise such SID/Label space. 249 The SID/Label Range TLV is a top-level TLV of the OSPFv3 Router 250 Information Opaque LSA (defined in [RFC7770]). 252 The SID/Label Range TLV MAY appear multiple times and has the 253 following format: 255 0 1 2 3 256 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 1 257 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 258 | Type | Length | 259 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 260 | Range Size | Reserved | 261 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 262 | Sub-TLVs (variable) | 263 +- -+ 264 | | 265 + + 267 where: 269 Type: 9 271 Length: Variable, in octets, dependent on Sub-TLVs. 273 Range Size: 3-octet SID/label range size (i.e., the number of SIDs 274 or labels in the range including the first SID/label). It MUST be 275 greater than 0. 277 Reserved: SHOULD be set to 0 on transmission and MUST be ignored 278 on reception. 280 Initially, the only supported Sub-TLV is the SID/Label Sub-TLV as 281 defined in Section 2.1. The SID/Label Sub-TLV MUST be included in 282 the SID/Label Range TLV. The SID/Label advertised in the SID/Label 283 Sub-TLV represents the first SID/Label in the advertised range. 285 Only a single SID/Label Sub-TLV MAY be advertised in SID/Label Range 286 TLV. If more then one SID/Label Sub-TLVs are present, the SID/Label 287 Range TLV MUST be ignored. 289 Multiple occurrences of the SID/Label Range TLV MAY be advertised, in 290 order to advertise multiple ranges. In such case: 292 o The originating router MUST encode each range into a different 293 SID/Label Range TLV. 295 o The originating router decides the order in which the set of SID/ 296 Label Range TLVs are advertised inside the Router Information 297 Opaque LSA. The originating router MUST ensure the order is the 298 same after a graceful restart (using checkpointing, non-volatile 299 storage, or any other mechanism) in order to assure the SID/label 300 range and SID index correspondence is preserved across graceful 301 restarts. 303 o The receiving router MUST adhere to the order in which the ranges 304 are advertised when calculating a SID/label from a SID index. 306 o The originating router MUST NOT advertise overlapping ranges. 308 o When a router receives multiple overlapping ranges, it MUST 309 conform to the procedures defined in 310 [I-D.ietf-spring-segment-routing-mpls]. 312 The following example illustrates the advertisement of multiple 313 ranges: 315 The originating router advertises the following ranges: 317 Range 1: Range Size: 100 SID/Label Sub-TLV: 100 318 Range 1: Range Size: 100 SID/Label Sub-TLV: 1000 319 Range 1: Range Size: 100 SID/Label Sub-TLV: 500 321 The receiving routers concatenate the ranges and build the Segment 322 Routing Global Block (SRGB) as follows: 324 SRGB = [100, 199] 325 [1000, 1099] 326 [500, 599] 328 The indexes span multiple ranges: 330 index=0 means label 100 331 ... 332 index 99 means label 199 333 index 100 means label 1000 334 index 199 means label 1099 335 ... 336 index 200 means label 500 337 ... 339 The OSPFv3 Router Information Opaque LSA can be advertised at any of 340 the defined flooding scopes (link, area, or autonomous system (AS)). 341 For the purpose of SID/Label Range TLV advertisement, area-scoped 342 flooding is REQUIRED. 344 3.3. SR Local Block TLV 346 The SR Local Block TLV (SRLB TLV) contains the range of labels the 347 node has reserved for local SIDs. SIDs from the SRLB MAY be used for 348 Adjacency-SIDs, but also by components other than the OSPFv3 349 protocol. As an example, an application or a controller can instruct 350 the router to allocate a specific local SID. Some controllers or 351 applications can use the control plane to discover the available set 352 of local SIDs on a particular router. In such cases, the SRLB is 353 advertised in the control plane. The requirement to advertise the 354 SRLB is further described in [I-D.ietf-spring-segment-routing-mpls]. 355 The SRLB TLV is used to advertise the SRLB. 357 The SRLB TLV is a top-level TLV of the OSPFv3 Router Information 358 Opaque LSA (defined in [RFC7770]). 