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Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) No issues found here. Summary: 0 errors (**), 0 flaws (~~), 1 warning (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group A. Lindem, Ed. 3 Internet-Draft P. Psenak 4 Intended status: Standards Track Cisco Systems 5 Expires: March 27, 2021 September 23, 2020 7 Extensions to OSPF for Advertising Prefix/Link Administrative Tags 8 draft-acee-lsr-ospf-admin-tags-06 10 Abstract 12 It is useful for routers in an OSPFv2 or OSPFv3 routing domain to be 13 able to associate tags with prefixes and links. Previously, OSPFv2 14 and OSPFv3 were relegated to a single tag for AS External and Not-So- 15 Stubby-Area (NSSA) prefixes. With the flexible encodings provided by 16 OSPFv2 Prefix/Link Attribute Advertisement and OSPFv3 Extended LSAs, 17 multiple administrative tags may advertised for all types of prefixes 18 and links. These administrative tags can be used for many 19 applications including route redistribution policy, selective prefix 20 prioritization, selective IP Fast-ReRoute (IPFRR) prefix protection, 21 and many others. 23 The ISIS protocol supports a similar mechanism that is described in 24 RFC 5130. 26 Status of This Memo 28 This Internet-Draft is submitted in full conformance with the 29 provisions of BCP 78 and BCP 79. 31 Internet-Drafts are working documents of the Internet Engineering 32 Task Force (IETF). Note that other groups may also distribute 33 working documents as Internet-Drafts. The list of current Internet- 34 Drafts is at https://datatracker.ietf.org/drafts/current/. 36 Internet-Drafts are draft documents valid for a maximum of six months 37 and may be updated, replaced, or obsoleted by other documents at any 38 time. It is inappropriate to use Internet-Drafts as reference 39 material or to cite them other than as "work in progress." 41 This Internet-Draft will expire on March 27, 2021. 43 Copyright Notice 45 Copyright (c) 2020 IETF Trust and the persons identified as the 46 document authors. All rights reserved. 48 This document is subject to BCP 78 and the IETF Trust's Legal 49 Provisions Relating to IETF Documents 50 (https://trustee.ietf.org/license-info) in effect on the date of 51 publication of this document. Please review these documents 52 carefully, as they describe your rights and restrictions with respect 53 to this document. Code Components extracted from this document must 54 include Simplified BSD License text as described in Section 4.e of 55 the Trust Legal Provisions and are provided without warranty as 56 described in the Simplified BSD License. 58 Table of Contents 60 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 61 1.1. Requirements notation . . . . . . . . . . . . . . . . . . 3 62 2. 32-Bit Administrative Tag Sub-TLV . . . . . . . . . . . . . . 3 63 3. Administrative Tag Applicability . . . . . . . . . . . . . . 4 64 4. Protocol Operation . . . . . . . . . . . . . . . . . . . . . 5 65 4.1. Equal-Cost Multipath Applicability . . . . . . . . . . . 5 66 5. Security Considerations . . . . . . . . . . . . . . . . . . . 6 67 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 68 7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 6 69 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 6 70 8.1. Normative References . . . . . . . . . . . . . . . . . . 6 71 8.2. Informative References . . . . . . . . . . . . . . . . . 7 72 Appendix A. 64-Bit Administrative Tag Sub-TLV . . . . . . . . . 8 73 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8 75 1. Introduction 77 It is useful for routers in an OSPFv2 [RFC2328] or OSPFv3 [RFC5340] 78 routing domain to be able to associate tags with prefixes and links. 79 Previously, OSPFv3 and OSPFv3 were relegated to a single tag for AS 80 External and Not-So-Stubby-Area (NSSA) prefixes. With the flexible 81 encodings provided by OSPFv2 Prefix/Link Attribute Advertisement 82 ([RFC7684]) and OSPFv3 Extended LSA ([RFC8362]), multiple 83 administrative tags may be advertised for all types of prefixes and 84 links. These administrative tags can be used many applications 85 including (but not limited to): 87 1. Controlling which routes are redistributed into other protocols 88 for readvertisement. 90 2. Prioritizing selected prefixes for faster convergence and 91 installation in the forwarding plane. 93 3. Identifying selected prefixes for Loop-Free Alternative (LFA) 94 protection. 96 Throughout this document, OSPF is used when the text applies to both 97 OSPFv2 and OSPFv3. OSPFv2 or OSPFv3 is used when the text is 98 specific to one version of the OSPF protocol. 100 The ISIS protocol supports a similar mechanism that is described in 101 RFC 5130 [RFC5130]. 103 1.1. Requirements notation 105 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 106 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 107 "OPTIONAL" in this document are to be interpreted as described in BCP 108 14 [RFC2119] [RFC8174] when, and only when, they appear in all 109 capitals, as shown here. 111 2. 