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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 5226 (Obsoleted by RFC 8126) ** Obsolete normative reference: RFC 7810 (Obsoleted by RFC 8570) Summary: 2 errors (**), 0 flaws (~~), 3 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 S. Previdi 5 Expires: August 31, 2017 Cisco Systems 6 W. Henderickx 7 Nokia 8 February 27, 2017 10 IS-IS TE Attributes per application 11 draft-ginsberg-isis-te-app-00.txt 13 Abstract 15 Existing traffic engineering related link attribute advertisements 16 have been defined and are used in RSVP-TE deployments. In cases 17 where multiple applications wish to make use of these link attributes 18 the current advertisements do not support application specific values 19 for a given attribute nor do they support indication of which 20 applications are using the advertised value for a given link. 22 This draft introduces new link attribute advertisements which address 23 both of these shortcomings. It also discusses backwards 24 compatibility issues and how to minimize duplicate advertisements in 25 the presence of routers which do not support the extensions defined 26 in this document. 28 Requirements Language 30 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 31 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 32 document are to be interpreted as described in RFC 2119 [RFC2119]. 34 Status of This Memo 36 This Internet-Draft is submitted in full conformance with the 37 provisions of BCP 78 and BCP 79. 39 Internet-Drafts are working documents of the Internet Engineering 40 Task Force (IETF). Note that other groups may also distribute 41 working documents as Internet-Drafts. The list of current Internet- 42 Drafts is at http://datatracker.ietf.org/drafts/current/. 44 Internet-Drafts are draft documents valid for a maximum of six months 45 and may be updated, replaced, or obsoleted by other documents at any 46 time. It is inappropriate to use Internet-Drafts as reference 47 material or to cite them other than as "work in progress." 48 This Internet-Draft will expire on August 31, 2017. 50 Copyright Notice 52 Copyright (c) 2017 IETF Trust and the persons identified as the 53 document authors. All rights reserved. 55 This document is subject to BCP 78 and the IETF Trust's Legal 56 Provisions Relating to IETF Documents 57 (http://trustee.ietf.org/license-info) in effect on the date of 58 publication of this document. Please review these documents 59 carefully, as they describe your rights and restrictions with respect 60 to this document. Code Components extracted from this document must 61 include Simplified BSD License text as described in Section 4.e of 62 the Trust Legal Provisions and are provided without warranty as 63 described in the Simplified BSD License. 65 Table of Contents 67 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 68 2. Requirements Discussion . . . . . . . . . . . . . . . . . . . 3 69 3. Legacy Advertisements . . . . . . . . . . . . . . . . . . . . 4 70 3.1. Legacy sub-TLVs . . . . . . . . . . . . . . . . . . . . . 4 71 3.2. Legacy SRLG Advertisements . . . . . . . . . . . . . . . 5 72 4. Advertising Application Specific Link Attributes . . . . . . 5 73 4.1. Application Bit Mask . . . . . . . . . . . . . . . . . . 6 74 4.2. Application Specific Link Attributes sub-TLV . . . . . . 6 75 4.3. Application Specific SRLG TLV . . . . . . . . . . . . . . 7 76 5. Interoperability, Backwards Compatibility and Migration 77 Concerns . . . . . . . . . . . . . . . . . . . . . . . . . . 8 78 5.1. RSVP-TE only deployments . . . . . . . . . . . . . . . . 9 79 5.2. Multiple Applications: Common Attributes with RSVP-TE . 9 80 5.3. Multiple Applications: All Attributes Not Shared w RSVP- 81 TE . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 82 5.4. Deprecating legacy advertisements . . . . . . . . . . . . 9 83 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10 84 7. Security Considerations . . . . . . . . . . . . . . . . . . . 11 85 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 11 86 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 11 87 9.1. Normative References . . . . . . . . . . . . . . . . . . 11 88 9.2. Informative References . . . . . . . . . . . . . . . . . 