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Summary: 0 errors (**), 0 flaws (~~), 2 warnings (==), 2 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group A. Lindem 3 Internet-Draft Ericsson 4 Intended status: Standards Track S. Mirtorabi 5 Expires: October 20, 2014 A. Roy 6 F. Baker 7 Cisco Systems 8 April 18, 2014 10 OSPFv3 LSA Extendibility 11 draft-ietf-ospf-ospfv3-lsa-extend-02.txt 13 Abstract 15 OSPFv3 requires functional extension beyond what can readily be done 16 with the fixed-format Link State Advertisement (LSA) as described in 17 RFC 5340. Without LSA extension, attributes associated with OSPFv3 18 links and advertised IPv6 prefixes must be advertised in separate 19 LSAs and correlated to the fixed-format LSAs. This document extends 20 the LSA format by encoding the existing OSPFv3 LSA information in 21 Type-Length-Value (TLV) tuples and allowing advertisement of 22 additional information with additional TLVs. Backward compatibility 23 mechanisms are also described. 25 Status of this Memo 27 This Internet-Draft is submitted in full conformance with the 28 provisions of BCP 78 and BCP 79. 30 Internet-Drafts are working documents of the Internet Engineering 31 Task Force (IETF). Note that other groups may also distribute 32 working documents as Internet-Drafts. The list of current Internet- 33 Drafts is at http://datatracker.ietf.org/drafts/current/. 35 Internet-Drafts are draft documents valid for a maximum of six months 36 and may be updated, replaced, or obsoleted by other documents at any 37 time. It is inappropriate to use Internet-Drafts as reference 38 material or to cite them other than as "work in progress." 40 This Internet-Draft will expire on October 20, 2014. 42 Copyright Notice 44 Copyright (c) 2014 IETF Trust and the persons identified as the 45 document authors. All rights reserved. 47 This document is subject to BCP 78 and the IETF Trust's Legal 48 Provisions Relating to IETF Documents 49 (http://trustee.ietf.org/license-info) in effect on the date of 50 publication of this document. Please review these documents 51 carefully, as they describe your rights and restrictions with respect 52 to this document. Code Components extracted from this document must 53 include Simplified BSD License text as described in Section 4.e of 54 the Trust Legal Provisions and are provided without warranty as 55 described in the Simplified BSD License. 57 This document may contain material from IETF Documents or IETF 58 Contributions published or made publicly available before November 59 10, 2008. The person(s) controlling the copyright in some of this 60 material may not have granted the IETF Trust the right to allow 61 modifications of such material outside the IETF Standards Process. 62 Without obtaining an adequate license from the person(s) controlling 63 the copyright in such materials, this document may not be modified 64 outside the IETF Standards Process, and derivative works of it may 65 not be created outside the IETF Standards Process, except to format 66 it for publication as an RFC or to translate it into languages other 67 than English. 69 Table of Contents 71 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 72 1.1. Requirements notation . . . . . . . . . . . . . . . . . . 4 73 1.2. Acknowledgments . . . . . . . . . . . . . . . . . . . . . 4 74 2. OSPFv3 Extended LSA Types . . . . . . . . . . . . . . . . . . 6 75 3. OSPFv3 Extended LSA TLVs . . . . . . . . . . . . . . . . . . . 7 76 3.1. Router-Link TLVs . . . . . . . . . . . . . . . . . . . . . 8 77 3.2. Attached-Routers TLV . . . . . . . . . . . . . . . . . . . 9 78 3.3. Inter-Area-Prefix TLV . . . . . . . . . . . . . . . . . . 10 79 3.4. Inter-Area-Router TLV . . . . . . . . . . . . . . . . . . 11 80 3.5. External-Prefix TLV . . . . . . . . . . . . . . . . . . . 12 81 3.6. Intra-Area-Prefix TLV . . . . . . . . . . . . . . . . . . 13 82 3.7. IPv6 Link-Local Address TLV . . . . . . . . . . . . . . . 14 83 3.8. IPv4 Link-Local Address TLV . . . . . . . . . . . . . . . 15 84 3.9. Forwarding-Address Sub-TLV . . . . . . . . . . . . . . . . 16 85 3.10. Route-Tag Sub-TLV . . . . . . . . . . . . . . . . . . . . 16 86 4. OSPFv3 Extended LSAs . . . . . . . . . . . . . . . . . . . . . 17 87 4.1. OSPFv3 E-Router-LSA . . . . . . . . . . . . . . . . . . . 17 88 4.2. OSPFv3 E-Network-LSA . . . . . . . . . . . . . . . . . . . 18 89 4.3. OSPFv3 E-Inter-Area-Prefix-LSA . . . . . . . . . . . . . . 19 90 4.4. OSPFv3 E-Inter-Area-Router-LSA . . . . . . . . . . . . . . 20 91 4.5. OSPFv3 E-AS-External-LSA . . . . . . . . . . . . . . . . . 21 92 4.6. OSPFv3 E-NSSA-LSA . . . . . . . . . . . . . . . . . . . . 22 93 4.7. OSPFv3 E-Link-LSA . . . . . . . . . . . . . . . . . . . . 23 94 4.8. OSPFv3 E-Intra-Area-Prefix-LSA . . . . . . . . . . . . . . 25 95 5. LSA Extension Backward Compatibility . . . . . . . . . . . . . 26 96 5.1. Extended LSA Mixed-Mode Backward Compatibility . . . . . . 27 97 5.1.1. Area Extended LSA Mixed-Mode Backward Compatibility . 28 98 5.2. LSA TLV Processing Backward Compatibility . . . . . . . . 28 99 6. Security Considerations . . . . . . . . . . . . . . . . . . . 30 100 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 31 101 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 32 102 8.1. Normative References . . . . . . . . . . . . . . . . . . . 32 103 8.2. Informative References . . . . . . . . . . . . . . . . . . 32 104 Appendix A. Global Configuration Parameters . . . . . . . . . . . 33 105 Appendix B. Area Configuration Parameters . . . . . . . . . . . . 