360 The SRLB TLV MAY appear multiple times in the OSPFv3 Router 361 Information Opaque LSA and has the following format: 363 0 1 2 3 364 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 1 365 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 366 | Type | Length | 367 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 368 | Range Size | Reserved | 369 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 370 | Sub-TLVs (variable) | 371 +- -+ 372 | | 373 + + 375 where: 377 Type: 14 379 Length: Variable, in octets, dependent on Sub-TLVs. 381 Range Size: 3-octet SID/label range size (i.e., the number of SIDs 382 or labels in the range including the first SID/label). It MUST be 383 greater than 0. 385 Reserved: SHOULD be set to 0 on transmission and MUST be ignored 386 on reception. 388 Initially, the only supported Sub-TLV is the SID/Label Sub-TLV as 389 defined in Section 2.1. The SID/Label Sub-TLV MUST be included in 390 the SRLB TLV. The SID/Label advertised in the SID/Label Sub-TLV 391 represents the first SID/Label in the advertised range. 393 Only a single SID/Label Sub-TLV MAY be advertised in the SRLB TLV. 394 If more then one SID/Label Sub-TLVs are present, the SRLB TLV MUST be 395 ignored. 397 The originating router MUST NOT advertise overlapping ranges. 399 Each time a SID from the SRLB is allocated, it SHOULD also be 400 reported to all components (e.g., controller or applications) in 401 order for these components to have an up-to-date view of the current 402 SRLB allocation. This is required to avoid collisions between 403 allocation instructions. 405 Within the context of OSPFv3, the reporting of local SIDs is done 406 through OSPFv3 Sub-TLVs such as the Adjacency-SID (Section 6). 407 However, the reporting of allocated local SIDs can also be done 408 through other means and protocols which are outside the scope of this 409 document. 411 A router advertising the SRLB TLV MAY also have other label ranges, 412 outside of the SRLB, used for its local allocation purposes which are 413 not advertised in the SRLB TLV. For example, it is possible that an 414 Adjacency-SID is allocated using a local label that is not part of 415 the SRLB. 417 The OSPFv3 Router Information Opaque LSA can be advertised at any of 418 the defined flooding scopes (link, area, or autonomous system (AS)). 419 For the purpose of SRLB TLV advertisement, area-scoped flooding is 420 REQUIRED. 422 3.4. SRMS Preference TLV 424 The Segment Routing Mapping Server Preference TLV (SRMS Preference 425 TLV) is used to advertise a preference associated with a node that 426 acts as an SR Mapping Server. The role of an SRMS is described in 427 [I-D.ietf-spring-segment-routing-ldp-interop]. SRMS preference is 428 defined in [I-D.ietf-spring-segment-routing-ldp-interop]. 430 The SRMS Preference TLV is a top-level TLV of the OSPFv3 Router 431 Information Opaque LSA (defined in [RFC7770]). 433 The SRMS Preference TLV MAY only be advertised once in the OSPFv3 434 Router Information Opaque LSA and has the following format: 436 0 1 2 3 437 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 1 438 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 439 | Type | Length | 440 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 441 | Preference | Reserved | 442 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 444 where: 446 Type: 15 448 Length: 4 octets 450 Preference: 1 octet. SRMS preference value from 0 to 255. 452 Reserved: SHOULD be set to 0 on transmission and MUST be ignored 453 on reception. 455 When multiple SRMS Preference TLVs are received from a given router, 456 the receiver MUST use the first occurrence of the TLV in the OSPFv3 457 Router Information Opaque LSA. If the SRMS Preference TLV appears in 458 multiple OSPFv3 Router Information Opaque LSAs that have different 459 flooding scopes, the SRMS Preference TLV in the OSPFv3 Router 460 Information Opaque LSA with the narrowest flooding scope MUST be 461 used. If the SRMS Preference TLV appears in multiple OSPFv3 Router 462 Information Opaque LSAs that have the same flooding scope, the SRMS 463 Preference TLV in the OSPFv3 Router Information Opaque LSA with the 464 numerically smallest Instance ID MUST be used and subsequent 465 instances of the SRMS Preference TLV MUST be ignored. 467 The OSPFv3 Router Information Opaque LSA can be advertised at any of 468 the defined flooding scopes (link, area, or autonomous system (AS)). 