12 89 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 12 91 1. Introduction 93 Advertisement of link attributes by the Intermediate-System-to- 94 Intermediate-System (IS-IS) protocol in support of traffic 95 engineering (TE) was introduced by [RFC5305] and extended by 97 [RFC5307], [RFC6119], and [RFC7810]. Use of these extensions has 98 been associated with deployments supporting Traffic Engineering over 99 Multiprotocol Label Switching (MPLS) in the presence of Resource 100 Reservation Protocol (RSVP) - more succinctly referred to as RSVP-TE. 101 Although implementations vary in their exact interpretation, it is 102 fair to say that the presence of any of the link attribute 103 advertisements currently defined (excluding link identifier 104 advertisements) are used by many implementations to imply the use of 105 that link by 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 (SR-TE) 110 and Loop Free Alternates (LFA). This has introduced ambiguity in 111 that if a deployment includes a mix of RSVP-TE support and SR-TE 112 support (for example) it is not possible to unambiguously indicate 113 which advertisements indicate support for/use by RSVP-TE and which 114 advertisements indicate support for/use by SR-TE. If the topologies 115 are fully congruent this may not be an issue, but any incongruence 116 leads to 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 SR-TE. If both RSVP-TE and SR-TE are deployed in 148 a network, links can be used by one or both of these applications. 149 As there is no requirement for the topology supported for SR-TE to be 150 congruent to the topology supported for RSVP-TE there is a clear 151 requirement to indicate independently which applications are 152 associated with a given link. 154 If both RSVP-TE and SR-TE are enabled on a given link it is also 155 possible that an attribute value such as Maximum Bandwidth to be 156 utilized by SR-TE may be different than/disjoint from the Maximum 157 Bandwidth to be utilized by RSVP-TE. This leads to the requirement 158 that the solution support the advertisement of unique values for a 159 given link/attribute/application. 161 As the number of applications which may wish to utilize link 162 attributes may grow in the future an additional requirement is that 163 the extensions defined allow the association of additional 164 applications to link attributes without altering the format of the 165 advertisements or introducing new backwards compatibility issues. 167 Finally, there may still be many cases where a single attribute value 168 can be shared among multiple applications, so the solution must 169 minimize advertising duplicate link/attribute pairs whenever 170 possible. 172 3. Legacy Advertisements 174 There are existing advertisements used in support of RSVP-TE. These 175 advertisements include sub-TLVs for TLVs 22, 23, 141, 222, and 223 176 and TLVs for SRLG advertisement. 178 3.1. Legacy sub-TLVs 179 Sub-TLVs for TLVs 22, 23, 141, 222, and 223 181 Code Point/Attribute Name 182 -------------------------- 183 3 Administrative group (color) 184 9 Maximum link bandwidth 185 10 Maximum reservable link bandwidth 186 11 Unreserved bandwidth 187 14 Extended Administrative Group 188 33 Unidirectional Link Delay 189 34 Min/Max Unidirectional Link Delay 190 35 Unidirectional Delay Variation 191 36 Unidirectional Link Loss 192 37 Unidirectional Residual Bandwidth 193 38 Unidirectional Available Bandwidth 194 39 Unidirectional Utilized Bandwidth 196 3.2. Legacy SRLG Advertisements 198 TLV 138 GMPLS-SRLG 199 Supports links identified by IPv4 addresses and 200 unnumbered links 202 TLV 139 IPv6 SRLG 203 Supports links identified by IPv6 addresses 205 Note that [RFC6119] prohibits the use of TLV 139 when it is possible 206 to use TLV 138. 208 4. Advertising Application Specific Link Attributes 210 Two new code points are defined in support of Application Specific 211 Link Attribute Advertisements: 213 1) Application Specific Link Attributes sub-TLV for TLVs 22, 23, 141, 214 222, and 223 216 2)Application Specific Shared Risk Link Group (SRLG) TLV 218 In support of these new advertisements, an application bit mask is 219 defined which identifies the application(s) associated with a given 220 advertisement. 222 The following sections define the format of these new advertisements. 