34 106 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 35 108 1. Introduction 110 OSPFv3 requires functional extension beyond what can readily be done 111 with the fixed-format Link State Advertisement (LSA) as described in 112 RFC 5340 [OSPFV3]. Without LSA extension, attributes associated with 113 OSPFv3 links and advertised IPv6 prefixes must be advertised in 114 separate LSAs and correlated to the fixed-format LSAs. This document 115 extends the LSA format by encoding the existing OSPFv3 LSA 116 information in Type-Length-Value (TLV) tuples and allowing 117 advertisement of additional information with additional TLVs. 118 Backward compatibility mechanisms are also described. 120 A similar extension was previously proposed in support of multi- 121 topology routing. Additional requirements for OSPFv3 LSA extension 122 include source/destination routing, route tagging, and others. 124 A final requirement is to limit the changes to OSPFv3 to those 125 necessary for TLV-based LSAs. For the most part, the semantics of 126 existing OSPFv3 LSAs are retained for their TLV-based successor LSAs 127 described herein. Additionally, encoding details, e.g., the 128 representation of IPv6 prefixes as described in section A.4.1 in RFC 129 5340 [OSPFV3], have been retained. This requirement was included to 130 increase the expedience of IETF adoption and deployment. 132 The following aspects of OSPFv3 LSA extension are described: 134 1. Extended LSA Types 136 2. Extended LSA TLVs 138 3. Extended LSA Formats 140 4. Backward Compatibility 142 1.1. Requirements notation 144 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 145 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 146 document are to be interpreted as described in [RFC-KEYWORDS]. 148 1.2. Acknowledgments 150 OSPFv3 TLV-based LSAs were first proposed in "Multi-topology routing 151 in OSPFv3 (MT-OSPFv3)" [MT-OSPFV3]. 153 Thanks for Peter Psenak for significant contributions to the backward 154 compatibility mechanisms. 156 Thanks go to Michael Barnes, Mike Dubrovsky, and Anton Smirnov for 157 review of the draft versions and discussions of backward 158 compatibility. 160 Thanks to Alan Davey for review and comments including the suggestion 161 to separate the extended LSA TLV definitions from the extended LSAs 162 definitions. 164 Thanks to David Lamparter for review and suggestions on backward 165 compatibility. 167 The RFC text was produced using Marshall Rose's xml2rfc tool. 169 2. OSPFv3 Extended LSA Types 171 In order to provide backward compatibility, new LSA codes must be 172 allocated. There are eight fixed-format LSAs defined in RFC 5340 173 [OSPFV3]. For ease of implementation and debugging, the LSA function 174 codes are the same as the fixed-format LSAs only with 32, i.e., 0x20, 175 added. The alternative to this mapping was to allocate a bit in the 176 LS Type indicating the new LSA format. However, this would have used 177 one half the LSA function code space for the migration of the eight 178 original fixed-format LSAs. For backward compatibility, the U-bit 179 will be set in LS Type so that the LSAs will be flooded by OSPFv3 180 routers that do not understand them. 182 LSA function code LS Type Description 183 ---------------------------------------------------- 184 33 0xA021 E-Router-LSA 185 34 0xA022 E-Network-LSA 186 35 0xA023 E-Inter-Area-Prefix-LSA 187 36 0xA024 E-Inter-Area-Router-LSA 188 37 0xC025 E-AS-External-LSA 189 38 N/A Unused (Not to be allocated) 190 39 0xA027 E-Type-7-LSA 191 40 0x8028 E-Link-LSA 192 41 0xA029 E-Intra-Area-Prefix-LSA 194 OSPFv3 Extended LSA Types 196 3. OSPFv3 Extended LSA TLVs 198 The format of the TLVs within the body of the extended LSAs is the 199 same as the format used by the Traffic Engineering Extensions to OSPF 200 [TE]. The variable TLV section consists of one or more nested Type/ 201 Length/Value (TLV) tuples. Nested TLVs are also referred to as sub- 202 TLVs. The format of each TLV is: 204 0 1 2 3 205 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 1 206 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 207 | Type | Length | 208 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 209 | Value... | 210 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 212 TLV Format 214 The Length field defines the length of the value portion in octets 215 (thus a TLV with no value portion would have a length of 0). The TLV 216 is padded to 4-octet alignment; padding is not included in the length 217 field (so a 3-octet value would have a length of 3, but the total 218 size of the TLV would be 8 octets). Nested TLVs are also 32-bit 219 aligned. For example, a 1-byte value would have the length field set 220 to 1, and 3 octets of padding would be added to the end of the value 221 portion of the TLV. 223 This document defines the following top-level TLV types: 225 o 0 - Reserved 227 o 1 - Router-Link TLV 229 o 2 - Attached-Routers TLV 231 o 3 - Inter-Area Prefix TLV 233 o 4 - Inter-Area Router TLV 235 o 5 - External Prefix TLV 237 o 6 - Intra-Area Prefix TLV 239 o 7 - IPv6 Link-Local Address TLV 240 o 8 - IPv4 Link-Local Address TLV 242 Additionally, this document defines the following sub-TLV types: 244 o 0 - Reserved 246 o 1 - Forwarding Address sub-TLV 248 o 2 - Route Tag sub-TLV 250 In general, TLVs and sub-TLVs MAY occur in any order and the 251 specification should define whether the TLV or sub-TLV is required 252 and the behavior when there are multiple occurances of the TLV or 253 sub-TLVs. 255 3.1. Router-Link TLVs 257 The Router-Link TLV defines a single router link and the field 258 definitions correspond directly to links in the OSPFv3 Router-LSA, 259 section A.4.3, [OSPFV3]. The Router-Link TLV is only applicable to 260 the E-Router-LSA (Section 4.1). Inclusion in other Extended LSAs 261 MUST be ignored. 263 0 1 2 3 264 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 1 265 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 266 | 1 (Router-Link) | TLV Length | 267 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 268 | Type | 0 | Metric | 269 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 270 | Interface ID | 271 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 272 | Neighbor Interface ID | 273 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 274 | Neighbor Router ID | 275 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 276 . . 