469 For the purpose of the SRMS Preference TLV advertisement, AS-scoped 470 flooding SHOULD be used. This is because SRMS servers can be located 471 in a different area then consumers of the SRMS advertisements. If 472 the SRMS advertisements from the SRMS server are only used inside the 473 SRMS server's area, area-scoped flooding MAY be used. 475 4. OSPFv3 Extended Prefix Range TLV 477 In some cases it is useful to advertise attributes for a range of 478 prefixes. The Segment Routing Mapping Server, which is described in 479 [I-D.ietf-spring-segment-routing-ldp-interop], is an example where we 480 need a single advertisement to advertise SIDs for multiple prefixes 481 from a contiguous address range. 483 The OSPFv3 Extended Prefix Range TLV is defined for this purpose. 485 The OSPFv3 Extended Prefix Range TLV is a top-level TLV of the 486 following LSAs defined in [I-D.ietf-ospf-ospfv3-lsa-extend]: 488 E-Intra-Area-Prefix-LSA 490 E-Inter-Area-Prefix-LSA 492 E-AS-External-LSA 494 E-Type-7-LSA 496 Multiple OSPFv3 Extended Prefix Range TLVs MAY be advertised in each 497 LSA mentioned above. The OSPFv3 Extended Prefix Range TLV has the 498 following format: 500 0 1 2 3 501 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 1 502 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 503 | Type | Length | 504 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 505 | Prefix Length | AF | Range Size | 506 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 507 | Flags | Reserved | 508 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 509 | Address Prefix (variable) | 510 | ... | 511 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 512 | Sub-TLVs (variable) | 513 +- -+ 514 | | 516 where: 518 Type: 9 520 Length: Variable, in octets, dependent on Sub-TLVs. 522 Prefix length: Length of prefix in bits. 524 AF: Address family for the prefix. 526 AF: 0 - IPv4 unicast 528 AF: 1 - IPv6 unicast 530 Range size: Represents the number of prefixes that are covered by 531 the advertisement. The Range Size MUST NOT exceed the number of 532 prefixes that could be satisfied by the prefix length without 533 including: 535 IPv4 multicast address range (224.0.0.0/3), if the AF is IPv4 536 unicast 538 Addresses from other than the IPv6 unicast address class, if 539 the AF is IPv6 unicast 541 Flags: Single octet field. The following flags are defined: 543 0 1 2 3 4 5 6 7 544 +--+--+--+--+--+--+--+--+ 545 |IA| | | | | | | | 546 +--+--+--+--+--+--+--+--+ 548 where: 550 IA-Flag: Inter-Area flag. If set, advertisement is of inter- 551 area type. An ABR that is advertising the OSPFv3 Extended 552 Prefix Range TLV between areas MUST set this bit. 554 This bit is used to prevent redundant flooding of Prefix Range 555 TLVs between areas as follows: 557 An ABR only propagates an inter-area Prefix Range 558 advertisement from the backbone area to connected non- 559 backbone areas if the advertisement is considered to be the 560 best one. The following rules are used to select the best 561 range from the set of advertisements for the same Prefix 562 Range: 564 An ABR always prefers intra-area Prefix Range 565 advertisements over inter-area advertisements. 567 An ABR does not consider inter-area Prefix Range 568 advertisements coming from non-backbone areas. 570 Reserved: SHOULD be set to 0 on transmission and MUST be ignored 571 on reception. 573 Address Prefix: 575 For the address family IPv4 unicast, the prefix itself is 576 encoded as a 32-bit value. The default route is represented by 577 a prefix of length 0. 579 For the address family IPv6 unicast, the prefix, encoded as an 580 even multiple of 32-bit words, padded with zeroed bits as 581 necessary. This encoding consumes ((PrefixLength + 31) / 32) 582 32-bit words. 584 Prefix encoding for other address families is beyond the scope 585 of this specification. 587 5. Prefix SID Sub-TLV 589 The Prefix SID Sub-TLV is a Sub-TLV of the following OSPFv3 TLVs as 590 defined in [I-D.ietf-ospf-ospfv3-lsa-extend] and in Section 4: 592 Intra-Area Prefix TLV 594 Inter-Area Prefix TLV 596 External Prefix TLV 598 OSPFv3 Extended Prefix Range TLV 600 It MAY appear more than once in the parent TLV and has the following 601 format: 603 0 1 2 3 604 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 1 605 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 606 | Type | Length | 607 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 608 | Flags | Algorithm | Reserved | 609 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 610 | SID/Index/Label (variable) | 611 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 612 where: 614 Type: 4 616 Length: 7 or 8 octets, dependent on the V-flag 618 Flags: Single octet field. The following flags are defined: 620 0 1 2 3 4 5 6 7 621 +--+--+--+--+--+--+--+--+ 622 | |NP|M |E |V |L | | | 623 +--+--+--+--+--+--+--+--+ 624 where: 626 NP-Flag: No-PHP flag. If set, then the penultimate hop MUST 627 NOT pop the Prefix-SID before delivering packets to the node 628 that advertised the Prefix-SID. 630 M-Flag: Mapping Server Flag. If set, the SID was advertised by 631 a Segment Routing Mapping Server as described in 632 [I-D.ietf-spring-segment-routing-ldp-interop]. 