idnits 2.17.1 draft-ietf-isis-te-app-01.txt: Checking boilerplate required by RFC 5378 and the IETF Trust (see https://trustee.ietf.org/license-info): ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/1id-guidelines.txt: ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/checklist : ---------------------------------------------------------------------------- No issues found here. Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year == Line 521 has weird spacing: '...pecific y ...' == Line 528 has weird spacing: '...pecific n ...' -- The document date (October 12, 2017) is 2387 days in the past. Is this intentional? 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references to lower-maturity documents in RFCs) ** Obsolete normative reference: RFC 7810 (Obsoleted by RFC 8570) == Outdated reference: A later version (-06) exists of draft-filsfils-spring-segment-routing-policy-01 Summary: 1 error (**), 0 flaws (~~), 4 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Networking Working Group L. Ginsberg 3 Internet-Draft P. Psenak 4 Intended status: Standards Track Cisco Systems 5 Expires: April 15, 2018 S. Previdi 6 Individual 7 W. Henderickx 8 Nokia 9 J. Drake 10 Juniper Networks 11 October 12, 2017 13 IS-IS TE Attributes per application 14 draft-ietf-isis-te-app-01.txt 16 Abstract 18 Existing traffic engineering related link attribute advertisements 19 have been defined and are used in RSVP-TE deployments. In cases 20 where multiple applications wish to make use of these link attributes 21 the current advertisements do not support application specific values 22 for a given attribute nor do they support indication of which 23 applications are using the advertised value for a given link. 25 This draft introduces new link attribute advertisements which address 26 both of these shortcomings. It also discusses backwards 27 compatibility issues and how to minimize duplicate advertisements in 28 the presence of routers which do not support the extensions defined 29 in this document. 31 Requirements Language 33 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 34 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 35 document are to be interpreted as described in RFC 2119 [RFC2119]. 37 Status of This Memo 39 This Internet-Draft is submitted in full conformance with the 40 provisions of BCP 78 and BCP 79. 42 Internet-Drafts are working documents of the Internet Engineering 43 Task Force (IETF). Note that other groups may also distribute 44 working documents as Internet-Drafts. The list of current Internet- 45 Drafts is at https://datatracker.ietf.org/drafts/current/. 47 Internet-Drafts are draft documents valid for a maximum of six months 48 and may be updated, replaced, or obsoleted by other documents at any 49 time. It is inappropriate to use Internet-Drafts as reference 50 material or to cite them other than as "work in progress." 52 This Internet-Draft will expire on April 15, 2018. 54 Copyright Notice 56 Copyright (c) 2017 IETF Trust and the persons identified as the 57 document authors. All rights reserved. 59 This document is subject to BCP 78 and the IETF Trust's Legal 60 Provisions Relating to IETF Documents 61 (https://trustee.ietf.org/license-info) in effect on the date of 62 publication of this document. Please review these documents 63 carefully, as they describe your rights and restrictions with respect 64 to this document. Code Components extracted from this document must 65 include Simplified BSD License text as described in Section 4.e of 66 the Trust Legal Provisions and are provided without warranty as 67 described in the Simplified BSD License. 69 Table of Contents 71 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 72 2. Requirements Discussion . . . . . . . . . . . . . . . . . . . 3 73 3. Legacy Advertisements . . . . . . . . . . . . . . . . . . . . 4 74 3.1. Legacy sub-TLVs . . . . . . . . . . . . . . . . . . . . . 4 75 3.2. Legacy SRLG Advertisements . . . . . . . . . . . . . . . 