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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 LSR Working Group P. Psenak, Ed. 3 Internet-Draft Cisco Systems, Inc. 4 Intended status: Standards Track A. Lindem 5 Expires: May 13, 2019 L. Ginsberg 6 Cisco Systems 7 W. Henderickx 8 Nokia 9 J. Tantsura 10 Nuage Networks 11 H. Gredler 12 RtBrick Inc. 13 J. Drake 14 Juniper Networks 15 November 9, 2018 17 OSPF Link Traffic Engineering (TE) Attribute Reuse 18 draft-ietf-ospf-te-link-attr-reuse-06.txt 20 Abstract 22 Various link attributes have been defined in OSPF in the context of 23 the MPLS Traffic Engineering (TE) and GMPLS. Many of these link 24 attributes can be used for applications other than MPLS Traffic 25 Engineering or GMPLS. This document defines how to distribute such 26 attributes in OSPFv2 and OSPFv3 for applications other than MPLS 27 Traffic Engineering or GMPLS. 29 Status of This Memo 31 This Internet-Draft is submitted in full conformance with the 32 provisions of BCP 78 and BCP 79. 34 Internet-Drafts are working documents of the Internet Engineering 35 Task Force (IETF). Note that other groups may also distribute 36 working documents as Internet-Drafts. The list of current Internet- 37 Drafts is at https://datatracker.ietf.org/drafts/current/. 39 Internet-Drafts are draft documents valid for a maximum of six months 40 and may be updated, replaced, or obsoleted by other documents at any 41 time. It is inappropriate to use Internet-Drafts as reference 42 material or to cite them other than as "work in progress." 44 This Internet-Draft will expire on May 13, 2019. 46 Copyright Notice 48 Copyright (c) 2018 IETF Trust and the persons identified as the 49 document authors. All rights reserved. 51 This document is subject to BCP 78 and the IETF Trust's Legal 52 Provisions Relating to IETF Documents 53 (https://trustee.ietf.org/license-info) in effect on the date of 54 publication of this document. Please review these documents 55 carefully, as they describe your rights and restrictions with respect 56 to this document. Code Components extracted from this document must 57 include Simplified BSD License text as described in Section 4.e of 58 the Trust Legal Provisions and are provided without warranty as 59 described in the Simplified BSD License. 61 This document may contain material from IETF Documents or IETF 62 Contributions published or made publicly available before November 63 10, 2008. The person(s) controlling the copyright in some of this 64 material may not have granted the IETF Trust the right to allow 65 modifications of such material outside the IETF Standards Process. 66 Without obtaining an adequate license from the person(s) controlling 67 the copyright in such materials, this document may not be modified 68 outside the IETF Standards Process, and derivative works of it may 69 not be created outside the IETF Standards Process, except to format 70 it for publication as an RFC or to translate it into languages other 71 than English. 73 Table of Contents 75 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 76 1.1. Requirements notation . . . . . . . . . . . . . . . . . . 4 77 2. Link attributes examples . . . . . . . . . . . . . . . . . . 4 78 3. Advertising Link Attributes . . . . . . . . . . . . . . . . . 4 79 3.1. OSPFv2 TE Opaque LSA and OSPFv3 Intra-Area-TE-LSA . . . . 4 80 3.2. OSPFv2 Extended Link Opaque LSA and OSPFv3 E-Router-LSA . 5 81 3.3. Selected Approach . . . . . . . . . . . . . . . . . . . . 6 82 4. Reused TE link attributes . . . . . . . . . . . . . . . . . . 6 83 4.1. Shared Risk Link Group (SRLG) . . . . . . . . . . . . . . 6 84 4.2. Extended Metrics . . . . . . . . . . . . . . . . . . . . 7 85 4.3. Traffic Engineering Metric . . . . . . . . . . . . . . . 8 86 4.4. Administrative Group . . . . . . . . . . . . . . . . . . 8 87 5. Advertisement of Application Specific Values . . . . . . . . 8 88 6. Maximum Link Bandwidth . . . . . . . . . . . . . . . . . . . 11 89 7. Local Interface IPv6 Address Sub-TLV . . . . . . . . . . . . 12 90 8. Remote Interface IPv6 Address Sub-TLV . . . . . . . . . . . . 12 91 9. Deployment Considerations . . . . . . . . . . . . . . . . . . 12 92 10. Attribute Advertisements and Enablement . . . . . . . . . . . 13 93 11. Backward Compatibility . . . . . . . . . . . . . . . . . . . 14 94 12. Security Considerations . . . . . . . . . . . . . . . . . . . 14 95 13. