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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 Cisco Systems, Inc. 4 Intended status: Standards Track S. Previdi, Ed. 5 Expires: May 20, 2019 Individual 6 November 16, 2018 8 OSPFv3 Extensions for Segment Routing 9 draft-ietf-ospf-ospfv3-segment-routing-extensions-18 11 Abstract 13 Segment Routing (SR) allows a flexible definition of end-to-end paths 14 within IGP topologies by encoding paths as sequences of topological 15 sub-paths, called "segments". These segments are advertised by the 16 link-state routing protocols (IS-IS and OSPF). 18 This draft describes the OSPFv3 extensions required for Segment 19 Routing with MPLS data plane. 21 Requirements Language 23 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 24 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 25 document are to be interpreted as described in [RFC2119]. 27 Status of This Memo 29 This Internet-Draft is submitted in full conformance with the 30 provisions of BCP 78 and BCP 79. 32 Internet-Drafts are working documents of the Internet Engineering 33 Task Force (IETF). Note that other groups may also distribute 34 working documents as Internet-Drafts. The list of current Internet- 35 Drafts is at https://datatracker.ietf.org/drafts/current/. 37 Internet-Drafts are draft documents valid for a maximum of six months 38 and may be updated, replaced, or obsoleted by other documents at any 39 time. It is inappropriate to use Internet-Drafts as reference 40 material or to cite them other than as "work in progress." 42 This Internet-Draft will expire on May 20, 2019. 44 Copyright Notice 46 Copyright (c) 2018 IETF Trust and the persons identified as the 47 document authors. All rights reserved. 49 This document is subject to BCP 78 and the IETF Trust's Legal 50 Provisions Relating to IETF Documents 51 (https://trustee.ietf.org/license-info) in effect on the date of 52 publication of this document. Please review these documents 53 carefully, as they describe your rights and restrictions with respect 54 to this document. Code Components extracted from this document must 55 include Simplified BSD License text as described in Section 4.e of 56 the Trust Legal Provisions and are provided without warranty as 57 described in the Simplified BSD License. 59 Table of Contents 61 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 62 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 63 3. Segment Routing Identifiers . . . . . . . . . . . . . . . . . 4 64 3.1. SID/Label Sub-TLV . . . . . . . . . . . . . . . . . . . . 4 65 4. Segment Routing Capabilities . . . . . . . . . . . . . . . . 5 66 4.1. SR-Algorithm TLV . . . . . . . . . . . . . . . . . . . . 5 67 4.2. SID/Label Range TLV . . . . . . . . . . . . . . . . . . . 6 68 4.3. SR Local Block TLV . . . . . . . . . . . . . . . . . . . 8 69 4.4. SRMS Preference TLV . . . . . . . . . . . . . . . . . . . 10 70 5. OSPFv3 Extended Prefix Range TLV . . . . . . . . . . . . . . 11 71 6. Prefix SID Sub-TLV . . . . . . . . . . . . . . . . . . . . . 13 72 7. Adjacency Segment Identifier (Adj-SID) . . . . . . . . . . . 17 73 7.1. Adj-SID Sub-TLV . . . . . . . . . . . . . . . . . . . . . 17 74 7.2. LAN Adj-SID Sub-TLV . . . . . . . . . . . . . . . . . . . 19 75 8. Elements of Procedure . . . . . . . . . . . . . . . . . . . . 20 76 8.1. Intra-area Segment routing in OSPFv3 . . . . . . . . . . 20 77 8.2. Inter-area Segment routing in OSPFv3 . . . . . . . . . . 21 78 8.3. Segment Routing for External Prefixes . . . . . . . . . . 22 79 8.4. Advertisement of Adj-SID . . . . . . . . . . . . . . . . 22 80 8.4.1. Advertisement of Adj-SID on Point-to-Point Links . . 22 81 8.4.2. Adjacency SID on Broadcast or NBMA Interfaces . . . . 22 82 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 23 83 9.1. OSPFv3 Extended-LSA TLV Registry . . . . . . . . . . . . 23 84 9.2. OSPFv3 Extended-LSA Sub-TLV registry . . . . . . . . . . 23 85 10. Security Considerations . . . . . . . . . . . . . . . . . . . 23 86 11. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 24 87 12. References . . . . . . . . . . . . . . . . . . . . . . . . . 25 88 12.1. Normative References . . . . . . . . . . . . . . . . . . 25 89 12.2. Informative References . . . . . . . . . . . . . . . . . 26 90 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 26 92 1. Introduction 94 Segment Routing (SR) allows a flexible definition of end-to-end paths 95 within IGP topologies by encoding paths as sequences of topological 96 sub-paths, called "segments". These segments are advertised by the 97 link-state routing protocols (IS-IS and OSPF). Prefix segments 98 represent an ECMP-aware shortest-path to a prefix (or a node), as per 99 the state of the IGP topology. Adjacency segments represent a hop 100 over a specific adjacency between two nodes in the IGP. A prefix 101 segment is typically a multi-hop path while an adjacency segment, in 102 most cases, is a one-hop path. SR's control-plane can be applied to 103 both IPv6 and MPLS data-planes, and does not require any additional 104 signalling (other than IGP extensions). The IPv6 data plane is out 105 of the scope of this specification - OSPFv3 extension for SR with 106 IPv6 data plane will be specified in a separate document. When used 107 in MPLS networks, SR paths do not require any LDP or RSVP-TE 108 signalling. However, SR can interoperate in the presence of LSPs 109 established with RSVP or LDP. 111 There are additional segment types, e.g., Binding SID defined in 112 [RFC8402]. 