634 E-Flag: Explicit-Null Flag. If set, any upstream neighbor of 635 the Prefix-SID originator MUST replace the Prefix-SID with the 636 Explicit-NULL label (0 for IPv4, 2 for IPv6) before forwarding 637 the packet. 639 V-Flag: Value/Index Flag. If set, then the Prefix-SID carries 640 an absolute value. If not set, then the Prefix-SID carries an 641 index. 643 L-Flag: Local/Global Flag. If set, then the value/index 644 carried by the Prefix-SID has local significance. If not set, 645 then the value/index carried by this Sub-TLV has global 646 significance. 648 Other bits: Reserved. These MUST be zero when sent and are 649 ignored when received. 651 Reserved: SHOULD be set to 0 on transmission and MUST be ignored 652 on reception. 654 Algorithm: Single octet identifying the algorithm the Prefix-SID 655 is associated with as defined in Section 3.1. 657 A router receiving a Prefix-SID from a remote node and with an 658 algorithm value that such remote node has not advertised in the 659 SR-Algorithm Sub-TLV (Section 3.1) MUST ignore the Prefix-SID Sub- 660 TLV. 662 SID/Index/Label: According to the V and L flags, it contains 663 either: 665 A 32-bit index defining the offset in the SID/Label space 666 advertised by this router. 668 A 24-bit label where the 20 rightmost bits are used for 669 encoding the label value. 671 If an OSPFv3 router advertises multiple Prefix-SIDs for the same 672 prefix, topology and algorithm, all of them MUST be ignored. 674 When calculating the outgoing label for the prefix, the router MUST 675 take into account, as described below, the E, NP, and M flags 676 advertised by the next-hop router if that router advertised the SID 677 for the prefix. This MUST be done regardless of whether the next-hop 678 router contributes to the best path to the prefix. 680 The NP-Flag (No-PHP) MUST be set and the E-flag MUST be clear for 681 Prefix-SIDs allocated to prefixes that are propagated between areas 682 by an ABR based on intra-area or inter-area reachability, unless the 683 advertised prefix is directly attached to such ABR. 685 The NP-Flag (No-PHP) MUST be set and the E-flag MUST be clear for 686 Prefix-SIDs allocated to redistributed prefixes, unless the 687 redistributed prefix is directly attached to the advertising 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 at 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 725 [I-D.ietf-ospf-ospfv3-lsa-extend]. 727 The Prefix is external type and the downstream neighbor is an 728 ASBR, which is advertising prefix reachability and is setting the 729 LA-bit in the Prefix Options as described in 730 [I-D.ietf-ospf-ospfv3-lsa-extend]. 732 When a Prefix-SID is advertised in the OSPFv3 Extended Prefix Range 733 TLV, then the value advertised in the Prefix SID Sub-TLV is 734 interpreted as a starting SID/Label value. 736 Example 1: If the following router addresses (loopback addresses) 737 need to be mapped into the corresponding Prefix SID indexes: 739 Router-A: 2001:DB8::1/128, Prefix-SID: Index 1 740 Router-B: 2001:DB8::2/128, Prefix-SID: Index 2 741 Router-C: 2001:DB8::3/128, Prefix-SID: Index 3 742 Router-D: 2001:DB8::4/128, Prefix-SID: Index 4 744 then the Address Prefix field in the OSPFv3 Extended Prefix Range TLV 745 would be set to 2001:DB8::1, the Prefix Length would be set to 128, 746 the Range Size would be set to 4, and the Index value in the Prefix- 747 SID Sub-TLV would be set to 1. 749 Example 2: If the following prefixes need to be mapped into the 750 corresponding Prefix-SID indexes: 752 2001:DB8:1::0/120, Prefix-SID: Index 51 753 2001:DB8:1::100/120, Prefix-SID: Index 52 754 2001:DB8:1::200/120, Prefix-SID: Index 53 755 2001:DB8:1::300/120, Prefix-SID: Index 54 756 2001:DB8:1::400/120, Prefix-SID: Index 55 757 2001:DB8:1::500/120, Prefix-SID: Index 56 758 2001:DB8:1::600/120, Prefix-SID: Index 57 760 then the Prefix field in the OSPFv3 Extended Prefix Range TLV would 761 be set to 2001:DB8:1::0, the Prefix Length would be set to 120, the 762 Range Size would be set to 7, and the Index value in the Prefix-SID 763 Sub-TLV would be set to 51. 