224 4.1. Application Bit Mask 226 Identification of the set of applications associated with the link 227 attribute advertisements utilizes a bit mask where the definition of 228 each bit is defined in a new IANA controlled registry. This encoding 229 is used by both the Application Specific Link Attributes sub-TLV and 230 the Application Specific SRLG TLV. 232 Bit Mask Length: Non-zero (1 octet) 233 Application Bit Mask: Size is (Bit Mask Length+7)/8 234 The following bits are assigned: 236 0 1 2 3 4 5 6 7 237 +-+-+-+-+-+-+-+-+ 238 |L|R|S|F| | 239 +-+-+-+-+-+-+-+-+ 241 L-bit: Applications listed MUST use the legacy 242 advertisements for the corresponding link 243 found in TLVs 22, 23, 141, 222, and 223 or 244 TLV 138 or TLV 139 as appropriate. 246 R-bit: RSVP-TE 248 S-bit: Segment Routing Traffic Engineering 250 F-bit: Loop Free Alternate 252 Bits are defined/sent starting with Bit 0. Additional bit 253 definitions that may be defined in the future SHOULD be assigned in 254 ascending bit order so as to minimize the number of bits that will 255 need to be transmitted. Undefined bits MUST be transmitted as 0 and 256 MUST be ignored on receipt. Bits that are NOT transmitted MUST be 257 treated as if they are set to 0 on receipt. 259 4.2. Application Specific Link Attributes sub-TLV 261 A new sub-TLV for TLVs 22, 23, 141, 222, and 223 is defined which 262 supports specification of the applications and application specific 263 attribute values. 265 Type: 15 (suggested value - to be assigned by IANA) 266 Length: Variable (1 octet) 267 Value: 269 Application Bit Mask (as defined in Section 3.1) 271 Link Attribute sub-sub-TLVs - format matches the 272 existing formats defined in [RFC5305] and [RFC7810] 274 When the L-bit is set in the Application Bit Mask all of the 275 applications specified in the bit mask MUST use the link attribute 276 sub-TLV advertisements listed in Section 3.1 for the corresponding 277 link. Application specific link attribute sub-sub-TLVs for the 278 corresponding link attributes MUST NOT be advertised for the set of 279 applications specified in the Application Bit Mask and all such 280 advertisements MUST be ignored on receipt. 282 Multiple sub-TLVs for the same link MAY be advertised. When multiple 283 sub-TLVs for the same link are advertised they SHOULD advertise non- 284 conflicting application/attribute pairs. In cases where there are 285 multiple sub-TLVs for the same link and there is a conflict in the 286 attribute information advertised the behavior of the receiver is 287 undefined. 289 For a given application, the setting of the L-bit MUST be the same in 290 all sub-TLVs for a given link. In cases where this constraint is 291 violated the L-bit MUST be considered set for this application. 293 A new registry of sub-sub-TLVs is to be created by IANA which defines 294 the link attribute sub-sub-TLV code points. A sub-sub-TLV is defined 295 for each of the existing sub-TLVs listed in Section 3.1. Format of 296 the sub-sub-TLVs matches the format of the corresponding legacy sub- 297 TLV and IANA is requested to assign the legacy sub-TLV identifer to 298 the corresponding sub-sub-TLV. 300 4.3. Application Specific SRLG TLV 302 A new TLV is defined to advertise application specific SRLGs for a 303 given link. Although similar in functionality to TLV 138 (defined by 304 [RFC5307]) and TLV 139 (defined by [RFC6119] a single TLV provides 305 support for IPv4, IPv6, and unnumbered identifiers for a link. 306 Unlike TLVs 138/139 it utilizes sub-TLVs to encode the link 307 identifiers in order to provide the flexible formatting required to 308 support multiple link identifier types. 310 Type: 238 (Suggested value - to be assigned by IANA) 311 Length: Number of octets in the value field (1 octet) 312 Value: 313 Neighbor System-ID + pseudo-node ID (7 octets) 314 Application Bit Mask (as defined in Section 3.1) 315 Length of sub-TLVs (1 octet) 316 Link Identifier sub-TLVs (variable) 317 0 or more SRLG Values (Each value is 4 octets) 319 The following Link Identifier sub-TLVs are defined. The type 320 values are suggested and will be assigned by IANA - but as 321 the formats are identical to existing sub-TLVs defined for 322 TLVs 22, 23, 141, 222, and 223 the use of the suggested sub-TLV 323 types is strongly encouraged. 