114 This draft describes the OSPFv3 extensions required for Segment 115 Routing with MPLS data plane. 117 Segment Routing architecture is described in [RFC8402]. 119 Segment Routing use cases are described in [RFC7855]. 121 2. Terminology 123 This section lists some of the terminology used in this document: 125 ABR - Area Border Router 127 Adj-SID - Adjacency Segment Identifier 129 AS - Autonomous System 131 ASBR - Autonomous System Boundary Router 133 IS-IS - Intermediate System to Intermediate System 135 LDP - Label Distribution Protocol 137 LSP - Label Switched Path 139 MPLS - Multi Protocol Label Switching 141 OSPF - Open Shortest Path First 143 SPF - Shortest Path First 144 RSVP - Resource Reservation Protocol 146 SID - Segment Identifier 148 SR - Segment Routing 150 SRGB - Segment Routing Global Block 152 SRLB - Segment Routing Local Block 154 SRMS - Segment Routing Mapping Server 156 TLV - Type Length Value 158 3. Segment Routing Identifiers 160 Segment Routing defines various types of Segment Identifiers (SIDs): 161 Prefix-SID, Adjacency-SID, LAN Adjacency SID, and Binding SID. 163 3.1. SID/Label Sub-TLV 165 The SID/Label Sub-TLV appears in multiple TLVs or Sub-TLVs defined 166 later in this document. It is used to advertise the SID or label 167 associated with a prefix or adjacency. The SID/Label Sub-TLV has 168 following format: 170 0 1 2 3 171 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 1 172 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 173 | Type | Length | 174 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 175 | SID/Label (variable) | 176 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 178 where: 180 Type: 7 182 Length: Variable, 3 or 4 octets 184 SID/Label: If length is set to 3, then the 20 rightmost bits 185 represent a label. If length is set to 4, then the value 186 represents a 32-bit SID. 188 The receiving router MUST ignore the SID/Label Sub-TLV if the 189 length is other than 3 or 4. 191 4. Segment Routing Capabilities 193 Segment Routing requires some additional router capabilities to be 194 advertised to other routers in the area. 196 These SR capabilities are advertised in the OSPFv3 Router Information 197 Opaque LSA (defined in [RFC7770]). 199 4.1. SR-Algorithm TLV 201 The SR-Algorithm TLV is a top-level TLV of the OSPFv3 Router 202 Information Opaque LSA (defined in [RFC7770]). 204 The SR-Algorithm TLV is optional. It SHOULD only be advertised once 205 in the OSPFv3 Router Information Opaque LSA. If the SR-Algorithm TLV 206 is not advertised by the node, such node is considered as not being 207 segment routing capable. 209 An SR router can use various algorithms when calculating reachability 210 to OSPFv3 routers or prefixes in an OSPFv3 area. Examples of these 211 algorithms are metric-based Shortest Path First (SPF), various 212 flavors of Constrained SPF, etc. The SR-Algorithm TLV allows a 213 router to advertise the algorithms currently used by the router to 214 other routers in an OSPFv3 area. The SR-Algorithm TLV has following 215 format: 217 0 1 2 3 218 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 1 219 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 220 | Type | Length | 221 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 222 | Algorithm 1 | Algorithm... | Algorithm n | | 223 +- -+ 224 | | 225 + + 227 where: 229 Type: 8 as defined in [I-D.ietf-ospf-segment-routing-extensions] 230 and applicable to OSPFv3. 232 Length: Variable, in octets, dependent on number of algorithms 233 advertised. 235 Algorithm: Single octet identifying the algorithm. Algorithms are 236 defined in "IGP Algorithm Type" registry under "Interior Gateway 237 Protocol (IGP) Parameters" [ALGOREG], defined in 238 [I-D.ietf-ospf-segment-routing-extensions]. 240 When multiple SR-Algorithm TLVs are received from a given router, the 241 receiver MUST use the first occurrence of the TLV in the OSPFv3 242 Router Information Opaque LSA. If the SR-Algorithm TLV appears in 243 multiple OSPFv3 Router Information Opaque LSAs that have different 244 flooding scopes, the SR-Algorithm TLV in the OSPFv3 Router 245 Information Opaque LSA with the area-scoped flooding scope MUST be 246 used. If the SR-Algorithm TLV appears in multiple OSPFv3 Router 247 Information Opaque LSAs that have the same flooding scope, the SR- 248 Algorithm TLV in the OSPFv3 Router Information Opaque LSA with the 249 numerically smallest Instance ID MUST be used and subsequent 250 instances of the SR-Algorithm TLV MUST be ignored. 252 The OSPFv3 Router Information Opaque LSA can be advertised at any of 253 the defined opaque flooding scopes (link, area, or Autonomous System 254 (AS)). For the purpose of SR-Algorithm TLV advertisement, at least 255 area-scoped flooding is REQUIRED. 257 4.2. SID/Label Range TLV 259 Prefix SIDs MAY be advertised in a form of an index as described in 260 Section 6. Such index defines the offset in the SID/Label space 261 advertised by the router. The SID/Label Range TLV is used to 262 advertise such SID/Label space. 264 The SID/Label Range TLV is a top-level TLV of the OSPFv3 Router 265 Information Opaque LSA (defined in [RFC7770]). 267 The SID/Label Range TLV MAY appear multiple times and has the 268 following format: 270 0 1 2 3 271 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 1 272 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 273 | Type | Length | 274 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 275 | Range Size | Reserved | 276 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 277 | Sub-TLVs (variable) | 278 +- -+ 279 | | 280 + + 282 where: 284 Type: 9 as defined in [I-D.ietf-ospf-segment-routing-extensions] 285 and applicable to OSPFv3. 