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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) ** Obsolete normative reference: RFC 7752 (Obsoleted by RFC 9552) ** Obsolete normative reference: RFC 8919 (Obsoleted by RFC 9479) ** Obsolete normative reference: RFC 8920 (Obsoleted by RFC 9492) == Outdated reference: A later version (-19) exists of draft-ietf-idr-eag-distribution-12 == Outdated reference: A later version (-26) exists of draft-ietf-lsr-flex-algo-13 Summary: 3 errors (**), 0 flaws (~~), 3 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Inter-Domain Routing K. Talaulikar 3 Internet-Draft P. Psenak 4 Intended status: Standards Track Cisco Systems 5 Expires: May 17, 2021 J. Tantsura 6 Apstra 7 November 13, 2020 9 Application-Specific Attributes Advertisement with BGP Link-State 10 draft-ietf-idr-bgp-ls-app-specific-attr-04 12 Abstract 14 Various link attributes have been defined in link-state routing 15 protocols like OSPF and IS-IS in the context of the MPLS Traffic 16 Engineering (TE) and GMPLS. BGP Link-State (BGP-LS) extensions have 17 been defined to distribute these attributes along with other topology 18 information from these link-state routing protocols. Many of these 19 link attributes can be used for applications other than MPLS-TE or 20 GMPLS. 22 Extensions to link-state routing protocols have been defined for such 23 link attributes that enable distribution of their application- 24 specific values. This document defines extensions to BGP-LS address- 25 family to enable advertisement of these application-specific 26 attributes as a part of the topology information from the network. 28 Status of This Memo 30 This Internet-Draft is submitted in full conformance with the 31 provisions of BCP 78 and BCP 79. 33 Internet-Drafts are working documents of the Internet Engineering 34 Task Force (IETF). Note that other groups may also distribute 35 working documents as Internet-Drafts. The list of current Internet- 36 Drafts is at https://datatracker.ietf.org/drafts/current/. 38 Internet-Drafts are draft documents valid for a maximum of six months 39 and may be updated, replaced, or obsoleted by other documents at any 40 time. It is inappropriate to use Internet-Drafts as reference 41 material or to cite them other than as "work in progress." 43 This Internet-Draft will expire on May 17, 2021. 45 Copyright Notice 47 Copyright (c) 2020 IETF Trust and the persons identified as the 48 document authors. All rights reserved. 50 This document is subject to BCP 78 and the IETF Trust's Legal 51 Provisions Relating to IETF Documents 52 (https://trustee.ietf.org/license-info) in effect on the date of 53 publication of this document. Please review these documents 54 carefully, as they describe your rights and restrictions with respect 55 to this document. Code Components extracted from this document must 56 include Simplified BSD License text as described in Section 4.e of 57 the Trust Legal Provisions and are provided without warranty as 58 described in the Simplified BSD License. 60 Table of Contents 62 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 63 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3 64 2. Application Specific Link Attributes TLV . . . . . . . . . . 3 65 3. Application Specific Link Attributes . . . . . . . . . . . . 5 66 4. Procedures . . . . . . . . . . . . . . . . . . . . . . . . . 7 67 5. Deployment Considerations . . . . . . . . . . . . . . . . . . 9 68 6. Backward Compatibility . . . . . . . . . . . . . . . . . . . 9 69 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10 70 8. Manageability Considerations . . . . . . . . . . . . . . . . 10 71 8.1. Operational Considerations . . . . . . . . . . . . . . . 10 72 8.2. Management Considerations . . . . . . . . . . . . . . . . 10 73 9. Security Considerations . . . . . . . . . . . . . . . . . . . 10 74 10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 11 75 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 11 76 11.1. Normative References . . . . . . . . . . . . . . . . . . 11 77 11.2. Informative References . . . . . . . . . . . . . . . . . 11 78 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 12 80 1. Introduction 82 Various link attributes have been defined in link-state routing 83 protocols (viz., IS-IS [RFC1195], OSPFv2 [RFC2328] and OSPFv3 84 [RFC5340] ) in the context of the MPLS traffic engineering and GMPLS. 