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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Inter-Domain Routing S. Previdi 3 Internet-Draft Huawei Technologies 4 Intended status: Standards Track K. Talaulikar, Ed. 5 Expires: September 9, 2019 C. Filsfils 6 Cisco Systems, Inc. 7 H. Gredler 8 RtBrick Inc. 9 M. Chen 10 Huawei Technologies 11 March 8, 2019 13 BGP Link-State extensions for Segment Routing 14 draft-ietf-idr-bgp-ls-segment-routing-ext-12 16 Abstract 18 Segment Routing (SR) allows for a flexible definition of end-to-end 19 paths by encoding paths as sequences of topological sub-paths, called 20 "segments". These segments are advertised by routing protocols e.g. 21 by the link state routing protocols (IS-IS, OSPFv2 and OSPFv3) within 22 IGP topologies. 24 This draft defines extensions to the BGP Link-state address-family in 25 order to carry segment routing information via BGP. 27 Requirements Language 29 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 30 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 31 "OPTIONAL" in this document are to be interpreted as described in BCP 32 14 [RFC2119] [RFC8174] when, and only when, they appear in all 33 capitals, as shown here. 35 Status of This Memo 37 This Internet-Draft is submitted in full conformance with the 38 provisions of BCP 78 and BCP 79. 40 Internet-Drafts are working documents of the Internet Engineering 41 Task Force (IETF). Note that other groups may also distribute 42 working documents as Internet-Drafts. The list of current Internet- 43 Drafts is at https://datatracker.ietf.org/drafts/current/. 45 Internet-Drafts are draft documents valid for a maximum of six months 46 and may be updated, replaced, or obsoleted by other documents at any 47 time. It is inappropriate to use Internet-Drafts as reference 48 material or to cite them other than as "work in progress." 49 This Internet-Draft will expire on September 9, 2019. 51 Copyright Notice 53 Copyright (c) 2019 IETF Trust and the persons identified as the 54 document authors. All rights reserved. 56 This document is subject to BCP 78 and the IETF Trust's Legal 57 Provisions Relating to IETF Documents 58 (https://trustee.ietf.org/license-info) in effect on the date of 59 publication of this document. Please review these documents 60 carefully, as they describe your rights and restrictions with respect 61 to this document. Code Components extracted from this document must 62 include Simplified BSD License text as described in Section 4.e of 63 the Trust Legal Provisions and are provided without warranty as 64 described in the Simplified BSD License. 66 Table of Contents 68 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 69 2. BGP-LS Extensions for Segment Routing . . . . . . . . . . . . 4 70 2.1. Node Attributes TLVs . . . . . . . . . . . . . . . . . . 5 71 2.1.1. SID/Label Sub-TLV . . . . . . . . . . . . . . . . . . 5 72 2.1.2. SR Capabilities TLV . . . . . . . . . . . . . . . . . 6 73 2.1.3. SR Algorithm TLV . . . . . . . . . . . . . . . . . . 7 74 2.1.4. SR Local Block TLV . . . . . . . . . . . . . . . . . 8 75 2.1.5. SRMS Preference TLV . . . . . . . . . . . . . . . . . 9 76 2.2. Link Attribute TLVs . . . . . . . . . . . . . . . . . . . 10 77 2.2.1. Adjacency SID TLV . . . . . . . . . . . . . . . . . . 10 78 2.2.2. LAN Adjacency SID TLV . . . . . . . . . . . . . . . . 12 79 2.2.3. L2 Bundle Member Attribute TLV . . . . . . . . . . . 14 80 2.3. Prefix Attribute TLVs . . . . . . . . . . . . . . . . . . 15 81 2.3.1. Prefix SID TLV . . . . . . . . . . . . . . . . . . . 16 82 2.3.2. Prefix Attribute Flags TLV . . . . . . . . . . . . . 17 83 2.3.3. Source Router Identifier (Source Router-ID) TLV . . . 18 84 2.3.4. Range TLV . . . . . . . . . . . . . . . . . . . . . . 19 85 2.4. Equivalent IS-IS Segment Routing TLVs/Sub-TLVs . . . . . 21 86 2.5. Equivalent OSPFv2/OSPFv3 Segment Routing TLVs/Sub-TLVs . 21 87 3. