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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 S. Previdi, Ed. 4 Intended status: Standards Track C. Filsfils 5 Expires: September 1, 2017 Cisco Systems, Inc. 6 H. Gredler 7 RtBrick Inc. 8 R. Shakir 9 Google, Inc. 10 W. Henderickx 11 Nokia 12 J. Tantsura 13 Individual 14 February 28, 2017 16 OSPFv3 Extensions for Segment Routing 17 draft-ietf-ospf-ospfv3-segment-routing-extensions-08 19 Abstract 21 Segment Routing (SR) allows for a flexible definition of end-to-end 22 paths within IGP topologies by encoding paths as sequences of 23 topological sub-paths, called "segments". These segments are 24 advertised by the link-state routing protocols (IS-IS and OSPF). 26 This draft describes the OSPFv3 extensions that are required for 27 Segment Routing. 29 Requirements Language 31 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 32 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 33 document are to be interpreted as described in RFC 2119 [RFC2119]. 35 Status of This Memo 37 This Internet-Draft is submitted in full conformance with the 38 provisions of BCP 78 and BCP 79. 40 Internet-Drafts are working documents of the Internet Engineering 41 Task Force (IETF). Note that other groups may also distribute 42 working documents as Internet-Drafts. The list of current Internet- 43 Drafts is at http://datatracker.ietf.org/drafts/current/. 45 Internet-Drafts are draft documents valid for a maximum of six months 46 and may be updated, replaced, or obsoleted by other documents at any 47 time. It is inappropriate to use Internet-Drafts as reference 48 material or to cite them other than as "work in progress." 49 This Internet-Draft will expire on September 1, 2017. 51 Copyright Notice 53 Copyright (c) 2017 IETF Trust and the persons identified as the 54 document authors. All rights reserved. 56 This document is subject to BCP 78 and the IETF Trust's Legal 57 Provisions Relating to IETF Documents 58 (http://trustee.ietf.org/license-info) in effect on the date of 59 publication of this document. Please review these documents 60 carefully, as they describe your rights and restrictions with respect 61 to this document. Code Components extracted from this document must 62 include Simplified BSD License text as described in Section 4.e of 63 the Trust Legal Provisions and are provided without warranty as 64 described in the Simplified BSD License. 66 Table of Contents 68 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 69 2. Segment Routing Identifiers . . . . . . . . . . . . . . . . . 3 70 2.1. SID/Label Sub-TLV . . . . . . . . . . . . . . . . . . . . 3 71 3. Segment Routing Capabilities . . . . . . . . . . . . . . . . 4 72 3.1. SR-Algorithm TLV . . . . . . . . . . . . . . . . . . . . 4 73 3.2. SID/Label Range TLV . . . . . . . . . . . . . . . . . . . 6 74 3.3. SR Local Block Sub-TLV . . . . . . . . . . . . . . . . . 7 75 3.4. SRMS Preference Sub-TLV . . . . . . . . . . . . . . . . . 9 76 3.5. SR-Forwarding Capabilities . . . . . . . . . . . . . . . 10 77 4. OSPFv3 Extended Prefix Range TLV . . . . . . . . . . . . . . 10 78 5. Prefix SID Sub-TLV . . . . . . . . . . . . . . . . . . . . . 12 79 6. SID/Label Binding Sub-TLV . . . . . . . . . . . . . . . . . . 16 80 6.1. ERO Metric Sub-TLV . . . . . . . . . . . . . . . . . . . 18 81 6.2. ERO Sub-TLVs . . . . . . . . . . . . . . . . . . . . . . 19 82 6.2.1. IPv4 ERO Sub-TLV . . . . . . . . . . . . . . . . . . 19 83 6.2.2. IPv6 ERO Sub-TLV . . . . . . . . . . . . . . . . . . 20 84 6.2.3. Unnumbered Interface ID ERO Sub-TLV . . . . . . . . . 21 85 6.2.4. IPv4 Backup ERO Sub-TLV . . . . . . . . . . . . . . . 22 86 6.2.5. IPv6 Backup ERO Sub-TLV . . . . . . . . . . . . . . . 23 87 6.2.6. Unnumbered Interface ID Backup ERO Sub-TLV . . . . . 24 88 7. Adjacency Segment Identifier (Adj-SID) . . . . . . . . . . . 25 89 7.1. Adj-SID Sub-TLV . . . . . . . . . . . . . . . . . . . . . 25 90 7.2. LAN Adj-SID Sub-TLV . . . . . . . . . . . . . . . . . . . 27 91 8. Elements of Procedure . . . . . . . . . . . . . . . . . . . . 29 92 8.1. Intra-area Segment routing in OSPFv3 . . . . . . . . . . 29 93 8.2. Inter-area Segment routing in OSPFv3 . . . . . . . . . . 30 94 8.3. SID for External Prefixes . . . . . . . . . . . . . . . . 31 95 8.4. Advertisement of Adj-SID . . . . . . . . . . . . . . . . 32 96 8.4.1. Advertisement of Adj-SID on Point-to-Point Links . . 32 97 8.4.2. Adjacency SID on Broadcast or NBMA Interfaces . . . . 32 98 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 32 99 9.1. OSPF Router Information (RI) TLVs Registry . . . . . . . 32 100 9.2. OSPFv3 Extend-LSA TLV Registry . . . . . . . . . . . . . 33 101 9.3. OSPFv3 Extend-LSA Sub-TLV registry . . . . . . . . . . . 33 102 10. Security Considerations . . . . . . . . . . . . . . . . . . . 33 103 11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 33 104 12. References . . . . . . . . . . . . . . . . . . . . . . . . . 34 105 12.1. Normative References . . . . . . . . . . . . . . . . . . 34 106 12.2. Informative References . . . . . . . . . . . . . . . . . 34 107 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 35 109 1. Introduction 111 Segment Routing (SR) allows for a flexible definition of end-to-end 112 paths within IGP topologies by encoding paths as sequences of 113 topological sub-paths, called "segments". These segments are 114 advertised by the link-state routing protocols (IS-IS and OSPF). 115 Prefix segments represent an ecmp-aware shortest-path to a prefix (or 116 a node), as per the state of the IGP topology. Adjacency segments 117 represent a hop over a specific adjacency between two nodes in the 118 IGP. A prefix segment is typically a multi-hop path while an 119 adjacency segment, in most of the cases, is a one-hop path. SR's 120 control-plane can be applied to both IPv6 and MPLS data-planes, and 121 does not require any additional signaling (other than the regular 122 IGP). For example, when used in MPLS networks, SR paths do not 123 require any LDP or RSVP-TE signaling. Still, SR can interoperate in 124 the presence of LSPs established with RSVP or LDP. 126 This draft describes the OSPFv3 extensions required for segment 127 routing. 129 Segment Routing architecture is described in 130 [I-D.ietf-spring-segment-routing]. 132 Segment Routing use cases are described in 133 [I-D.filsfils-spring-segment-routing-use-cases]. 135 2. Segment Routing Identifiers 137 Segment Routing defines various types of Segment Identifiers (SIDs): 138 Prefix-SID, Adjacency-SID, LAN Adjacency SID and Binding SID. 140 2.1. SID/Label Sub-TLV 142 The SID/Label Sub-TLV appears in multiple TLVs or Sub-TLVs defined 143 later in this document. It is used to advertise the SID or label 144 associated with a prefix or adjacency. The SID/Label TLV has 145 following format: 147 0 1 2 3 148 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 1 149 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 150 | Type | Length | 151 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 152 | SID/Label (variable) | 153 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 155 where: 157 Type: TBD, suggested value 3 159 Length: variable, 3 or 4 bytes 161 SID/Label: if length is set to 3, then the 20 rightmost bits 162 represent a label. If length is set to 4, then the value 163 represents a 32 bit SID. 165 The receiving router MUST ignore the SID/Label Sub-TLV if the 166 length is other then 3 or 4. 168 3. Segment Routing Capabilities 170 Segment Routing requires some additional capabilities of the router 171 to be advertised to other routers in the area. 173 These SR capabilities are advertised in OSPFv3 Router Information LSA 174 (defined in [RFC4970]). 