85 All these attributes are distributed by these protocols using TLVs 86 that were originally defined for traditional MPLS Traffic Engineering 87 (i.e., using RSVP-TE [RFC3209]) or GMPLS [RFC4202] applications. 89 In recent years new applications have been introduced that have use 90 cases for many of the link attributes historically used by RSVP-TE 91 and GMPLS. Such applications include Segment Routing (SR) [RFC8402] 92 and Loop Free Alternates (LFA) [RFC5286]. This has introduced 93 ambiguity in that if a deployment includes a mix of RSVP-TE support 94 and SR support (for example) it is not possible to unambiguously 95 indicate which advertisements are to be used by RSVP-TE and which 96 advertisements are to be used by SR. If the topologies are fully 97 congruent this may not be an issue, but any incongruence leads to 98 ambiguity. An additional issue arises in cases where both 99 applications are supported on a link but the link attribute values 100 associated with each application differ. Current advertisements do 101 not support advertising application-specific values for the same 102 attribute on a specific link. IGP Flexible Algorithm 103 [I-D.ietf-lsr-flex-algo] is one such application use case that MAY 104 use application-specific link attributes. 106 [RFC8920] and [RFC8919] define extensions for OSPF and IS-IS 107 respectively that address these issues. Also, as evolution of use 108 cases for link attributes can be expected to continue in the years to 109 come, these documents define a solution that is easily extensible to 110 the introduction of new applications and new use cases. 112 BGP Link-State extensions [RFC7752] have been specified to enable 113 distribution of the link-state topology information from the IGPs to 114 an application like a controller or Path Computation Engine (PCE) via 115 BGP. The controller/PCE gets the end-to-end topology information 116 across IGP domains so it can perform path computations for use cases 117 like end-to-end traffic engineering (TE) using RSVP-TE or SR-based 118 mechanisms. A similar challenge to what was described above is hence 119 also faced by such centralized computation entities. 121 There is thus a need for BGP-LS extensions to also report link 122 attributes on a per-application basis on the same lines as introduced 123 in the link-state routing protocols. This document defines these 124 BGP-LS extensions and also covers the backward compatibility issues 125 related to existing BGP-LS deployments. 127 1.1. Requirements Language 129 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 130 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 131 "OPTIONAL" in this document are to be interpreted as described in BCP 132 14 [RFC2119] [RFC8174] when, and only when, they appear in all 133 capitals, as shown here. 135 2. Application Specific Link Attributes TLV 137 The BGP-LS [RFC7752] specifies the Link NLRI for advertisement of 138 links and their attributes using the BGP-LS Attribute. The 139 Application-Specific Link Attributes (ASLA) TLV is a new optional 140 top-level BGP-LS Attribute TLV that is introduced for Link NLRIs. It 141 is defined such that it may act as a container for certain existing 142 and future link attributes that require application-specific 143 definition. 145 The format of this TLV is as follows and is similar to the 146 corresponding ASLA sub-TLVs defined for OSPF and IS-IS in [RFC8920] 147 and [RFC8919] respectively. 149 0 1 2 3 150 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 1 151 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 152 | Type | Length | 153 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 154 | SABML | UDABML | Reserved | 155 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 156 | Standard Application Identifier Bit Mask (variable) // 157 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 158 | User-Defined Application Identifier Bit Mask (variable) // 159 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 160 | Link Attribute sub-TLVs // 161 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 163 Figure 1: Application-Specific Link Attributes TLV 165 where: 167 o Type: 1122 169 o Length: variable. 171 o SABML : Standard Application Identifier Bit Mask Length in octets. 