5 76 4. Advertising Application Specific Link Attributes . . . . . . 5 77 4.1. Application Identifier Bit Mask . . . . . . . . . . . . . 5 78 4.2. Application Specific Link Attributes sub-TLV . . . . . . 7 79 4.3. Application Specific SRLG TLV . . . . . . . . . . . . . . 8 80 5. Deployment Considerations . . . . . . . . . . . . . . . . . . 9 81 6. Attribute Advertisements and Enablement . . . . . . . . . . . 10 82 7. Interoperability, Backwards Compatibility and Migration 83 Concerns . . . . . . . . . . . . . . . . . . . . . . . . . . 10 84 7.1. RSVP-TE only deployments . . . . . . . . . . . . . . . . 11 85 7.2. Multiple Applications: Common Attributes with RSVP-TE . 11 86 7.3. Multiple Applications: All Attributes Not Shared w RSVP- 87 TE . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 88 7.4. Deprecating legacy advertisements . . . . . . . . . . . . 11 89 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12 90 9. Security Considerations . . . . . . . . . . . . . . . . . . . 13 91 10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 13 92 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 13 93 11.1. Normative References . . . . . . . . . . . . . . . . . . 13 94 11.2. Informative References . . . . . . . . . . . . . . . . . 14 95 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 14 97 1. Introduction 99 Advertisement of link attributes by the Intermediate-System-to- 100 Intermediate-System (IS-IS) protocol in support of traffic 101 engineering (TE) was introduced by [RFC5305] and extended by 102 [RFC5307], [RFC6119], and [RFC7810]. Use of these extensions has 103 been associated with deployments supporting Traffic Engineering over 104 Multiprotocol Label Switching (MPLS) in the presence of Resource 105 Reservation Protocol (RSVP) - more succinctly referred to as RSVP-TE. 107 In recent years new applications have been introduced which have use 108 cases for many of the link attributes historically used by RSVP-TE. 109 Such applications include Segment Routing Traffic Engineering (SRTE) 110 and Loop Free Alternates (LFA). This has introduced ambiguity in 111 that if a deployment includes a mix of RSVP-TE support and SRTE 112 support (for example) it is not possible to unambiguously indicate 113 which advertisements are to be used by RSVP-TE and which 114 advertisements are to be used by SRTE. If the topologies are fully 115 congruent this may not be an issue, but any incongruence leads to 116 ambiguity. 118 An additional issue arises in cases where both applications are 119 supported on a link but the link attribute values associated with 120 each application differ. Current advertisements do not support 121 advertising application specific values for the same attribute on a 122 specific link. 124 This document defines extensions which address these issues. Also, 125 as evolution of use cases for link attributes can be expected to 126 continue in the years to come, this document defines a solution which 127 is easily extensible to the introduction of new applications and new 128 use cases. 130 2. Requirements Discussion 132 As stated previously, evolution of use cases for link attributes can 133 be expected to continue - so any discussion of existing use cases is 134 limited to requirements which are known at the time of this writing. 135 However, in order to determine the functionality required beyond what 136 already exists in IS-IS, it is only necessary to discuss use cases 137 which justify the key points identified in the introduction - which 138 are: 140 1. Support for indicating which applications are using the link 141 attribute advertisements on a link 143 2. Support for advertising application specific values for the same 144 attribute on a link 146 [RFC7855] discusses use cases/requirements for SR. Included among 147 these use cases is SRTE which is defined in [SR-POLICY]. If both 148 RSVP-TE and SRTE are deployed in a network, link attribute 149 advertisements can be used by one or both of these applications. As 150 there is no requirement for the link attributes advertised on a given 151 link used by SRTE to be identical to the link attributes advertised 152 on that same link used by RSVP-TE, there is a clear requirement to 153 indicate independently which link attribute advertisements are to be 154 used by each application. 