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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: January 9, 2020 July 8, 2019 7 Extensions to OSPF for Advertising Prefix/Link Administrative Tags 8 draft-acee-lsr-ospf-admin-tags-02 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 January 9, 2020. 43 Copyright Notice 45 Copyright (c) 2019 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 1.1.1. Requirements Language . . . . . . . . . . . . . . . . 3 63 2. 32-Bit Administrative Tag Sub-TLV . . . . . . . . . . . . . . 3 64 3. Administrative Tag Applicability . . . . . . . . . . . . . . 4 65 4. Protocol Operation . . . . . . . . . . . . . . . . . . . . . 5 66 4.1. Equal-Cost Multipath Applicability . . . . . . . . . . . 5 67 5. Security Considerations . . . . . . . . . . . . . . . . . . . 6 68 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 69 7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 6 70 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 6 71 8.1. Normative References . . . . . . . . . . . . . . . . . . 6 72 8.2. Informative References . . . . . . . . . . . . . . . . . 7 73 Appendix A. 64-Bit Administrative Tag Sub-TLV . . . . . . . . . 7 74 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8 76 1. Introduction 78 It is useful for routers in an OSPFv2 [RFC2328] or OSPFv3 [RFC5340] 79 routing domain to be able to associate tags with prefixes and links. 80 Previously, OSPFv3 and OSPFv3 were relegated to a single tag for AS 81 External and Not-So-Stubby-Area (NSSA) prefixes. With the flexible 82 encodings provided by OSPFv2 Prefix/Link Attribute Advertisement 83 ([RFC7684]) and OSPFv3 Extended LSA ([RFC8362]), multiple 84 administrative tags may be advertised for all types of prefixes and 85 links. These administrative tags can be used many applications 86 including (but not limited to): 88 1. Controlling which routes are redistributed into other protocols 89 for readvertisement. 91 2. Prioritizing selected prefixes for faster convergence and 92 installation in the forwarding plane. 94 3. Identifying selected prefixes for Loop-Free Alternative (LFA) 95 protection. 97 Throughout this document, OSPF is used when the text applies to both 98 OSPFv2 and OSPFv3. OSPFv2 or OSPFv3 is used when the text is 99 specific to one version of the OSPF protocol. 101 The ISIS protocol supports a similar mechanism that is described in 102 RFC 5130 [RFC5130]. 104 1.1. Requirements notation 106 1.1.1. Requirements Language 108 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 109 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 110 "OPTIONAL" in this document are to be interpreted as described in BCP 111 14 [RFC2119] [RFC8174] when, and only when, they appear in all 112 capitals, as shown here. 114 2. 32-Bit Administrative Tag Sub-TLV 116 This document creates a new Administrative Tag Sub-TLV for OSPFv2 and 117 OSPFv3. This Sub-TLV specifies one or more 32-bit unsigned integers 118 that may be associated with an OSPF advertised prefix or OSPF Link. 119 The precise usage of these tags is beyond the scope of this document. 121 The format of this Sub-TLV is the same as the format used by the 122 Traffic Engineering Extensions to OSPF [RFC3630]. The LSA payload 123 consists of one or more nested Type/Length/Value (TLV) triplets. The 124 format of each TLV is: 126 0 1 2 3 127 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 1 128 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 129 | Type | Length | 130 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 131 | Value... | 132 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 134 TLV Format 136 The Length field defines the length of the value portion in octets 137 (thus a TLV with no value portion would have a length of 0). The TLV 138 is padded to 4-octet alignment; padding is not included in the length 139 field (so a 3-octet value would have a length of 3, but the total 140 size of the TLV would be 8 octets). 