277 . sub-TLVs . 278 . . 279 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 281 Router-Link TLV 283 3.2. Attached-Routers TLV 285 The Attached-Routers TLV defines all the routers attached to an 286 OSPFv3 multi-access network. The field definitions correspond 287 directly to content of the OSPFv3 Network-LSA, section A.4.4, 288 [OSPFV3]. The Attached-Routers TLV is only applicable to the 289 E-Network-LSA (Section 4.2). Inclusion in other Extended LSAs MUST 290 be ignored. 292 0 1 2 3 293 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 1 294 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 295 | 2 (Attached-Routers) | TLV Length | 296 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 297 | Adjacent Neighbor Router ID | 298 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 299 . . 300 . Additional Adjacent Neighbors . 301 . . 302 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 304 Attached-Routers TLV 306 There are two reasons for not having a separate TLV or sub-TLV for 307 each adjacent neighbor. The first is to discourage using the 308 E-Network-LSA for more than its current role of solely advertising 309 the routers attached to a multi-access network. The router's metric 310 as well as the attributes of individual attached routers should be 311 advertised in their respective E-Router-LSAs. The second reason is 312 that there is only a single E-Network-LSA per multi-access link with 313 the Link State ID set to the Designated Router's Interface ID and, 314 consequently, compact encoding has been chosen to decrease the 315 likelihood that the size of the E-Network-LSA will require IPv6 316 fragmentation when advertised in an OSPFv3 Link State Update packet. 318 3.3. Inter-Area-Prefix TLV 320 The Inter-Area-Prefix TLV defines a single OSPFV3 inter-area prefix. 321 The field definitions correspond directly to the content of an OSPFv3 322 IPv6 Prefix as defined in Section A.4.1, [OSPFV3] and an OSPFv3 323 Inter-Area-Prefix-LSA, as defined in section A.4.5, [OSPFV3]. The 324 Inter-Area-Prefix TLV is only applicable to the E-Inter-Area-Prefix- 325 LSA (Section 4.3). Inclusion in other Extended LSAs MUST be ignored. 327 0 1 2 3 328 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 1 329 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 330 | 3 (Inter-Area Prefix) | TLV Length | 331 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 332 | 0 | Metric | 333 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 334 | PrefixLength | PrefixOptions | 0 | 335 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 336 | Address Prefix | 337 | ... | 338 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 339 . . 340 . sub-TLVs . 341 . . 342 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 344 Inter-Area Prefix TLV 346 3.4. Inter-Area-Router TLV 348 The Inter-Area-Router TLV defines a single OSPFv3 Autonomous System 349 Boundary Router (ASBR) reachable in another area. The field 350 definitions correspond directly to the content of an OSPFv3 Inter- 351 Area-Router-LSA, as defined in section A.4.6, [OSPFV3]. The Inter- 352 Area-Router TLV is only applicable to the E-Inter-Area-Router-LSA 353 (Section 4.4). Inclusion in other Extended LSAs MUST be ignored. 355 0 1 2 3 356 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 1 357 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 358 | 4 (Inter-Area Router) | TLV Length | 359 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 360 | 0 | Options | 361 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 362 | 0 | Metric | 363 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 364 | Destination Router ID | 365 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 366 . . 367 . sub-TLVs . 368 . . 369 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 371 Inter-Area Router TLV 373 3.5. External-Prefix TLV 375 The External-Prefix TLV defines a single OSPFv3 external prefix. The 376 field definitions correspond directly to the content of an OSPFv3 377 IPv6 Prefix as defined in Section A.4.1, [OSPFV3] and an OSPFv3 AS- 378 External-LSA, as defined in section A.4.7, [OSPFV3]. The External- 379 Prefix TLV is only applicable to the E-AS-External-LSA (Section 4.5) 380 and the E-NSSA-LSA (Section 4.6). Inclusion in other Extended LSAs 381 MUST be ignored. 383 0 1 2 3 384 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 1 385 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 386 | 5 (External Prefix) | TLV Length | 387 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 388 | |E| | | Metric | 389 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 390 | PrefixLength | PrefixOptions | 0 | 391 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 392 | Address Prefix | 393 | ... | 394 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 395 . . 396 . sub-TLVs . 397 . . 398 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 400 External Prefix TLV 402 In the External-Prefix TLV, the optional Forwarding Address and 403 External Route Tag are now sub-TLVs. Given the Referenced LS type 404 and Referenced Link State ID from the AS-External-LSA have never been 405 used or even specified, they have been omitted from the External 406 Prefix TLV. If there were ever a requirement for a referenced LSA, 407 it could be satisfied with a sub-TLV. 409 The following sub-TLVs are defined for optional inclusion in the 410 External Prefix TLV: 412 o 1 - Forwarding Address sub-TLV (Section 3.9) 414 o 2 - Route Tag sub-TLV (Section 3.10) 416 3.6. Intra-Area-Prefix TLV 418 The Intra-Area-Prefix TLV defines a single OSPFv3 intra-area prefix. 