287 Length: Variable, in octets, dependent on Sub-TLVs. 289 Range Size: 3-octet SID/label range size (i.e., the number of SIDs 290 or labels in the range including the first SID/label). It MUST be 291 greater than 0. 293 Reserved: SHOULD be set to 0 on transmission and MUST be ignored 294 on reception. 296 Initially, the only supported Sub-TLV is the SID/Label Sub-TLV as 297 defined in Section 3.1. The SID/Label Sub-TLV MUST be included in 298 the SID/Label Range TLV. The SID/Label advertised in the SID/Label 299 Sub-TLV represents the first SID/Label in the advertised range. 301 Only a single SID/Label Sub-TLV MAY be advertised in SID/Label Range 302 TLV. If more than one SID/Label Sub-TLVs are present, the SID/Label 303 Range TLV MUST be ignored. 305 Multiple occurrences of the SID/Label Range TLV MAY be advertised, in 306 order to advertise multiple ranges. In such case: 308 o The originating router MUST encode each range into a different 309 SID/Label Range TLV. 311 o The originating router decides the order in which the set of SID/ 312 Label Range TLVs are advertised inside the Router Information 313 Opaque LSA. The originating router MUST ensure the order is the 314 same after a graceful restart (using checkpointing, non-volatile 315 storage, or any other mechanism) in order to assure the SID/label 316 range and SID index correspondence is preserved across graceful 317 restarts. 319 o The receiving router MUST adhere to the order in which the ranges 320 are advertised when calculating a SID/label from a SID index. 322 o The originating router MUST NOT advertise overlapping ranges. 324 o When a router receives multiple overlapping ranges, it MUST 325 conform to the procedures defined in section 2.3 of 326 [I-D.ietf-spring-segment-routing-mpls]. 328 The following example illustrates the advertisement of multiple 329 ranges: 331 The originating router advertises the following ranges: 333 Range 1: Range Size: 100 SID/Label Sub-TLV: 100 334 Range 1: Range Size: 100 SID/Label Sub-TLV: 1000 335 Range 1: Range Size: 100 SID/Label Sub-TLV: 500 337 The receiving routers concatenate the ranges and build the Segment 338 Routing Global Block (SRGB) as follows: 340 SRGB = [100, 199] 341 [1000, 1099] 342 [500, 599] 344 The indexes span multiple ranges: 346 index=0 means label 100 347 ... 348 index 99 means label 199 349 index 100 means label 1000 350 index 199 means label 1099 351 ... 352 index 200 means label 500 353 ... 355 The OSPFv3 Router Information Opaque LSA can be advertised at any of 356 the defined flooding scopes (link, area, or autonomous system (AS)). 357 For the purpose of SID/Label Range TLV advertisement, at least area- 358 scoped flooding is REQUIRED. 360 4.3. SR Local Block TLV 362 The SR Local Block TLV (SRLB TLV) contains the range of labels the 363 node has reserved for local SIDs. SIDs from the SRLB MAY be used for 364 Adjacency-SIDs, but also by components other than the OSPFv3 365 protocol. As an example, an application or a controller can instruct 366 the router to allocate a specific local SID. Some controllers or 367 applications can use the control plane to discover the available set 368 of local SIDs on a particular router. In such cases, the SRLB is 369 advertised in the control plane. The requirement to advertise the 370 SRLB is further described in [I-D.ietf-spring-segment-routing-mpls]. 371 The SRLB TLV is used to advertise the SRLB. 373 The SRLB TLV is a top-level TLV of the OSPFv3 Router Information 374 Opaque LSA (defined in [RFC7770]). 376 The SRLB TLV MAY appear multiple times in the OSPFv3 Router 377 Information Opaque LSA and has the following format: 379 0 1 2 3 380 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 1 381 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 382 | Type | Length | 383 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 384 | Range Size | Reserved | 385 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 386 | Sub-TLVs (variable) | 387 +- -+ 388 | | 389 + + 391 where: 393 Type: 14 as defined in [I-D.ietf-ospf-segment-routing-extensions] 394 and applicable to OSPFv3. 396 Length: Variable, in octets, dependent on Sub-TLVs. 398 Range Size: 3-octet SID/label range size (i.e., the number of SIDs 399 or labels in the range including the first SID/label). It MUST be 400 greater than 0. 402 Reserved: SHOULD be set to 0 on transmission and MUST be ignored 403 on reception. 405 Initially, the only supported Sub-TLV is the SID/Label Sub-TLV as 406 defined in Section 3.1. The SID/Label Sub-TLV MUST be included in 407 the SRLB TLV. The SID/Label advertised in the SID/Label Sub-TLV 408 represents the first SID/Label in the advertised range. 410 Only a single SID/Label Sub-TLV MAY be advertised in the SRLB TLV. 411 If more than one SID/Label Sub-TLVs are present, the SRLB TLV MUST be 412 ignored. 414 The originating router MUST NOT advertise overlapping ranges. 416 When a router receives multiple overlapping ranges, it MUST conform 417 to the procedures defined in section 2.3 of 418 [I-D.ietf-spring-segment-routing-mpls]. 420 Each time a SID from the SRLB is allocated, it SHOULD also be 421 reported to all components (e.g., controller or applications) in 422 order for these components to have an up-to-date view of the current 423 SRLB allocation. This is required to avoid collisions between 424 allocation instructions. 426 Within the context of OSPFv3, the reporting of local SIDs is done 427 through OSPFv3 Sub-TLVs such as the Adjacency-SID (Section 7). 