176 3.1. SR-Algorithm TLV 178 The SR-Algorithm TLV is a TLV of the OSPFv3 Router Information LSA 179 (defined in [RFC4970]). 181 The SR-Algorithm TLV is optional. It MAY only be advertised once in 182 the OSPFv3 Router Information LSA. If the SID/Label Range TLV, as 183 defined in Section 3.2, is advertised, then the SR-Algorithm TLV MUST 184 also be advertised. If the SR-Algorithm TLV is not advertised by the 185 node, such node is considered as not being segment routing capable. 187 An OSPFv3 router may use various algorithms when calculating 188 reachability to other nodes in area or to prefixes attached to these 189 nodes. Examples of these algorithms are metric based Shortest Path 190 First (SPF), various sorts of Constrained SPF, etc. The SR-Algorithm 191 TLV allows a router to advertise the algorithms that the router is 192 currently using to other routers in an area. The SR-Algorithm TLV 193 has following structure: 195 0 1 2 3 196 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 1 197 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 198 | Type | Length | 199 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 200 | Algorithm 1 | Algorithm... | Algorithm n | | 201 +- -+ 202 | | 203 + + 205 where: 207 Type: TBD, suggested value 8 209 Length: variable 211 Algorithm: Single octet identifying the algorithm. The following 212 value has been defined: 214 0: Shortest Path First (SPF) algorithm based on link metric. 215 This is the standard shortest path algorithm as computed by the 216 OSPF protocol. Consistent with the deployed practice for link- 217 state protocols, Algorithm 0 permits any node to overwrite the 218 SPF path with a different path based on its local policy. If 219 the SR-Algorithm Sub-TLV is advertised, Algorithm 0 MUST be 220 included. 222 1: Strict Shortest Path First (SPF) algorithm based on link 223 metric. The algorithm is identical to Algorithm 0 but 224 Algorithm 1 requires that all nodes along the path will honor 225 the SPF routing decision. Local policy at the node claiming 226 the support of Algorithm 1 MUST NOT alter the forwarding 227 decision computed by Algorithm 1. 229 When multiple SR-Algorithm sub-TLVs are received from a given router 230 the receiver SHOULD use the first occurrence of the sub-TLV in the 231 OSPFv3 Router Information LSA. If the SR-Algorithm sub-TLV appears 232 in multiple OSPFv3 Router Information LSAs that have different 233 flooding scopes, the SR-Algorithm sub-TLV in the OSPFv3 Router 234 Information LSA with the lowest flooding scope SHOULD be used. If 235 the SR-Algorithm sub-TLV appears in multiple OSPFv3 Router 236 Information LSAs that have the same flooding scope, the SR-Algorithm 237 sub-TLV in the OSPFv3 Router Information LSA with the numerically 238 smallest Instance ID SHOULD be used and subsequent instances of the 239 SR-Algorithm sub-TLV SHOULD be ignored. 241 The RI LSA can be advertised at any of the defined flooding scopes 242 (link, area, or autonomous system (AS)). For the purpose of the SR- 243 Algorithm TLV propagation, area scope flooding is required. 245 3.2. SID/Label Range TLV 247 The SID/Label Range TLV is a TLV of the OSPFv3 Router Information LSA 248 (defined in [RFC4970]). 250 The SID/Label Sub-TLV MAY appear multiple times and has following 251 format: 253 0 1 2 3 254 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 255 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 256 | Type | Length | 257 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 258 | Range Size | Reserved | 259 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 260 | Sub-TLVs (variable) | 261 +- -+ 262 | | 263 + + 265 where: 267 Type: TBD, suggested value 9 269 Length: variable 271 Range Size: 3 octets of SID/label range 273 Initially, the only supported Sub-TLV is the SID/Label TLV as defined 274 in Section 2.1. The SID/Label advertised in the SID/Label TLV 275 represents the first SID/Label in the advertised range. 277 Multiple occurrence of the SID/Label Range TLV MAY be advertised, in 278 order to advertise multiple ranges. In such case: 280 o The originating router MUST encode each range into a different 281 SID/Label Range TLV. 283 o The originating router decides the order in which the set of SID/ 284 Label Range TLVs are advertised in the OSPFv3 Router Information 285 LSA. The originating router MUST ensure the order is same after a 286 graceful restart (using checkpointing, non-volatile storage or any 287 other mechanism) in order to assure the SID/label range and SID 288 index correspondence is preserved across graceful restarts. 290 o The receiving router must adhere to the order in which the ranges 291 are advertised when calculating a SID/label from the SID index. 293 o A router not supporting multiple occurrences of the SID/Label 294 Range TLV MUST use first advertised SID/Label Range TLV. 296 The following example illustrates the advertisement of multiple 297 ranges: 299 The originating router advertises the following ranges: 300 Range 1: [100, 199] 301 Range 2: [1000, 1099] 302 Range 3: [500, 599] 304 The receiving routers concatenate the ranges and build the Segment Routing Global Block 305 (SRGB) is as follows: 307 SRGB = [100, 199] 308 [1000, 1099] 309 [500, 599] 311 The indexes span multiple ranges: 313 index=0 means label 100 314 ... 315 index 99 means label 199 316 index 100 means label 1000 317 index 199 means label 1099 318 ... 319 index 200 means label 500 320 ... 322 The RI LSA can be advertised at any of the defined flooding scopes 323 (link, area, or autonomous system (AS)). For the purpose of the SID/ 324 Label Range TLV propagation, area scope flooding is required. 326 3.3. SR Local Block Sub-TLV 328 The SR Local Block (SRLB) Sub-TLV contains the range of labels the 329 node has reserved for local SIDs. Local SIDs are used, e.g., for 330 Adjacency-SIDs, and may also be allocated by other components than 331 OSPF protocol. As an example, an application or a controller may 332 instruct the router to allocate a specific local SID. Therefore, in 333 order for such applications or controllers to know what are the local 334 SIDs available in the router, it is required that the router 335 advertises its SRLB. The SRLB Sub-TLV is used for that purpose. 337 The SR Local Block (SRLB) Sub-TLV is a top-level TLV of the OSPFv3 338 Router Information Opaque LSA (defined in [RFC7770]). 340 The SR Local Block Sub-TLV MAY only be advertised once in the OSPFv3 341 Router Information Opaque LSA and has the following format: 343 0 1 2 3 344 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 1 345 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 346 | Type | Length | 347 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 348 | Range Size | Reserved | 349 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 350 | Sub-TLVs (variable) | 351 +- -+ 352 | | 353 + + 355 where: 357 Type: TBD, suggested value 12 359 Length: variable 361 Range Size: 3 octets of the SID/label range. MUST be higher then 362 0. 364 Initially, the only supported Sub-TLV is the SID/Label TLV as defined 365 in Section 2.1. The SID/Label advertised in the SID/Label TLV 366 represents the first SID/Label in the advertised range. 368 When multiple SRLB sub-TLVs are received from a given router the 369 behavior of the receiving system is undefined. 371 When multiple SRLB sub-TLVs are received from a given router the 372 receiver SHOULD use the first occurrence of the sub-TLV in the OSPFv3 373 Router Information LSA. If the SRLB sub-TLV appears in multiple 374 OSPFv3 Router Information LSAs that have different flooding scopes, 375 the SRLB sub-TLV in the OSPFv3 Router Information LSA with the lowest 376 flooding scope SHOULD be used. If the SRLB sub-TLV appears in 377 multiple OSPFv3 Router Information LSAs that have the same flooding 378 scope, the SRLB sub-TLV in the OSPFv3 Router Information LSA with the 379 numerically smallest Instance ID SHOULD be used and subsequent 380 instances of the SRLB sub-TLV SHOULD be ignored. 