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14 96 13.1. OSPFv2 . . . . . . . . . . . . . . . . . . . . . . . . . 14 97 13.2. OSPFv3 . . . . . . . . . . . . . . . . . . . . . . . . . 15 98 14. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 16 99 15. References . . . . . . . . . . . . . . . . . . . . . . . . . 16 100 15.1. Normative References . . . . . . . . . . . . . . . . . . 16 101 15.2. Informative References . . . . . . . . . . . . . . . . . 17 102 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 18 104 1. Introduction 106 Various link attributes have been defined in OSPFv2 [RFC2328] and 107 OSPFv3 [RFC5340] in the context of the MPLS traffic engineering and 108 GMPLS. All these attributes are distributed by OSPFv2 as sub-TLVs of 109 the Link-TLV advertised in the OSPFv2 TE Opaque LSA [RFC3630]. In 110 OSPFv3, they are distributed as sub-TLVs of the Link-TLV advertised 111 in the OSPFv3 Intra-Area-TE-LSA as defined in [RFC5329]. 113 Many of these link attributes are useful outside of traditional MPLS 114 Traffic Engineering or GMPLS. This brings its own set of problems, 115 in particular how to distribute these link attributes in OSPFv2 and 116 OSPFv3 when MPLS TE and GMPLS are not deployed or are deployed in 117 parallel with other applications that use these link attributes. 119 [RFC7855] discusses use cases/requirements for SR. Included among 120 these use cases is SRTE. If both RSVP-TE and SRTE are deployed in a 121 network, link attribute advertisements can be used by one or both of 122 these applications. As there is no requirement for the link 123 attributes advertised on a given link used by SRTE to be identical to 124 the link attributes advertised on that same link used by RSVP-TE, 125 there is a clear requirement to indicate independently which link 126 attribute advertisements are to be used by each application. 128 As the number of applications which may wish to utilize link 129 attributes may grow in the future, an additional requirement is that 130 the extensions defined allow the association of additional 131 applications to link attributes without altering the format of the 132 advertisements or introducing new backwards compatibility issues. 134 Finally, there may still be many cases where a single attribute value 135 can be shared among multiple applications, so the solution should 136 minimize advertising duplicate link/attribute when possible. 138 1.1. Requirements notation 140 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 141 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 142 document are to be interpreted as described in [RFC2119]. 144 2. Link attributes examples 146 This section lists some of the link attributes originally defined for 147 MPLS Traffic Engineering that can be used for other applications in 148 OSPFv2 and OSPFv3. The list doesn't necessarily contain all the 149 required attributes. 151 1. Remote Interface IP address [RFC3630] - OSPFv2 currently cannot 152 distinguish between parallel links between two OSPFv2 routers. 153 As a result, the two-way connectivity check performed during SPF 154 may succeed when the two routers disagree on which of the links 155 to use for data traffic. 157 2. Link Local/Remote Identifiers - [RFC4203] - Used for the two-way 158 connectivity check for parallel unnumbered links. Also used for 159 identifying adjacencies for unnumbered links in Segment Routing 160 traffic engineering. 162 3. Shared Risk Link Group (SRLG) [RFC4203] - In IPFRR, the SRLG is 163 used to compute diverse backup paths [RFC5714]. 165 4. Unidirectional Link Delay/Loss Metrics [RFC7471] - Could be used 166 for the shortest path first (SPF) computation using alternate 167 metrics within an OSPF area. 169 3. Advertising Link Attributes 171 This section outlines possible approaches for advertising link 172 attributes originally defined for MPLS Traffic Engineering or GMPLS 173 when they are used for other applications. 175 3.1. OSPFv2 TE Opaque LSA and OSPFv3 Intra-Area-TE-LSA 177 One approach for advertising link attributes is to continue to use 178 the OSPFv2 TE Opaque LSA [RFC3630] or the OSPFv3 Intra-Area-TE-LSA 179 [RFC5329]. There are several problems with this approach: 181 1. Whenever the link is advertised in an OSPFv2 TE Opaque LSA or in 182 an OSPFv3 Intra-Area-TE-LSA, the link becomes a part of the TE 183 topology, which may not match IP routed topology. By making the 184 link part of the TE topology, remote nodes may mistakenly believe 185 that the link is available for MPLS TE or GMPLS, when, in fact, 186 MPLS is not enabled on the link. 188 2. The OSPFv2 TE Opaque LSA and OSPFv3 Intra-Area-TE-LSA advertise 189 link attributes that are not used or required by MPLS TE or 190 GMPLS. There is no mechanism in these TE LSAs to indicate which 191 of the link attributes are passed to the MPLS TE application and 192 which are used by other applications including OSPF itself. 