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 23 88 3.1. TLV/Sub-TLV Code Points Summary . . . . . . . . . . . . . 23 89 4. Manageability Considerations . . . . . . . . . . . . . . . . 24 90 5. Security Considerations . . . . . . . . . . . . . . . . . . . 25 91 6. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 26 92 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 26 93 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 26 94 8.1. Normative References . . . . . . . . . . . . . . . . . . 26 95 8.2. Informative References . . . . . . . . . . . . . . . . . 28 96 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 29 98 1. Introduction 100 Segment Routing (SR) allows for a flexible definition of end-to-end 101 paths by combining sub-paths called "segments". A segment can 102 represent any instruction, topological or service-based. A segment 103 can have a local semantic to an SR node or global within a domain. 104 Within IGP topologies an SR path is encoded as a sequence of 105 topological sub-paths, called "IGP segments". These segments are 106 advertised by the link-state routing protocols (IS-IS, OSPFv2 and 107 OSPFv3). 109 [RFC8402] defines the Link-State IGP segments - Prefix, Node, Anycast 110 and Adjacency segments. Prefix segments, by default, represent an 111 ECMP-aware shortest-path to a prefix, as per the state of the IGP 112 topology. Adjacency segments represent a hop over a specific 113 adjacency between two nodes in the IGP. A prefix segment is 114 typically a multi-hop path while an adjacency segment, in most of the 115 cases, is a one-hop path. Node and Anycast Segments are variations 116 of the Prefix Segment with their specific characteristics. 118 When Segment Routing is enabled in an IGP domain, segments are 119 advertised in the form of Segment Identifiers (SIDs). The IGP link- 120 state routing protocols have been extended to advertise SIDs and 121 other SR-related information. IGP extensions are described in: IS-IS 122 [I-D.ietf-isis-segment-routing-extensions], OSPFv2 123 [I-D.ietf-ospf-segment-routing-extensions] and OSPFv3 124 [I-D.ietf-ospf-ospfv3-segment-routing-extensions]. Using these 125 extensions, Segment Routing can be enabled within an IGP domain. 127 Segment Routing (SR) allows advertisement of single or multi-hop 128 paths. The flooding scope for the IGP extensions for Segment routing 129 is IGP area-wide. Consequently, the contents of a Link State 130 Database (LSDB) or a Traffic Engineering Database (TED) has the scope 131 of an IGP area and therefore, by using the IGP alone it is not enough 132 to construct segments across multiple IGP Area or AS boundaries. 134 In order to address the need for applications that require 135 topological visibility across IGP areas, or even across Autonomous 136 Systems (AS), the BGP-LS address-family/sub-address-family have been 137 defined to allow BGP to carry Link-State information. The BGP 138 Network Layer Reachability Information (NLRI) encoding format for 139 BGP-LS and a new BGP Path Attribute called the BGP-LS attribute are 140 defined in [RFC7752]. The identifying key of each Link-State object, 141 namely a node, link, or prefix, is encoded in the NLRI and the 142 properties of the object are encoded in the BGP-LS attribute. 144 +------------+ 145 | Consumer | 146 +------------+ 147 ^ 148 | 149 v 150 +-------------------+ 151 | BGP Speaker | +-----------+ 152 | (Route-Reflector) | | Consumer | 153 +-------------------+ +-----------+ 154 ^ ^ ^ ^ 155 | | | | 156 +---------------+ | +-------------------+ | 157 | | | | 158 v v v v 159 +-----------+ +-----------+ +-----------+ 160 | BGP | | BGP | | BGP | 161 | Speaker | | Speaker | . . . | Speaker | 162 +-----------+ +-----------+ +-----------+ 163 ^ ^ ^ 164 | | | 165 IGP IGP IGP 167 Figure 1: Link State info collection 169 Figure 1 describes a typical deployment scenario. In each IGP area, 170 one or more nodes are configured with BGP-LS. These BGP speakers 171 form an IBGP mesh by connecting to one or more route-reflectors. 