382 Each time a SID from the SRLB is allocated, it SHOULD also be 383 reported to all components (e.g.: controller or applications) in 384 order for these components to have an up-to-date view of the current 385 SRLB allocation. This is required to avoid collision between 386 allocation instructions. 388 Within the context of OSPFv3, the reporting of local SIDs is done 389 through OSPF Sub-TLVs such as the Adjacency-SID (Section 7). 390 However, the reporting of allocated local SIDs may also be done 391 through other means and protocols which mechanisms are outside the 392 scope of this document. 394 A router advertising the SRLB TLV may also have other label ranges, 395 outside of the SRLB, used for its local allocation purposes which are 396 NOT advertised in the SRLB. For example, it is possible that an 397 Adjacency-SID is allocated using a local label that is not part of 398 the SRLB. 400 The OSPFv3 RI LSA can be advertised at any of the defined flooding 401 scopes (link, area, or autonomous system (AS)). For the purpose of 402 SR Local Block Sub-TLV TLV advertisement, area scope flooding is 403 required. 405 3.4. SRMS Preference Sub-TLV 407 The Segment Routing Mapping Server (SRMS) Preference sub-TLV is used 408 to advertise a preference associated with the node that acts as a SR 409 Mapping Server. SRMS preference is defined in 410 [I-D.ietf-spring-conflict-resolution]. 412 The SRMS Preference Sub-TLV is a top-level TLV of the OSPFv3 Router 413 Information Opaque LSA (defined in [RFC7770]). 415 The SRMS Preference Sub-TLV MAY only be advertised once in the OSPFv3 416 Router Information Opaque LSA and has the following format: 418 0 1 2 3 419 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 1 420 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 421 | Type | Length | 422 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 423 | Preference | Reserved | 424 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 426 where: 428 Type: TBD, suggested value 13 430 Length: 4 octets 432 Preference: 1 octet. SRMS preference value from 0 to 255. 434 When multiple SRMS Preference sub-TLVs are received from a given 435 router the receiver SHOULD use the first occurrence of the sub-TLV in 436 the OSPFv3 Router Information LSA. If the SRMS Preference sub-TLV 437 appears in multiple OSPFv3 Router Information LSAs that have 438 different flooding scopes, the SRLB sub-TLV in the OSPFv3 Router 439 Information LSA with the lowest flooding scope SHOULD be used. If 440 the SRMS Preference sub-TLV appears in multiple OSPFv3 Router 441 Information LSAs that have the same flooding scope, the SRMS 442 Preference sub-TLV in the OSPFv3 Router Information LSA with the 443 numerically smallest Instance ID SHOULD be used and subsequent 444 instances of the SRMS Preference sub-TLV SHOULD be ignored. 446 The OSPFv3 RI LSA can be advertised at any of the defined flooding 447 scopes (link, area, or autonomous system (AS)). For the purpose of 448 the SRMS Preference Sub-TLV advertisement, AS scope flooding is 449 required. If the SRMS advertisements from the SRMS server are only 450 used inside the area to which the SRMS server is attached, area scope 451 flooding may be used. 453 3.5. SR-Forwarding Capabilities 455 OSPFv3 router supporting Segment Routing needs to advertise its SR 456 data-plane capabilities. Data-plane capabilities are advertised in 457 OSPF Router Informational Capabilities TLV, which is defined in 458 section 2.3 of RFC 4970 [RFC4970]. 460 Two new bits are allocated in the OSPF Router Informational 461 Capability Bits as follows: 463 Bit-6 - MPLS IPv6 flag. If set, then the router is capable of 464 processing SR MPLS encapsulated IPv6 packets on all interfaces. 466 Bit-7 - If set, then the router is capable of processing the IPv6 467 Segment Routing Header on all interfaces as defined in 468 [I-D.previdi-6man-segment-routing-header]. 470 For the purpose of the SR-Forwarding Capabilities propagation, area 471 scope flooding is required. 473 4. OSPFv3 Extended Prefix Range TLV 475 In some cases it is useful to advertise attributes for a range of 476 prefixes. Segment Routing Mapping Server, which is described in 477 [I-D.filsfils-spring-segment-routing-ldp-interop], is an example 478 where we need a single advertisement to advertise SIDs for multiple 479 prefixes from a contiguous address range. The OSPFv3 Extended Prefix 480 Range TLV is defined for this purpose. 482 The OSPFv3 Extended Prefix Range TLV is a new top level TLV of the 483 following LSAs defined in [I-D.ietf-ospf-ospfv3-lsa-extend]: 485 E-Intra-Area-Prefix-LSA 487 E-Inter-Area-Prefix-LSA 489 E-AS-External-LSA 491 E-Type-7-LSA 493 Multiple OSPFv3 Extended Prefix Range TLVs MAY be advertised in these 494 extended LSAs. The OSPFv3 Extended Prefix Range TLV has the 495 following format: 497 0 1 2 3 498 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 1 499 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 500 | Type | Length | 501 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 502 | Prefix Length | AF | Range Size | 503 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 504 | Flags | Reserved | 505 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 506 | Address Prefix (variable) | 507 | ... | 508 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 509 | Sub-TLVs (variable) | 510 +- -+ 511 | | 513 where: 515 Type: TBD, suggested value 9. 517 Length: variable 519 Prefix length: length of the prefix 521 AF: 0 - IPv6 unicast 523 Range size: represents the number of prefixes that are covered by 524 the advertisement. The Range Size MUST NOT exceed the number of 525 prefixes that could be satisfied by the prefix length without 526 including addresses from other than the IPv6 unicast address 527 class. 529 Flags: 1 octet field. The following flags are defined: 531 0 1 2 3 4 5 6 7 532 +--+--+--+--+--+--+--+--+ 533 |IA| | | | | | | | 534 +--+--+--+--+--+--+--+--+ 536 where: 538 IA-Flag: Inter-Area flag. If set, advertisement is of inter- 539 area type. ABR that is advertising the OSPF Extended Prefix 540 Range TLV between areas MUST set this bit. 542 This bit is used to prevent redundant flooding of Prefix Range 543 TLVs between areas as follows: 545 An ABR always prefers intra-area Prefix Range advertisement 546 over inter-area one. 548 An ABR does not consider inter-area Prefix Range 549 advertisements coming from non backbone area. 551 An ABR propagates inter-area Prefix Range advertisement from 552 backbone area to connected non backbone areas only if such 553 advertisement is considered to be the best one. 555 Address Prefix: the prefix, encoded as an even multiple of 32-bit 556 words, padded with zeroed bits as necessary. This encoding 557 consumes ((PrefixLength + 31) / 32) 32-bit words. The Address 558 Prefix represents the first prefix in the prefix range. 560 5. Prefix SID Sub-TLV 562 The Prefix SID Sub-TLV is a Sub-TLV of the following OSPFv3 TLVs as 563 defined in [I-D.ietf-ospf-ospfv3-lsa-extend] and in Section 4: 565 Intra-Area Prefix TLV 567 Inter-Area Prefix TLV 569 External Prefix TLV 571 OSPFv3 Extended Prefix Range TLV 573 It MAY appear more than once in the parent TLV and has the following 574 format: 576 0 1 2 3 577 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 1 578 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 579 | Type | Length | 580 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 581 | Flags | Algorithm | Reserved | 582 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 583 | SID/Index/Label (variable) | 584 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 586 where: 588 Type: TBD, suggested value 4. 