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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in RFCs) == Unused Reference: 'RFC7794' is defined on line 445, but no explicit reference was found in the text == Outdated reference: A later version (-15) exists of draft-ietf-idr-bgpls-inter-as-topology-ext-09 Summary: 0 errors (**), 0 flaws (~~), 3 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 LSR Working Group A. Wang 3 Internet-Draft China Telecom 4 Intended status: Standards Track Z. Hu 5 Expires: 1 February 2022 Huawei Technologies 6 G. Mishra 7 Verizon Inc. 8 J. Sun 9 ZTE Corporation 10 31 July 2021 12 Advertisement of Stub Link Attributes 13 draft-wang-lsr-stub-link-attributes-00 15 Abstract 17 This document describes the mechanism that can be used to 18 differentiate the stub links from the normal interfaces within ISIS 19 or OSPF domain. 21 Status of This Memo 23 This Internet-Draft is submitted in full conformance with the 24 provisions of BCP 78 and BCP 79. 26 Internet-Drafts are working documents of the Internet Engineering 27 Task Force (IETF). Note that other groups may also distribute 28 working documents as Internet-Drafts. The list of current Internet- 29 Drafts is at https://datatracker.ietf.org/drafts/current/. 31 Internet-Drafts are draft documents valid for a maximum of six months 32 and may be updated, replaced, or obsoleted by other documents at any 33 time. It is inappropriate to use Internet-Drafts as reference 34 material or to cite them other than as "work in progress." 36 This Internet-Draft will expire on 1 February 2022. 38 Copyright Notice 40 Copyright (c) 2021 IETF Trust and the persons identified as the 41 document authors. All rights reserved. 43 This document is subject to BCP 78 and the IETF Trust's Legal 44 Provisions Relating to IETF Documents (https://trustee.ietf.org/ 45 license-info) in effect on the date of publication of this document. 46 Please review these documents carefully, as they describe your rights 47 and restrictions with respect to this document. Code Components 48 extracted from this document must include Simplified BSD License text 49 as described in Section 4.e of the Trust Legal Provisions and are 50 provided without warranty as described in the Simplified BSD License. 52 Table of Contents 54 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 55 2. Conventions used in this document . . . . . . . . . . . . . . 3 56 3. Consideration for flagging passive interface . . . . . . . . 3 57 4. Passive Interface Attribute . . . . . . . . . . . . . . . . . 4 58 4.1. OSPFv2 Extended Stub-Link TLV . . . . . . . . . . . . . . 4 59 4.2. OSPFv3 Router-Stub-Link TLV . . . . . . . . . . . . . . . 5 60 4.3. ISIS Stub-link TLV . . . . . . . . . . . . . . . . . . . 6 61 4.4. Stub-Link Prefix Sub-TLV . . . . . . . . . . . . . . . . 7 62 5. Security Considerations . . . . . . . . . . . . . . . . . . . 8 63 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 64 7. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 9 65 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 9 66 8.1. Normative References . . . . . . . . . . . . . . . . . . 9 67 8.2. Informative References . . . . . . . . . . . . . . . . . 10 68 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 11 70 1. Introduction 72 Stub links are used commonly within an operators enterprise or 73 service provider networks. One of the most common use cases for stub 74 links is in a data center Layer 2 and Layer 3 Top of Rack(TOR) switch 75 where the inter connected links between the TOR switches and uplinks 76 to the core switch are only a few links and a majority of the links 77 are Layer 3 VLAN switched virtual interface trunked between the TOR 78 switches serving Layer 2 broadcast domains. In this scenario all the 79 VLANs are made as stub links as it is recommended to limit the number 80 of network LSAs between routers and switches to avoid unnecessary 81 hello processing overhead. 83 Another common use case is an inter-as routing scenario where the 84 same routing protocol but different IGP instance is running between 85 the adjacent BGP domains. Using stub link on the inter-as 86 connections can ensure that prefixes contained within a domain are 87 only reachable within the domain itself and not allow the link state 88 database to be merged between domain which could result in 89 undesirable consequences. 91 For operator which runs different IGP domains that interconnect with 92 each other via the stub links, there is desire to obtain the inter-as 93 topology information as described in 94 [I-D.ietf-idr-bgpls-inter-as-topology-ext]. If the router that runs 95 BGP-LS within one IGP domain can distinguish stub links from other 96 normal interfaces, it is then easy for the router to report these 97 stub links using BGP-LS to a centralized PCE controller. 