172 This way, all BGP speakers (specifically the route-reflectors) obtain 173 Link-State information from all IGP areas (and from other ASes from 174 EBGP peers). An external component connects to the route-reflector 175 to obtain this information (perhaps moderated by a policy regarding 176 what information is or isn't advertised to the external component) as 177 described in [RFC7752]. 179 This document describes extensions to BGP-LS to advertise the SR 180 information. An external component (e.g., a controller) then can 181 collect SR information from across an SR domain (as described in 182 [RFC8402]) and construct the end-to-end path (with its associated 183 SIDs) that need to be applied to an incoming packet to achieve the 184 desired end-to-end forwarding. The SR domain may be comprised of a 185 single AS or multiple ASes. 187 2. BGP-LS Extensions for Segment Routing 189 This document defines SR extensions to BGP-LS and specifies the TLVs 190 and sub-TLVs for advertising SR information within the BGP-LS 191 Attribute. Section 2.4 and Section 2.5 lists the equivalent TLVs and 192 sub-TLVs in IS-IS, OSPFv2 and OSPFv3 protocols. 194 BGP-LS [RFC7752] defines the BGP-LS NLRI that can be a Node NLRI, a 195 Link NLRI or a Prefix NLRI. BGP-LS [RFC7752] defines the TLVs that 196 map link-state information to BGP-LS NLRI within the BGP-LS 197 Attribute. This document adds additional BGP-LS Attribute TLVs in 198 order to encode SR information. It does not introduce any changes to 199 the encoding of the BGP-LS NLRIs. 201 2.1. Node Attributes TLVs 203 The following Node Attribute TLVs are defined: 205 +------+-----------------+---------------+ 206 | Type | Description | Section | 207 +------+-----------------+---------------+ 208 | 1161 | SID/Label | Section 2.1.1 | 209 | 1034 | SR Capabilities | Section 2.1.2 | 210 | 1035 | SR Algorithm | Section 2.1.3 | 211 | 1036 | SR Local Block | Section 2.1.4 | 212 | 1037 | SRMS Preference | Section 2.1.5 | 213 +------+-----------------+---------------+ 215 Table 1: Node Attribute TLVs 217 These TLVs should only be added to the BGP-LS Attribute associated 218 with the Node NLRI describing the IGP node that is originating the 219 corresponding IGP TLV/sub-TLV described below. 221 2.1.1. SID/Label Sub-TLV 223 The SID/Label TLV is used as a sub-TLV by the SR Capabilities 224 (Section 2.1.2) and Segment Routing Local Block (SRLB) 225 (Section 2.1.4) TLVs and has the following format: 227 0 1 2 3 228 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 1 229 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 230 | Type | Length | 231 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 232 | SID/Label (variable) | 233 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 235 Figure 2: SID/Label sub-TLV Format 237 Where: 239 Type: 1161 241 Length: Either 3 or 4 depending whether the value is encoded as a 242 label or an index/SID. 244 SID/Label: If length is set to 3, then the 20 rightmost bits 245 represent a label (the total TLV size is 7). If length is set to 246 4, then the value represents a 32 bit SID (the total TLV size is 247 8). 249 2.1.2. SR Capabilities TLV 251 The SR Capabilities TLV is used in order to advertise the node's SR 252 Capabilities including its Segment Routing Global Base (SRGB) 253 range(s). In the case of IS-IS, the capabilities also include the 254 IPv4 and IPv6 support for the SR-MPLS forwarding plane. This 255 information is derived from the protocol specific advertisements. 257 o IS-IS, as defined by the SR Capabilities sub-TLV in 258 [I-D.ietf-isis-segment-routing-extensions]. 260 o OSPFv2/OSPFv3, as defined by the SID/Label Range TLV in 261 [I-D.ietf-ospf-segment-routing-extensions] and 262 [I-D.ietf-ospf-ospfv3-segment-routing-extensions]. 