765 6. Adjacency Segment Identifier (Adj-SID) 767 An Adjacency Segment Identifier (Adj-SID) represents a router 768 adjacency in Segment Routing. 770 6.1. Adj-SID Sub-TLV 772 Adj-SID is an optional Sub-TLV of the Router-Link TLV as defined in 773 [I-D.ietf-ospf-ospfv3-lsa-extend]. It MAY appear multiple times in 774 the Router-Link TLV. The Adj-SID Sub-TLV has the following format: 776 0 1 2 3 777 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 1 778 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 779 | Type | Length | 780 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 781 | Flags | Weight | Reserved | 782 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 783 | SID/Label/Index (variable) | 784 +---------------------------------------------------------------+ 786 where: 788 Type: 5 790 Length: 7 or 8 octets, dependent on the V flag. 792 Flags: Single octet field containing the following flags: 794 0 1 2 3 4 5 6 7 795 +-+-+-+-+-+-+-+-+ 796 |B|V|L|G|P| | 797 +-+-+-+-+-+-+-+-+ 799 where: 801 B-Flag: Backup Flag. If set, the Adj-SID refers to an 802 adjacency that is eligible for protection (e.g., using IPFRR or 803 MPLS-FRR) as described in section 3.5 of 804 [I-D.ietf-spring-segment-routing]. 806 The V-Flag: Value/Index Flag. If set, then the Adj-SID carries 807 an absolute value. If not set, then the Adj-SID carries an 808 index. 810 The L-Flag: Local/Global Flag. If set, then the value/index 811 carried by the Adj-SID has local significance. If not set, 812 then the value/index carried by this Sub-TLV has global 813 significance. 815 The G-Flag: Group Flag. When set, the G-Flag indicates that 816 the Adj-SID refers to a group of adjacencies (and therefore MAY 817 be assigned to other adjacencies as well). 819 P-Flag. Persistent flag. When set, the P-Flag indicates that 820 the Adj-SID is persistently allocated, i.e., the Adj-SID value 821 remains consistent across router restart and/or interface flap. 823 Other bits: Reserved. These MUST be zero when sent and are 824 ignored when received. 826 Reserved: SHOULD be set to 0 on transmission and MUST be ignored 827 on reception. 829 Weight: Weight used for load-balancing purposes. The use of the 830 weight is defined in [I-D.ietf-spring-segment-routing]. 832 SID/Index/Label: According to the V and L flags, it contains 833 either: 835 A 32-bit index defining the offset in the SID/Label space 836 advertised by this router. 838 A 24-bit label where the 20 rightmost bits are used for 839 encoding the label value. 841 An SR-capable router MAY allocate an Adj-SID for each of its 842 adjacencies and set the B-Flag when the adjacency is eligible for 843 protection by an FRR mechanism (IP or MPLS) as described in 844 [I-D.ietf-spring-segment-routing]. 846 An SR-capable router MAY allocate more than one Adj-SID to an 847 adjacency 849 An SR-capable router MAY allocate the same Adj-SID to different 850 adjacencies 852 When the P-flag is not set, the Adj-SID MAY be persistent. When the 853 P-flag is set, the Adj-SID MUST be persistent. 855 6.2. LAN Adj-SID Sub-TLV 857 LAN Adj-SID is an optional Sub-TLV of the Router-Link TLV. It MAY 858 appear multiple times in the Router-Link TLV. It is used to 859 advertise a SID/Label for an adjacency to a non-DR router on a 860 broadcast, NBMA, or hybrid [RFC6845] network. 862 0 1 2 3 863 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 1 864 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 865 | Type | Length | 866 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 867 | Flags | Weight | Reserved | 868 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 869 | Neighbor ID | 870 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 871 | SID/Label/Index (variable) | 872 +---------------------------------------------------------------+ 874 where: 876 Type: 6 878 Length: 11 or 12 octets, dependent on V-flag. 880 Flags: same as in Section 6.1 882 Weight: Weight used for load-balancing purposes. The use of the 883 weight is defined in [I-D.ietf-spring-segment-routing]. 885 Reserved: SHOULD be set to 0 on transmission and MUST be ignored 886 on reception. 888 Neighbor ID: The Router ID of the neighbor for which the LAN-Adj- 889 SID is advertised. 891 SID/Index/Label: According to the V and L flags, it contains 892 either: 894 A 32-bit index defining the offset in the SID/Label space 895 advertised by this router. 