419 The field definitions correspond directly to the content of an OSPFv3 420 IPv6 Prefix as defined in Section A.4.1, [OSPFV3] and an OSPFv3 Link- 421 LSA, as defined in section A.4.9, [OSPFV3]. The Intra-Area-Prefix 422 TLV is only applicable to the E-Link-LSA (Section 4.7) and the 423 E-Intra-Area-Prefix-LSA (Section 4.8). Inclusion in other Extended 424 LSAs MUST be ignored. 426 0 1 2 3 427 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 1 428 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 429 | 6 (Intra-Area Prefix) | TLV Length | 430 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 431 | 0 | Metric | 432 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 433 | PrefixLength | PrefixOptions | 0 | 434 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 435 | Address Prefix | 436 | ... | 437 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 438 . . 439 . sub-TLVs . 440 . . 441 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 443 Intra-Area Prefix TLV 445 3.7. IPv6 Link-Local Address TLV 447 The IPv6 Link-Local Address TLV is to be used with IPv6 address 448 families as defined in [OSPFV3-AF]. The IPv6 Link-Local Address TLV 449 is only applicable to the E-Link-LSA (Section 4.7). Inclusion in 450 other Extended LSAs MUST be ignored. 452 0 1 2 3 453 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 1 454 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 455 | 7 (IPv6 Local-Local Address) | TLV Length | 456 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 457 | | 458 +- -+ 459 | | 460 +- IPv6 Link-Local Interface Address -+ 461 | | 462 +- -+ 463 | | 464 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 465 . . 466 . sub-TLVs . 467 . . 468 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 470 IPv6 Link-Local Address TLV 472 3.8. IPv4 Link-Local Address TLV 474 The IPv4 Link-Local Address TLV is to be used with IPv4 address 475 families as defined in [OSPFV3-AF]. The IPv4 Link-Local Address TLV 476 is only applicable to the E-Link-LSA (Section 4.7). Inclusion in 477 other Extended LSAs MUST be ignored. 479 0 1 2 3 480 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 1 481 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 482 | 8 (IPv4 Local-Local Address) | TLV Length | 483 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 484 | IPv4 Link-Local Interface Address | 485 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 486 . . 487 . sub-TLVs . 488 . . 489 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 491 IPv4 Link-Local Address TLV 493 3.9. Forwarding-Address Sub-TLV 495 The Forwarding Address TLV has identical semantics to the optional 496 forwarding address in section A.4.7 of [OSPFV3]. The Forwarding 497 Address TLV is applicable to the External-Prefix TLV (Section 3.5). 498 Specification as a sub-TLV of other TLVs is not defined herein. The 499 sub-TLV is optional and the first specified instance is used as the 500 Forwarding Address as defined in [OSPFV3]. Instances subsequent to 501 the first are ignored. 503 0 1 2 3 504 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 1 505 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 506 | 1 - Forwarding Address | sub-TLV Length | 507 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 508 | | 509 +- -+ 510 | | 511 +- Forwarding Address -+ 512 | | 513 +- -+ 514 | | 515 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 517 Forwarding Address Tag TLV 519 3.10. Route-Tag Sub-TLV 521 The optional Route Tag sub-TLV has identical semantics to the 522 optional External Route Tag in section A.4.7 of [OSPFV3]. The Route 523 Tag sub-TLV is applicable to the External-Prefix TLV (Section 3.5). 524 Specification as a sub-TLV of other TLVs is not defined herein. The 525 sub-TLV is optional and the first specified instance is used as the 526 Route Tag as defined in [OSPFV3]. Instances subsequent to the first 527 are ignored. 529 0 1 2 3 530 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 1 531 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 532 | 2 - Route Tag | sub-TLV Length | 533 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 534 | Route Tag | 535 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 537 Route Tag Sub-TLV 539 4. OSPFv3 Extended LSAs 541 This section specifies the OSPFv3 Extended LSA formats and encoding. 542 The Extended OSPFv3 LSAs corresponded directly to the original OSPFv3 543 LSAs specifed in [OSPFV3]. 545 4.1. OSPFv3 E-Router-LSA 547 The E-Router-LSA has an LS Type of 0xA021 and has the same base 548 information content as the Router-LSA defined in section A.4.3 of 549 [OSPFV3]. However, unlike the existing Router-LSA, it is fully 550 extendable and represented as TLVs. 552 0 1 2 3 553 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 1 554 +-+-+-+--+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 555 | LS Age |1|0|1| 0x21 | 556 +-+-+-+--+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 557 | Link State ID | 558 +-+-+-+--+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 559 | Advertising Router | 560 +-+-+-+--+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 561 | LS Sequence Number | 562 +-+-+-+--+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 563 | LS Checksum | Length | 564 +-+-+-+--+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 565 | 0 |Nt|x|V|E|B| Options | 566 +-+-+-+--+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 567 . . 568 . TLVs . 569 . . 