99 Draft [I-D.dunbar-lsr-5g-edge-compute-ospf-ext] describes the case 100 that edge compute server attach the network and needs to flood some 101 performance index information to the network to facilitate the 102 network select the optimized application resource. The edge compute 103 server will also not run IGP protocol. 105 And, stub links are normally the boundary of one IGP domain, knowing 106 them can facilitate the operators to apply various policies on such 107 interfaces, for example, to secure their networks, or filtering the 108 incoming traffic with scrutiny. 110 But OSPF and ISIS have no position to flag such stub links and their 111 associated attributes now. 113 This document defines the protocol extension for OSPF and ISIS to 114 indicate the stub links and their associated attributes. 116 2. Conventions used in this document 118 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 119 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 120 document are to be interpreted as described in [RFC2119] . 122 3. Consideration for flagging passive interface 124 ISIS[RFC5029] defines the Link-Attributes Sub-TLV to carry the link 125 attribute information, but this Sub-TLV can only be carried within 126 the TLV 22, which is used to described the attached neighbor. For 127 stub link, there is no ISIS neighbor, then it is not appropriate to 128 use this Sub-TLV to indicate the attribute of such link. 130 OSPFv2[RFC2328] defines link type field within Router LSA, the type 3 131 for connections to a stub network can be used to identified the stub 132 link. But in OSPFv3[RFC5340], type 3 within the Router-LSA has been 133 reserved. The information that associated with stub network has been 134 put in the Intra-Area-Prefix-LSAs. 136 It is necessary to define one general solution for ISIS and OSPF to 137 flag the stub link and transfer the associated attributes then. 139 4. Passive Interface Attribute 141 The following sections define the protocol extension to indicate the 142 stub link and its associated attributes in OSPFv2/v3 and ISIS. 144 4.1. OSPFv2 Extended Stub-Link TLV 146 [RFC7684] defines the OSPFv2 Extended Link Opaque LSA to contain the 147 additional link attribute TLV. Currently, only OSPFv2 Extended Link 148 TLV is defined to contain the link related sub-TLV. Because stub 149 link is not the normal link that participate in the OSPFv2 process, 150 we select to define one new top TLV within the OSPFv2 Extended Link 151 Opaque LSA to contain the stub link related attribute information. 153 The OSPFv2 Extended Stub-Link TLV has the following format: 155 0 1 2 3 156 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 1 157 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 158 | Type(Stub-Link) | Length | 159 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 160 | Link Type | Reserved | Metric | 161 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 162 | Link ID | 163 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 164 | Link Data | 165 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 166 | Sub-TLVs (variable) | 167 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 168 Figure 1: OSPFv2 Extended Stub-Link TLV 170 Type: The TLV type. The value is 2(TBD) for this stub-link type 172 Length: Variable, dependent on sub-TLVs 174 Link Type: Define the type of the stub-link. This document defines 175 the followings type: 177 * 0: Reserved 179 * 1: AS boundary link 181 * 2: Loopback link 183 * 3: Vlan interface link 185 * 4-255: For future extension 186 Metric: Link metric used for inter-AS traffic engineering. 188 Link ID: Link ID is defined in Section A.4.2 of [RFC2328] 190 Link Data: Link Data is defined in Section A.4.2 of [RFC2328] 192 Sub-TLVs: Existing sub-TLV that defined within "OSPFv2 Extended Link 193 TLV Sub-TLV" can be included if necessary, the definition of new sub- 194 TLV can refer to Section 4.4 196 If this TLV is advertised multiple times in the same OSPFv2 Extended 197 Link Opaque LSA, only the first instance of the TLV is used by 198 receiving OSPFv2 routers. This situation SHOULD be logged as an 199 error. 201 If this TLV is advertised multiple times for the same link in 202 different OSPFv2 Extended Link Opaque LSAs originated by the same 203 OSPFv2 router, the OSPFv2 Extended Stub-Link TLV in the OSPFv2 204 Extended Link Opaque LSA with the smallest Opaque ID is used by 205 receiving OSPFv2 routers. This situation may be logged as a warning. 207 It is RECOMMENDED that OSPFv2 routers advertising OSPFv2 Extended 208 Stub-Link TLVs in different OSPFv2 Extended Link Opaque LSAs re- 209 originate these LSAs in ascending order of Opaque ID to minimize the 210 disruption. 212 This document creates a registry for Stub-Link attribute in 213 Section 6. 