428 However, the reporting of allocated local SIDs can also be done 429 through other means and protocols which are outside the scope of this 430 document. 432 A router advertising the SRLB TLV MAY also have other label ranges, 433 outside of the SRLB, used for its local allocation purposes which are 434 not advertised in the SRLB TLV. For example, it is possible that an 435 Adjacency-SID is allocated using a local label that is not part of 436 the SRLB. 438 The OSPFv3 Router Information Opaque LSA can be advertised at any of 439 the defined flooding scopes (link, area, or autonomous system (AS)). 440 For the purpose of SRLB TLV advertisement, at least area-scoped 441 flooding is REQUIRED. 443 4.4. SRMS Preference TLV 445 The Segment Routing Mapping Server Preference TLV (SRMS Preference 446 TLV) is used to advertise a preference associated with a node that 447 acts as an SR Mapping Server. The role of an SRMS is described in 448 [I-D.ietf-spring-segment-routing-ldp-interop]. SRMS preference is 449 defined in [I-D.ietf-spring-segment-routing-ldp-interop]. 451 The SRMS Preference TLV is a top-level TLV of the OSPFv3 Router 452 Information Opaque LSA (defined in [RFC7770]). 454 The SRMS Preference TLV MAY only be advertised once in the OSPFv3 455 Router Information Opaque LSA and has the following format: 457 0 1 2 3 458 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 1 459 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 460 | Type | Length | 461 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 462 | Preference | Reserved | 463 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 465 where: 467 Type: 15 as defined in [I-D.ietf-ospf-segment-routing-extensions] 468 and applicable to OSPFv3. 470 Length: 4 octets 472 Preference: 1 octet. SRMS preference value from 0 to 255. 474 Reserved: SHOULD be set to 0 on transmission and MUST be ignored 475 on reception. 477 When multiple SRMS Preference TLVs are received from a given router, 478 the receiver MUST use the first occurrence of the TLV in the OSPFv3 479 Router Information Opaque LSA. If the SRMS Preference TLV appears in 480 multiple OSPFv3 Router Information Opaque LSAs that have different 481 flooding scopes, the SRMS Preference TLV in the OSPFv3 Router 482 Information Opaque LSA with the narrowest flooding scope MUST be 483 used. If the SRMS Preference TLV appears in multiple OSPFv3 Router 484 Information Opaque LSAs that have the same flooding scope, the SRMS 485 Preference TLV in the OSPFv3 Router Information Opaque LSA with the 486 numerically smallest Instance ID MUST be used and subsequent 487 instances of the SRMS Preference TLV MUST be ignored. 489 The OSPFv3 Router Information Opaque LSA can be advertised at any of 490 the defined flooding scopes (link, area, or autonomous system (AS)). 491 For the purpose of the SRMS Preference TLV advertisement, AS-scoped 492 flooding SHOULD be used. This is because SRMS servers can be located 493 in different areas than consumers of the SRMS advertisements. If 494 SRMS advertisements from an SRMS server are only used inside the SRMS 495 server's area, area-scoped flooding MAY be used. 497 5. OSPFv3 Extended Prefix Range TLV 499 In some cases it is useful to advertise attributes for a range of 500 prefixes. The Segment Routing Mapping Server, which is described in 501 [I-D.ietf-spring-segment-routing-ldp-interop], is an example of where 502 we need a single advertisement to advertise SIDs for multiple 503 prefixes from a contiguous address range. 505 The OSPFv3 Extended Prefix Range TLV is defined for this purpose. 507 The OSPFv3 Extended Prefix Range TLV is a top-level TLV of the 508 following LSAs defined in [RFC8362]: 510 E-Intra-Area-Prefix-LSA 512 E-Inter-Area-Prefix-LSA 514 E-AS-External-LSA 516 E-Type-7-LSA 518 Multiple OSPFv3 Extended Prefix Range TLVs MAY be advertised in each 519 LSA mentioned above. The OSPFv3 Extended Prefix Range TLV has the 520 following format: 522 0 1 2 3 523 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 1 524 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 525 | Type | Length | 526 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 527 | Prefix Length | AF | Range Size | 528 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 529 | Flags | Reserved | 530 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 531 | Address Prefix (variable) | 532 | ... | 533 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 534 | Sub-TLVs (variable) | 535 +- -+ 536 | | 538 where: 540 Type: 9 542 Length: Variable, in octets, dependent on Sub-TLVs. 544 Prefix length: Length of prefix in bits. 546 AF: Address family for the prefix. 548 AF: 0 - IPv4 unicast 550 AF: 1 - IPv6 unicast 552 Range size: Represents the number of prefixes that are covered by 553 the advertisement. The Range Size MUST NOT exceed the number of 554 prefixes that could be satisfied by the prefix length without 555 including: 557 Addresses from the IPv4 multicast address range (224.0.0.0/3), 558 if the AF is IPv4 unicast 560 Addresses other than the IPv6 unicast addresses, if the AF is 561 IPv6 unicast 563 Flags: Reserved. MUST be zero when sent and are ignored when 564 received. 566 Reserved: SHOULD be set to 0 on transmission and MUST be ignored 567 on reception. 569 Address Prefix: 571 For the address family IPv4 unicast, the prefix itself is 572 encoded as a 32-bit value. The default route is represented by 573 a prefix of length 0. 