156 As the number of applications which may wish to utilize link 157 attributes may grow in the future, an additional requirement is that 158 the extensions defined allow the association of additional 159 applications to link attributes without altering the format of the 160 advertisements or introducing new backwards compatibility issues. 162 Finally, there may still be many cases where a single attribute value 163 can be shared among multiple applications, so the solution must 164 minimize advertising duplicate link/attribute pairs whenever 165 possible. 167 3. Legacy Advertisements 169 There are existing advertisements used in support of RSVP-TE. These 170 advertisements include sub-TLVs for TLVs 22, 23, 141, 222, and 223 171 and TLVs for SRLG advertisement. 173 3.1. Legacy sub-TLVs 175 Sub-TLVs for TLVs 22, 23, 141, 222, and 223 177 Code Point/Attribute Name 178 -------------------------- 179 3 Administrative group (color) 180 9 Maximum link bandwidth 181 10 Maximum reservable link bandwidth 182 11 Unreserved bandwidth 183 14 Extended Administrative Group 184 33 Unidirectional Link Delay 185 34 Min/Max Unidirectional Link Delay 186 35 Unidirectional Delay Variation 187 36 Unidirectional Link Loss 188 37 Unidirectional Residual Bandwidth 189 38 Unidirectional Available Bandwidth 190 39 Unidirectional Utilized Bandwidth 192 3.2. Legacy SRLG Advertisements 194 TLV 138 GMPLS-SRLG 195 Supports links identified by IPv4 addresses and 196 unnumbered links 198 TLV 139 IPv6 SRLG 199 Supports links identified by IPv6 addresses 201 Note that [RFC6119] prohibits the use of TLV 139 when it is possible 202 to use TLV 138. 204 4. Advertising Application Specific Link Attributes 206 Two new code points are defined in support of Application Specific 207 Link Attribute Advertisements: 209 1) Application Specific Link Attributes sub-TLV for TLVs 22, 23, 141, 210 222, and 223 212 2)Application Specific Shared Risk Link Group (SRLG) TLV 214 In support of these new advertisements, an application bit mask is 215 defined which identifies the application(s) associated with a given 216 advertisement. 218 The following sections define the format of these new advertisements. 220 4.1. Application Identifier Bit Mask 222 Identification of the set of applications associated with link 223 attribute advertisements utilizes two bit masks. One bit mask is for 224 standard applications where the definition of each bit is defined in 225 a new IANA controlled registry. A second bit mask is for non- 226 standard User Defined Applications(UDAs). 228 The encoding defined below is used by both the Application Specific 229 Link Attributes sub-TLV and the Application Specific SRLG TLV. 231 0 1 2 3 4 5 6 7 232 +-+-+-+-+-+-+-+-+ 233 | SABML+F | 1 octet 234 +-+-+-+-+-+-+-+-+ 235 | UDABML+F | 1 octet 236 +-+-+-+-+-+-+-+-+ 237 | SABM ... 0 - 127 octets 238 +-+-+-+-+-+-+-+-+ 239 | UDABM ... 0 - 127 octets 240 +-+-+-+-+-+-+-+-+ 242 SABML+F (1 octet) 243 Standard Application Bit Mask Length/Flags 245 0 1 2 3 4 5 6 7 246 +-+-+-+-+-+-+-+-+ 247 |L| SA-Length | 248 +-+-+-+-+-+-+-+-+ 250 L-flag: Applications listed (both Standard and 251 User Defined) MUST use the legacy advertisements 252 for the corresponding link found in TLVs 22, 23, 253 141, 222, and 223 or TLV 138 or TLV 139 as appropriate. 255 SA-Length: Indicates the length in octets (0-127) of the Bit Mask 256 for Standard Applications. 258 UDABML+F (1 octet) 259 User Defined Application Bit Mask Length/Flags 261 0 1 2 3 4 5 6 7 262 +-+-+-+-+-+-+-+-+ 263 |R| UDA-Length | 264 +-+-+-+-+-+-+-+-+ 266 R: Reserved. Transmitted as 0 and ignored on receipt 268 UDA-Length: Indicates the length in octets (0-127) of the Bit Mask 269 for User Defined Applications. 