590 Length: variable 592 Flags: 1 octet field. The following flags are defined: 594 0 1 2 3 4 5 6 7 595 +--+--+--+--+--+--+--+--+ 596 | |NP|M |E |V |L | | | 597 +--+--+--+--+--+--+--+--+ 599 where: 601 NP-Flag: No-PHP flag. If set, then the penultimate hop MUST 602 NOT pop the Prefix-SID before delivering the packet to the node 603 that advertised the Prefix-SID. 605 M-Flag: Mapping Server Flag. If set, the SID is advertised 606 from the Segment Routing Mapping Server functionality as 607 described in [I-D.filsfils-spring-segment-routing-ldp-interop]. 609 E-Flag: Explicit-Null Flag. If set, any upstream neighbor of 610 the Prefix-SID originator MUST replace the Prefix-SID with a 611 Prefix-SID having an Explicit-NULL value (0 for IPv4) before 612 forwarding the packet. 614 The V-Flag: Value/Index Flag. If set, then the Prefix-SID 615 carries an absolute value. If not set, then the Prefix-SID 616 carries an index. 618 The L-Flag: Local/Global Flag. If set, then the value/index 619 carried by the Prefix-SID has local significance. If not set, 620 then the value/index carried by this Sub-TLV has global 621 significance. 623 Other bits: Reserved. These MUST be zero when sent and are 624 ignored when received. 626 Algorithm: one octet identifying the algorithm the Prefix-SID is 627 associated with as defined in Section 3.1. 629 A router receiving a Prefix-SID from a remote node and with an 630 algorithm value that such remote node has not advertised in the 631 SR-Algorithm sub-TLV (Section 3.1) MUST ignore the Prefix-SID sub- 632 TLV. 634 SID/Index/Label: label or index value depending on the V-bit 635 setting. 637 Examples: 639 A 32 bit global index defining the offset in the SID/Label 640 space advertised by this router - in this case the V and L 641 flags MUST NOT be set. 643 A 24 bit local label where the 20 rightmost bits are used 644 for encoding the label value - in this case the V and L 645 flags MUST be set. 647 If multiple Prefix-SIDs are advertised for the same prefix, the 648 receiving router MUST use the first encoded SID and MAY use the 649 subsequent SIDs. 651 When propagating Prefix-SIDs between areas, if multiple prefix-SIDs 652 are advertised for a prefix, an implementation SHOULD preserve the 653 original order when advertising prefix-SIDs to other areas. This 654 allows implementations that only support a single Prefix-SID to have 655 a consistent view across areas. 657 When calculating the outgoing label for the prefix, the router MUST 658 take into account E and P flags advertised by the next-hop router, if 659 next-hop router advertised the SID for the prefix. This MUST be done 660 regardless of whether the next-hop router contributes to the best 661 path to the prefix. 663 The NP-Flag (No-PHP) MUST be set for Prefix-SIDs allocated to inter- 664 area prefixes that are originated by the ABR based on intra-area or 665 inter-area reachability between areas. When the inter-area prefix is 666 generated based on a prefix which is directly attached to the ABR, 667 NP-Flag SHOULD NOT be set 668 The NP-Flag (No-PHP) MUST be set on the Prefix-SIDs allocated to 669 redistributed prefixes, unless the redistributed prefix is directly 670 attached to ASBR, in which case the NP-Flag SHOULD NOT be set. 672 If the NP-Flag is not set then any upstream neighbor of the Prefix- 673 SID originator MUST pop the Prefix-SID. This is equivalent to the 674 penultimate hop popping mechanism used in the MPLS dataplane. In 675 such case, MPLS EXP bits of the Prefix-SID are not preserved for the 676 final destination (the Prefix-SID being removed). If the NP-Flag is 677 clear then the received E-flag is ignored. 679 If the NP-Flag is set then: 681 If the E-flag is not set then any upstream neighbor of the Prefix- 682 SID originator MUST keep the Prefix-SID on top of the stack. This 683 is useful when the originator of the Prefix-SID must stitch the 684 incoming packet into a continuing MPLS LSP to the final 685 destination. This could occur at an inter-area border router 686 (prefix propagation from one area to another) or at an inter- 687 domain border router (prefix propagation from one domain to 688 another). 690 If the E-flag is set then any upstream neighbor of the Prefix-SID 691 originator MUST replace the Prefix-SID with a Prefix-SID having an 692 Explicit-NULL value. This is useful, e.g., when the originator of 693 the Prefix-SID is the final destination for the related prefix and 694 the originator wishes to receive the packet with the original EXP 695 bits. 697 When M-Flag is set, NP-flag and E-flag MUST be ignored at reception. 699 As the Mapping Server does not specify the originator of a prefix 700 advertisement it is not possible to determine PHP behavior solely 701 based on the Mapping Server advertisement. However, PHP behavior may 702 safely be done in following cases: 704 Prefix is of intra-area type and the downstream neighbor is the 705 originator of the prefix. 707 Prefix is of inter-area type and downstream neighbor is an ABR, 708 which is advertising the prefix reachability and is setting LA-bit 709 in the Prefix Options as described in section 3.1 of 710 [I-D.ietf-ospf-ospfv3-lsa-extend]. 712 Prefix is of external type and downstream neighbor is an ASBR, 713 which is advertising the prefix reachability and is setting LA-bit 714 in the Prefix Options as described in section 3.1 of 715 [I-D.ietf-ospf-ospfv3-lsa-extend]. 717 When a Prefix-SID is advertised in an Extended Prefix Range TLV, then 718 the value advertised in Prefix SID Sub-TLV is interpreted as a 719 starting SID value. 721 Example 1: if the following router addresses (loopback addresses) 722 need to be mapped into the corresponding Prefix SID indexes: 724 Router-A: 192::1/128, Prefix-SID: Index 1 725 Router-B: 192::2/128, Prefix-SID: Index 2 726 Router-C: 192::3/128, Prefix-SID: Index 3 727 Router-D: 192::4/128, Prefix-SID: Index 4 729 then the Address Prefix field in the OSPFv3 Extended Prefix Range TLV 730 is set to 192::1, Prefix Length would be set to 128, Range Size would 731 be set to 4 and the Index value in the Prefix-SID Sub-TLV would be 732 set to 1. 734 Example 2: If the following prefixes need to be mapped into the 735 corresponding Prefix-SID indexes: 737 10:1:1::0/120, Prefix-SID: Index 51 738 10:1:1::100/120, Prefix-SID: Index 52 739 10:1:1::200/120, Prefix-SID: Index 53 740 10:1:1::300/120, Prefix-SID: Index 54 741 10:1:1::400/120, Prefix-SID: Index 55 742 10:1:1::500/120, Prefix-SID: Index 56 743 10:1:1::600/120, Prefix-SID: Index 57 745 then the Address Prefix field in the OSPFv3 Extended Prefix Range TLV 746 is set to 10:1:1::0, Prefix Length would be set to 120, Range Size 747 would be set to 7 and the Index value in the Prefix-SID Sub-TLV would 748 be set to 51. 750 6. SID/Label Binding Sub-TLV 752 The SID/Label Binding Sub-TLV is used to advertise SID/Label mapping 753 for a path to the prefix. 755 The SID/Label Binding Sub-TLV MAY be originated by any router in an 756 OSPFv3 domain. The router may advertise a SID/Label binding to a FEC 757 along with at least a single 'nexthop style' anchor. The protocol 758 supports more than one 'nexthop style' anchor to be attached to a 759 SID/Label binding, which results into a simple path description 760 language. In analogy to RSVP the terminology for this is called an 761 'Explicit Route Object' (ERO). Since ERO style path notation allows 762 anchoring SID/label bindings to both link and node IP addresses, any 763 Label Switched Path (LSP) can be described. Furthermore, SID/Label 764 Bindings from external protocols can also be re-advertised. 