194 3. Link attributes used for non-TE applications are partitioned 195 across multiple LSAs - the TE Opaque LSA and the Extended Link 196 Opaque LSA in OSPFv2 and the OSPFv3 Intra-Area-TE-LSA and OSPFv3 197 Extended LSA Router-Link TLV [RFC8362] in OSPFv3. This 198 partitioning will require implementations to lookup multiple LSAs 199 to extract link attributes for a single link, bringing needless 200 complexity to OSPF implementations. 202 The advantage of this approach is that there is no additional 203 standardization requirement to advertise the TE/GMPL attributes for 204 other applications. Additionally, link attributes are only 205 advertised once when both OSPF TE and other applications are deployed 206 on the same link. This is not expected to be a common deployment 207 scenario. 209 3.2. OSPFv2 Extended Link Opaque LSA and OSPFv3 E-Router-LSA 211 An alternative approach for advertising link attributes is to use 212 Extended Link Opaque LSAs as defined in [RFC7684] for OSPFv2 and 213 Extended Router-LSAs [RFC8362] for OSPFv3. These LSAs were defined 214 as a generic containers for distribution of the extended link 215 attributes. There are several advantages in using them: 217 1. Advertisement of the link attributes does not make the link part 218 of the TE topology. It avoids any conflicts and is fully 219 compatible with the [RFC3630] and [RFC5329]. 221 2. The OSPFv2 TE Opaque LSA and OSPFv3 Intra-Area-TE-LSA remains 222 truly opaque to OSPFv2 and OSPFv3 as originally defined in 223 [RFC3630] and [RFC5329] respectively. Their contents are not 224 inspected by OSPF, that act as a pure transport. 226 3. There is clear distinction between link attributes used by TE and 227 link attributes used by other OSPFv2 or OSPFv3 applications. 229 4. All link attributes that are used by other applications are 230 advertised in a single LSA, the Extended Link Opaque LSA in 231 OSPFv2 or the OSPFv3 E-Router-LSA [RFC8362] in OSPFv3. 233 The disadvantage of this approach is that in rare cases, the same 234 link attribute is advertised in both the TE Opaque and Extended Link 235 Attribute LSAs in OSPFv2 or the Intra-Area-TE-LSA and E-Router-LSA in 236 OSPFv3. Additionally, there will be additional standardization 237 effort. However, this could also be viewed as an advantage as the 238 non-TE use cases for the TE link attributes are documented and 239 validated by the LSR working group. 241 3.3. Selected Approach 243 It is RECOMMENDED to use the Extended Link Opaque LSA [RFC7684] and 244 E-Router-LSA [RFC8362] to advertise any link attributes used for non- 245 TE applications in OSPFv2 or OSPFv3 respectively, including those 246 that have been originally defined for TE applications. 248 It is also RECOMMENDED that TE link attributes used for RSVP-TE/GMPLS 249 continue to use OSPFv2 TE Opaque LSA [RFC3630] and OSPFv3 Intra-Area- 250 TE-LSA [RFC5329]. 252 It is also RECOMMENDED to keep the format of the link attribute TLVs 253 that have been defined for TE applications unchanged even when they 254 are used for non-TE applications. 256 Finally, it is RECOMMENDED to allocate unique code points for these 257 TE link attribute TLVs in the OSPFv2 Extended Link TLV Sub-TLV 258 Registry [RFC7684] and in the OSPFv3 Extended LSA Sub-TLV Registry 259 [RFC8362]. For each reused TLV, the code point will be defined in an 260 IETF document along with the expected use-case(s). 262 4. Reused TE link attributes 264 This section defines the use case and code points for the OSPFv2 265 Extended Link TLV Sub-TLV Registry and OSPFv3 Extended LSA Sub-TLV 266 Registry for some of the link attributes that have been originally 267 defined for TE or GMPLS. 269 Remote interface IP address and Link Local/Remote Identifiers have 270 been added as sub-TLVs of OSPFv2 Extended Link TLV by [RFC8379]. 271 Link Local/Remote Identifiers are already included in the OSPFv3 272 Router-Link TLV [RFC8362]. 