215 4.2. OSPFv3 Router-Stub-Link TLV 217 [RFC8362] extend the LSA format by encoding the existing OSPFv3 LSA 218 [RFC5340] in TLV tuples and allowing advertisement of additional 219 information with additional TLV. 221 This document defines the Router-Stub-Link TLV to describes stub link 222 of a single router. The Router-Stub-Link TLV is only applicable to 223 the E-Router-LSA. Inclusion in other Extended LSA MUST be ignored. 225 0 1 2 3 226 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 1 227 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 228 | Type(Router-Stub-Link) | Length | 229 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 230 | Link Type | Reserved | Metric | 231 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 232 | Interface ID | 233 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 234 | Sub-TLVs(Variable) | 235 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 236 Figure 2: OSPFv3 Router-Stub-Link TLV 238 Type: OSPFv3 Extended-LSA TLV Type. Value is 10(TBD) for Router- 239 Stub-Link TLV. 241 Length: Variable, dependent on sub-TLVs 243 Link Type: Define the type of the stub-link. This document defines 244 the followings type: 246 * 0: Reserved 248 * 1: AS boundary link 250 * 2: Loopback link 252 * 3: Vlan interface link 254 * 4-255: For future extension 256 Metric: Link metric used for inter-AS traffic engineering. 258 Interface ID: 32-bit number uniquely identifying this interface among 259 the collection of this router's interfaces. For example, in some 260 implementations it may be possible to use the MIB-II IfIndex 261 [RFC2863]. 263 Sub-TLVs: Existing sub-TLV that defined within "OSPFv3 Extended-LSA 264 Sub-TLV" can be included if necessary. The definition of new sub-TLV 265 can refer to Section 4.4. 267 4.3. ISIS Stub-link TLV 269 This document defines one new top TLV to contain the stub link 270 attributes, which is shown in Figure 4: 272 0 1 2 3 273 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 1 274 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 275 | Type(Stub-Link) | Length | 276 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 277 | Link Type | Reserved | Metric | 278 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 279 | Interface ID | 280 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 281 | Sub-TLVs(Variable) | 282 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 283 Figure 3: ISIS Stub-Link TLV 285 Type: ISIS TLV Codepoint. Value is 28(TBD) for stub-link TLV. 287 Length: Variable, dependent on sub-TLVs 289 Link Type: Define the type of the stub-link. This document defines 290 the followings type: 292 * 0: Reserved 294 * 1: AS boundary link 296 * 2: Loopback link 298 * 3: Vlan interface link 300 * 4-255: For future extension 302 Metric: Link metric used for inter-AS traffic engineering. 304 Interface ID: 32-bit number uniquely identifying this interface among 305 the collection of this router's interfaces. For example, in some 306 implementations it may be possible to use the MIB-II IfIndex 307 [RFC2863]. 309 Sub-TLVs: Existing sub-TLV that defined within "Sub-TLVs for TLVs 22, 310 23, 25, 141, 222, and 223" can be included if necessary. The 311 definition of new sub-TLV can refer to Section 4.4. 313 4.4. Stub-Link Prefix Sub-TLV 315 This document defines one new sub-TLV that can be contained within 316 the OSPFv2 Extended Stub-Link TLV , OSPFv3 Router-Stub-Link TLV or 317 ISIS Stub-Link TLV, to describe the prefix information associated 318 with the stub link. 320 The format of the sub-TLV is the followings: 322 0 1 2 3 323 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 1 324 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 325 | Type | Length | 326 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 327 | IPv4 Prefix or IPv6 Prefix Subobject | 328 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 329 Figure 4: Stub-Link Prefix Sub-TLV 331 Type: The TLV type. The value is 01(TBD) for this Stub-Link Prefix 332 type 334 Length: Variable, dependent on associated subobjects 336 Subobject: IPv4 prefix subobject or IPv6 prefix subobject, as that 337 defined in [RFC3209] 339 If the stub link has multiple address, then multiple subobjects will 340 be included within this sub-TLV. 342 5. Security Considerations 344 Security concerns for ISIS are addressed in [RFC5304] and[RFC5310] 346 Security concern for OSPFv3 is addressed in [RFC4552] 348 Advertisement of the additional information defined in this document 349 introduces no new security concerns. 