325 Type Description 326 4 Link Local/Remote Identifiers (see [RFC5307]) 327 6 IPv4 interface address (see [RFC5305]) 328 8 IPv4 neighbor address (see [RFC5305]) 329 12 IPv6 Interface Address (see [RFC6119]) 330 13 IPv6 Neighbor Address (see [RFC6119]) 332 At least one set of link identifiers (IPv4, IPv6, or unnumbered) MUST 333 be present. TLVs which do not meet this requirement MUST be ignored. 335 Multiple TLVs for the same link MAY be advertised. 337 When the L-bit is set in the Application Bit Mask SRLG values MUST 338 NOT be included in the TLV. Any SRLG values which are advertised 339 MUST be ignored. Based on the link identifiers advertised the 340 corresponding legacy TLV (see Section 3.2) can be identified and the 341 SRLG values advertised in the legacy TLV MUST be used by the set of 342 applications specified in the Application Bit Mask. 344 For a given application, the setting of the L-bit MUST be the same in 345 all TLVs for a given link. In cases where this constraint is 346 violated the L-bit MUST be considered set for this application. 348 5. Interoperability, Backwards Compatibility and Migration Concerns 350 Existing deployments of RSVP-TE utilize the legacy advertisements 351 listed in Section 3. Routers which do not support the extensions 352 defined in this document will only process legacy advertisements and 353 are likely to infer that RSVP-TE is enabled on the links for which 354 legacy advertisements exist. It is expected that deployments using 355 the legacy advertisements will persist for a significant period of 356 time - therefore deployments using the extensions defined in this 357 document must be able to co-exist with use of the legacy 358 advertisements by routers which do not support the extensions defined 359 in this document. The following sub-sections discuss 360 interoperability and backwards compatibility concerns for a number of 361 deployment scenarios. 363 Note that in all cases the defined strategy can be employed on a per 364 link basis. 366 5.1. RSVP-TE only deployments 368 In deployments where RSVP-TE is the only application utilizing link 369 attribute advertisements use of the the legacy advertisements can 370 continue without change. 372 5.2. Multiple Applications: Common Attributes with RSVP-TE 374 In cases where multiple applications are utilizing a given link, one 375 of the applications is RSVP-TE, and all link attributes for a given 376 link are common to the set of applications utilizing that link, 377 interoperability is achieved by using legacy advertisements and 378 sending application specific advertisements with L-bit set and no 379 link attribute values. This avoids duplication of link attribute 380 advertisements. 382 5.3. Multiple Applications: All Attributes Not Shared w RSVP-TE 384 In cases where one or more applications other than RSVP-TE are 385 utilizing a given link and one or more link attribute values are NOT 386 shared with RSVP-TE, it is necessary to use application specific 387 advertisements as defined in this document. Attributes for 388 applications other than RSVP-TE MUST be advertised using application 389 specific advertisements which have the L-bit clear. In cases where 390 some link attributes are shared with RSVP-TE this requires duplicate 391 advertisements for those attributes. 393 The discussion in this section applies to cases where RSVP-TE is NOT 394 enabled on a link and to cases where RSVP-TE is enabled on the link 395 but some link attributes cannot be shared with RSVP-TE. 397 5.4. Deprecating legacy advertisements 399 The extensions defined in this document support RSVP-TE as one of the 400 supported applications - so a long term goal for deployments would be 401 to deprecate use of the legacy advertisements in support of RSVP-TE. 402 This can be done in the following step-wise manner: 404 1)Upgrade all routers to support extensions in this document 405 2)Readvertise all legacy link attributes using application specific 406 advertisements with L-bit clear and R-bit set. 408 3)Remove legacy advertisements 410 6. IANA Considerations 412 This document defines a new sub-TLV for TLVs 22, 23, 141, 222, and 413 223. 415 Type Description 22 23 141 222 223 416 ---- --------------------- -- -- --- --- --- 417 15 Application Specific y y y y y 418 Link Attributes 420 This document defines one new TLV: 422 Type Description IIH SNP LSP Purge 423 ---- --------------------- --- --- --- ----- 424 238 Application Specific n n y n 425 SRLG 427 This document requests a new IANA registry be created to control the 428 assignment of sub-sub-TLV codepoints for the Application Specific 429 Link Attributes sub-TLV. The suggested name of the new registry is 430 "sub-sub-TLV code points for application link attributes". The 431 registration procedure is "Expert Review" as defined in [RFC5226]. 