274 4.1. Shared Risk Link Group (SRLG) 276 The SRLG of a link can be used in IPFRR to compute a backup path that 277 does not share any SRLG group with the protected link. 279 To advertise the SRLG of the link in the OSPFv2 Extended Link TLV, 280 the same format for the sub-TLV defined in section 1.3 of [RFC4203] 281 is used and TLV type TBD1 is used. Similarly, for OSPFv3 to 282 advertise the SRLG in the OSPFv3 Router-Link TLV, TLV type TBD2 is 283 used. 285 4.2. Extended Metrics 287 [RFC3630] defines several link bandwidth types. [RFC7471] defines 288 extended link metrics that are based on link bandwidth, delay and 289 loss characteristics. All these can be used to compute best paths 290 within an OSPF area to satisfy requirements for bandwidth, delay 291 (nominal or worst case) or loss. 293 To advertise extended link metrics in the OSPFv2 Extended Link TLV, 294 the same format for the sub-TLVs defined in [RFC7471] is used with 295 the following TLV types: 297 TBD3 - Unidirectional Link Delay 299 TBD4 - Min/Max Unidirectional Link Delay 301 TBD5 - Unidirectional Delay Variation 303 TBD6 - Unidirectional Link Loss 305 TBD7 - Unidirectional Residual Bandwidth 307 TBD8 - Unidirectional Available Bandwidth 309 TBD9 - Unidirectional Utilized Bandwidth 311 To advertise extended link metrics in the OSPFv3 Extended LSA Router- 312 Link TLV, the same format for the sub-TLVs defined in [RFC7471] is 313 used with the following TLV types: 315 TBD10 - Unidirectional Link Delay 317 TBD11 - Min/Max Unidirectional Link Delay 319 TBD12 - Unidirectional Delay Variation 321 TBD13 - Unidirectional Link Loss 323 TBD14 - Unidirectional Residual Bandwidth 325 TBD15 - Unidirectional Available Bandwidth 327 TBD16 - Unidirectional Utilized Bandwidth 329 4.3. Traffic Engineering Metric 331 [RFC3630] defines Traffic Engineering Metric. 333 To advertise the Traffic Engineering Metric in the OSPFv2 Extended 334 Link TLV, the same format for the sub-TLV defined in section 2.5.5 of 335 [RFC3630] is used and TLV type TBD27 is used. Similarly, for OSPFv3 336 to advertise the Traffic Engineering Metric in the OSPFv3 Router-Link 337 TLV, TLV type TBD28 is used. 339 4.4. Administrative Group 341 [RFC3630] and [RFC7308] define the Administrative Group and Extended 342 Administrative Group sub-TLVs respectively. 344 One use case where advertisement of the Extended Administrative 345 Group(s) for a link is required is described in 346 [I-D.ietf-lsr-flex-algo]. 348 To advertise the Administrative Group and Extended Administrative 349 Group in the OSPFv2 Extended Link TLV, the same format for the sub- 350 TLVs defined in [RFC3630] and [RFC7308] is used with the following 351 TLV types: 353 TBD17 - Administrative Group 355 TBD18 - Extended Administrative Group 357 To advertise Administrative Group and Extended Administrative Group 358 in the OSPFv3 Router-Link TLV, the same format for the sub-TLVs 359 defined in [RFC3630] and [RFC7308] is used with the following TLV 360 types: 362 TBD19 - Administrative Group 364 TBD20 - Extended Administrative Group 366 5. Advertisement of Application Specific Values 368 Multiple applications can utilize link attributes that are advertised 369 by OSPF. Some examples of applications using the link attributes are 370 Segment Routing Traffic Engineering and LFA [RFC5286]. 372 In some cases the link attribute MAY have different values for 373 different applications. An example could be SRLG [Section 4.1], 374 where values used by LFA could be different then the values used by 375 Segment Routing Traffic Engineering. 377 To allow advertisement of the application specific values of the link 378 attribute, a new Application Specific Link Attributes (ASLA) sub-TLV 379 is defined. The ASLA sub-TLV is a sub-TLV of the OSPFv2 Extended 380 Link TLV [RFC7471] and OSPFv3 Router-Link TLV [RFC8362]. The ASLA 381 sub-TLV is an optional sub-TLV and can appear multiple times in the 382 OSPFv2 Extended Link TLV and OSPFv3 Router-Link TLV. It has the 383 following format: 385 0 1 2 3 386 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 1 387 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 388 | Type | Length | 389 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 390 | SABML | UDABML | Reserved | 391 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 392 | Standard Application Bit-Mask | 393 +- -+ 394 | ... | 395 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 396 | User Defined Application Bit-Mask | 397 +- -+ 398 | ... | 399 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 400 | Link Attribute sub-sub-TLVs | 401 +- -+ 402 | ... | 404 where: 406 Type: TBD21 (OSPFv2), TBD22 (OSPFv3) 408 Length: variable 410 SABML: Standard Application Bit-Mask Length. It MUST be a 411 multiple of 4 bytes. If the Standard Application Bit-Mask is not 412 present, the Standard Application Bit-Mask Length MUST be set to 413 0. 