351 6. IANA Considerations 353 IANA is requested to the allocation in following registries: 355 +=========================+===========+======================+ 356 | Registry | Type | Meaning | 357 +=========================+===========+======================+ 358 |OSPFv2 Extended Link | 2 |Stub-Link TLV | 359 |Opaque LSA TLV | | | 360 +-------------------------+-----------+----------------------+ 361 |OSPFv3 Extended-LSA TLV | 10 |Router-Stub-Link TLV | 362 +-------------------------+-----------+----------------------+ 363 |IS-IS TLV Codepoint | 28 |Stub-Link TLV | 364 +-------------------------+-----------+----------------------+ 365 Figure 5: Newly defined TLV in existing IETF registry 367 IANA is requested to allocate one new registry that can be referred 368 by OSPFv2, OSPFv3 and ISIS respectively. 370 +=========================+==================================+ 371 | New Registry | Meaning | 372 +=========================+==================================+ 373 |Stub-Link Attribute | Attributes for stub-link | 374 +-------------------------+----------------------------------+ 375 Figure 6: Newly defined Registry for stub-link attributes 377 One new sub-TLV is defined in this document under this registry 378 codepoint: 380 +=========================+===========+===============================+ 381 | Registry | Type | Meaning | 382 +=========================+===========+===============================+ 383 |Stub-Link Attribute | 0 | Reserved 384 +=========================+===========+===============================+ 385 | | 1 |Stub-Link Prefix sub-TLV | 386 +-------------------------+-----------+-------------------------------+ 387 | | 2-65535 |Reserved | 388 +-------------------------+-----------+-------------------------------+ 389 Figure 7: Stub-Link Prefix Sub-TLV 391 7. Acknowledgement 393 Thanks Shunwan Zhang, Tony Li, Les Ginsberg, Acee Lindem, Dhruv 394 Dhody, Jeff Tantsura and Robert Raszuk for their suggestions and 395 comments on this idea. 397 8. References 399 8.1. Normative References 401 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 402 Requirement Levels", BCP 14, RFC 2119, 403 DOI 10.17487/RFC2119, March 1997, 404 . 406 [RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328, 407 DOI 10.17487/RFC2328, April 1998, 408 . 410 [RFC2863] McCloghrie, K. and F. Kastenholz, "The Interfaces Group 411 MIB", RFC 2863, DOI 10.17487/RFC2863, June 2000, 412 . 414 [RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V., 415 and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP 416 Tunnels", RFC 3209, DOI 10.17487/RFC3209, December 2001, 417 . 419 [RFC4552] Gupta, M. and N. Melam, "Authentication/Confidentiality 420 for OSPFv3", RFC 4552, DOI 10.17487/RFC4552, June 2006, 421 . 423 [RFC5029] Vasseur, JP. and S. Previdi, "Definition of an IS-IS Link 424 Attribute Sub-TLV", RFC 5029, DOI 10.17487/RFC5029, 425 September 2007, . 427 [RFC5304] Li, T. and R. Atkinson, "IS-IS Cryptographic 428 Authentication", RFC 5304, DOI 10.17487/RFC5304, October 429 2008, . 431 [RFC5310] Bhatia, M., Manral, V., Li, T., Atkinson, R., White, R., 432 and M. Fanto, "IS-IS Generic Cryptographic 433 Authentication", RFC 5310, DOI 10.17487/RFC5310, February 434 2009, . 436 [RFC5340] Coltun, R., Ferguson, D., Moy, J., and A. Lindem, "OSPF 437 for IPv6", RFC 5340, DOI 10.17487/RFC5340, July 2008, 438 . 440 [RFC7684] Psenak, P., Gredler, H., Shakir, R., Henderickx, W., 441 Tantsura, J., and A. Lindem, "OSPFv2 Prefix/Link Attribute 442 Advertisement", RFC 7684, DOI 10.17487/RFC7684, November 443 2015, . 445 [RFC7794] Ginsberg, L., Ed., Decraene, B., Previdi, S., Xu, X., and 446 U. Chunduri, "IS-IS Prefix Attributes for Extended IPv4 447 and IPv6 Reachability", RFC 7794, DOI 10.17487/RFC7794, 448 March 2016, . 450 [RFC8362] Lindem, A., Roy, A., Goethals, D., Reddy Vallem, V., and 451 F. Baker, "OSPFv3 Link State Advertisement (LSA) 452 Extensibility", RFC 8362, DOI 10.17487/RFC8362, April 453 2018, . 455 8.2. Informative References 457 [I-D.dunbar-lsr-5g-edge-compute-ospf-ext] 458 Dunbar, L., Chen, H., and A. Wang, "OSPF extension for 5G 459 Edge Computing Service", Work in Progress, Internet-Draft, 460 draft-dunbar-lsr-5g-edge-compute-ospf-ext-04, 10 March 461 2021, . 464 [I-D.ietf-idr-bgpls-inter-as-topology-ext] 465 Wang, A., Chen, H., Talaulikar, K., and S. Zhuang, "BGP-LS 466 Extension for Inter-AS Topology Retrieval", Work in 467 Progress, Internet-Draft, draft-ietf-idr-bgpls-inter-as- 468 topology-ext-09, 28 September 2020, 469 . 472 Authors' Addresses 474 Aijun Wang 475 China Telecom 476 Beiqijia Town, Changping District 477 Beijing 478 102209 479 China 481 Email: wangaj3@chinatelecom.cn 483 Zhibo Hu 484 Huawei Technologies 485 Huawei Bld., No.156 Beiqing Rd. 486 Beijing 487 100095 488 China 490 Email: huzhibo@huawei.com 492 Gyan S. Mishra 493 Verizon Inc. 494 13101 Columbia Pike 495 Silver Spring, MD 20904 496 United States of America 498 Email: gyan.s.mishra@verizon.com 499 Jinsong Sun 500 ZTE Corporation 501 No. 68, Ziijnhua Road 502 Nan Jing 503 210012 504 China 506 Email: sun.jinsong@zte.com.cn