32-Bit Administrative Tag Sub-TLV 113 This document creates a new Administrative Tag Sub-TLV for OSPFv2 and 114 OSPFv3. This Sub-TLV specifies one or more 32-bit unsigned integers 115 that may be associated with an OSPF advertised prefix or OSPF Link. 116 The precise usage of these tags is beyond the scope of this document. 118 The format of this Sub-TLV is the same as the format used by the 119 Traffic Engineering Extensions to OSPF [RFC3630]. The LSA payload 120 consists of one or more nested Type/Length/Value (TLV) triplets. The 121 format of each TLV is: 123 0 1 2 3 124 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 1 125 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 126 | Type | Length | 127 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 128 | Value... | 129 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 131 TLV Format 133 The Length field defines the length of the value portion in octets 134 (thus a TLV with no value portion would have a length of 0). The TLV 135 is padded to 4-octet alignment; padding is not included in the length 136 field (so a 3-octet value would have a length of 3, but the total 137 size of the TLV would be 8 octets). 139 The format of the 32-bit Administrative Tag TLV is as follows: 141 0 1 2 3 142 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 1 143 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 144 | Type | Length | 145 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 146 | First 32-bit Administrative Tag | 147 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 148 | o | 149 o 150 | o | 151 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 152 | Last 32-bit Administrative Tag | 153 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 155 Type A 16-bit field set to TBD. The value MAY be different 156 depending upon the IANA registry from which it is 157 allocated. 159 Length A 16-bit field that indicates the length of the value 160 portion in octets and will be a multiple of 4 octets 161 dependent on the number of administrative tags 162 advertised. If the sub-TLV is specified, at least one 163 administrative tag must be advertised. 165 Value A variable length list of one or more administrative 166 tags. 168 32-bit Administrative Tag Sub-TLV 170 This sub-TLV will carry one or more 32-bit unsigned integer values 171 that will be used as administrative tags. 173 3. Administrative Tag Applicability 175 The administrative tag TLV specified herein will be valid as a sub- 176 TLV of the following TLVs specified in [RFC7684]: 178 1. Extended Prefix TLV advertised in the OSPFv2 Extended Prefix LSA 180 2. Extended Link TLV advertised in the OSPFv2 Extended Prefix LSA 182 The administrative tag TLV specified herein will be valid as a sub- 183 TLV of the following TLVs specified in [RFC8362]: 185 1. Router-Link TLV advertised in the E-Router-LSA 187 2. Inter-Area-Prefix TLV advertised in the E-Inter-Area-Prefix-LSA 188 3. Intra-Area-Prefix TLV advertised in the E-Link-LSA and the E- 189 Intra-Area-Prefix-LSA 191 4. External-Prefix TLV advertised in the E-AS-External-LSA and the 192 E-NSSA-LSA 194 4. Protocol Operation 196 An OSPF router supporting this specification MUST propagate 197 administrative tags when acting as an Area Border Router and 198 originating summary advertisements into other areas. Similarly, an 199 OSPF router supporting this specification and acting as an ABR for a 200 Not-So-Stubby Area (NSSA) MUST propagate tags when translating NSSA 201 routes to AS External advertisements [RFC3101]. The number of tags 202 supported MAY limit the number of tags that are propagated. When 203 propagating multiple tags, the order of the the tags must be 204 preserved. 206 For configured area ranges, NSSA ranges, and configurated 207 summarization of redistributed routes, tags from component routes 208 SHOULD NOT be propagated to the summary. Implementations SHOULD 209 provide a mechanism to configure tags for area ranges, NSSA ranges, 210 and redistributed route summaries. 212 An OSPF router supporting this specification MUST be able to 213 advertise and interpret one 32-bit tag for prefixes and links. An 214 OSPF router supporting this specification MAY be able to advertise 215 and propagate multiple 32-bit tags. The maximum tags that an 216 implementation supports is a local matter depending upon supported 217 applications using the prefix or link tags. 219 When a single tag is advertised for AS External or NSSA LSA prefix, 220 the existing tag in OSPFv2 and OSPFv3 AS-External-LSA and NSSA-LSA 221 encodings SHOULD be utilized. This will facilitate backward 222 compatibilty with implementations that do not support this 223 specification. 