415 UDABML: User Defined Application Bit-Mask Length. It MUST be a 416 multiple of 4 bytes. If the User Defined Application Bit-Mask is 417 not present, the User Defined Application Bit-Mask Length MUST be 418 set to 0. 420 Standard Application Bit-Mask: Optional set of bits, where each 421 bit represents a single standard application. Bits are defined in 422 [I-D.ietf-isis-te-app], which also request a new IANA "Link 423 Attribute Applications" registry under "Interior Gateway Protocol 424 (IGP) Parameters" for them. The bits are repeated here for 425 informational purpose: 427 Bit-0: RSVP Traffic Engineering 429 Bit-1: Segment Routing Traffic Engineering 431 Bit-2: Loop Free Alternate (LFA). Includes all LFA types 433 Bit-3: Flexible Algorithm 435 User Defined Application Bit-Mask: Optional set of bits, where 436 each bit represents a single user defined application. 438 Standard Application Bits are defined/sent starting with Bit 0. 439 Additional bit definitions that are defined in the future SHOULD be 440 assigned in ascending bit order so as to minimize the number of 441 octets that will need to be transmitted. 443 User Defined Application bits have no relationship to Standard 444 Application bits and are NOT managed by IANA or any other standards 445 body. It is recommended that bits are used starting with Bit 0 so as 446 to minimize the number of octets required to advertise all of them. 448 Undefined bits in both Bit-Masks MUST be transmitted as 0 and MUST be 449 ignored on receipt. Bits that are NOT transmitted MUST be treated as 450 if they are set to 0 on receipt. 452 If the link attribute advertisement is limited to be used by a 453 specific set of applications, corresponding Bit-Masks MUST be present 454 and application specific bit(s) MUST be set for all applications that 455 use the link attributes advertised in the ASLA sub-TLV. 457 Application Bit-Masks apply to all link attributes that support 458 application specific values and are advertised in the ASLA sub-TLV. 460 The advantage of not making the Application Bit-Masks part of the 461 attribute advertisement itself is that we can keep the format of the 462 link attributes that have been defined previously and reuse the same 463 format when advertising them in the ASLA sub-TLV. 465 When neither the Standard Application Bits nor the User Defined 466 Application bits are set (i.e., both SABML and UDABML are 0) in the 467 ASLA sub-TLV, then the link attributes included in it MUST be 468 considered as being applicable to all applications. 470 If, however, another advertisement of the same link attribute 471 includes any Application Bit-Mask in the ASLA sub-TLV, applications 472 that are listed in the Application Bit-Masks of such ASLA sub-TLV 473 SHOULD use the attribute advertisement which has the application 474 specific bit set in the Application Bit-Masks. 476 If the same application is listed in the Application Bit-Masks of 477 more then one ASLA sub-TLV, the application SHOULD use the first 478 advertisement and ignore any subsequent advertisements of the same 479 attribute. This situation SHOULD be logged as an error. 481 This document defines the initial set of link attributes that MUST 482 use ASLA sub-TLV if advertised in the OSPFv2 Extended Link TLV or in 483 the OSPFv3 Router-Link TLV. If the ASLA sub-TLV includes any link 484 attribute(s) NOT listed below, they MUST be ignored. Documents which 485 define new link attributes MUST state whether the new attributes 486 support application specific values and as such MUST be advertised in 487 an ASLA sub-TLV. The link attributes that MUST be advertised in ASLA 488 sub-TLVs are: 490 - Shared Risk Link Group 492 - Unidirectional Link Delay 494 - Min/Max Unidirectional Link Delay 496 - Unidirectional Delay Variation 498 - Unidirectional Link Loss 500 - Unidirectional Residual Bandwidth 502 - Unidirectional Available Bandwidth 504 - Unidirectional Utilized Bandwidth 506 - Administrative Group 508 - Extended Administrative Group 510 - Traffic Engineering Metric 512 6. Maximum Link Bandwidth 514 Maximum link bandwidth is an application independent attribute of the 515 link that is defined in [RFC3630]. Because it is an application 516 independent attribute, it MUST NOT be advertised in ASLA sub-TLV. 517 Instead, it MAY be advertised as a sub-TLV of the Extended Link 518 Opaque LSA Extended Link TLV in OSPFv2 [RFC7684] or sub-TLV of OSPFv3 519 E-Router-LSA Router-Link TLV in OSPFv3 [RFC8362]. 