766 The SID/Label Binding Sub-TLV may be used for advertising SID/Label 767 Bindings and their associated Primary and Backup paths. In one 768 single TLV, either a primary ERO Path, backup ERO Path, or both are 769 advertised. If a router wants to advertise multiple parallel paths, 770 then it can generate several TLVs for the same Prefix/FEC. Each 771 occurrence of a Binding TLV for a given FEC Prefix will add a new 772 path. 774 SID/Label Binding Sub-TLV is a Sub-TLV of the following OSPFv3 TLVs, 775 as defined in [I-D.ietf-ospf-ospfv3-lsa-extend] and in Section 4: 777 Intra-Area Prefix TLV 779 Inter-Area Prefix TLV 781 External Prefix TLV 783 OSPFv3 Extended Prefix Range TLV 785 Multiple SID/Label Binding Sub-TLVs can be present in these TLVs. 786 The SID/Label Binding Sub-TLV has following format: 788 0 1 2 3 789 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 1 790 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 791 | Type | Length | 792 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 793 | Flags | Weight | Reserved | 794 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 795 | Sub-TLVs (variable) | 796 +- -+ 797 | | 799 where: 801 Type: TBD, suggested value 7 803 Length: variable 805 Flags: 1 octet field of following flags: 807 0 1 2 3 4 5 6 7 808 +-+-+-+-+-+-+-+-+ 809 |M| | 810 +-+-+-+-+-+-+-+-+ 812 where: 814 M-bit - When the bit is set the binding represents the 815 mirroring context as defined in 816 [I-D.minto-rsvp-lsp-egress-fast-protection]. 818 Weight: weight used for load-balancing purposes. The use of the 819 weight is defined in section 3.5.1 of 820 [I-D.ietf-spring-segment-routing]. 822 SID/Label Binding Sub-TLV currently supports following Sub-TLVs: 824 SID/Label Sub-TLV as described in Section 2.1. This Sub-TLV MUST 825 appear in the SID/Label Binding Sub-TLV and it MUST only appear 826 once. 828 ERO Metric Sub-TLV as defined in Section 6.1. 830 ERO Sub-TLVs as defined in Section 6.2. 832 6.1. ERO Metric Sub-TLV 834 The ERO Metric Sub-TLV is a Sub-TLV of the SID/Label Binding Sub-TLV. 836 The ERO Metric Sub-TLV advertises the cost of an ERO path. It is 837 used to compare the cost of a given source/destination path. A 838 router SHOULD advertise the ERO Metric Sub-TLV in an advertised ERO 839 TLV. The cost of the ERO Metric Sub-TLV SHOULD be set to the 840 cumulative IGP or TE path cost of the advertised ERO. Since 841 manipulation of the Metric field may attract or repel traffic to and 842 from the advertised segment, it MAY be manually overridden. 844 0 1 2 3 845 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 1 846 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 847 | Type | Length | 848 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 849 | Metric (4 octets) | 850 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 852 ERO Metric Sub-TLV format 854 where: 856 Type: TBD, suggested value 8 858 Length: Always 4 860 Metric: A 4 octet metric representing the aggregate IGP or TE path 861 cost. 863 6.2. ERO Sub-TLVs 865 All 'ERO' information represents an ordered set which describes the 866 segments of a path. The first ERO Sub-TLV describes the first 867 segment of a path. Similiarly, the last ERO Sub-TLV describes the 868 segment closest to the egress point. If a router extends or stitches 869 a path, it MUST prepend the new segment's path information to the ERO 870 list. This applies equally to advertised backup EROs. 872 All ERO Sub-TLVs must immediately follow the (SID)/Label Sub-TLV. 874 All Backup ERO Sub-TLVs must immediately follow the last ERO Sub-TLV. 876 6.2.1. IPv4 ERO Sub-TLV 878 IPv4 ERO Sub-TLV is a Sub-TLV of the SID/Label Binding Sub-TLV. 880 The IPv4 ERO Sub-TLV describes a path segment using IPv4 Address 881 style of encoding. Its semantics have been borrowed from [RFC3209]. 883 0 1 2 3 884 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 1 885 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 886 | Type | Length | 887 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 888 | Flags | Reserved | 889 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 890 | IPv4 Address (4 octets) | 891 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 893 IPv4 ERO Sub-TLV format 895 where: 897 Type: TBD, suggested value 9 899 Length: 8 bytes 901 Flags: 1 octet field of following flags: 903 0 1 2 3 4 5 6 7 904 +-+-+-+-+-+-+-+-+ 905 |L| | 906 +-+-+-+-+-+-+-+-+ 908 where: 910 L-bit - If the L-bit is set, then the segment path is 911 designated as 'loose'. Otherwise, the segment path is 912 designated as 'strict'. 914 IPv4 Address - the address of the explicit route hop. 916 6.2.2. IPv6 ERO Sub-TLV 918 IPv6 ERO Sub-TLV is a Sub-TLV of the SID/Label Binding Sub-TLV. 920 The IPv6 ERO Sub-TLV (Type TBA) describes a path segment using IPv6 921 Address style of encoding. Its semantics have been borrowed from 922 [RFC3209]. 924 0 1 2 3 925 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 1 926 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 927 | Type | Length | 928 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 929 | Flags | Reserved | 930 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 931 | | 932 +- -+ 933 | | 934 +- IPv6 Address -+ 935 | | 936 +- -+ 937 | | 938 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 940 IPv6 ERO Sub-TLV format 942 where: 944 Type: TBD, suggested value 10 946 Length: 8 bytes 948 Flags: 1 octet field of following flags: 950 0 1 2 3 4 5 6 7 951 +-+-+-+-+-+-+-+-+ 952 |L| | 953 +-+-+-+-+-+-+-+-+ 955 where: 957 L-bit - If the L-bit is set, then the segment path is 958 designated as 'loose'. Otherwise, the segment path is 959 designated as 'strict'. 961 IPv6 Address - the address of the explicit route hop. 963 6.2.3. Unnumbered Interface ID ERO Sub-TLV 965 The Unnumbered Interface ID ERO Sub-TLV is a Sub-TLV of the SID/Label 966 Binding Sub-TLV. 968 The appearance and semantics of the 'Unnumbered Interface ID' have 969 been borrowed from [RFC3477]. 971 The Unnumbered Interface-ID ERO Sub-TLV describes a path segment that 972 spans over an unnumbered interface. Unnumbered interfaces are 973 referenced using the interface index. Interface indices are assigned 974 local to the router and therefore not unique within a domain. All 975 elements in an ERO path need to be unique within a domain and hence 976 need to be disambiguated using a domain unique Router-ID. 978 0 1 2 3 979 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 1 980 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 981 | Type | Length | 982 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 983 | Flags | Reserved | 984 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 985 | Router ID | 986 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 987 | Interface ID | 988 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 990 where: 992 Unnumbered Interface ID ERO Sub-TLV format 994 Type: TBD, suggested value 11 996 Length: 12 bytes 998 Flags: 1 octet field of following flags: 1000 0 1 2 3 4 5 6 7 1001 +-+-+-+-+-+-+-+-+ 1002 |L| | 1003 +-+-+-+-+-+-+-+-+ 1005 where: 1007 L-bit - If the L-bit is set, then the segment path is 1008 designated as 'loose'. Otherwise, the segment path is 1009 designated as 'strict'. 1011 Router-ID: Router-ID of the next-hop. 1013 Interface ID: is the identifier assigned to the link by the router 1014 specified by the Router-ID. 1016 6.2.4. IPv4 Backup ERO Sub-TLV 1018 IPv4 Prefix Backup ERO Sub-TLV is a Sub-TLV of the SID/Label Binding 1019 Sub-TLV. 1021 The IPv4 Backup ERO Sub-TLV describes a path segment using IPv4 1022 Address style of encoding. Its semantics have been borrowed from 1023 [RFC3209]. 