142 The format of the 32-bit Administrative Tag TLV is as follows: 144 0 1 2 3 145 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 1 146 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 147 | Type | Length | 148 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 149 | First 32-bit Administrative Tag | 150 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 151 | o | 152 o 153 | o | 154 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 155 | Last 32-bit Administrative Tag | 156 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 158 Type A 16-bit field set to TBD. The value MAY be different 159 depending upon the IANA registry from which it is 160 allocated. 162 Length A 16-bit field that indicates the length of the value 163 portion in octets and will be a multiple of 4 octets 164 dependent on the number of administrative tags 165 advertised. If the sub-TLV is specified, at least one 166 administrative tag must be advertised. 168 Value A variable length list of one or more administrative 169 tags. 171 32-bit Administrative Tag Sub-TLV 173 This sub-TLV will carry one or more 32-bit unsigned integer values 174 that will be used as administrative tags. 176 3. Administrative Tag Applicability 178 The administrative tag TLV specified herein will be valid as a sub- 179 TLV of the following TLVs specified in [RFC7684]: 181 1. Extended Prefix TLV advertised in the OSPFv2 Extended Prefix LSA 183 2. Extended Link TLV advertised in the OSPFv2 Extended Prefix LSA 185 The administrative tag TLV specified herein will be valid as a sub- 186 TLV of the following TLVs specified in [RFC8362]: 188 1. Router-Link TLV advertised in the E-Router-LSA 190 2. Inter-Area-Prefix TLV advertised in the E-Inter-Area-Prefix-LSA 191 3. Intra-Area-Prefix TLV advertised in the E-Link-LSA and the E- 192 Intra-Area-LSA 194 4. External-Prefix TLV advertised in the E-AS-External-LSA and the 195 E-NSSA-LSA 197 4. Protocol Operation 199 An OSPF router supporting this specification MUST propagate 200 administrative tags when acting as an Area Border Router and 201 originating summary advertisements into other areas. Similarly, an 202 OSPF router supporting this specification and acting as an ABR for a 203 Not-So-Stubby Area (NSSA) MUST propagate tags when translating NSSA 204 routes to AS External advertisements [RFC3101]. The number of tags 205 supported MAY limit the number of tags that are propagated. When 206 propagating multiple tags, the order of the the tags must be 207 preserved. 209 For configured area ranges, NSSA ranges, and configurated 210 summarization of redistributed routes, tags from component routes 211 SHOULD NOT be propagated to the summary. Implementations SHOULD 212 provide a mechanism to configure tags for area ranges, NSSA ranges, 213 and redistributed route summaries. 215 An OSPF router supporting this specification MUST be able to 216 advertise and interpret one 32-bit tag for prefixes and links. An 217 OSPF router supporting this specification MAY be able to advertise 218 and propagate multiple 32-bit tags. The maximum tags that an 219 implementation supports is a local matter depending upon supported 220 applications using the prefix or link tags. 222 When a single tag is advertised for AS External or NSSA LSA prefix, 223 the existing tag in OSPFv2 and OSPFv3 AS-External-LSA and NSSA-LSA 224 encodings SHOULD be utilized. This will facilitate backward 225 compatibilty with implementations that do not support this 226 specification. 228 4.1. Equal-Cost Multipath Applicability 230 When multiple LSAs contribute to an OSPF route, it is possible that 231 these LSAs will all have different tags. In this situation, the OSPF 232 router MUST associate the tags from one of the LSAs contributing a 233 path and, if the implementation supports multiple tags, MAY associate 234 tags for multiple contributing LSAs up to the maximum number of tags 235 supported. 237 5. Security Considerations 239 This document describes both a generic mechanism for advertising 240 administrative tags for OSPF prefixes and links. The administrative 241 tags are generally less critical than the topology information 242 currently advertised by the base OSPF protocol. The security 243 considerations for the generic mechanism are dependent on the future 244 application and, as such, should be described as additional 245 capabilities are proposed for advertisement. Security considerations 246 for the base OSPF protocol are covered in [RFC2328] and [RFC5340]. 