172 The values MUST be 0, 4, or 8. If the Standard Application 173 Identifier Bit Mask is not present, the SABML MUST be set to 0. 175 o UDABML : User-Defined Application Identifier Bit Mask Length in 176 octets. The values MUST be 0, 4, or 8. If the User-Defined 177 Application Identifier Bit Mask is not present, the UDABML MUST be 178 set to 0. 180 o Standard Application Identifier Bit Mask : of size 0, 4, or 8 181 octets as indicated by the SABML. Optional set of bits, where 182 each bit represents a single standard application. The bits are 183 defined in the IANA "IGP Parameters" registries under the "Link 184 Attribute Applications" registry [RFC8919]. 186 o User-Defined Application Identifier Bit Mask : of size 0, 4, or 8 187 octets as indicated by the UDABML. Optional set of bits, where 188 each bit represents a single user-defined application. The bits 189 are not managed or assigned by IANA or any other standards body 190 and definition is left to the implementation. 192 o sub-TLVs : BGP-LS Attribute TLVs corresponding to the Link NLRI 193 that are application-specific (as specified in Section 3) are 194 included as sub-TLVs of the ASLA TLV. 196 An ASLA TLV with both the SABML and UDABML set to 0 (i.e. without any 197 application identifier bit masks) indicates that the link attribute 198 sub-TLVs that it encloses are applicable for all applications. 200 The ASLA TLV and its sub-TLVs can only be added to the BGP-LS 201 Attribute associated with the Link NLRI of the node that originates 202 the underlying IGP link attribute TLVs/sub-TLVs. The procedures for 203 originating link attributes in the ASLA TLV from underlying IGPs are 204 specified in Section 4. 206 When the node is not running any of the IGPs but running a protocol 207 like BGP, then the link attributes for the node's local links MAY be 208 originated as part of the BGP-LS Attribute using the ASLA TLV and its 209 sub-TLVs within the Link NLRI corresponding to the local node. 211 3. Application Specific Link Attributes 213 Several BGP-LS Attribute TLVs corresponding to the Link NLRI are 214 defined in BGP-LS and more may be added in the future. The following 215 types of link attributes are required to be considered as application 216 specific. 218 o those that have different values for different applications (e.g., 219 a different TE metric value used for RSVP-TE than for SR TE) 221 o those that are applicable to multiple applications but need to be 222 used only by specific application (e.g., certain SRLG values are 223 configured on a node for LFA but the same do not need to be used 224 for RSVP-TE) 226 The following table lists the currently defined BGP-LS Attributes 227 TLVs corresponding to Link NLRI that have application-specific 228 semantics. They were originally defined with semantics for RSVP-TE 229 and GMPLS applications. 231 +----------+----------------------+---------------------------------+ 232 | TLV Code | Description | Reference Document | 233 | Point | | | 234 +----------+----------------------+---------------------------------+ 235 | 1088 | Administrative group | [RFC7752] | 236 | | (color) | | 237 | 1092 | TE Metric | [RFC7752] | 238 | 1096 | SRLG | [RFC7752] | 239 | 1114 | Unidirectional link | [RFC8571] | 240 | | delay | | 241 | 1115 | Min/Max | [RFC8571] | 242 | | Unidirectional link | | 243 | | delay | | 244 | 1116 | Unidirectional link | [RFC8571] | 245 | | delay variation | | 246 | 1117 | Unidirectional | [RFC8571] | 247 | | packet loss | | 248 | 1118 | Unidirectional | [RFC8571] | 249 | | residual bandwidth | | 250 | 1119 | Unidirectional | [RFC8571] | 251 | | available bandwidth | | 252 | 1120 | Unidirectional | [RFC8571] | 253 | | bandwidth | | 254 | | utilization | | 255 | 1173 | Extended | [I-D.ietf-idr-eag-distribution] | 256 | | Administrative group | | 257 | | (color) | | 258 +----------+----------------------+---------------------------------+ 260 Table 1: BGP-LS Attribute TLVs also used as sub-TLVs of ASLA TLV 262 All the BGP-LS Attribute TLVs defined in the table above are 263 RECOMMENDED to continue to be advertised at the top-level in the BGP- 264 LS Attribute for carrying attributes specific to RSVP-TE without the 265 use of the ASLA TLV. 267 When a new link attribute is introduced, it may be thought of as 268 being specific to only a single application. However, subsequently, 269 it may be also shared by other applications and/or require 270 application-specific values. In such cases, it is RECOMMENDED to err 271 on the side of caution and define such attributes as application- 272 specific to ensure flexibility in the future. 