897 A 24-bit label where the 20 rightmost bits are used for 898 encoding the label value. 900 When the P-flag is not set, the Adj-SID MAY be persistent. When 901 the P-flag is set, the Adj-SID MUST be persistent. 903 7. Elements of Procedure 905 7.1. Intra-area Segment routing in OSPFv3 907 An OSPFv3 router that supports segment routing MAY advertise Prefix- 908 SIDs for any prefix to which it is advertising reachability (e.g., a 909 loopback IP address as described in Section 5). 911 A Prefix-SID can also be advertised by SR Mapping Servers (as 912 described in [I-D.ietf-spring-segment-routing-ldp-interop]). A 913 Mapping Server advertises Prefix-SIDs for remote prefixes that exist 914 in the OSPFv3 routing domain. Multiple Mapping Servers can advertise 915 Prefix-SIDs for the same prefix, in which case the same Prefix-SID 916 MUST be advertised by all of them. The SR Mapping Server could use 917 either area flooding scope or autonomous system flooding scope when 918 advertising Prefix SID for prefixes, based on the configuration of 919 the SR Mapping Server. Depending on the flooding scope used, the SR 920 Mapping Server chooses the OSPFv3 LSA type that will be used. If the 921 area flooding scope is needed, an E-Intra-Area-Prefix-LSA 922 ([I-D.ietf-ospf-ospfv3-lsa-extend]) is used. If autonomous system 923 flooding scope is needed, an E-AS-External-LSA 924 ([I-D.ietf-ospf-ospfv3-lsa-extend]) is used. 926 When a Prefix-SID is advertised by the Mapping Server, which is 927 indicated by the M-flag in the Prefix-SID Sub-TLV (Section 5), the 928 route type as implied by the LSA type is ignored and the Prefix-SID 929 is bound to the corresponding prefix independent of the route type. 931 Advertisement of the Prefix-SID by the Mapping Server using an Inter- 932 Area Prefix TLV, External-Prefix TLV, or Intra-Area-Prefix TLV 933 ([I-D.ietf-ospf-ospfv3-lsa-extend]) does not itself contribute to the 934 prefix reachability. The NU-bit MUST be set in the PrefixOptions 935 field of the LSA which is used by the Mapping Server to advertise SID 936 or SID Range, which prevents the advertisement from contributing to 937 prefix reachability. 939 An SR Mapping Server MUST use the OSPFv3 Extended Prefix Range TLVs 940 when advertising SIDs for prefixes. Prefixes of different route- 941 types can be combined in a single OSPFv3 Extended Prefix Range TLV 942 advertised by an SR Mapping Server. 944 Area-scoped OSPFv3 Extended Prefix Range TLVs are propagated between 945 areas. Similar to propagation of prefixes between areas, an ABR only 946 propagates the OSPFv3 Extended Prefix Range TLV that it considers to 947 be the best from the set it received. The rules used to pick the 948 best OSPFv3 Extended Prefix Range TLV are described in Section 4. 950 When propagating an OSPFv3 Extended Prefix Range TLV between areas, 951 ABRs MUST set the IA-Flag, that is used to prevent redundant flooding 952 of the OSPFv3 Extended Prefix Range TLV between areas as described in 953 Section 4. 955 7.2. Inter-area Segment routing in OSPFv3 957 In order to support SR in a multi-area environment, OSPFv3 MUST 958 propagate Prefix-SID information between areas. The following 959 procedure is used to propagate Prefix SIDs between areas. 961 When an OSPFv3 ABR advertises an Inter-Area-Prefix-LSA from an intra- 962 area prefix to all its connected areas, it will also include Prefix- 963 SID Sub-TLV, as described in Section 5. The Prefix-SID value will be 964 set as follows: 966 The ABR will look at its best path to the prefix in the source 967 area and find the advertising router associated with the best path 968 to that prefix. 970 The ABR will then determine if such router advertised a Prefix-SID 971 for the prefix and use it when advertising the Prefix-SID to other 972 connected areas. 974 If no Prefix-SID was advertised for the prefix in the source area 975 by the router that contributes to the best path to the prefix, the 976 originating ABR will use the Prefix-SID advertised by any other 977 router when propagating the Prefix-SID for the prefix to other 978 areas. 980 When an OSPFv3 ABR advertises Inter-Area-Prefix-LSA LSAs from an 981 inter-area route to all its connected areas, it will also include 982 Prefix-SID Sub-TLV, as described in Section 5. The Prefix-SID value 983 will be set as follows: 985 The ABR will look at its best path to the prefix in the backbone 986 area and find the advertising router associated with the best path 987 to that prefix. 