432 The following assignments are made by this document: 434 Type Description 435 --------------------------------------------------------- 436 3 Administrative group (color) 437 9 Maximum link bandwidth 438 10 Maximum reservable link bandwidth 439 11 Unreserved bandwidth 440 14 Extended Administrative Group 441 33 Unidirectional Link Delay 442 34 Min/Max Unidirectional Link Delay 443 35 Unidirectional Delay Variation 444 36 Unidirectional Link Loss 445 37 Unidirectional Residual Bandwidth 446 38 Unidirectional Available Bandwidth 447 39 Unidirectional Utilized Bandwidth 449 This document requests a new IANA registry be created to control the 450 assignment of application bit identifiers. The suggested name of the 451 new registry is "Link Attribute Applications". The registration 452 procedure is "Expert Review" as defined in [RFC5226]. The following 453 assignments are made by this document: 455 Bit # Name 456 --------------------------------------------------------- 457 0 Legacy Attributes (L-bit) 458 1 RSVP-TE (R-bit) 459 2 Segment Routing Traffic Engineering (S-bit) 460 3 Loop Free Alternate (F-bit) 462 This document requests a new IANA registry be created to control the 463 assignment of sub-TLV types for the application specific SRLG TLV. 464 The suggested name of the new registry is "Sub-TLVs for TLV 238". 465 The registration procedure is "Expert Review" as defined in 466 [RFC5226]. The following assignments are made by this document: 468 Value Description 469 --------------------------------------------------------- 470 4 Link Local/Remote Identifiers (see [RFC5307]) 471 6 IPv4 interface address (see [RFC5305]) 472 8 IPv4 neighbor address (see [RFC5305]) 473 12 IPv6 Interface Address (see [RFC6119]) 474 13 IPv6 Neighbor Address (see [RFC6119]) 476 7. Security Considerations 478 Security concerns for IS-IS are addressed in [ISO10589, [RFC5304], 479 and [RFC5310]. 481 8. Acknowledgements 483 TBD 485 9. References 487 9.1. Normative References 489 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 490 Requirement Levels", BCP 14, RFC 2119, 491 DOI 10.17487/RFC2119, March 1997, 492 . 494 [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an 495 IANA Considerations Section in RFCs", BCP 26, RFC 5226, 496 DOI 10.17487/RFC5226, May 2008, 497 . 499 [RFC5304] Li, T. and R. Atkinson, "IS-IS Cryptographic 500 Authentication", RFC 5304, DOI 10.17487/RFC5304, October 501 2008, . 503 [RFC5305] Li, T. and H. Smit, "IS-IS Extensions for Traffic 504 Engineering", RFC 5305, DOI 10.17487/RFC5305, October 505 2008, . 507 [RFC5307] Kompella, K., Ed. and Y. Rekhter, Ed., "IS-IS Extensions 508 in Support of Generalized Multi-Protocol Label Switching 509 (GMPLS)", RFC 5307, DOI 10.17487/RFC5307, October 2008, 510 . 512 [RFC5310] Bhatia, M., Manral, V., Li, T., Atkinson, R., White, R., 513 and M. Fanto, "IS-IS Generic Cryptographic 514 Authentication", RFC 5310, DOI 10.17487/RFC5310, February 515 2009, . 517 [RFC6119] Harrison, J., Berger, J., and M. Bartlett, "IPv6 Traffic 518 Engineering in IS-IS", RFC 6119, DOI 10.17487/RFC6119, 519 February 2011, . 521 [RFC7810] Previdi, S., Ed., Giacalone, S., Ward, D., Drake, J., and 522 Q. Wu, "IS-IS Traffic Engineering (TE) Metric Extensions", 523 RFC 7810, DOI 10.17487/RFC7810, May 2016, 524 . 526 9.2. Informative References 528 [RFC7855] Previdi, S., Ed., Filsfils, C., Ed., Decraene, B., 529 Litkowski, S., Horneffer, M., and R. Shakir, "Source 530 Packet Routing in Networking (SPRING) Problem Statement 531 and Requirements", RFC 7855, DOI 10.17487/RFC7855, May 532 2016, . 534 Authors' Addresses 536 Les Ginsberg 537 Cisco Systems 538 821 Alder Drive 539 Milpitas, CA 95035 540 USA 542 Email: ginsberg@cisco.com 543 Peter Psenak 544 Cisco Systems 545 Apollo Business Center Mlynske nivy 43 546 Bratislava 821 09 547 Slovakia 549 Email: ppsenak@cisco.com 551 Stefano Previdi 552 Cisco Systems 553 Via Del Serafico 200 554 Rome 0144 555 Italy 557 Email: sprevidi@cisco.com 559 Wim Henderickx 560 Nokia 561 Copernicuslaan 50 562 Antwerp 2018 94089 563 Belgium 565 Email: wim.henderickx@nokia.com