274 BGP-LS Attribute TLVs corresponding to Link NLRI that are defined in 275 the future MUST specify if they are application-specific and hence 276 are REQUIRED to be encoded within an ASLA TLV. 278 Only application-specific link attributes need to be advertised 279 within the ASLA TLV. Link attributes that do not have application- 280 specific semantics SHOULD NOT be advertised within the ASLA TLV. 281 Receivers SHOULD ignore any non-application-specific attribute sub- 282 TLVs within the ASLA TLV. 284 4. Procedures 286 The procedures described in this section apply to networks where all 287 BGP-LS originators and consumers support this specification. The 288 backward compatibility aspects and operations in deployments where 289 there are some BGP-LS originators or consumers that do not support 290 this specification are described further in Section 6. 292 The BGP-LS originator learns of the association of an application- 293 specific attribute to one or more applications from either the 294 underlying IGP protocol LSA/LSPs from which it is advertising the 295 topology information or from the local node configuration when 296 advertising attributes for the local node only. 298 The association of an application-specific link attribute with a 299 specific application context when advertising attributes for the 300 local node only (e.g., when running BGP as the only routing protocol) 301 is an implementation specific matter and outside the scope of this 302 document. 304 [RFC8920] and [RFC8919] specify the mechanisms for advertising 305 application-specific link attributes in OSPFv2/v3 and IS-IS 306 respectively. These IGP specifications also describe the backward 307 compatibility aspects and the existing RSVP-TE/GMPLS specific TLV 308 encoding mechanisms in the respective protocols. 310 A BGP-LS originator node that is advertising link-state information 311 from the underlying IGP determines the protocol encoding of 312 application-specific link attributes based on the following rules: 314 1. Application-specific link attributes received from an IGP node 315 using existing RSVP-TE/GMPLS encodings MUST be encoded using the 316 respective BGP-LS top-level TLVs listed in Table 1. 318 2. Application-specific link attributes received from an IGP node 319 using ASLA sub-TLV MUST be encoded in the BGP-LS ASLA TLV as sub- 320 TLVs. 322 3. In case of IS-IS, the following specific procedures are to be 323 followed: 325 * When application-specific link attributes are received from a 326 node with the L bit set in the ASLA sub-TLV AND application 327 bits other than RSVP-TE are set in the application bit masks 328 then the application-specific link attributes advertised in 329 the corresponding legacy IS-IS TLVs/sub-TLVs MUST be encoded 330 within the BGP-LS ASLA TLV as sub-TLVs with the application 331 bits, other than the RSVP-TE bit, copied from the IS-IS ASLA 332 sub-TLV. The link attributes advertised in the legacy IS-IS 333 TLVs/sub-TLVs are also advertised in BGP-LS top-level TLVs 334 listed in Table 1. Note that this is true regardless of 335 whether the RSVP-TE bit was set in the IS-IS ASLA TLV/sub-TLV. 337 * When the ASLA sub-TLV has the RSVP-TE application bit set, 338 then the link attributes for the corresponding ASLA sub-TLV 339 MUST be encoded using the respective BGP-LS top-level TLVs 340 listed in Table 1. 342 * [RFC8919] allows the advertisement of the Maximum Link 343 Bandwidth within an ASLA sub-TLV even though it is not an 344 application-specific attribute. However, when originating the 345 Maximum Link Bandwidth into BGP-LS, the attribute MUST be 346 encoded only in the top-level BGP-LS Maximum Link Bandwidth 347 TLV (1089) and not within the BGP-LS ASLA TLV. 349 * [RFC8919] also allows the advertisement of the Maximum 350 Reservable Link Bandwidth and the Unreserved Bandwidth within 351 an ASLA sub-TLV even though these attributes are specific to 352 RSVP-TE application. However, when originating the Maximum 353 Reservable Link Bandwidth and Unreserved Bandwidth into BGP- 354 LS, these attributes MUST be encoded only in the BGP-LS top- 355 level Maximum Reservable Link Bandwidth TLV (1090) and 356 Unreserved Bandwidth TLV (1091) respectively and not within 357 the BGP-LS ASLA TLV. 359 These rules ensure that a BGP-LS originator performs the 360 advertisement for all application-specific link attributes from the 361 IGP nodes that support or do not support the ASLA extension. 