225 4.1. Equal-Cost Multipath Applicability 227 When multiple LSAs contribute to an OSPF route, it is possible that 228 these LSAs will all have different tags. In this situation, the OSPF 229 router MUST associate the tags from one of the LSAs contributing a 230 path and, if the implementation supports multiple tags, MAY associate 231 tags for multiple contributing LSAs up to the maximum number of tags 232 supported. 234 5. Security Considerations 236 This document describes a generic mechanism for advertising 237 administrative tags for both OSPF prefixes and links. The 238 administrative tags are generally less critical than the topology 239 information currently advertised by the base OSPF protocol. The 240 security considerations for the generic mechanism are dependent on 241 the future application and, as such, should be described as 242 additional capabilities are proposed for advertisement. Security 243 considerations for the base OSPF protocol are covered in [RFC2328] 244 and [RFC5340]. 246 6. IANA Considerations 248 The following values should be allocated from the OSPF Extended 249 Prefix TLV Sub-TLV Registry [RFC7684]: 251 o TBD - 32-bit Administrative Tag TLV 253 The following values should be allocated from the OSPF Extended Link 254 TLV Sub-TLV Registry [RFC7684]: 256 o TBD - 32-bit Administrative Tag TLV 258 The following values should be allocated from the OSPFv3 Extended-LSA 259 Sub-TLV Registry [RFC8362]: 261 o TBD - 32-bit Administrative Tag TLV 263 7. Acknowledgments 265 The authors of RFC 5130 are acknowledged since this document draws 266 upon both the ISIS specification and deployment experience. 268 Thanks to Donnie Savage for his comments and questions. 270 The RFC text was produced using Marshall Rose's xml2rfc tool. 272 8. References 274 8.1. Normative References 276 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 277 Requirement Levels", BCP 14, RFC 2119, 278 DOI 10.17487/RFC2119, March 1997, 279 . 281 [RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328, 282 DOI 10.17487/RFC2328, April 1998, 283 . 285 [RFC3630] Katz, D., Kompella, K., and D. Yeung, "Traffic Engineering 286 (TE) Extensions to OSPF Version 2", RFC 3630, 287 DOI 10.17487/RFC3630, September 2003, 288 . 290 [RFC5340] Coltun, R., Ferguson, D., Moy, J., and A. Lindem, "OSPF 291 for IPv6", RFC 5340, DOI 10.17487/RFC5340, July 2008, 292 . 294 [RFC7684] Psenak, P., Gredler, H., Shakir, R., Henderickx, W., 295 Tantsura, J., and A. Lindem, "OSPFv2 Prefix/Link Attribute 296 Advertisement", RFC 7684, DOI 10.17487/RFC7684, November 297 2015, . 299 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 300 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 301 May 2017, . 303 [RFC8362] Lindem, A., Roy, A., Goethals, D., Reddy Vallem, V., and 304 F. Baker, "OSPFv3 Link State Advertisement (LSA) 305 Extensibility", RFC 8362, DOI 10.17487/RFC8362, April 306 2018, . 308 8.2. Informative References 310 [RFC3101] Murphy, P., "The OSPF Not-So-Stubby Area (NSSA) Option", 311 RFC 3101, DOI 10.17487/RFC3101, January 2003, 312 . 314 [RFC5130] Previdi, S., Shand, M., Ed., and C. Martin, "A Policy 315 Control Mechanism in IS-IS Using Administrative Tags", 316 RFC 5130, DOI 10.17487/RFC5130, February 2008, 317 . 319 Appendix A. 64-Bit Administrative Tag Sub-TLV 321 The definition of the 64-bit tag was considered but discard given 322 that there is no strong requirement or use case. The specification 323 is included here for information. 325 This sub-TLV will carry one or more 64-bit unsigned integer values 326 that will be used as administrative tags. 328 The format of the 64-bit Administrative Tag TLV is as follows: 330 0 1 2 3 331 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 1 332 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 333 | Type | Length | 334 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 335 | First 64-bit Administrative Tag | 336 | | 337 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 338 | o | 339 o 340 | o | 341 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 342 | Last 64-bit Administrative Tag | 343 | | 344 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 346 Type A 16-bit field set to TBD. The value MAY be different 347 depending upon the registry from which it is allocated. 349 Length A 16-bit field that indicates the length of the value 350 portion in octets and will be a multiple of 8 octets 351 dependent on the number of administrative tags 352 advertised. If the sub-TLV is specified, at least one 353 administrative tag must be advertised. 355 Value A variable length list of one or more 64-bit 356 administrative tags. 358 64-bit Administrative Tag TLV 360 Authors' Addresses 361 Acee Lindem (editor) 362 Cisco Systems 363 301 Midenhall Way 364 Cary, NC 27513 365 USA 367 EMail: acee@cisco.com 369 Peter Psenak 370 Cisco Systems 371 Apollo Business Center 372 Mlynske nivy 43 373 Bratislava, 821 09 374 Slovakia 376 EMail: ppsenak@cisco.com