1025 0 1 2 3 1026 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 1027 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1028 | Type | Length | 1029 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1030 | Flags | Reserved | 1031 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1032 | IPv4 Address (4 octets) | 1033 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1035 IPv4 Backup ERO Sub-TLV format 1037 where: 1039 Type: TBD, suggested value 12 1041 Length: 8 bytes 1043 Flags: 1 octet field of following flags: 1045 0 1 2 3 4 5 6 7 1046 +-+-+-+-+-+-+-+-+ 1047 |L| | 1048 +-+-+-+-+-+-+-+-+ 1050 where: 1052 L-bit - If the L-bit is set, then the segment path is 1053 designated as 'loose'. Otherwise, the segment path is 1054 designated as 'strict'.' 1056 IPv4 Address - the address of the explicit route hop. 1058 6.2.5. IPv6 Backup ERO Sub-TLV 1060 The IPv6 ERO Sub-TLV is a Sub-TLV of the SID/Label Binding Sub-TLV. 1062 The IPv6 Backup ERO Sub-TLV describes a Backup path segment using 1063 IPv6 Address style of encoding. Its appearance and semantics have 1064 been borrowed from [RFC3209]. 1066 The 'L' bit in the Flags is a one-bit attribute. If the L bit is 1067 set, then the value of the attribute is 'loose.' Otherwise, the 1068 value of the attribute is 'strict.' 1070 0 1 2 3 1071 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 1072 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1073 | Type | Length | 1074 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1075 | Flags | Reserved | 1076 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1077 | | 1078 +- -+ 1079 | | 1080 +- IPv6 Address -+ 1081 | | 1082 +- -+ 1083 | | 1084 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1086 IPv6 Backup ERO Sub-TLV format 1088 where: 1090 Type: TBD, suggested value 13 1092 Length: 8 bytes 1093 Flags: 1 octet field of following flags: 1095 0 1 2 3 4 5 6 7 1096 +-+-+-+-+-+-+-+-+ 1097 |L| | 1098 +-+-+-+-+-+-+-+-+ 1100 where: 1102 L-bit - If the L-bit is set, then the segment path is 1103 designated as 'loose'. Otherwise, the segment path is 1104 designated as 'strict'. 1106 IPv6 Address - the address of the explicit route hop. 1108 6.2.6. Unnumbered Interface ID Backup ERO Sub-TLV 1110 The Unnumbered Interface ID Backup Sub-TLV is a Sub-TLV of the SID/ 1111 Label Binding Sub-TLV. 1113 The appearance and semantics of the 'Unnumbered Interface ID' have 1114 been borrowed from [RFC3477]. 1116 The Unnumbered Interface-ID Backup ERO Sub-TLV describes a path 1117 segment that spans over an unnumbered interface. Unnumbered 1118 interfaces are referenced using the interface index. Interface 1119 indices are assigned local to the router and are therefore not unique 1120 within a domain. All elements in an ERO path need to be unique 1121 within a domain and hence need to be disambiguated with specification 1122 of the unique Router-ID. 1124 0 1 2 3 1125 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 1126 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1127 | Type | Length | 1128 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1129 | Flags | Reserved | 1130 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1131 | Router ID | 1132 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1133 | Interface ID | 1134 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1136 Unnumbered Interface ID Backup ERO Sub-TLV format 1138 where: 1140 Type: TBD, suggested value 14 1141 Length: 12 bytes 1143 Flags: 1 octet field of following flags: 1145 0 1 2 3 4 5 6 7 1146 +-+-+-+-+-+-+-+-+ 1147 |L| | 1148 +-+-+-+-+-+-+-+-+ 1150 where: 1152 L-bit - If the L-bit is set, then the segment path is 1153 designated as 'loose'. Otherwise, the segment path is 1154 designated as 'strict'. 1156 Router-ID: Router-ID of the next-hop. 1158 Interface ID: is the identifier assigned to the link by the router 1159 specified by the Router-ID. 1161 7. Adjacency Segment Identifier (Adj-SID) 1163 An Adjacency Segment Identifier (Adj-SID) represents a router 1164 adjacency in Segment Routing. 1166 7.1. Adj-SID Sub-TLV 1168 The extended OSPFv3 LSAs, as defined in 1169 [I-D.ietf-ospf-ospfv3-lsa-extend], are used to advertise prefix SID 1170 in OSPFv3 1172 The Adj-SID Sub-TLV is an optional Sub-TLV of the Router-Link TLV as 1173 defined in [I-D.ietf-ospf-ospfv3-lsa-extend]. It MAY appear multiple 1174 times in Router-Link TLV. Examples where more than one Adj-SID may 1175 be used per neighbor are described in section 4 of 1176 [I-D.filsfils-spring-segment-routing-use-cases]. The Adj-SID Sub-TLV 1177 has the following format: 1179 0 1 2 3 1180 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 1181 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1182 | Type | Length | 1183 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1184 | Flags | Weight | Reserved | 1185 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1186 | SID/Label/Index (variable) | 1187 +---------------------------------------------------------------+ 1189 where: 1191 Type: TBD, suggested value 5. 1193 Length: variable. 1195 Flags. 1 octet field of following flags: 1197 0 1 2 3 4 5 6 7 1198 +-+-+-+-+-+-+-+-+ 1199 |B|V|L|G|P| | 1200 +-+-+-+-+-+-+-+-+ 1202 where: 1204 B-Flag: Backup-flag. If set, the Adj-SID refers to an 1205 adjacency that is eligible for protection (e.g.: using IPFRR or 1206 MPLS-FRR) as described in section 3.5 of 1207 [I-D.ietf-spring-segment-routing]. 1209 The V-Flag: Value/Index Flag. If set, then the Adj-SID carries 1210 an absolute value. If not set, then the Adj-SID carries an 1211 index. 1213 The L-Flag: Local/Global Flag. If set, then the value/index 1214 carried by the Adj-SID has local significance. If not set, 1215 then the value/index carried by this Sub-TLV has global 1216 significance. 1218 The G-Flag. Group Flag. When set, the G-Flag indicates that 1219 the Adj-SID refers to a set of adjacencies (and therefore MAY 1220 be assigned to other adjacencies as well). 1222 P-Flag. Persistent flag. When set, the P-Flag indicates that 1223 the Adj-SID is persistently allocated, i.e., the Adj-SID value 1224 remains consistent across router restart and/or interface flap. 1226 Other bits: Reserved. These MUST be zero when sent and are 1227 ignored when received. 1229 Weight: weight used for load-balancing purposes. The use of the 1230 weight is defined in section 3.5.1 of 1231 [I-D.ietf-spring-segment-routing]. 1233 SID/Index/Label: label or index value depending on the V-bit 1234 setting. 1236 Examples: 1238 A 32 bit global index defining the offset in the SID/Label 1239 space advertised by this router - in this case the V and L 1240 flags MUST NOT be set. 1242 A 24 bit local label where the 20 rightmost bits are used 1243 for encoding the label value - in this case the V and L 1244 flags MUST be set. 1246 16 octet IPv6 address - in this case the V-flag MUST be set. 1247 The L-flag MUST NOT be set if the IPv6 address is globally 1248 unique. 1250 An SR capable router MAY allocate an Adj-SID for each of its 1251 adjacencies and set the B-Flag when the adjacency is eligible for 1252 protection by an FRR mechanism (IP or MPLS) as described in section 1253 3.5 of [I-D.ietf-spring-segment-routing]. 1255 An SR capable router MAY allocate more than one Adj-SID to an 1256 adjacency 1258 An SR capable router MAY allocate the same Adj-SID to different 1259 adjacencies 1261 When the P-flag is not set, the Adj-SID MAY be persistent. When the 1262 P-flag is set, the Adj-SID MUST be persistent. 1264 7.2. LAN Adj-SID Sub-TLV 1266 The LAN Adj-SID is an optional Sub-TLV of the Router-Link TLV. It 1267 MAY appear multiple times in the Router-Link TLV. It is used to 1268 advertise a SID/Label for an adjacency to a non-DR neighbor on a 1269 broadcast or NBMA network. 