575 For the address family IPv6 unicast, the prefix, encoded as an 576 even multiple of 32-bit words, padded with zeroed bits as 577 necessary. This encoding consumes ((PrefixLength + 31) / 32) 578 32-bit words. 580 Prefix encoding for other address families is beyond the scope 581 of this specification. 583 If the OSPFv3 Extended Prefix Range TLVs advertising the exact same 584 range appears in multiple LSAs of the same type, originated by the 585 same OSPFv3 router, the LSA with the numerically smallest Instance ID 586 MUST be used and subsequent instances of the OSPFv3 Extended Prefix 587 Range TLVs MUST be ignored. 589 6. Prefix SID Sub-TLV 591 The Prefix SID Sub-TLV is a Sub-TLV of the following OSPFv3 TLVs as 592 defined in [RFC8362] and in Section 5: 594 Intra-Area Prefix TLV 596 Inter-Area Prefix TLV 598 External Prefix TLV 600 OSPFv3 Extended Prefix Range TLV 602 It MAY appear more than once in the parent TLV and has the following 603 format: 605 0 1 2 3 606 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 1 607 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 608 | Type | Length | 609 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 610 | Flags | Algorithm | Reserved | 611 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 612 | SID/Index/Label (variable) | 613 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 614 where: 616 Type: 4 618 Length: 7 or 8 octets, dependent on the V-flag 619 Flags: Single octet field. The following flags are defined: 621 0 1 2 3 4 5 6 7 622 +--+--+--+--+--+--+--+--+ 623 | |NP|M |E |V |L | | | 624 +--+--+--+--+--+--+--+--+ 625 where: 627 NP-Flag: No-PHP flag. If set, then the penultimate hop MUST 628 NOT pop the Prefix-SID before delivering packets to the node 629 that advertised the Prefix-SID. 631 M-Flag: Mapping Server Flag. If set, the SID was advertised by 632 a Segment Routing Mapping Server as described in 633 [I-D.ietf-spring-segment-routing-ldp-interop]. 635 E-Flag: Explicit-Null Flag. If set, any upstream neighbor of 636 the Prefix-SID originator MUST replace the Prefix-SID with the 637 Explicit-NULL label (0 for IPv4, 2 for IPv6) before forwarding 638 the packet. 640 V-Flag: Value/Index Flag. If set, then the Prefix-SID carries 641 an absolute value. If not set, then the Prefix-SID carries an 642 index. 644 L-Flag: Local/Global Flag. If set, then the value/index 645 carried by the Prefix-SID has local significance. If not set, 646 then the value/index carried by this Sub-TLV has global 647 significance. 649 Other bits: Reserved. These MUST be zero when sent and are 650 ignored when received. 652 Reserved: SHOULD be set to 0 on transmission and MUST be ignored 653 on reception. 655 Algorithm: Single octet identifying the algorithm the Prefix-SID 656 is associated with as defined in Section 4.1. 658 A router receiving a Prefix-SID from a remote node and with an 659 algorithm value that such remote node has not advertised in the 660 SR-Algorithm Sub-TLV (Section 4.1) MUST ignore the Prefix-SID Sub- 661 TLV. 663 SID/Index/Label: According to the V and L flags, it contains 664 either: 666 A 32-bit index defining the offset in the SID/Label space 667 advertised by this router. 669 A 24-bit label where the 20 rightmost bits are used for 670 encoding the label value. 672 If an OSPFv3 router advertises multiple Prefix-SIDs for the same 673 prefix, topology, and algorithm, all of them MUST be ignored. 675 When calculating the outgoing label for the prefix, the router MUST 676 take into account, as described below, the E, NP, and M flags 677 advertised by the next-hop router if that router advertised the SID 678 for the prefix. This MUST be done regardless of whether the next-hop 679 router contributes to the best path to the prefix. 681 The NP-Flag (No-PHP) MUST be set and the E-flag MUST be clear for 682 Prefix-SIDs allocated to prefixes that are propagated between areas 683 by an ABR based on intra-area or inter-area reachability, unless the 684 advertised prefix is directly attached to such ABR. 686 The NP-Flag (No-PHP) MUST be set and the E-flag MUST be clear for 687 Prefix-SIDs allocated to redistributed prefixes, unless the 688 redistributed prefix is directly attached to the advertising 689 Autonomous System Boundary Router (ASBR). 691 If the NP-Flag is not set, then any upstream neighbor of the Prefix- 692 SID originator MUST pop the Prefix-SID. This is equivalent to the 693 penultimate hop popping mechanism used in the MPLS dataplane. If the 694 NP-flag is not set, then the received E-flag is ignored. 696 If the NP-flag is set then: 698 If the E-flag is not set, then any upstream neighbor of the 699 Prefix-SID originator MUST keep the Prefix-SID on top of the 700 stack. This is useful when the originator of the Prefix-SID needs 701 to stitch the incoming packet into a continuing MPLS LSP to the 702 final destination. This could occur at an Area Border Router 703 (prefix propagation from one area to another) or at an AS Boundary 704 Router (prefix propagation from one domain to another). 706 If the E-flag is set, then any upstream neighbor of the Prefix-SID 707 originator MUST replace the Prefix-SID with an Explicit-NULL 708 label. This is useful, e.g., when the originator of the Prefix- 709 SID is the final destination for the related prefix and the 710 originator wishes to receive the packet with the original EXP 711 bits. 713 When the M-Flag is set, the NP-flag and the E-flag MUST be ignored on 714 reception. 