570 +-+-+-+--+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 572 Extended Router-LSA 574 All LSA Header fields are the same as defined for the Router-LSA. 575 Initially, only the top-level Router-Link TLV Section 3.1 is 576 applicable and an E-Router-LSA may include multiple Router-Link TLVs. 577 Like the existing Router-LSA, the LSA length is used to determine the 578 end of the LSA including TLVs. 580 4.2. OSPFv3 E-Network-LSA 582 The E-Network-LSA has an LS Type of 0xA022 and has the same base 583 information content as the Network-LSA defined in section A.4.4 of 584 [OSPFV3]. However, unlike the existing Network-LSA, it is fully 585 extendable and represented as TLVs. 587 0 1 2 3 588 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 1 589 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 590 | LS Age |1|0|1| 0x22 | 591 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 592 | Link State ID | 593 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 594 | Advertising Router | 595 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 596 | LS Sequence Number | 597 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 598 | LS Checksum | Length | 599 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 600 | 0 | Options | 601 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 602 . . 603 . TLVs . 604 . . 605 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 607 E-Network-LSA 609 All LSA Header fields are the same as defined for the Network-LSA. 610 Like the existing Network-LSA, the LSA length is used to determine 611 the end of the LSA including TLVs. Initially, only the top-level 612 Attached-Routers TLV Section 3.2 is applicable. 614 4.3. OSPFv3 E-Inter-Area-Prefix-LSA 616 The E-Inter-Area-Prefix-LSA has an LS Type of 0xA023 and has the same 617 base information content as the Inter-Area-Prefix-LSA defined in 618 section A.4.5 of [OSPFV3]. However, unlike the existing Inter-Area- 619 Prefix-LSA, it is fully extendable and represented as TLVs. 621 0 1 2 3 622 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 1 623 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 624 | LS Age |1|0|1| 0x23 | 625 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 626 | Link State ID | 627 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 628 | Advertising Router | 629 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 630 | LS Sequence Number | 631 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 632 | LS Checksum | Length | 633 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 634 . . 635 . TLVs . 636 . . 637 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 639 E-Inter-Area-Prefix-LSA 641 All LSA Header fields are the same as defined for the Inter-Area- 642 Prefix-LSA. In order to retain compatibility and semantics with the 643 current OSPFv3 specification, each Inter-Area-Prefix LSA MUST contain 644 a single Inter-Area Prefix TLV. This will facilitate migration and 645 avoid changes to functions such as incremental SPF computation. 647 Like the existing Inter-Area-Prefix-LSA, the LSA length is used to 648 determine the end of the LSA including TLV. Initially, only the top- 649 level Inter-Area-Prefix TLV (Section 3.3) is applicable. 651 4.4. OSPFv3 E-Inter-Area-Router-LSA 653 The E-Inter-Area-Router-LSA has an LS Type of 0xA024 and has the same 654 base information content as the Inter-Area-Router-LSAE defined in 655 section A.4.6 of [OSPFV3]. However, unlike the Inter-Area-Router- 656 LSA, it is fully extendable and represented as TLVs. 658 0 1 2 3 659 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 1 660 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 661 | LS Age |1|0|1| 0x24 | 662 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 663 | Link State ID | 664 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 665 | Advertising Router | 666 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 667 | LS Sequence Number | 668 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 669 | LS Checksum | Length | 670 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 671 . . 672 . TLVs . 673 . . 674 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 676 E-Inter-Area-Router-LSA 678 All LSA Header fields are the same as defined for the Inter-Area- 679 Router-LSA. In order to retain compatibility and semantics with the 680 current OSPFv3 specification, each Inter-Area-Router LSA MUST contain 681 a single Inter-Area Router TLV. This will facilitate migration and 682 avoid changes to functions such as incremental SPF computation. 684 Like the existing Inter-Area-Router-LSA, the LSA length is used to 685 determine the end of the LSA including TLV. Initially, only the top- 686 level Inter-Area-Router TLV (Section 3.4) is applicable. 688 4.5. OSPFv3 E-AS-External-LSA 690 The E-AS-External-LSA has an LS Type of 0xC025 and has the same base 691 information content as the AS-External-LSA defined in section A.4.7 692 of [OSPFV3]. However, unlike the existing AS-External-LSA, it is 693 fully extendable and represented as TLVs. 695 0 1 2 3 696 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 1 697 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 698 | LS Age |1|1|0| 0x25 | 699 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 700 | Link State ID | 701 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 702 | Advertising Router | 703 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 704 | LS Sequence Number | 705 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 706 | LS Checksum | Length | 707 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 708 . . 709 . TLVs . 710 . . 711 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 713 E-AS-External-LSA 715 All LSA Header fields are the same as defined for the AS-External- 716 LSA. In order to retain compatibility and semantics with the current 717 OSPFv3 specification, each LSA MUST contain a single External Prefix 718 TLV. This will facilitate migration and avoid changes to OSPFv3 719 processes such as incremental SPF computation. 721 Like the existing AS-External-LSA, the LSA length is used to 722 determine the end of the LSA including sub-TLVs. Initially, only the 723 top-level External-Prefix TLV (Section 3.5) is applicable. 