989 The ABR will then determine if such router advertised a Prefix-SID 990 for the prefix and use it when advertising the Prefix-SID to other 991 connected areas. 993 If no Prefix-SID was advertised for the prefix in the backbone 994 area by the ABR that contributes to the best path to the prefix, 995 the originating ABR will use the Prefix-SID advertised by any 996 other router when propagating the Prefix-SID for the prefix to 997 other areas. 999 7.3. Segment Routing for External Prefixes 1001 AS-External-LSAs are flooded domain wide. When an ASBR, which 1002 supports SR, originates an E-AS-External-LSA, it SHOULD also include 1003 a Prefix-SID Sub-TLV, as described in Section 5. The Prefix-SID 1004 value will be set to the SID that has been reserved for that prefix. 1006 When an NSSA [RFC3101] ABR translates an E-NSSA-LSA into an E-AS- 1007 External-LSA, it SHOULD also advertise the Prefix-SID for the prefix. 1008 The NSSA ABR determines its best path to the prefix advertised in the 1009 translated E-NSSA-LSA and finds the advertising router associated 1010 with that path. If the advertising router has advertised a Prefix- 1011 SID for the prefix, then the NSSA ABR uses it when advertising the 1012 Prefix-SID for the E-AS-External-LSA. Otherwise, the Prefix-SID 1013 advertised by any other router will be used. 1015 7.4. Advertisement of Adj-SID 1017 The Adjacency Segment Routing Identifier (Adj-SID) is advertised 1018 using the Adj-SID Sub-TLV as described in Section 6. 1020 7.4.1. Advertisement of Adj-SID on Point-to-Point Links 1022 An Adj-SID MAY be advertised for any adjacency on a P2P link that is 1023 in neighbor state 2-Way or higher. If the adjacency on a P2P link 1024 transitions from the FULL state, then the Adj-SID for that adjacency 1025 MAY be removed from the area. If the adjacency transitions to a 1026 state lower then 2-Way, then the Adj-SID advertisement MUST be 1027 withdrawn from the area. 1029 7.4.2. Adjacency SID on Broadcast or NBMA Interfaces 1031 Broadcast, NBMA, or hybrid [RFC6845] networks in OSPFv3 are 1032 represented by a star topology where the Designated Router (DR) is 1033 the central point to which all other routers on the broadcast, NBMA, 1034 or hybrid network connect. As a result, routers on the broadcast, 1035 NBMA, or hybrid network advertise only their adjacency to the DR. 1036 Routers that do not act as DR do not form or advertise adjacencies 1037 with each other. They do, however, maintain 2-Way adjacency state 1038 with each other and are directly reachable. 1040 When Segment Routing is used, each router on the broadcast, NBMA, or 1041 hybrid network MAY advertise the Adj-SID for its adjacency to the DR 1042 using the Adj-SID Sub-TLV as described in Section 6.1. 1044 SR-capable routers MAY also advertise a LAN-Adj-SID for other 1045 neighbors (e.g., BDR, DR-OTHER) on the broadcast, NBMA, or hybrid 1046 network using the LAN-Adj-SID Sub-TLV as described in Section 6.2. 1048 8. IANA Considerations 1050 This specification updates several existing OSPFv3 registries. 1052 8.1. OSPFv3 Extended-LSA TLV Registry 1054 Following values are allocated: 1056 o suggested value 9 - OSPFv3 Extended Prefix Range TLV 1058 8.2. OSPFv3 Extended-LSA Sub-TLV registry 1060 o 4 - Prefix SID Sub-TLV 1062 o 5 - Adj-SID Sub-TLV 1064 o 6 - LAN Adj-SID Sub-TLV 1066 o 7 - SID/Label Sub-TLV 1068 9. Security Considerations 1070 With the OSPFv3 segment routing extensions defined herein, OSPFv3 1071 will now program the MPLS data plane [RFC3031] in addition to the IP 1072 data plane. Previously, LDP [RFC5036] or another label distribution 1073 mechanism was required to advertise MPLS labels and program the MPLS 1074 data plane. 1076 In general, the same types of attacks that can be carried out on the 1077 IP control plane can be carried out on the MPLS control plane 1078 resulting in traffic being misrouted in the respective data planes. 1079 However, the latter can be more difficult to detect and isolate. 