521 To advertise the Maximum link bandwidth in the OSPFv2 Extended Link 522 TLV, the same format for sub-TLV defined in [RFC3630] is used with 523 TLV type TBD23. 525 To advertise the Maximum link bandwidth in the OSPFv3 Router-Link 526 TLV, the same format for sub-TLV defined in [RFC3630] is used with 527 TLV type TBD24. 529 7. Local Interface IPv6 Address Sub-TLV 531 The Local Interface IPv6 Address Sub-TLV is an application 532 independent attribute of the link that is defined in [RFC5329]. 533 Because it is an application independent attribute, it MUST NOT be 534 advertised in the ASLA sub-TLV. Instead, it MAY be advertised as a 535 sub-TLV of the OSPFv3 E-Router-LSA Router-Link TLV [RFC8362]. 537 To advertise the Local Interface IPv6 Address Sub-TLV in the OSPFv3 538 Router-Link TLV, the same format for sub-TLV defined in [RFC5329] is 539 used with TLV type TBD25. 541 8. Remote Interface IPv6 Address Sub-TLV 543 The Remote Interface IPv6 Address Sub-TLV is an application 544 independent attribute of the link that is defined in [RFC5329]. 545 Because it is an application independent attribute, it MUST NOT be 546 advertised in the ASLA sub-TLV. Instead, it MAY be advertised as a 547 sub-TLV of the OSPFv3 E-Router-LSA Router-Link TLV [RFC8362]. 549 To advertise the Remote Interface IPv6 Address Sub-TLV in the OSPFv3 550 Router-Link TLV, the same format for sub-TLV defined in [RFC5329] is 551 used with TLV type TBD26. 553 9. Deployment Considerations 555 If link attributes are advertised associated with zero length 556 application bit masks for both standard applications and user defined 557 applications, then that set of link attributes MAY be used by any 558 application. If support for a new application is introduced on any 559 node in a network in the presence of such advertisements, these 560 advertisements MAY be used by the new application. If this is not 561 what is intended, then existing advertisements MUST be readvertised 562 with an explicit set of applications specified before a new 563 application is introduced. 565 10. Attribute Advertisements and Enablement 567 This document defines extensions to support the advertisement of 568 application specific link attributes. 570 Whether the presence of link attribute advertisements for a given 571 application indicates that the application is enabled on that link 572 depends upon the application. Similarly, whether the absence of link 573 attribute advertisements indicates that the application is not 574 enabled depends upon the application. 576 In the case of RSVP-TE, the advertisement of application specific 577 link attributes implies that RSVP is enabled on that link. 579 In the case of SRTE, advertisement of application specific link 580 attributes does NOT indicate enablement of SRTE. The advertisements 581 are only used to support constraints which may be applied when 582 specifying an explicit path. SRTE is implicitly enabled on all links 583 which are part of the Segment Routing enabled topology independent of 584 the existence of link attribute advertisements. 586 In the case of LFA, advertisement of application specific link 587 attributes does NOT indicate enablement of LFA on that link. 588 Enablement is controlled by local configuration. 590 In the case of Flexible Algorithm, advertisement of application 591 specific link attributes does NOT indicate enablement of Flexible 592 Algorithm on that link. Rather the attributes are used to determine 593 what links are included/excluded in the algorithm specific 594 constrained SPF. This is fully specified in 595 [I-D.ietf-lsr-flex-algo]. 597 If, in the future, additional standard applications are defined to 598 use this mechanism, the specification defining this use MUST define 599 the relationship between application specific link attribute 600 advertisements and enablement for that application. 