362 Furthermore, it also ensures that the top-level BGP-LS TLVs defined 363 for RSVP-TE and GMPLS applications continue to be used for 364 advertisement of their application-specific attributes. 366 A BGP-LS consumer node would normally receive all the application- 367 specific link attributes corresponding to RSVP-TE and GMPLS 368 applications as existing top-level BGP-LS TLVs while for other 369 applications they are encoded in ASLA TLV(s) with appropriate 370 applicable bit mask setting. A BGP-LS consumer that implements this 371 specification SHOULD prefer the application-specific attribute value 372 received via sub-TLVs within the ASLA TLV over the value received via 373 the top level TLVs. 375 5. Deployment Considerations 377 SR-TE and LFA applications have been deployed in some networks using 378 the IGP link attributes defined originally for RSVP-TE as discussed 379 in [RFC8920] and [RFC8919]. The corresponding BGP-LS top-level link 380 attribute TLVs originally defined for RSVP-TE have also been 381 similarly used for SR-TE and LFA applications by BGP-LS consumers. 382 Such usage MAY continue without requiring the support of the 383 application-specific link attribute encodings described in this 384 document as long as the following conditions are met: 386 o The application is SRTE or LFA and RSVP-TE is not deployed 387 anywhere in the network 389 o The application is SRTE or LFA, RSVP-TE is deployed in the 390 network, and both the set of links on which SRTE and/or LFA 391 advertisements are required and the attribute values used by SRTE 392 and/or LFA on all such links is fully congruent with the links and 393 attribute values used by RSVP-TE 395 6. Backward Compatibility 397 The backward compatibility aspects for BGP-LS are associated with the 398 originators (i.e., nodes) and consumers (e.g., PCE, controllers, 399 applications, etc.) of the topology information. BGP-LS 400 implementations have been originating link attributes and consuming 401 them without any application-specific scoping prior to the extensions 402 specified in this document. 404 IGP backwards compatibility aspects associated with application- 405 specific link attributes for RSVP-TE, SRTE and LFA applications are 406 discussed in the Backward Compatibility sections of [RFC8920] and 407 [RFC8919]. While the backwards compatibility aspects ensure 408 compatibility of IGP advertisements, they also serve to ensure the 409 backward compatibility of the BGP-LS advertisements used by BGP-LS 410 consumers. In deployments where the BGP-LS originators or consumers 411 do not support the extensions specified in this document, the IGPs 412 need to continue to advertise link attributes intended for use by 413 SRTE and LFA applications using the RSVP-TE/GMPLS encodings. This 414 allows BGP-LS advertisements to be consistent with the behavior prior 415 to the extensions defined in this document 417 It is RECOMMENDED that nodes that support this specification are 418 selected as originators of BGP-LS information when advertising the 419 link-state information from the IGPs. 421 7. IANA Considerations 423 This document requests assignment of code-points from the registry 424 "BGP-LS Node Descriptor, Link Descriptor, Prefix Descriptor, and 425 Attribute TLVs" based on table below which reflects the values 426 assigned via the early allocation process. The column "IS-IS TLV/ 427 Sub-TLV" defined in the registry does not require any value and 428 should be left empty. 430 +------------+------------------------------------------+----------+ 431 | Code Point | Description | Length | 432 +------------+------------------------------------------+----------+ 433 | 1122 | Application-Specific Link Attributes TLV | variable | 434 +------------+------------------------------------------+----------+ 436 8. Manageability Considerations 438 This section is structured as recommended in [RFC5706]. 