271 SABM (variable length) 272 Standard Application Bit Mask 274 (SA-Length * 8) bits 276 This is omitted if SA-Length is 0. 278 0 1 2 3 4 5 6 7 ... 279 +-+-+-+-+-+-+-+-+... 280 |R|S|F| ... 281 +-+-+-+-+-+-+-+-+... 283 R-bit: RSVP-TE 284 S-bit: Segment Routing Traffic Engineering 286 F-bit: Loop Free Alternate 288 UDABM (variable length) 289 User Defined Application Bit Mask 291 (UDA Length * 8) bits 293 0 1 2 3 4 5 6 7 ... 294 +-+-+-+-+-+-+-+-+... 295 | ... 296 +-+-+-+-+-+-+-+-+... 298 This is omitted if UDA-Length is 0. 300 NOTE: If both SA-length and UDA-Length are zero, then the 301 attributes associated with this attribute identifier bit mask 302 MAY be used by any Standard Application and any User Defined 303 Application. 305 Standard Application Bits are defined/sent starting with Bit 0. 306 Additional bit definitions that may be defined in the future SHOULD 307 be assigned in ascending bit order so as to minimize the number of 308 octets that will need to be transmitted. Undefined bits MUST be 309 transmitted as 0 and MUST be ignored on receipt. Bits that are NOT 310 transmitted MUST be treated as if they are set to 0 on receipt. 312 User Defined Application bits have no relationship to Standard 313 Application bits and are NOT managed by IANA or any other standards 314 body. It is recommended that bits are used starting with Bit 0 so as 315 to minimize the number of octets required to advertise all UDAs. 317 4.2. Application Specific Link Attributes sub-TLV 319 A new sub-TLV for TLVs 22, 23, 141, 222, and 223 is defined which 320 supports specification of the applications and application specific 321 attribute values. 323 Type: 15 (suggested value - to be assigned by IANA) 324 Length: Variable (1 octet) 325 Value: 327 Application Bit Mask (as defined in Section 3.1) 329 Link Attribute sub-sub-TLVs - format matches the 330 existing formats defined in [RFC5305] and [RFC7810] 332 When the L-flag is set in the Application Identifiers, all of the 333 applications specified in the bit mask MUST use the link attribute 334 sub-TLV advertisements listed in Section 3.1 for the corresponding 335 link. Application specific link attribute sub-sub-TLVs for the 336 corresponding link attributes MUST NOT be advertised for the set of 337 applications specified in the Standard/User Application Bit Masks and 338 all such advertisements MUST be ignored on receipt. 340 Multiple sub-TLVs for the same link MAY be advertised. When multiple 341 sub-TLVs for the same link are advertised, they SHOULD advertise non- 342 conflicting application/attribute pairs. A conflict exists when the 343 same application is associated with two different values of the same 344 link attribute for a given link. In cases where conflicting values 345 for the same application/attribute/link are advertised all the 346 conflicting values MUST be ignored. 348 For a given application, the setting of the L-flag MUST be the same 349 in all sub-TLVs for a given link. In cases where this constraint is 350 violated, the L-flag MUST be considered set for this application. 352 A new registry of sub-sub-TLVs is to be created by IANA which defines 353 the link attribute sub-sub-TLV code points. A sub-sub-TLV is defined 354 for each of the existing sub-TLVs listed in Section 3.1. Format of 355 the sub-sub-TLVs matches the format of the corresponding legacy sub- 356 TLV and IANA is requested to assign the legacy sub-TLV identifer to 357 the corresponding sub-sub-TLV. 359 4.3. Application Specific SRLG TLV 361 A new TLV is defined to advertise application specific SRLGs for a 362 given link. Although similar in functionality to TLV 138 (defined by 363 [RFC5307]) and TLV 139 (defined by [RFC6119], a single TLV provides 364 support for IPv4, IPv6, and unnumbered identifiers for a link. 365 Unlike TLVs 138/139, it utilizes sub-TLVs to encode the link 366 identifiers in order to provide the flexible formatting required to 367 support multiple link identifier types. 