248 6. IANA Considerations 250 The following values should be allocated from the OSPF Extended 251 Prefix TLV Sub-TLV Registry [RFC7684]: 253 o TBD - 32-bit Administrative Tag TLV 255 The following values should be allocated from the OSPF Extended Link 256 TLV Sub-TLV Registry [RFC7684]: 258 o TBD - 32-bit Administrative Tag TLV 260 The following values should be allocated from the OSPFv3 Extended-LSA 261 Sub-TLV Registry [RFC8362]: 263 o TBD - 32-bit Administrative Tag TLV 265 7. Acknowledgments 267 The authors of RFC 5130 are acknowledged since this document draws 268 upon both the ISIS specification and deployment experience. 270 Thanks to Donnie Savage for his comments and questions. 272 The RFC text was produced using Marshall Rose's xml2rfc tool. 274 8. References 276 8.1. Normative References 278 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 279 Requirement Levels", BCP 14, RFC 2119, 280 DOI 10.17487/RFC2119, March 1997, 281 . 283 [RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328, 284 DOI 10.17487/RFC2328, April 1998, 285 . 287 [RFC3630] Katz, D., Kompella, K., and D. Yeung, "Traffic Engineering 288 (TE) Extensions to OSPF Version 2", RFC 3630, 289 DOI 10.17487/RFC3630, September 2003, 290 . 292 [RFC5340] Coltun, R., Ferguson, D., Moy, J., and A. Lindem, "OSPF 293 for IPv6", RFC 5340, DOI 10.17487/RFC5340, July 2008, 294 . 296 [RFC7684] Psenak, P., Gredler, H., Shakir, R., Henderickx, W., 297 Tantsura, J., and A. Lindem, "OSPFv2 Prefix/Link Attribute 298 Advertisement", RFC 7684, DOI 10.17487/RFC7684, November 299 2015, . 301 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 302 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 303 May 2017, . 305 [RFC8362] Lindem, A., Roy, A., Goethals, D., Reddy Vallem, V., and 306 F. Baker, "OSPFv3 Link State Advertisement (LSA) 307 Extensibility", RFC 8362, DOI 10.17487/RFC8362, April 308 2018, . 310 8.2. Informative References 312 [RFC3101] Murphy, P., "The OSPF Not-So-Stubby Area (NSSA) Option", 313 RFC 3101, DOI 10.17487/RFC3101, January 2003, 314 . 316 [RFC5130] Previdi, S., Shand, M., Ed., and C. Martin, "A Policy 317 Control Mechanism in IS-IS Using Administrative Tags", 318 RFC 5130, DOI 10.17487/RFC5130, February 2008, 319 . 321 Appendix A. 64-Bit Administrative Tag Sub-TLV 323 The definition of the 64-bit tag was considered but discard given 324 that there is no strong requirement or use case. The specification 325 is included here for information. 327 This sub-TLV will carry one or more 64-bit unsigned integer values 328 that will be used as administrative tags. 330 The format of the 64-bit Administrative Tag TLV is as follows: 332 0 1 2 3 333 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 1 334 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 335 | Type | Length | 336 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 337 | First 64-bit Administrative Tag | 338 | | 339 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 340 | o | 341 o 342 | o | 343 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 344 | Last 64-bit Administrative Tag | 345 | | 346 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 348 Type A 16-bit field set to TBD. The value MAY be different 349 depending upon the registry from which it is allocated. 351 Length A 16-bit field that indicates the length of the value 352 portion in octets and will be a multiple of 8 octets 353 dependent on the number of administrative tags 354 advertised. If the sub-TLV is specified, at least one 355 administrative tag must be advertised. 357 Value A variable length list of one or more 64-bit 358 administrative tags. 360 64-bit Administrative Tag TLV 362 Authors' Addresses 364 Acee Lindem (editor) 365 Cisco Systems 366 301 Midenhall Way 367 Cary, NC 27513 368 USA 370 Email: acee@cisco.com 371 Peter Psenak 372 Cisco Systems 373 Apollo Business Center 374 Mlynske nivy 43 375 Bratislava, 821 09 376 Slovakia 378 Email: ppsenak@cisco.com