1271 0 1 2 3 1272 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 1273 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1274 | Type | Length | 1275 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1276 | Flags | Weight | Reserved | 1277 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1278 | Neighbor ID | 1279 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1280 | SID/Label/Index (variable) | 1281 +---------------------------------------------------------------+ 1283 where: 1285 Type: TBD, suggested value 6. 1287 Length: variable. 1289 Flags. 1 octet field of following flags: 1291 0 1 2 3 4 5 6 7 1292 +-+-+-+-+-+-+-+-+ 1293 |B|V|L|G|P| | 1294 +-+-+-+-+-+-+-+-+ 1296 where: 1298 B-Flag: Backup-flag: set if the LAN-Adj-SID refer to an 1299 adjacency that is eligible for protection (e.g.: using IPFRR or 1300 MPLS-FRR) as described in section 3.1 of 1301 [I-D.filsfils-spring-segment-routing-use-cases]. 1303 The V-Flag: Value/Index Flag. If set, then the LAN Adj-SID 1304 carries an absolute value. If not set, then the LAN Adj-SID 1305 carries an index. 1307 The L-Flag: Local/Global Flag. If set, then the value/index 1308 carried by the LAN Adj-SID has local significance. If not set, 1309 then the value/index carried by this subTLV has global 1310 significance. 1312 The G-Flag. Group Flag. When set, the G-Flag indicates that 1313 the LAN Adj-SID refers to a set of adjacencies (and therefore 1314 MAY be assigned to other adjacencies as well). 1316 P-Flag. Persistent flag. When set, the P-Flag indicates that 1317 the Adj-SID is persistently allocated, i.e., the Adj-SID value 1318 remains consistent across router restart and/or interface flap. 1320 Other bits: Reserved. These MUST be zero when sent and are 1321 ignored when received. 1323 Weight: weight used for load-balancing purposes. The use of the 1324 weight is defined in section 3.5.1 of 1325 [I-D.ietf-spring-segment-routing]. 1327 Neighbor ID: The Router ID of the neighbor for which the Adj-SID 1328 is advertised. 1330 SID/Index/Label: label or index value depending on the V-bit 1331 setting. 1333 Examples: 1335 A 32 bit global index defining the offset in the SID/Label 1336 space advertised by this router - in this case the V and L 1337 flags MUST NOT be set. 1339 A 24 bit local label where the 20 rightmost bits are used 1340 for encoding the label value - in this case the V and L 1341 flags MUST be set. 1343 16 octet IPv6 address - in this case the V-flag MUST be set. 1344 The L-flag MUST NOT be set if the IPv6 address is globally 1345 unique. 1347 When the P-flag is not set, the Adj-SID MAY be persistent. When 1348 the P-flag is set, the Adj-SID MUST be persistent. 1350 8. Elements of Procedure 1352 8.1. Intra-area Segment routing in OSPFv3 1354 An OSPFv3 router that supports segment routing MAY advertise Prefix- 1355 SIDs for any prefix that it is advertising reachability for (e.g., 1356 loopback IP address) as described in Section 5. 1358 If multiple routers advertise a Prefix-SID for the same prefix, then 1359 the Prefix-SID MUST be the same. This is required in order to allow 1360 traffic load-balancing when multiple equal cost paths to the 1361 destination exist in the network. 1363 The Prefix-SID can also be advertised by the SR Mapping Servers (as 1364 described in [I-D.filsfils-spring-segment-routing-ldp-interop]). The 1365 Mapping Server advertises Prefix-SID for remote prefixes that exist 1366 in the network. Multiple Mapping Servers can advertise Prefix-SID 1367 for the same prefix, in which case the same Prefix-SID MUST be 1368 advertised by all of them. The SR Mapping Server could use either 1369 area scope or autonomous system flooding scope when advertising 1370 Prefix SID for prefixes, based on the configuration of the SR Mapping 1371 Server. Depending on the flooding scope used, the SR Mapping Server 1372 chooses the LSA that will be used. If the area flooding scope is 1373 needed, E-Intra-Area-Prefix-LSA ([I-D.ietf-ospf-ospfv3-lsa-extend]) 1374 is used. If autonomous system flooding scope is needed, E-AS- 1375 External-LSA ([I-D.ietf-ospf-ospfv3-lsa-extend]) is used. 1377 When a Prefix-SID is advertised by the Mapping Server, which is 1378 indicated by the M-flag in the Prefix-SID Sub-TLV (Section 5), the 1379 route type as implied by the LSA type is ignored and the Prefix-SID 1380 is bound to the corresponding prefix independent of the route type. 1382 Advertisement of the Prefix-SID by the Mapping Server using Inter- 1383 Area Prefix TLV, External-Prefix TLV or Intra-Area-Prefix TLV 1384 ([I-D.ietf-ospf-ospfv3-lsa-extend]) does not itself contribute to the 1385 prefix reachability. The NU-bit MUST be set in the PrefixOptions 1386 field of the LSA which is used by the Mapping Server to advertise SID 1387 or SID range, which prevents the advertisement to contribute to 1388 prefix reachability. 1390 SR Mapping Server MUST use OSPF Extended Prefix Range TLV when 1391 advertising SIDs for prefixes. Prefixes of different route-types can 1392 be combined in a single OSPF Extended Prefix Range TLV advertised by 1393 the SR Mapping Server. 1395 Area scoped OSPF Extended Prefix Range TLV are propagated between 1396 areas. Similar to propagation of prefixes between areas, ABR only 1397 propagates the OSPF Extended Prefix Range TLV that it considers to be 1398 the best from the set it received. The rules used to pick the best 1399 OSPF Extended Prefix Range TLV is described in Section 4. 1401 When propagating OSPF Extended Prefix Range TLV between areas, ABR 1402 MUST set the IA-Flag, that is used to prevent redundant flooding of 1403 the OSPF Extended Prefix Range TLV between areas as described in 1404 Section 4. 1406 8.2. Inter-area Segment routing in OSPFv3 1408 In order to support SR in a multi-area environment, OSPFv3 must 1409 propagate Prefix-SID information between areas. The following 1410 procedure is used in order to propagate Prefix SIDs between areas. 1412 When an OSPFv3 ABR advertises a Inter-Area-Prefix-LSA from an intra- 1413 area prefix to all its connected areas, it will also include Prefix- 1414 SID Sub-TLV, as described in Section 5. The Prefix-SID value will be 1415 set as follows: 1417 The ABR will look at its best path to the prefix in the source 1418 area and find out the advertising router associated with the best 1419 path to that prefix. 1421 The ABR will then determine if such router advertised a Prefix-SID 1422 for the prefix and use it when advertising the Prefix-SID to other 1423 connected areas. 1425 If no Prefix-SID was advertised for the prefix in the source area 1426 by the router that contributes to the best path to the prefix, the 1427 originating ABR will use the Prefix-SID advertised by any other 1428 router when propagating Prefix-SID for the prefix to other areas. 1430 When an OSPFv3 ABR advertises Inter-Area-Prefix-LSA LSAs from an 1431 inter-area route to all its connected areas it will also include 1432 Prefix-SID Sub-TLV, as described in Section 5. The Prefix-SID value 1433 will be set as follows: 1435 The ABR will look at its best path to the prefix in the source 1436 area and find out the advertising router associated with the best 1437 path to that prefix. 1439 The ABR will then look if such router advertised a Prefix-SID for 1440 the prefix and use it when advertising the Prefix-SID to other 1441 connected areas. 1443 If no Prefix-SID was advertised for the prefix in the source area 1444 by the ABR that contributes to the best path to the prefix, the 1445 originating ABR will use the Prefix-SID advertised by any other 1446 router when propagating Prefix-SID for the prefix to other areas. 1448 8.3. SID for External Prefixes 1450 AS-External-LSAs are flooded domain wide. When an ASBR, which 1451 supports SR, generates E-AS-External-LSA, it should also include 1452 Prefix-SID Sub-TLV, as described in Section 5. The Prefix-SID value 1453 will be set to the SID that has been reserved for that prefix. 