716 As the Mapping Server does not specify the originator of a prefix 717 advertisement, it is not possible to determine PHP behavior solely 718 based on the Mapping Server advertisement. However, PHP behavior 719 SHOULD be done in following cases: 721 The Prefix is intra-area type and the downstream neighbor is the 722 originator of the prefix. 724 The Prefix is inter-area type and the downstream neighbor is an 725 ABR, which is advertising prefix reachability and is setting the 726 LA-bit in the Prefix Options as described in [RFC8362]. 728 The Prefix is external type and the downstream neighbor is an 729 ASBR, which is advertising prefix reachability and is setting the 730 LA-bit in the Prefix Options as described in [RFC8362]. 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 7. Adjacency Segment Identifier (Adj-SID) 767 An Adjacency Segment Identifier (Adj-SID) represents a router 768 adjacency in Segment Routing. 770 7.1. Adj-SID Sub-TLV 772 The Adj-SID Sub-TLV is an optional Sub-TLV of the Router-Link TLV as 773 defined in [RFC8362]. It MAY appear multiple times in the Router- 774 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 [RFC8402]. 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 the same 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 [RFC8402]. 831 SID/Index/Label: According to the V-Flag, it contains either: 833 A 32-bit index defining the offset in the SID/Label space 834 advertised by this router. 836 A 24-bit label where the 20 rightmost bits are used for 837 encoding the label value. 839 An SR-capable router MAY allocate an Adj-SID for each of its 840 adjacencies and set the B-Flag when the adjacency is eligible for 841 protection by an FRR mechanism (IP or MPLS) as described in 842 [RFC8402]. 844 An SR-capable router MAY allocate more than one Adj-SID to an 845 adjacency. 847 An SR-capable router MAY allocate the same Adj-SID to different 848 adjacencies. 850 When the P-flag is not set, the Adj-SID MAY be persistent. When the 851 P-flag is set, the Adj-SID MUST be persistent. 853 7.2. LAN Adj-SID Sub-TLV 855 The LAN Adj-SID Sub-TLV is an optional Sub-TLV of the Router-Link 856 TLV. It MAY appear multiple times in the Router-Link TLV. It is 857 used to advertise a SID/Label for an adjacency to a non-DR router on 858 a broadcast, NBMA, or hybrid [RFC6845] network. 860 0 1 2 3 861 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 1 862 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 863 | Type | Length | 864 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 865 | Flags | Weight | Reserved | 866 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 867 | Neighbor ID | 868 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 869 | SID/Label/Index (variable) | 870 +---------------------------------------------------------------+ 872 where: 874 Type: 6 876 Length: 11 or 12 octets, dependent on V-flag. 878 Flags: same as in Section 7.1 880 Weight: Weight used for load-balancing purposes. The use of the 881 weight is defined in [RFC8402]. 883 Reserved: SHOULD be set to 0 on transmission and MUST be ignored 884 on reception. 886 Neighbor ID: The Router ID of the neighbor for which the LAN-Adj- 887 SID is advertised. 889 SID/Index/Label: According to the V and L flags, it contains 890 either: 892 A 32-bit index defining the offset in the SID/Label space 893 advertised by this router. 895 A 24-bit label where the 20 rightmost bits are used for 896 encoding the label value. 898 When the P-flag is not set, the Adj-SID MAY be persistent. When 899 the P-flag is set, the Adj-SID MUST be persistent. 901 8. Elements of Procedure 903 8.1. Intra-area Segment routing in OSPFv3 905 An OSPFv3 router that supports segment routing MAY advertise Prefix- 906 SIDs for any prefix to which it is advertising reachability (e.g., a 907 loopback IP address as described in Section 6). 909 A Prefix-SID can also be advertised by SR Mapping Servers (as 910 described in [I-D.ietf-spring-segment-routing-ldp-interop]). A 911 Mapping Server advertises Prefix-SIDs for remote prefixes that exist 912 in the OSPFv3 routing domain. Multiple Mapping Servers can advertise 913 Prefix-SIDs for the same prefix, in which case the same Prefix-SID 914 MUST be advertised by all of them. The SR Mapping Server could use 915 either area flooding scope or autonomous system flooding scope when 916 advertising Prefix SIDs for prefixes, based on the configuration of 917 the SR Mapping Server. Depending on the flooding scope used, the SR 918 Mapping Server chooses the OSPFv3 LSA type that will be used. If the 919 area flooding scope is needed, an E-Intra-Area-Prefix-LSA [RFC8362] 920 is used. If autonomous system flooding scope is needed, an E-AS- 921 External-LSA [RFC8362] is used. 923 When a Prefix-SID is advertised by the Mapping Server, which is 924 indicated by the M-flag in the Prefix-SID Sub-TLV (Section 6), the 925 route type as implied by the LSA type is ignored and the Prefix-SID 926 is bound to the corresponding prefix independent of the route type. 928 Advertisement of the Prefix-SID by the Mapping Server using an Inter- 929 Area Prefix TLV, External-Prefix TLV, or Intra-Area-Prefix TLV 930 [RFC8362] does not itself contribute to the prefix reachability. The 931 NU-bit MUST be set in the PrefixOptions field of the LSA which is 932 used by the Mapping Server to advertise SID or SID Range, which 933 prevents the advertisement from contributing to prefix reachability. 935 An SR Mapping Server MUST use the OSPFv3 Extended Prefix Range TLVs 936 when advertising SIDs for prefixes. Prefixes of different route- 937 types can be combined in a single OSPFv3 Extended Prefix Range TLV 938 advertised by an SR Mapping Server. 