725 4.6. OSPFv3 E-NSSA-LSA 727 The E-NSSA-LSA will have the same format and TLVs as the Extended AS- 728 External-LSA Section 4.5. This is the same relationship as exists 729 between the NSSA-LSA defined in section A.4.8 of [OSPFV3], and the 730 AS-External-LSA. The NSSA-LSA will have type 0xA027 which implies 731 area flooding scope. Future requirements may dictate that supported 732 TLVs differ between the E-AS-External-LSA and the E-NSSA-LSA. 733 However, future requirements are beyond the scope of this document. 735 4.7. OSPFv3 E-Link-LSA 737 The E-Link-LSA has an LS Type of 0x8028 and will have the same base 738 information content as the Link-LSA defined in section A.4.9 of 739 [OSPFV3]. However, unlike the existing Link-LFA, it is extendable 740 and represented as TLVs. 742 0 1 2 3 743 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 1 744 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 745 | LS Age |1|0|0| 0x28 | 746 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 747 | Link State ID | 748 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 749 | Advertising Router | 750 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 751 | LS Sequence Number | 752 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 753 | LS Checksum | Length | 754 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 755 | Rtr Priority | Options | 756 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 757 . . 758 . TLVs . 759 . . 760 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 762 E-Link-LSA 764 All LSA Header fields are the same as defined for the Link-LSA. 766 Only the Intra-Area-Prefix TLV (Section 3.6), IPv6 Link-Local Address 767 TLV (Section 3.7), and IPv4 Link-Local Address TLV (Section 3.8) are 768 applicable to the E-Link-LSA. Like the Link-LSA, the E-Link-LSA 769 affords advertisement of multiple intra-area prefixes. Hence, 770 multiple Intra-Area Prefix TLVs (Section 3.6) may be specified and 771 the LSA length defines the end of the LSA including all TLVs. 773 Only a single instance of the IPv6 Link-Local Address TLV 774 (Section 3.7) SHOULD be included in the E-Link-LSA. Instances 775 following the first MUST be ignored. For IPv4 address families as 776 defined in [OSPFV3-AF], this TLV MUST be ignored. 778 Similarly, only a single instance of the IPv4 Link-Local Address TLV 779 (Section 3.8) SHOULD be included in the E-Link-LSA. Instances 780 following the first MUST be ignored. For OSPFv3 IPv6 address 781 families as defined in [OSPFV3-AF], this TLV MUST be ignored. 783 Future specifications may support advertisement of routing and 784 topology information for multiple address families. However, this is 785 beyond the scope of this document. 787 4.8. OSPFv3 E-Intra-Area-Prefix-LSA 789 The E-Intra-Area-Prefix-LSA has an LS Type of 0xA029 and has the same 790 base information content as the Intra-Area-Prefix-LSA defined in 791 section A.4.10 of [OSPFV3]. However, unlike the Intra-Area-Prefix- 792 LSA, it is fully extendable and represented as TLVs. 794 0 1 2 3 795 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 1 796 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 797 | LS Age |1|0|1| 0x29 | 798 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 799 | Link State ID | 800 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 801 | Advertising Router | 802 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 803 | LS Sequence Number | 804 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 805 | LS Checksum | Length | 806 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 807 | 0 | Referenced LS Type | 808 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 809 | Referenced Link State ID | 810 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 811 | Referenced Advertising Router | 812 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 813 . . 814 . TLVs . 815 . . 816 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 818 E-Intra-Area-Prefix-LSA 820 All LSA Header fields are the same as defined for the Intra-Area- 821 Prefix-LSA. 823 Like the Intra-Area-Prefix-LSA, the E-Intra-Area-Link-LSA affords 824 advertisement of multiple intra-area prefixes. Hence, multiple 825 Intra-Area Prefix TLVs may be specified and the LSA length defines 826 the end of the LSA including all TLVs. 828 5. LSA Extension Backward Compatibility 830 In the context of this document, backward compatibility is solely 831 related to the capability of an OSPFv3 router to receive, process, 832 and originate the TLV-based LSAs defined herein. Unrecognized TLVs 833 and sub-TLVs are ignored. Backward compatibility for future OSPFv3 834 extensions utilizing the TLV-based LSAs is out of scope and must be 835 covered in the documents describing those extensions. Both full and, 836 if applicable, partial deployment SHOULD be specified for future TLV- 837 based OSPFv3 LSA extensions. 839 For simplicity and to avoid the scaling impact of maintaining both 840 TLV and non-TLV based versions of the same LSA within a routing 841 domain, the base backward compatibility mode will not allow mixing of 842 LSA formats. Different formats could still be supported with 843 multiple OSPFv3 instances and separate OSPFv3 routing domains. 844 Additionally, a more complex mode is provided in Section 5.1, where 845 both formats of LSA coexist. In order to facilitate backward 846 compatibility, the OSPFv3 options field (as described in Appendix A.2 847 of RFC 5340 [OSPFV3]), will contain two additional options bits. The 848 EL-bits will be used to indicate that the OSPFv3 router's level of 849 Extended LSA support. An OSPFv3 router configured to support 850 extended LSAs WILL set its options field EL-bits in OSPFv3 Hello and 851 Database Description packets as follows: 853 B'00' 854 None - Extended LSAs are not originate nor used in the SPF 855 calculation. 