602 This document allows the advertisement of application specific link 603 attributes with no application identifiers i.e., both the Standard 604 Application Bit Mask and the User Defined Application Bit Mask are 605 not present Section 5. This supports the use of the link attribute 606 by any application. In the presence of an application where the 607 advertisement of link attribute advertisements is used to infer the 608 enablement of an application on that link (e.g., RSVP-TE), the 609 absence of the application identifier leaves ambiguous whether that 610 application is enabled on such a link. This needs to be considered 611 when making use of the "any application" encoding. 613 11. Backward Compatibility 615 Link attributes may be concurrently advertised in both the TE Opaque 616 LSA and the Extended Link Opaque LSA in OSPFv2 and the OSPFv3 Intra- 617 Area-TE-LSA and OSPFv3 Extended LSA Router-Link TLV in OSPFv3. 619 In fact, there is at least one OSPF implementation that utilizes the 620 link attributes advertised in TE Opaque LSAs [RFC3630] for Non-RSVP 621 TE applications. For example, this implementation of LFA and remote 622 LFA utilizes links attributes such as Shared Risk Link Groups (SRLG) 623 [RFC4203] and Admin Group [[RFC3630] advertised in TE Opaque LSAs. 624 These applications are described in [RFC5286], [RFC7490], [RFC7916] 625 and [RFC8102]. 627 When an OSPF routing domain includes routers using link attributes 628 from the OSPFv2 TE Opaque LSAs or the OSPFv3 Intra-Area-TE-LSA for 629 Non-RSVP TE applications such as LFA, OSPF routers in that domain 630 SHOULD continue to advertise such OSPFv2 TE Opaque LSAs or the OSPFv3 631 Intra-Area-TE-LSA. If there are also OSPF routers using the link 632 attributes described herein for any other application, OSPF routers 633 in the routing domain will also need to advertise these attributes in 634 OSPFv2 Extended Link Attributes LSAs or OSPFv3 E-Router-LSA. In such 635 a deployment, the advertised attributes SHOULD be the same and Non- 636 RSVP application access to link attributes is a matter of local 637 policy. 639 12. Security Considerations 641 Implementations must assure that malformed TLV and Sub-TLV 642 permutations do not result in errors that cause hard OSPF failures. 644 13. IANA Considerations 646 13.1. OSPFv2 648 OSPFv2 Extended Link TLV Sub-TLVs registry [RFC7684] defines sub-TLVs 649 at any level of nesting for OSPFv2 Extended Link TLVs. This 650 specification updates OSPFv2 Extended Link TLV sub-TLVs registry with 651 the following TLV types: 653 TBD21 (10 Recommended) - Application Specific Link Attributes 655 TBD1 (11 Recommended) - Shared Risk Link Group 657 TBD3 (12 Recommended) - Unidirectional Link Delay 659 TBD4 (13 Recommended) - Min/Max Unidirectional Link Delay 660 TBD5 (14 Recommended) - Unidirectional Delay Variation 662 TBD6 (15 Recommended) - Unidirectional Link Loss 664 TBD7 (16 Recommended) - Unidirectional Residual Bandwidth 666 TBD8 (17 Recommended) - Unidirectional Available Bandwidth 668 TBD9 (18 Recommended) - Unidirectional Utilized Bandwidth 670 TBD9 (19 Recommended) - Administrative Group 672 TBD17 (20 Recommended) - Extended Administrative Group 674 TBD23 (21 Recommended) - Maximum Link Bandwidth 676 TBD27 (22 Recommended) - Traffic Engineering Metric 678 13.2. OSPFv3 680 OSPFv3 Extended LSA Sub-TLV Registry [RFC8362] defines sub-TLVs at 681 any level of nesting for OSPFv3 Extended LSAs. This specification 682 updates OSPFv3 Extended LSA Sub-TLV Registry with the following TLV 683 types: 685 TBD22 (9 Recommended) - Application Specific Link Attributes 687 TBD2 (10 Recommended) - Shared Risk Link Group 689 TBD10 (11 Recommended) - Unidirectional Link Delay 691 TBD11 (12 Recommended) - Min/Max Unidirectional Link Delay 693 TBD12 (13 Recommended) - Unidirectional Delay Variation 695 TBD13 (14 Recommended) - Unidirectional Link Loss 697 TBD14 (15 Recommended) - Unidirectional Residual Bandwidth 699 TBD15 (16 Recommended) - Unidirectional Available Bandwidth 701 TBD16 (17 Recommended) - Unidirectional Utilized Bandwidth 703 TBD19 (18 Recommended) - Administrative Group 705 TBD20 (19 Recommended) - Extended Administrative Group 707 TBD24 (20 Recommended) - Maximum Link Bandwidth 708 TBD25 (21 Recommended) - Local Interface IPv6 Address Sub-TLV 710 TBD26 (22 Recommended) - Local Interface IPv6 Address Sub-TLV 712 TBD28 (23 Recommended) - Traffic Engineering Metric 714 14. Acknowledgments 716 Thanks to Chris Bowers for his review and comments. 718 15. References 720 15.1. Normative References 722 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 723 Requirement Levels", BCP 14, RFC 2119, 724 DOI 10.17487/RFC2119, March 1997, 725 . 