940 Area-scoped OSPFv3 Extended Prefix Range TLVs are propagated between 941 areas. Similar to propagation of prefixes between areas, an ABR only 942 propagates the OSPFv3 Extended Prefix Range TLV that it considers to 943 be the best from the set it received. The rules used to pick the 944 best OSPFv3 Extended Prefix Range TLV are described in Section 5. 946 When propagating an OSPFv3 Extended Prefix Range TLV between areas, 947 ABRs MUST set the IA-Flag, that is used to prevent redundant flooding 948 of the OSPFv3 Extended Prefix Range TLV between areas as described in 949 Section 5. 951 8.2. Inter-area Segment routing in OSPFv3 953 In order to support SR in a multi-area environment, OSPFv3 MUST 954 propagate Prefix-SID information between areas. The following 955 procedure is used to propagate Prefix SIDs between areas. 957 When an OSPFv3 ABR advertises an Inter-Area-Prefix-LSA from an intra- 958 area prefix to all its connected areas, it will also include the 959 Prefix-SID Sub-TLV, as described in Section 6. The Prefix-SID value 960 will be set as follows: 962 The ABR will look at its best path to the prefix in the source 963 area and find the advertising router associated with the best path 964 to that prefix. 966 The ABR will then determine if such router advertised a Prefix-SID 967 for the prefix and use it when advertising the Prefix-SID to other 968 connected areas. 970 If no Prefix-SID was advertised for the prefix in the source area 971 by the router that contributes to the best path to the prefix, the 972 originating ABR will use the Prefix-SID advertised by any other 973 router when propagating the Prefix-SID for the prefix to other 974 areas. 976 When an OSPFv3 ABR advertises Inter-Area-Prefix-LSA LSAs from an 977 inter-area route to all its connected areas, it will also include the 978 Prefix-SID Sub-TLV, as described in Section 6. The Prefix-SID value 979 will be set as follows: 981 The ABR will look at its best path to the prefix in the backbone 982 area and find the advertising router associated with the best path 983 to that prefix. 985 The ABR will then determine if such router advertised a Prefix-SID 986 for the prefix and use it when advertising the Prefix-SID to other 987 connected areas. 989 If no Prefix-SID was advertised for the prefix in the backbone 990 area by the ABR that contributes to the best path to the prefix, 991 the originating ABR will use the Prefix-SID advertised by any 992 other router when propagating the Prefix-SID for the prefix to 993 other areas. 995 8.3. Segment Routing for External Prefixes 997 AS-External-LSAs are flooded domain wide. When an ASBR, which 998 supports SR, originates an E-AS-External-LSA, it SHOULD also include 999 a Prefix-SID Sub-TLV, as described in Section 6. The Prefix-SID 1000 value will be set to the SID that has been reserved for that prefix. 1002 When an NSSA [RFC3101] ABR translates an E-NSSA-LSA into an E-AS- 1003 External-LSA, it SHOULD also advertise the Prefix-SID for the prefix. 1004 The NSSA ABR determines its best path to the prefix advertised in the 1005 translated E-NSSA-LSA and finds the advertising router associated 1006 with that path. If the advertising router has advertised a Prefix- 1007 SID for the prefix, then the NSSA ABR uses it when advertising the 1008 Prefix-SID for the E-AS-External-LSA. Otherwise, the Prefix-SID 1009 advertised by any other router will be used. 1011 8.4. Advertisement of Adj-SID 1013 The Adjacency Segment Routing Identifier (Adj-SID) is advertised 1014 using the Adj-SID Sub-TLV as described in Section 7. 1016 8.4.1. Advertisement of Adj-SID on Point-to-Point Links 1018 An Adj-SID MAY be advertised for any adjacency on a P2P link that is 1019 in neighbor state 2-Way or higher. If the adjacency on a P2P link 1020 transitions from the FULL state, then the Adj-SID for that adjacency 1021 MAY be removed from the area. If the adjacency transitions to a 1022 state lower than 2-Way, then the Adj-SID advertisement MUST be 1023 withdrawn from the area. 1025 8.4.2. Adjacency SID on Broadcast or NBMA Interfaces 1027 Broadcast, NBMA, or hybrid [RFC6845] networks in OSPFv3 are 1028 represented by a star topology where the Designated Router (DR) is 1029 the central point to which all other routers on the broadcast, NBMA, 1030 or hybrid network connect. As a result, routers on the broadcast, 1031 NBMA, or hybrid network advertise only their adjacency to the DR. 1032 Routers that do not act as DR do not form or advertise adjacencies 1033 with each other. They do, however, maintain 2-Way adjacency state 1034 with each other and are directly reachable. 1036 When Segment Routing is used, each router on the broadcast, NBMA, or 1037 hybrid network MAY advertise the Adj-SID for its adjacency to the DR 1038 using the Adj-SID Sub-TLV as described in Section 7.1. 1040 SR-capable routers MAY also advertise a LAN-Adj-SID for other 1041 neighbors (e.g., BDR, DR-OTHER) on the broadcast, NBMA, or hybrid 1042 network using the LAN-Adj-SID Sub-TLV as described in Section 7.2. 1044 9. IANA Considerations 1046 This specification updates several existing OSPFv3 registries. 1048 9.1. OSPFv3 Extended-LSA TLV Registry 1050 Following values are allocated: 1052 o 9 - OSPFv3 Extended Prefix Range TLV 1054 9.2. OSPFv3 Extended-LSA Sub-TLV registry 1056 o 4 - Prefix SID Sub-TLV 1058 o 5 - Adj-SID Sub-TLV 1060 o 6 - LAN Adj-SID Sub-TLV 1062 o 7 - SID/Label Sub-TLV 1064 10. Security Considerations 1066 With the OSPFv3 segment routing extensions defined herein, OSPFv3 1067 will now program the MPLS data plane [RFC3031]. Previously, LDP 1068 [RFC5036] or another label distribution mechanism was required to 1069 advertise MPLS labels and program the MPLS data plane. 