857 B'01' 858 MixedModeOriginateOnly - Both extended and non-extended LSAs are 859 originated. Non-extended LSAs are used in the SPF computation. 861 B'10' 862 MixedModeOriginateSPF - Both extended and non-extended LSAs are 863 originated. Extended LSAs are used in the SPF computation. 865 B'11' 866 Full - Only extended LSAs are originated and used in the SPF 867 computation. 869 If Full is specified for ExtendedLSASupport, the OSPFv3 router MUST 870 NOT form adjacencies with OSPFv3 Routers sending OSPFv3 Hello and 871 Database Description packets with the options field EL-bits set to 872 MixedModeOriginateOnly or None. Similarly, if MixModeOriginateSPF is 873 specified for ExtendedLSASupport, the OSPFv3 router MUST NOT form 874 adjacencies with OSPFv3 Routers sending OSPFv3 Hello and Database 875 Description packets with the options field EL-bits set to None 876 (B'00'). In this manner, OSPFv3 routers using new encodings can be 877 completely isolated from those OSPFv3 routers depending on the RFC 878 5340 encoding and not setting their options field EL-bits since the 879 default setting indicates no support for extended LSAs. 881 1 2 882 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 883 +-+-+-+-+-+-+-+-+-+-+-+-+-+--+-+--+-+-+--+-+-+-+-+--+ 884 | | | | | | | | | | | | EL|AT|L|AF|*|*|DC|R|N|x|E|V6| 885 +-+-+-+-+-+-+-+-+-+-+-+-+-+--+-+--+-+-+--+-+-+-+-+--+ 886 The Options field 888 EL-bits 889 These bits indicate the level of Extended LSA support. 890 B'00' - Extended LSAs are not originate nor used in the 891 SPF calculation. 892 B'01' - Both extended and non-extended LSAs are originated. 893 Non-extended LSAs are used in the SPF computation. 894 B'10' - Both extended and non-extended LSAs are originated. 895 Extended LSAs are used in the SPF computation. 896 B'11' - Only extended LSA are originated and used in the 897 SPF computation. 899 Options Field EL-bits 901 The EL-bits will also be set in the LSA options field in Extended and 902 Non-Extended LSAs. While the value of the EL-bits has no functional 903 significance in the LSA options field, visibility of every OSPFv3 904 Router's extended LSA support is expected to be very useful for 905 management and troubleshooting during the migration period. 907 5.1. Extended LSA Mixed-Mode Backward Compatibility 909 An implementation MAY support configuration allowing a graceful 910 transition from the non-extended (non-TLV-based) LSAs to the extended 911 (TLV-based) LSAs in an OSPFv3 routing domain. In these routing 912 domains, the OSPFv3 routers configured with a value of 913 MixedModeOriginateOnly or MixedModeOriginateSPF for 914 ExtendedLSASupport, (Appendix A), MUST originate both the extended 915 and non-extended versions of the OSPFv3 LSAs described herein. For 916 the purposes of Shortest Path First (SPF) computation, the non- 917 extended OSPFv3 LSAs are used for SPF computation when 918 MixedModeOriginateOnly is configured and the extended LSAs are used 919 when MixedModeOriginateSPF is specified. The extended LSAs MAY be 920 used for functions other than routing computation as long as backward 921 compatibility is specified in the documents specifying those 922 functions. 924 In this manner, OSPFv3 routing domains utilizing the new encodings 925 can be gradually migrated with a worst-case overhead cost of 926 approximately doubling the number of LSAs in the routing domain. The 927 transition within an OSPFv3 routing domain would progress as follows: 929 1. Configure OSPFv3 Router ExtendedLSASupport to 930 MixedModeOriginateOnly so that routers originate the extended 931 LSAs. 933 2. When all the OSPFv3 Routers have been reconfigured to 934 MixedModeOriginateOnly, gradually reconfigure OSPFv3 Routers to 935 use the extended LSAs by configuring ExtendedLSASupport to 936 MixedModeOriginateSPF. This can be done on a small subset of 937 OSPFv3 Routers and the route tables can be verified. 939 3. When all the OSPFv3 Routers have been reconfigured to 940 MixedModeOriginateSPF and the routing has been verified, 941 reconfigure OSPFv3 Routers to purge or simply not refresh the 942 non-extended OSPFv3 LSA by configuring ExtendedLSASupport to 943 Full. 945 5.1.1. Area Extended LSA Mixed-Mode Backward Compatibility 947 An implementation MAY also support configuration allowing graceful 948 transition from the non-extended LSAs to the extended LSAs within a 949 single area. In these areas, the parameter AreaExtendedLSASupport 950 (Appendix B) may be configured to take precedence over the global 951 parameter ExtendedLSASupport. However, the AreaExtendedLSASupport 952 will only apply to link and area scoped LSAs within the area and area 953 based SPF calculations. The default is for the 954 AreaExtendedLSASupport to be inherited from the ExtendedLSASupport. 955 The configuration of ExtendedLSASupport will apply to AS-External 956 LSAs even when AreaExtendedLSASupport takes precedence. 958 5.2. LSA TLV Processing Backward Compatibility 960 This section defines the general rules for processing LSA TLVs. To 961 ensure compatibility of future TLV-based LSA extensions, all 962 implementations MUST adhere to these rules: 964 1. Unrecognized TLVs and sub-TLVs are ignored when parsing or 965 processing Extended-LSAs. 967 2. Whether or not partial deployment of a given TLV is supported 968 MUST be specified. 970 3. If partial deployment is not supported, mechanisms to ensure the 971 corresponding feature are not deployed MUST be specified in the 972 document defining the new TLV or sub-TLV. 974 4. If partial deployment is supported, backward compatibility and 975 partial deployment MUST be specified in the document defining the 976 new TLV or sub-TLV. 978 6. Security Considerations 980 In general, extendible OSPFv3 LSAs are subject to the same security 981 concerns as those described in RFC 5340 [OSPFV3]. Additionally, 982 implementations must assure that malformed TLV and Sub-TLV 983 permutations do not result in errors that cause hard OSPFv3 failures. 