727 [RFC3630] Katz, D., Kompella, K., and D. Yeung, "Traffic Engineering 728 (TE) Extensions to OSPF Version 2", RFC 3630, 729 DOI 10.17487/RFC3630, September 2003, 730 . 732 [RFC5329] Ishiguro, K., Manral, V., Davey, A., and A. Lindem, Ed., 733 "Traffic Engineering Extensions to OSPF Version 3", 734 RFC 5329, DOI 10.17487/RFC5329, September 2008, 735 . 737 [RFC5340] Coltun, R., Ferguson, D., Moy, J., and A. Lindem, "OSPF 738 for IPv6", RFC 5340, DOI 10.17487/RFC5340, July 2008, 739 . 741 [RFC5714] Shand, M. and S. Bryant, "IP Fast Reroute Framework", 742 RFC 5714, DOI 10.17487/RFC5714, January 2010, 743 . 745 [RFC7308] Osborne, E., "Extended Administrative Groups in MPLS 746 Traffic Engineering (MPLS-TE)", RFC 7308, 747 DOI 10.17487/RFC7308, July 2014, 748 . 750 [RFC7684] Psenak, P., Gredler, H., Shakir, R., Henderickx, W., 751 Tantsura, J., and A. Lindem, "OSPFv2 Prefix/Link Attribute 752 Advertisement", RFC 7684, DOI 10.17487/RFC7684, November 753 2015, . 755 [RFC8362] Lindem, A., Roy, A., Goethals, D., Reddy Vallem, V., and 756 F. Baker, "OSPFv3 Link State Advertisement (LSA) 757 Extensibility", RFC 8362, DOI 10.17487/RFC8362, April 758 2018, . 760 15.2. Informative References 762 [I-D.ietf-idr-ls-distribution] 763 Gredler, H., Medved, J., Previdi, S., Farrel, A., and S. 764 Ray, "North-Bound Distribution of Link-State and TE 765 Information using BGP", draft-ietf-idr-ls-distribution-13 766 (work in progress), October 2015. 768 [I-D.ietf-isis-te-app] 769 Ginsberg, L., Psenak, P., Previdi, S., Henderickx, W., and 770 J. Drake, "IS-IS TE Attributes per application", draft- 771 ietf-isis-te-app-05 (work in progress), October 2018. 773 [I-D.ietf-lsr-flex-algo] 774 Psenak, P., Hegde, S., Filsfils, C., Talaulikar, K., and 775 A. Gulko, "IGP Flexible Algorithm", draft-ietf-lsr-flex- 776 algo-00 (work in progress), May 2018. 778 [I-D.ietf-ospf-segment-routing-extensions] 779 Psenak, P., Previdi, S., Filsfils, C., Gredler, H., 780 Shakir, R., Henderickx, W., and J. Tantsura, "OSPF 781 Extensions for Segment Routing", draft-ietf-ospf-segment- 782 routing-extensions-25 (work in progress), April 2018. 784 [RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328, 785 DOI 10.17487/RFC2328, April 1998, 786 . 788 [RFC4203] Kompella, K., Ed. and Y. Rekhter, Ed., "OSPF Extensions in 789 Support of Generalized Multi-Protocol Label Switching 790 (GMPLS)", RFC 4203, DOI 10.17487/RFC4203, October 2005, 791 . 793 [RFC5286] Atlas, A., Ed. and A. Zinin, Ed., "Basic Specification for 794 IP Fast Reroute: Loop-Free Alternates", RFC 5286, 795 DOI 10.17487/RFC5286, September 2008, 796 . 798 [RFC7471] Giacalone, S., Ward, D., Drake, J., Atlas, A., and S. 799 Previdi, "OSPF Traffic Engineering (TE) Metric 800 Extensions", RFC 7471, DOI 10.17487/RFC7471, March 2015, 801 . 803 [RFC7490] Bryant, S., Filsfils, C., Previdi, S., Shand, M., and N. 804 So, "Remote Loop-Free Alternate (LFA) Fast Reroute (FRR)", 805 RFC 7490, DOI 10.17487/RFC7490, April 2015, 806 . 808 [RFC7855] Previdi, S., Ed., Filsfils, C., Ed., Decraene, B., 809 Litkowski, S., Horneffer, M., and R. Shakir, "Source 810 Packet Routing in Networking (SPRING) Problem Statement 811 and Requirements", RFC 7855, DOI 10.17487/RFC7855, May 812 2016, . 814 [RFC7916] Litkowski, S., Ed., Decraene, B., Filsfils, C., Raza, K., 815 Horneffer, M., and P. Sarkar, "Operational Management of 816 Loop-Free Alternates", RFC 7916, DOI 10.17487/RFC7916, 817 July 2016, . 819 [RFC8102] Sarkar, P., Ed., Hegde, S., Bowers, C., Gredler, H., and 820 S. Litkowski, "Remote-LFA Node Protection and 821 Manageability", RFC 8102, DOI 10.17487/RFC8102, March 822 2017, . 824 [RFC8379] Hegde, S., Sarkar, P., Gredler, H., Nanduri, M., and L. 825 Jalil, "OSPF Graceful Link Shutdown", RFC 8379, 826 DOI 10.17487/RFC8379, May 2018, 827 . 829 Authors' Addresses 831 Peter Psenak (editor) 832 Cisco Systems, Inc. 833 Eurovea Centre, Central 3 834 Pribinova Street 10 835 Bratislava 81109 836 Slovakia 838 Email: ppsenak@cisco.com 840 Acee Lindem 841 Cisco Systems 842 301 Midenhall Way 843 Cary, NC 27513 844 USA 846 Email: acee@cisco.com 847 Les Ginsberg 848 Cisco Systems 849 821 Alder Drive 850 MILPITAS, CA 95035 851 USA 853 Email: ginsberg@cisco.com 855 Wim Henderickx 856 Nokia 857 Copernicuslaan 50 858 Antwerp, 2018 94089 859 Belgium 861 Email: wim.henderickx@nokia.com 863 Jeff Tantsura 864 Nuage Networks 865 US 867 Email: jefftant.ietf@gmail.com 869 Hannes Gredler 870 RtBrick Inc. 872 Email: hannes@rtbrick.com 874 John Drake 875 Juniper Networks 877 Email: jdrake@juniper.net