1455 When an NSSA ASBR translates an E-NSSA-LSA into an E-AS-External-LSA, 1456 it should also advertise the Prefix-SID for the prefix. The NSSA ABR 1457 determines its best path to the prefix advertised in the translated 1458 E-NSSA-LSA and finds the advertising router associated with that 1459 path. If the advertising router has advertised a Prefix-SID for the 1460 prefix, then the NSSA ABR uses it when advertising the Prefix-SID in 1461 the E-AS-External-LSA. Otherwise the Prefix-SID advertised by any 1462 other router will be used. 1464 8.4. Advertisement of Adj-SID 1466 The Adjacency Segment Routing Identifier (Adj-SID) is advertised 1467 using the Adj-SID Sub-TLV as described in Section 7. 1469 8.4.1. Advertisement of Adj-SID on Point-to-Point Links 1471 An Adj-SID MAY be advertised for any adjacency on p2p link that is in 1472 a state 2-Way or higher. If the adjacency on a p2p link transitions 1473 from the FULL state, then the Adj-SID for that adjacency MAY be 1474 removed from the area. If the adjacency transitions to a state lower 1475 then 2-Way, then the Adj-SID advertisement MUST be removed from the 1476 area. 1478 8.4.2. Adjacency SID on Broadcast or NBMA Interfaces 1480 Broadcast or NBMA networks in OSPFv3 are represented by a star 1481 topology where the Designated Router (DR) is the central point to 1482 which all other routers on the broadcast or NBMA network connect. As 1483 a result, routers on the broadcast or NBMA network advertise only 1484 their adjacency to the DR. Routers that do not act as DR do not form 1485 or advertise adjacencies with each other. They do, however, maintain 1486 a 2-Way adjacency state with each other and are directly reachable. 1488 When Segment Routing is used, each router on the broadcast or NBMA 1489 network MAY advertise the Adj-SID for its adjacency to the DR using 1490 Adj-SID Sub-TLV as described in Section 7.1. 1492 SR capable routers MAY also advertise an Adj-SID for other neighbors 1493 (e.g. BDR, DR-OTHER) on the broadcast or NBMA network using the LAN 1494 ADJ-SID Sub-TLV as described in Section 7.2. 1496 9. IANA Considerations 1498 This specification updates several existing OSPF registries. 1500 9.1. OSPF Router Information (RI) TLVs Registry 1502 o 8 (IANA Preallocated) - SR-Algorithm TLV 1504 o 9 (IANA Preallocated) - SID/Label Range TLV 1506 o 12 - SR Local Block Sub-TLV 1508 o 13 - SRMS Preference Sub-TLV 1510 9.2. OSPFv3 Extend-LSA TLV Registry 1512 Following values are allocated: 1514 o suggested value 9 - OSPF Extended Prefix Range TLV 1516 9.3. OSPFv3 Extend-LSA Sub-TLV registry 1518 o suggested value 3 - SID/Label Sub-TLV 1520 o suggested value 4 - Prefix SID Sub-TLV 1522 o suggested value 5 - Adj-SID Sub-TLV 1524 o suggested value 6 - LAN Adj-SID Sub-TLV 1526 o suggested value 7 - SID/Label Binding Sub-TLV 1528 o suggested value 8 - ERO Metric Sub-TLV 1530 o suggested value 9 - IPv4 ERO Sub-TLV 1532 o suggested value 10 - IPv6 ERO Sub-TLV 1534 o suggested value 11 - Unnumbered Interface ID ERO Sub-TLV 1536 o suggested value 12 - IPv4 Backup ERO Sub-TLV 1538 o suggested value 13 - IPv6 Backup ERO Sub-TLV 1540 o suggested value 14 - Unnumbered Interface ID Backup ERO Sub-TLV 1542 10. Security Considerations 1544 Implementations must assure that malformed permutations of the newly 1545 defined sub-TLvs do not result in errors which cause hard OSPFv3 1546 failures. 1548 11. Acknowledgements 1550 Thanks to Acee Lindem for the detail review of the draft, 1551 corrections, as well as discussion about details of the encoding. 1553 We would like to thank Anton Smirnov for his contribution. 1555 Many thanks to Yakov Rekhter, John Drake and Shraddha Hedge for their 1556 contribution on earlier definition of the "Binding / MPLS Label TLV". 1558 12. References 1560 12.1. Normative References 1562 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 1563 Requirement Levels", BCP 14, RFC 2119, 1564 DOI 10.17487/RFC2119, March 1997, 1565 . 1567 [RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V., 1568 and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP 1569 Tunnels", RFC 3209, DOI 10.17487/RFC3209, December 2001, 1570 . 1572 [RFC3477] Kompella, K. and Y. Rekhter, "Signalling Unnumbered Links 1573 in Resource ReSerVation Protocol - Traffic Engineering 1574 (RSVP-TE)", RFC 3477, DOI 10.17487/RFC3477, January 2003, 1575 . 1577 [RFC4970] Lindem, A., Ed., Shen, N., Vasseur, JP., Aggarwal, R., and 1578 S. Shaffer, "Extensions to OSPF for Advertising Optional 1579 Router Capabilities", RFC 4970, DOI 10.17487/RFC4970, July 1580 2007, . 1582 [RFC7770] Lindem, A., Ed., Shen, N., Vasseur, JP., Aggarwal, R., and 1583 S. Shaffer, "Extensions to OSPF for Advertising Optional 1584 Router Capabilities", RFC 7770, DOI 10.17487/RFC7770, 1585 February 2016, . 1587 12.2. Informative References 1589 [I-D.filsfils-spring-segment-routing-ldp-interop] 1590 Filsfils, C., Previdi, S., Bashandy, A., Decraene, B., 1591 Litkowski, S., Horneffer, M., Milojevic, I., Shakir, R., 1592 Ytti, S., Henderickx, W., Tantsura, J., and E. Crabbe, 1593 "Segment Routing interoperability with LDP", draft- 1594 filsfils-spring-segment-routing-ldp-interop-02 (work in 1595 progress), September 2014. 1597 [I-D.filsfils-spring-segment-routing-use-cases] 1598 Filsfils, C., Francois, P., Previdi, S., Decraene, B., 1599 Litkowski, S., Horneffer, M., Milojevic, I., Shakir, R., 1600 Ytti, S., Henderickx, W., Tantsura, J., Kini, S., and E. 1601 Crabbe, "Segment Routing Use Cases", draft-filsfils- 1602 spring-segment-routing-use-cases-01 (work in progress), 1603 October 2014. 1605 [I-D.ietf-ospf-ospfv3-lsa-extend] 1606 Lindem, A., Mirtorabi, S., Roy, A., and F. Baker, "OSPFv3 1607 LSA Extendibility", draft-ietf-ospf-ospfv3-lsa-extend-13 1608 (work in progress), October 2016. 1610 [I-D.ietf-spring-conflict-resolution] 1611 Ginsberg, L., Psenak, P., Previdi, S., and M. Pilka, 1612 "Segment Routing Conflict Resolution", draft-ietf-spring- 1613 conflict-resolution-01 (work in progress), June 2016. 1615 [I-D.ietf-spring-segment-routing] 1616 Filsfils, C., Previdi, S., Bashandy, A., Decraene, B., 1617 Litkowski, S., Horneffer, M., Shakir, R., Tantsura, J., 1618 and E. Crabbe, "Segment Routing Architecture", draft-ietf- 1619 spring-segment-routing-01 (work in progress), February 1620 2015. 1622 [I-D.minto-rsvp-lsp-egress-fast-protection] 1623 Jeganathan, J., Gredler, H., and Y. Shen, "RSVP-TE LSP 1624 egress fast-protection", draft-minto-rsvp-lsp-egress-fast- 1625 protection-03 (work in progress), November 2013. 1627 [I-D.previdi-6man-segment-routing-header] 1628 Previdi, S., Filsfils, C., Field, B., Leung, I., Linkova, 1629 J., Kosugi, T., Vyncke, E., and D. Lebrun, "IPv6 Segment 1630 Routing Header (SRH)", draft-previdi-6man-segment-routing- 1631 header-08 (work in progress), October 2015. 1633 Authors' Addresses 1635 Peter Psenak (editor) 1636 Cisco Systems, Inc. 1637 Apollo Business Center 1638 Mlynske nivy 43 1639 Bratislava 821 09 1640 Slovakia 1642 Email: ppsenak@cisco.com 1644 Stefano Previdi (editor) 1645 Cisco Systems, Inc. 1646 Via Del Serafico, 200 1647 Rome 00142 1648 Italy 1650 Email: sprevidi@cisco.com 1651 Clarence Filsfils 1652 Cisco Systems, Inc. 1653 Brussels 1654 Belgium 1656 Email: cfilsfil@cisco.com 1658 Hannes Gredler 1659 RtBrick Inc. 1660 Austria 1662 Email: hannes@rtbrick.com 1664 Rob Shakir 1665 Google, Inc. 1666 1600 Amphitheatre Parkway 1667 Mountain View, CA 94043 1668 US 1670 Email: robjs@google.com 1672 Wim Henderickx 1673 Nokia 1674 Copernicuslaan 50 1675 Antwerp 2018 1676 BE 1678 Email: wim.henderickx@nokia.com 1680 Jeff Tantsura 1681 Individual 1682 US 1684 Email: jefftant.ietf@gmail.com