1081 Existing security extensions as described in [RFC5340] and 1082 [I-D.ietf-ospf-ospfv3-lsa-extend] apply to these segment routing 1083 extensions. While OSPFv3 is under a single administrative domain, 1084 there can be deployments where potential attackers have access to one 1085 or more networks in the OSPFv3 routing domain. In these deployments, 1086 stronger authentication mechanisms such as those specified in 1087 [RFC4552] or [RFC7166] SHOULD be used. 1089 Implementations MUST assure that malformed TLV and Sub-TLV defined in 1090 this document are detected and do not provide a vulnerability for 1091 attackers to crash the OSPFv3 router or routing process. Reception 1092 of a malformed TLV or Sub-TLV SHOULD be counted and/or logged for 1093 further analysis. Logging of malformed TLVs and Sub-TLVs SHOULD be 1094 rate-limited to prevent a Denial of Service (DoS) attack (distributed 1095 or otherwise) from overloading the OSPFv3 control plane. 1097 10. Contributors 1099 Acee Lindem gave a substantial contribution to the content of this 1100 document. 1102 11. Acknowledgements 1104 We would like to thank Anton Smirnov for his contribution. 1106 12. References 1108 12.1. Normative References 1110 [I-D.ietf-ospf-ospfv3-lsa-extend] 1111 Lindem, A., Roy, A., Goethals, D., Vallem, V., and F. 1112 Baker, "OSPFv3 LSA Extendibility", draft-ietf-ospf-ospfv3- 1113 lsa-extend-23 (work in progress), January 2018. 1115 [I-D.ietf-spring-segment-routing] 1116 Filsfils, C., Previdi, S., Ginsberg, L., Decraene, B., 1117 Litkowski, S., and R. Shakir, "Segment Routing 1118 Architecture", draft-ietf-spring-segment-routing-15 (work 1119 in progress), January 2018. 1121 [I-D.ietf-spring-segment-routing-ldp-interop] 1122 Bashandy, A., Filsfils, C., Previdi, S., Decraene, B., and 1123 S. Litkowski, "Segment Routing interworking with LDP", 1124 draft-ietf-spring-segment-routing-ldp-interop-11 (work in 1125 progress), April 2018. 1127 [I-D.ietf-spring-segment-routing-mpls] 1128 Bashandy, A., Filsfils, C., Previdi, S., Decraene, B., 1129 Litkowski, S., and R. Shakir, "Segment Routing with MPLS 1130 data plane", draft-ietf-spring-segment-routing-mpls-13 1131 (work in progress), April 2018. 1133 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 1134 Requirement Levels", BCP 14, RFC 2119, 1135 DOI 10.17487/RFC2119, March 1997, 1136 . 1138 [RFC3031] Rosen, E., Viswanathan, A., and R. Callon, "Multiprotocol 1139 Label Switching Architecture", RFC 3031, 1140 DOI 10.17487/RFC3031, January 2001, 1141 . 1143 [RFC3101] Murphy, P., "The OSPF Not-So-Stubby Area (NSSA) Option", 1144 RFC 3101, DOI 10.17487/RFC3101, January 2003, 1145 . 1147 [RFC5036] Andersson, L., Ed., Minei, I., Ed., and B. Thomas, Ed., 1148 "LDP Specification", RFC 5036, DOI 10.17487/RFC5036, 1149 October 2007, . 1151 [RFC5340] Coltun, R., Ferguson, D., Moy, J., and A. Lindem, "OSPF 1152 for IPv6", RFC 5340, DOI 10.17487/RFC5340, July 2008, 1153 . 1155 [RFC6845] Sheth, N., Wang, L., and J. Zhang, "OSPF Hybrid Broadcast 1156 and Point-to-Multipoint Interface Type", RFC 6845, 1157 DOI 10.17487/RFC6845, January 2013, 1158 . 1160 [RFC7770] Lindem, A., Ed., Shen, N., Vasseur, JP., Aggarwal, R., and 1161 S. Shaffer, "Extensions to OSPF for Advertising Optional 1162 Router Capabilities", RFC 7770, DOI 10.17487/RFC7770, 1163 February 2016, . 1165 [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for 1166 Writing an IANA Considerations Section in RFCs", BCP 26, 1167 RFC 8126, DOI 10.17487/RFC8126, June 2017, 1168 . 1170 12.2. Informative References 1172 [RFC4552] Gupta, M. and N. Melam, "Authentication/Confidentiality 1173 for OSPFv3", RFC 4552, DOI 10.17487/RFC4552, June 2006, 1174 . 1176 [RFC7166] Bhatia, M., Manral, V., and A. Lindem, "Supporting 1177 Authentication Trailer for OSPFv3", RFC 7166, 1178 DOI 10.17487/RFC7166, March 2014, 1179 . 1181 [RFC7855] Previdi, S., Ed., Filsfils, C., Ed., Decraene, B., 1182 Litkowski, S., Horneffer, M., and R. Shakir, "Source 1183 Packet Routing in Networking (SPRING) Problem Statement 1184 and Requirements", RFC 7855, DOI 10.17487/RFC7855, May 1185 2016, . 1187 Authors' Addresses 1189 Peter Psenak (editor) 1190 Cisco Systems, Inc. 1191 Eurovea Centre, Central 3 1192 Pribinova Street 10 1193 Bratislava 81109 1194 Slovakia 1196 Email: ppsenak@cisco.com 1198 Clarence Filsfils 1199 Cisco Systems, Inc. 1200 Brussels 1201 Belgium 1203 Email: cfilsfil@cisco.com 1205 Stefano Previdi (editor) 1206 Individual 1208 Email: stefano.previdi@net 1210 Hannes Gredler 1211 RtBrick Inc. 1212 Austria 1214 Email: hannes@rtbrick.com 1216 Rob Shakir 1217 Google, Inc. 1218 1600 Amphitheatre Parkway 1219 Mountain View, CA 94043 1220 US 1222 Email: robjs@google.com 1223 Wim Henderickx 1224 Nokia 1225 Copernicuslaan 50 1226 Antwerp 2018 1227 BE 1229 Email: wim.henderickx@nokia.com 1231 Jeff Tantsura 1232 Nuage Networks 1233 US 1235 Email: jefftant.ietf@gmail.com