985 If there were ever a requirement to digitally sign OSPFv3 LSAs as 986 described for OSPFv2 LSAs in RFC 2154 [OSPF-DIGITAL-SIGNATURE], the 987 mechanisms described herein would greatly simplify the extension. 989 7. IANA Considerations 991 This specification defines nine OSPFv3 Extended LSA types as 992 described in Section 2. 994 This specification also creates two registries OSPFv3 Extended-LSAs 995 TLVs and sub-TLVs. The TLV and Sub-TLV code-points in these 996 registries are common to all Extended-LSAs and their respective 997 definitions must define where they are applicable. 999 The OSPFv3 Extend-LSA TLV registry will define top-level TLVs for 1000 Extended-LSAs and should be placed in the existing OSPFv3 IANA 1001 registry. New values can be allocated via IETF Consensus or IESG 1002 Approval. 1004 Nine values are allocated by this specification: 1006 o 0 - Reserved 1008 o 1 - Router-Link TLV 1010 o 2 - Attached-Routers TLV 1012 o 3 - Inter-Area Prefix TLV 1014 o 4 - Inter-Area Router TLV 1016 o 5 - External Prefix TLV 1018 o 6 - Intra-Area Prefix TLV 1020 o 7 - IPv6 Link-Local Address TLV 1022 o 8 - IPv4 Link-Local Address TLV 1024 The OSPFv3 Extend-LSA sub-TLV registry will define sub-TLVs at any 1025 level of nesting for Extended-LSAs and should be placed in the 1026 existing OSPFv3 IANA registry. New values can be allocated via IETF 1027 Consensus or IESG Approval. 1029 Three values are allocated by this specification: 1031 o 0 - Reserved 1033 o 1 - Forwarding Address 1035 o 2 - Route Tag 1037 8. References 1039 8.1. Normative References 1041 [OSPFV3] Coltun, R., Ferguson, D., Moy, J., and A. Lindem, "OSPF 1042 for IPv6", RFC 5340, July 2008. 1044 [OSPFV3-AF] 1045 Lindem, A., Mirtorabi, S., Roy, A., Barnes, M., and R. 1046 Aggarwal, "Support of Address Families in OSPFv3", 1047 RFC 5838, April 2010. 1049 [RFC-KEYWORDS] 1050 Bradner, S., "Key words for use in RFCs to Indicate 1051 Requirement Levels", RFC 2119, March 1997. 1053 [TE] Katz, D., Yeung, D., and K. Kompella, "Traffic Engineering 1054 Extensions to OSPF", RFC 3630, September 2003. 1056 8.2. Informative References 1058 [MT-OSPFV3] 1059 Mirtorabi, S. and A. Roy, "Multi-topology routing in 1060 OSPFv3 (MT-OSPFV3)", draft-ietf-ospf-mt-ospfv3-04.txt 1061 (work in progress). 1063 [OSPF-DIGITAL-SIGNATURE] 1064 Murphy, S., Badger, M., and B. Wellington, "OSPF with 1065 Digital Signatures", RFC 2154, June 1997. 1067 Appendix A. Global Configuration Parameters 1069 An additional global configurable parameter will be added to the 1070 OSPFv3 protocol. 1072 ExtendedLSASupport 1073 This is an enumeration type indicating the extent to which the 1074 OSPFv3 instance supports the TLV format described herein for 1075 Extended LSAs. The valid values for the enumeration are: 1077 * None - Extended LSAs will not be originated or used in the SPF 1078 calculation. This is the default. 1080 * MixedModeOriginateOnly - Both extended and non-extended LSAs 1081 will be originated. OSPFv3 adjacencies will be formed with 1082 OSPFv3 routers not supporting this specification. The non- 1083 extended LSAs are used for the SPF computation. 1085 * MixedModeOriginateSPF - Both extended and non-extended LSAs 1086 will be originated. OSPFv3 adjacencies will be formed with 1087 OSPFv3 routers not supporting this specification. The extended 1088 LSAs are used for the SPF computation. 1090 * Full - Extended LSAs will be originated and adjacencies will 1091 not be formed with OSPFv3 routers not supporting this 1092 specification. Only Extended LSAs will be originated. 1094 Appendix B. Area Configuration Parameters 1096 An additional area configurable parameter will be added to the OSPFv3 1097 protocol. 1099 AreaExtendedLSASupport 1100 This is an enumeration type indicating the extent to which the 1101 OSPFv3 area supports the TLV format described herein for Extended 1102 LSAs. The valid value for the enumeration are: 1104 * InheritGlobal - The AreaExtendedLSASupport will be inherited 1105 from ExtendedLSASupport. This is the default. 1107 * None - Non-extended LSAs will not be originated or used in the 1108 SPF calculation. 1110 * MixedModeOriginateOnly - Both extended and non-extended link 1111 and area scoped LSAs will be originated. OSPFv3 adjacencies 1112 will be formed with OSPFv3 routers not supporting this 1113 specification. The non-extended LSAs are used for the SPF 1114 computation. 1116 * MixedModeOriginateSPF - Both extended and non-extended link and 1117 area scoped LSAs will be originated. OSPFv3 adjacencies will 1118 be formed with OSPFv3 routers not supporting this 1119 specification. The extended LSAs are used for the area SPF 1120 computation. 1122 * Full - Link and area scoped extended LSAs will be originated 1123 and adjacencies will not be formed with OSPFv3 routers not 1124 supporting this specification. Only Extended LSAs will be 1125 originated. 1127 For regular areas, i.e., areas where AS scoped LSAs are flooded, 1128 configuring None or MixedModeOriginateOnly for AreaExtendedLSASupport 1129 when Full is specified for ExtendedLSASupport is contradictory and 1130 MAY be prohibited by the implementation. 1132 Authors' Addresses 1134 Acee Lindem 1135 Ericsson 1136 301 Midenhall Way 1137 Cary, NC 27513 1138 USA 1140 Email: acee.lindem@ericsson.com 1142 Sina Mirtorabi 1143 Cisco Systems 1144 170 Tasman Drive 1145 San Jose, CA 95134 1146 USA 1148 Email: sina@cisco.com 1150 Abhay Roy 1151 Cisco Systems 1152 170 Tasman Drive 1153 San Jose, CA 95134 1154 USA 1156 Email: akr@cisco.com 1158 Fred Baker 1159 Cisco Systems 1160 Santa Barbara, CA 93117 1161 USA 1163 Email: fred@cisco.com