440 The new protocol extensions introduced in this document augment the 441 existing IGP topology information defined in [RFC7752]. Procedures 442 and protocol extensions defined in this document do not affect the 443 BGP protocol operations and management other than as discussed in the 444 Manageability Considerations section of [RFC7752]. Specifically, the 445 malformed NLRIs attribute tests in the Fault Management section of 446 [RFC7752] now encompass the BGP-LS TLVs defined in this document. 448 8.1. Operational Considerations 450 No additional operation considerations are defined in this document. 452 8.2. Management Considerations 454 No additional management considerations are defined in this document. 456 9. Security Considerations 458 The new protocol extensions introduced in this document augment the 459 existing IGP topology information defined in [RFC7752]. Procedures 460 and protocol extensions defined in this document do not affect the 461 BGP security model other than as discussed in the Security 462 Considerations section of [RFC7752]. 464 10. Acknowledgements 466 The authors would like to thank Les Ginsberg, Baalajee S, Amalesh 467 Maity, and Acee Lindem for their review and feedback on this 468 document. 470 11. References 472 11.1. Normative References 474 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 475 Requirement Levels", BCP 14, RFC 2119, 476 DOI 10.17487/RFC2119, March 1997, 477 . 479 [RFC7752] Gredler, H., Ed., Medved, J., Previdi, S., Farrel, A., and 480 S. Ray, "North-Bound Distribution of Link-State and 481 Traffic Engineering (TE) Information Using BGP", RFC 7752, 482 DOI 10.17487/RFC7752, March 2016, 483 . 485 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 486 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 487 May 2017, . 489 [RFC8919] Ginsberg, L., Psenak, P., Previdi, S., Henderickx, W., and 490 J. Drake, "IS-IS Application-Specific Link Attributes", 491 RFC 8919, DOI 10.17487/RFC8919, October 2020, 492 . 494 [RFC8920] Psenak, P., Ed., Ginsberg, L., Henderickx, W., Tantsura, 495 J., and J. Drake, "OSPF Application-Specific Link 496 Attributes", RFC 8920, DOI 10.17487/RFC8920, October 2020, 497 . 499 11.2. Informative References 501 [I-D.ietf-idr-eag-distribution] 502 Wang, Z., WU, Q., Tantsura, J., and K. Talaulikar, 503 "Distribution of Traffic Engineering Extended Admin Groups 504 using BGP-LS", draft-ietf-idr-eag-distribution-12 (work in 505 progress), May 2020. 507 [I-D.ietf-lsr-flex-algo] 508 Psenak, P., Hegde, S., Filsfils, C., Talaulikar, K., and 509 A. Gulko, "IGP Flexible Algorithm", draft-ietf-lsr-flex- 510 algo-13 (work in progress), October 2020. 512 [RFC1195] Callon, R., "Use of OSI IS-IS for routing in TCP/IP and 513 dual environments", RFC 1195, DOI 10.17487/RFC1195, 514 December 1990, . 516 [RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328, 517 DOI 10.17487/RFC2328, April 1998, 518 . 520 [RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V., 521 and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP 522 Tunnels", RFC 3209, DOI 10.17487/RFC3209, December 2001, 523 . 525 [RFC4202] Kompella, K., Ed. and Y. Rekhter, Ed., "Routing Extensions 526 in Support of Generalized Multi-Protocol Label Switching 527 (GMPLS)", RFC 4202, DOI 10.17487/RFC4202, October 2005, 528 . 530 [RFC5286] Atlas, A., Ed. and A. Zinin, Ed., "Basic Specification for 531 IP Fast Reroute: Loop-Free Alternates", RFC 5286, 532 DOI 10.17487/RFC5286, September 2008, 533 . 535 [RFC5340] Coltun, R., Ferguson, D., Moy, J., and A. Lindem, "OSPF 536 for IPv6", RFC 5340, DOI 10.17487/RFC5340, July 2008, 537 . 539 [RFC5706] Harrington, D., "Guidelines for Considering Operations and 540 Management of New Protocols and Protocol Extensions", 541 RFC 5706, DOI 10.17487/RFC5706, November 2009, 542 . 544 [RFC8402] Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L., 545 Decraene, B., Litkowski, S., and R. Shakir, "Segment 546 Routing Architecture", RFC 8402, DOI 10.17487/RFC8402, 547 July 2018, . 549 [RFC8571] Ginsberg, L., Ed., Previdi, S., Wu, Q., Tantsura, J., and 550 C. Filsfils, "BGP - Link State (BGP-LS) Advertisement of 551 IGP Traffic Engineering Performance Metric Extensions", 552 RFC 8571, DOI 10.17487/RFC8571, March 2019, 553 . 555 Authors' Addresses 556 Ketan Talaulikar 557 Cisco Systems 558 India 560 Email: ketant@cisco.com 562 Peter Psenak 563 Cisco Systems 564 Slovakia 566 Email: ppsenak@cisco.com 568 Jeff Tantsura 569 Apstra 571 Email: jefftant.ietf@gmail.com