369 Type: 238 (Suggested value - to be assigned by IANA) 370 Length: Number of octets in the value field (1 octet) 371 Value: 372 Neighbor System-ID + pseudo-node ID (7 octets) 373 Application Bit Mask (as defined in Section 3.1) 374 Length of sub-TLVs (1 octet) 375 Link Identifier sub-TLVs (variable) 376 0 or more SRLG Values (Each value is 4 octets) 378 The following Link Identifier sub-TLVs are defined. The type 379 values are suggested and will be assigned by IANA - but as 380 the formats are identical to existing sub-TLVs defined for 381 TLVs 22, 23, 141, 222, and 223 the use of the suggested sub-TLV 382 types is strongly encouraged. 384 Type Description 385 4 Link Local/Remote Identifiers (see [RFC5307]) 386 6 IPv4 interface address (see [RFC5305]) 387 8 IPv4 neighbor address (see [RFC5305]) 388 12 IPv6 Interface Address (see [RFC6119]) 389 13 IPv6 Neighbor Address (see [RFC6119]) 391 At least one set of link identifiers (IPv4, IPv6, or unnumbered) MUST 392 be present. TLVs which do not meet this requirement MUST be ignored. 394 Multiple TLVs for the same link MAY be advertised. 396 When the L-flag is set in the Application Identifiers, SRLG values 397 MUST NOT be included in the TLV. Any SRLG values which are 398 advertised MUST be ignored. Based on the link identifiers advertised 399 the corresponding legacy TLV (see Section 3.2) can be identified and 400 the SRLG values advertised in the legacy TLV MUST be used by the set 401 of applications specified in the Application Bit Mask. 403 For a given application, the setting of the L-flag MUST be the same 404 in all TLVs for a given link. In cases where this constraint is 405 violated, the L-flag MUST be considered set for this application. 407 5. Deployment Considerations 409 If link attributes are advertised associated with zero length 410 application bit masks for both standard applications and user defined 411 applications, then that set of link attributes MAY be used by any 412 application. If support for a new application is introduced on any 413 node in a network in the presence of such advertisements, these 414 advertisements MAY be used by the new application. If this is not 415 what is intended, then existing advertisements MUST be readvertised 416 with an explicit set of applications specified before a new 417 application is introduced. 419 6. Attribute Advertisements and Enablement 421 This document defines extensions to support the advertisement of 422 application specific link attributes. 424 Whether the presence of link attribute advertisements for a given 425 application indicates that the application is enabled on that link 426 depends upon the application. Similarly, whether the absence of link 427 attribute advertisements indicates that the application is not 428 enabled depends upon the application. 430 The advertisement of link attributes to be used by RSVP-TE implies 431 that RSVP is enabled on that link. 433 In the case of SRTE, advertisement of application specific link 434 attributes does NOT indicate enablement of SRTE. The advertisements 435 are only used to support constraints which may be applied when 436 specifying an explicit path. SRTE is implicitly enabled on all links 437 which are part of the Segment Routing enabled topology independent of 438 the existence of link attribute advertisements 440 In the case of LFA, advertisement of link attributes does NOT 441 indicate enablement of that application on that link. Enablement is 442 controlled by local configuration and/or the use of administrative 443 tags. 445 If, in the future, additional standard applications are defined to 446 use this mechanism, the specification defining this use MUST define 447 the relationship between application specific link attribute 448 advertisements and enablement for that application. 