1071 In general, the same types of attacks that can be carried out on the 1072 IP control plane can be carried out on the MPLS control plane 1073 resulting in traffic being misrouted in the respective data planes. 1074 However, the latter can be more difficult to detect and isolate. 1076 Existing security extensions as described in [RFC5340] and [RFC8362] 1077 apply to these segment routing extensions. While OSPFv3 is under a 1078 single administrative domain, there can be deployments where 1079 potential attackers have access to one or more networks in the OSPFv3 1080 routing domain. In these deployments, stronger authentication 1081 mechanisms such as those specified in [RFC4552] or [RFC7166] SHOULD 1082 be used. 1084 Implementations MUST assure that malformed TLV and Sub-TLV defined in 1085 this document are detected and do not provide a vulnerability for 1086 attackers to crash the OSPFv3 router or routing process. Reception 1087 of a malformed TLV or Sub-TLV SHOULD be counted and/or logged for 1088 further analysis. Logging of malformed TLVs and Sub-TLVs SHOULD be 1089 rate-limited to prevent a Denial of Service (DoS) attack (distributed 1090 or otherwise) from overloading the OSPFv3 control plane. 1092 11. Contributors 1094 The following people gave a substantial contribution to the content 1095 of this document and should be considered as co-authors: 1097 Clarence Filsfils 1098 Cisco Systems, Inc. 1099 Brussels 1100 Belgium 1102 Email: cfilsfil@cisco.com 1104 Hannes Gredler 1105 RtBrick Inc. 1106 Austria 1108 Email: hannes@rtbrick.com 1110 Rob Shakir 1111 Google, Inc. 1112 1600 Amphitheatre Parkway 1113 Mountain View, CA 94043 1114 US 1116 Email: robjs@google.com 1118 Wim Henderickx 1119 Nokia 1120 Copernicuslaan 50 1121 Antwerp 2018 1122 BE 1124 Email: wim.henderickx@nokia.com 1126 Jeff Tantsura 1127 Nuage Networks 1128 US 1130 Email: jefftant.ietf@gmail.com 1132 Thanks to Acee Lindem for his substantial contribution to the content 1133 of this document. 1135 We would like to thank Anton Smirnov for his contribution as well. 1137 12. References 1139 12.1. Normative References 1141 [ALGOREG] "IGP Algorithm Types", . 1144 [I-D.ietf-ospf-segment-routing-extensions] 1145 Psenak, P., Previdi, S., Filsfils, C., Gredler, H., 1146 Shakir, R., Henderickx, W., and J. Tantsura, "OSPF 1147 Extensions for Segment Routing", draft-ietf-ospf-segment- 1148 routing-extensions-25 (work in progress), April 2018. 1150 [I-D.ietf-spring-segment-routing-ldp-interop] 1151 Bashandy, A., Filsfils, C., Previdi, S., Decraene, B., and 1152 S. Litkowski, "Segment Routing interworking with LDP", 1153 draft-ietf-spring-segment-routing-ldp-interop-15 (work in 1154 progress), September 2018. 1156 [I-D.ietf-spring-segment-routing-mpls] 1157 Bashandy, A., Filsfils, C., Previdi, S., Decraene, B., 1158 Litkowski, S., and R. Shakir, "Segment Routing with MPLS 1159 data plane", draft-ietf-spring-segment-routing-mpls-15 1160 (work in progress), October 2018. 1162 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 1163 Requirement Levels", BCP 14, RFC 2119, 1164 DOI 10.17487/RFC2119, March 1997, 1165 . 1167 [RFC3031] Rosen, E., Viswanathan, A., and R. Callon, "Multiprotocol 1168 Label Switching Architecture", RFC 3031, 1169 DOI 10.17487/RFC3031, January 2001, 1170 . 1172 [RFC3101] Murphy, P., "The OSPF Not-So-Stubby Area (NSSA) Option", 1173 RFC 3101, DOI 10.17487/RFC3101, January 2003, 1174 . 1176 [RFC5036] Andersson, L., Ed., Minei, I., Ed., and B. Thomas, Ed., 1177 "LDP Specification", RFC 5036, DOI 10.17487/RFC5036, 1178 October 2007, . 1180 [RFC5340] Coltun, R., Ferguson, D., Moy, J., and A. Lindem, "OSPF 1181 for IPv6", RFC 5340, DOI 10.17487/RFC5340, July 2008, 1182 . 1184 [RFC6845] Sheth, N., Wang, L., and J. Zhang, "OSPF Hybrid Broadcast 1185 and Point-to-Multipoint Interface Type", RFC 6845, 1186 DOI 10.17487/RFC6845, January 2013, 1187 . 1189 [RFC7770] Lindem, A., Ed., Shen, N., Vasseur, JP., Aggarwal, R., and 1190 S. Shaffer, "Extensions to OSPF for Advertising Optional 1191 Router Capabilities", RFC 7770, DOI 10.17487/RFC7770, 1192 February 2016, . 1194 [RFC8362] Lindem, A., Roy, A., Goethals, D., Reddy Vallem, V., and 1195 F. Baker, "OSPFv3 Link State Advertisement (LSA) 1196 Extensibility", RFC 8362, DOI 10.17487/RFC8362, April 1197 2018, . 1199 [RFC8402] Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L., 1200 Decraene, B., Litkowski, S., and R. Shakir, "Segment 1201 Routing Architecture", RFC 8402, DOI 10.17487/RFC8402, 1202 July 2018, . 1204 12.2. Informative References 1206 [RFC4552] Gupta, M. and N. Melam, "Authentication/Confidentiality 1207 for OSPFv3", RFC 4552, DOI 10.17487/RFC4552, June 2006, 1208 . 1210 [RFC7166] Bhatia, M., Manral, V., and A. Lindem, "Supporting 1211 Authentication Trailer for OSPFv3", RFC 7166, 1212 DOI 10.17487/RFC7166, March 2014, 1213 . 1215 [RFC7855] Previdi, S., Ed., Filsfils, C., Ed., Decraene, B., 1216 Litkowski, S., Horneffer, M., and R. Shakir, "Source 1217 Packet Routing in Networking (SPRING) Problem Statement 1218 and Requirements", RFC 7855, DOI 10.17487/RFC7855, May 1219 2016, . 1221 Authors' Addresses 1223 Peter Psenak (editor) 1224 Cisco Systems, Inc. 1225 Eurovea Centre, Central 3 1226 Pribinova Street 10 1227 Bratislava 81109 1228 Slovakia 1230 Email: ppsenak@cisco.com 1231 Stefano Previdi (editor) 1232 Individual 1234 Email: stefano.previdi@net