264 The SR Capabilities TLV has the following format: 266 0 1 2 3 267 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 1 268 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 269 | Type | Length | 270 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 271 | Flags | Reserved | 272 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 274 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 275 | Range Size | 276 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 277 // SID/Label sub-TLV (variable) // 278 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 280 Figure 3: SR Capabilities TLV Format 282 Where: 284 Type: 1034 285 Length: Variable. Minimum length is 12. 287 Flags: 1 octet of flags as defined in 288 [I-D.ietf-isis-segment-routing-extensions] for IS-IS. The flags 289 are not currently defined for OSPFv2 and OSPFv3 and SHOULD be set 290 to 0 and MUST be ignored on receipt. 292 Reserved: 1 octet that SHOULD be set to 0 and MUST be ignored on 293 receipt. 295 One or more entries, each of which have the following format: 297 Range Size: 3 octet with a non-zero value indicating the number 298 of labels in the range. 300 SID/Label sub-TLV (as defined in Section 2.1.1) which encodes 301 the first label in the range. Since the SID/Label sub-TLV is 302 used to indicate the first label of the SRGB range, only label 303 encoding is valid under the SR Capabilities TLV. 305 2.1.3. SR Algorithm TLV 307 The SR Algorithm TLV is used in order to advertise the SR Algorithms 308 supported by the node. This information is derived from the protocol 309 specific advertisements. 311 o IS-IS, as defined by the SR Algorithm sub-TLV in 312 [I-D.ietf-isis-segment-routing-extensions]. 314 o OSPFv2/OSPFv3, as defined by the SR Algorithm TLV in 315 [I-D.ietf-ospf-segment-routing-extensions] and 316 [I-D.ietf-ospf-ospfv3-segment-routing-extensions]. 318 The SR Algorithm TLV has the following format: 320 0 1 2 3 321 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 1 322 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 323 | Type | Length | 324 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 325 | Algorithm 1 | Algorithm... | Algorithm N | | 326 +- -+ 327 | | 328 + + 330 Figure 4: SR Algorithm TLV Format 332 Where: 334 Type: 1035 336 Length: Variable. Minimum length is 1 and maximum can be 256. 338 Algorithm: 1 octet identifying the algorithm. 340 2.1.4. SR Local Block TLV 342 The SR Local Block (SRLB) TLV contains the range(s) of labels the 343 node has reserved for local SIDs. Local SIDs are used, e.g., in IGP 344 (IS-IS, OSPF) for Adjacency-SIDs, and may also be allocated by 345 components other than IGP protocols. As an example, an application 346 or a controller may instruct a node to allocate a specific local SID. 347 Therefore, in order for such applications or controllers to know the 348 range of local SIDs available, it is required that the node 349 advertises its SRLB. 351 This information is derived from the protocol specific 352 advertisements. 354 o IS-IS, as defined by the SR Local Block sub-TLV in 355 [I-D.ietf-isis-segment-routing-extensions]. 357 o OSPFv2/OSPFv3, as defined by the SR Local Block TLV in 358 [I-D.ietf-ospf-segment-routing-extensions] and 359 [I-D.ietf-ospf-ospfv3-segment-routing-extensions]. 361 The SRLB TLV has the following format: 363 0 1 2 3 364 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 1 365 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 366 | Type | Length | 367 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 368 | Flags | Reserved | 369 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 371 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 372 | Range Size | 373 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 374 // SID/Label sub-TLV (variable) // 375 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 377 Figure 5: SRLB TLV Format 379 Where: 381 Type: 1036 383 Length: Variable. Minimum length is 12. 385 Flags: 1 octet of flags. None are defined at this stage. 