450 7. Interoperability, Backwards Compatibility and Migration Concerns 452 Existing deployments of RSVP-TE utilize the legacy advertisements 453 listed in Section 3. Routers which do not support the extensions 454 defined in this document will only process legacy advertisements and 455 are likely to infer that RSVP-TE is enabled on the links for which 456 legacy advertisements exist. It is expected that deployments using 457 the legacy advertisements will persist for a significant period of 458 time - therefore deployments using the extensions defined in this 459 document must be able to co-exist with use of the legacy 460 advertisements by routers which do not support the extensions defined 461 in this document. The following sub-sections discuss 462 interoperability and backwards compatibility concerns for a number of 463 deployment scenarios. 465 Note that in all cases the defined strategy can be employed on a per 466 link basis. 468 7.1. RSVP-TE only deployments 470 In deployments where RSVP-TE is the only application utilizing link 471 attribute advertisements, use of the the legacy advertisements can 472 continue without change. 474 7.2. Multiple Applications: Common Attributes with RSVP-TE 476 In cases where multiple applications are utilizing a given link, one 477 of the applications is RSVP-TE, and all link attributes for a given 478 link are common to the set of applications utilizing that link, 479 interoperability is achieved by using legacy advertisements and 480 sending application specific advertisements with L-bit set and no 481 link attribute values. This avoids duplication of link attribute 482 advertisements. 484 7.3. Multiple Applications: All Attributes Not Shared w RSVP-TE 486 In cases where one or more applications other than RSVP-TE are 487 utilizing a given link and one or more link attribute values are NOT 488 shared with RSVP-TE, it is necessary to use application specific 489 advertisements as defined in this document. Attributes for 490 applications other than RSVP-TE MUST be advertised using application 491 specific advertisements which have the L-bit clear. In cases where 492 some link attributes are shared with RSVP-TE, this requires duplicate 493 advertisements for those attributes. 495 The discussion in this section applies to cases where RSVP-TE is NOT 496 using any advertised attributes on a link and to cases where RSVP-TE 497 is using some link attribute advertisements on the link but some link 498 attributes cannot be shared with RSVP-TE. 500 7.4. Deprecating legacy advertisements 502 The extensions defined in this document support RSVP-TE as one of the 503 supported applications - so a long term goal for deployments would be 504 to deprecate use of the legacy advertisements in support of RSVP-TE. 505 This can be done in the following step-wise manner: 507 1)Upgrade all routers to support extensions in this document 509 2)Readvertise all legacy link attributes using application specific 510 advertisements with L-bit clear and R-bit set. 512 3)Remove legacy advertisements 514 8. IANA Considerations 516 This document defines a new sub-TLV for TLVs 22, 23, 141, 222, and 517 223. 519 Type Description 22 23 141 222 223 520 ---- --------------------- --- --- --- --- --- 521 15 Application Specific y y y y y 522 Link Attributes 524 This document defines one new TLV: 526 Type Description IIH SNP LSP Purge 527 ---- --------------------- --- --- --- ----- 528 238 Application Specific n n y n 529 SRLG 531 This document requests a new IANA registry be created to control the 532 assignment of sub-sub-TLV codepoints for the Application Specific 533 Link Attributes sub-TLV. The suggested name of the new registry is 534 "sub-sub-TLV code points for application link attributes". The 535 registration procedure is "Expert Review" as defined in [RFC8126]. 536 The following assignments are made by this document: 538 Type Description 539 --------------------------------------------------------- 540 3 Administrative group (color) 541 9 Maximum link bandwidth 542 10 Maximum reservable link bandwidth 543 11 Unreserved bandwidth 544 14 Extended Administrative Group 545 33 Unidirectional Link Delay 546 34 Min/Max Unidirectional Link Delay 547 35 Unidirectional Delay Variation 548 36 Unidirectional Link Loss 549 37 Unidirectional Residual Bandwidth 550 38 Unidirectional Available Bandwidth 551 39 Unidirectional Utilized Bandwidth 553 This document requests a new IANA registry be created to control the 554 assignment of application bit identifiers. The suggested name of the 555 new registry is "Link Attribute Applications". The registration 556 procedure is "Expert Review" as defined in [RFC8126]. The following 557 assignments are made by this document: 559 Bit # Name 560 --------------------------------------------------------- 561 0 RSVP-TE (R-bit) 562 1 Segment Routing Traffic Engineering (S-bit) 563 2 Loop Free Alternate (F-bit) 565 This document requests a new IANA registry be created to control the 566 assignment of sub-TLV types for the application specific SRLG TLV. 567 The suggested name of the new registry is "Sub-TLVs for TLV 238". 568 The registration procedure is "Expert Review" as defined in 569 [RFC8126]. The following assignments are made by this document: 571 Value Description 572 --------------------------------------------------------- 573 4 Link Local/Remote Identifiers (see [RFC5307]) 574 6 IPv4 interface address (see [RFC5305]) 575 8 IPv4 neighbor address (see [RFC5305]) 576 12 IPv6 Interface Address (see [RFC6119]) 577 13 IPv6 Neighbor Address (see [RFC6119]) 579 9. Security Considerations 581 Security concerns for IS-IS are addressed in [ISO10589, [RFC5304], 582 and [RFC5310]. 584 10. Acknowledgements 586 The authors would like to thank Eric Rosen and Acee Lindem for their 587 careful review and content suggestions. 589 11. References 591 11.1. Normative References 593 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 594 Requirement Levels", BCP 14, RFC 2119, 595 DOI 10.17487/RFC2119, March 1997, 596 . 598 [RFC5304] Li, T. and R. Atkinson, "IS-IS Cryptographic 599 Authentication", RFC 5304, DOI 10.17487/RFC5304, October 600 2008, . 602 [RFC5305] Li, T. and H. Smit, "IS-IS Extensions for Traffic 603 Engineering", RFC 5305, DOI 10.17487/RFC5305, October 604 2008, . 606 [RFC5307] Kompella, K., Ed. and Y. Rekhter, Ed., "IS-IS Extensions 607 in Support of Generalized Multi-Protocol Label Switching 608 (GMPLS)", RFC 5307, DOI 10.17487/RFC5307, October 2008, 609 . 611 [RFC5310] Bhatia, M., Manral, V., Li, T., Atkinson, R., White, R., 612 and M. Fanto, "IS-IS Generic Cryptographic 613 Authentication", RFC 5310, DOI 10.17487/RFC5310, February 614 2009, . 616 [RFC6119] Harrison, J., Berger, J., and M. Bartlett, "IPv6 Traffic 617 Engineering in IS-IS", RFC 6119, DOI 10.17487/RFC6119, 618 February 2011, . 620 [RFC7810] Previdi, S., Ed., Giacalone, S., Ward, D., Drake, J., and 621 Q. Wu, "IS-IS Traffic Engineering (TE) Metric Extensions", 622 RFC 7810, DOI 10.17487/RFC7810, May 2016, 623 . 625 [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for 626 Writing an IANA Considerations Section in RFCs", BCP 26, 627 RFC 8126, DOI 10.17487/RFC8126, June 2017, 628 . 630 11.2. Informative References 632 [RFC7855] Previdi, S., Ed., Filsfils, C., Ed., Decraene, B., 633 Litkowski, S., Horneffer, M., and R. Shakir, "Source 634 Packet Routing in Networking (SPRING) Problem Statement 635 and Requirements", RFC 7855, DOI 10.17487/RFC7855, May 636 2016, . 638 [SR-POLICY] 639 "Segment Routing Policy for Traffic Engineering, draft- 640 filsfils-spring-segment-routing-policy-01(work in 641 progress)", July 2017. 643 Authors' Addresses 645 Les Ginsberg 646 Cisco Systems 647 821 Alder Drive 648 Milpitas, CA 95035 649 USA 651 Email: ginsberg@cisco.com 652 Peter Psenak 653 Cisco Systems 654 Apollo Business Center Mlynske nivy 43 655 Bratislava 821 09 656 Slovakia 658 Email: ppsenak@cisco.com 660 Stefano Previdi 661 Individual 663 Email: stefano@previdi.net 665 Wim Henderickx 666 Nokia 667 Copernicuslaan 50 668 Antwerp 2018 94089 669 Belgium 671 Email: wim.henderickx@nokia.com 673 John Drake 674 Juniper Networks 676 Email: jdrake@juniper.net