387 Reserved: 1 octet that SHOULD be set to 0 and MUST be ignored on 388 receipt. 390 One or more entries, each of which have the following format: 392 Range Size: 3 octet value indicating the number of labels in 393 the range. 395 SID/Label sub-TLV (as defined in Section 2.1.1) which encodes 396 the first label in the range. Since the SID/Label sub-TLV is 397 used to indicate the first label of the SRLB range, only label 398 encoding is valid under the SR Local Block TLV. 400 2.1.5. SRMS Preference TLV 402 The Segment Routing Mapping Server (SRMS) Preference TLV is used in 403 order to associate a preference with SRMS advertisements from a 404 particular source. [I-D.ietf-spring-segment-routing-ldp-interop] 405 specifies the SRMS functionality along with SRMS preference of the 406 node advertising the SRMS Prefix-to-SID Mapping ranges. 408 This information is derived from the protocol specific 409 advertisements. 411 o IS-IS, as defined by the SRMS Preference sub-TLV in 412 [I-D.ietf-isis-segment-routing-extensions]. 414 o OSPFv2/OSPFv3, as defined by the SRMS Preference TLV in 415 [I-D.ietf-ospf-segment-routing-extensions] and 416 [I-D.ietf-ospf-ospfv3-segment-routing-extensions]. 418 The SRMS Preference TLV has the following format: 420 0 1 2 3 421 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 1 422 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 423 | Type | Length | 424 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 425 | Preference | 426 +-+-+-+-+-+-+-+-+ 428 Figure 6: SRMS Preference TLV Format 430 Where: 432 Type: 1037 434 Length: 1. 436 Preference: 1 octet. Unsigned 8 bit SRMS preference. 438 The use of the SRMS Preference TLV is defined in 439 [I-D.ietf-isis-segment-routing-extensions], 440 [I-D.ietf-ospf-segment-routing-extensions] and 441 [I-D.ietf-ospf-ospfv3-segment-routing-extensions]. 443 2.2. Link Attribute TLVs 445 The following Link Attribute TLVs are are defined: 447 +------+-----------------------+---------------+ 448 | Type | Description | Section | 449 +------+-----------------------+---------------+ 450 | 1099 | Adjacency SID TLV | Section 2.2.1 | 451 | 1100 | LAN Adjacency SID TLV | Section 2.2.2 | 452 | 1172 | L2 Bundle Member TLV | Section 2.2.3 | 453 +------+-----------------------+---------------+ 455 Table 2: Link Attribute TLVs 457 These TLVs should only be added to the BGP-LS Attribute associated 458 with the Link NLRI describing the link of the IGP node that is 459 originating the corresponding IGP TLV/sub-TLV described below. 461 2.2.1. Adjacency SID TLV 463 The Adjacency SID TLV is used in order to advertise information 464 related to an Adjacency SID. This information is originated as in 465 Adj-SID sub-TLV of IS-IS [I-D.ietf-isis-segment-routing-extensions], 466 OSPFv2 [I-D.ietf-ospf-segment-routing-extensions] and OSPFv3 467 [I-D.ietf-ospf-ospfv3-segment-routing-extensions]. 469 The Adjacency SID TLV has the following format: 471 0 1 2 3 472 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 1 473 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 474 | Type | Length | 475 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 476 | Flags | Weight | Reserved | 477 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 478 | SID/Label/Index (variable) | 479 +---------------------------------------------------------------+ 481 Figure 7: Adjacency SID TLV Format 483 Where: 485 Type: 1099 487 Length: Variable, 7 or 8 depending on Label or Index encoding of 488 the SID 490 Flags. 1 octet value which sould be parsed as: 492 * IS-IS Adj-SID flags are defined in 493 [I-D.ietf-isis-segment-routing-extensions] section 2.2.1. 495 * OSPFv2 Adj-SID flags are defined in 496 [I-D.ietf-ospf-segment-routing-extensions] section 6.1. 498 * OSPFv3 Adj-SID flags are defined in 499 [I-D.ietf-ospf-segment-routing-extensions] section 7.1. 501 Weight: Weight used for load-balancing purposes. 503 Reserved: 2 octets that SHOULD be set to 0 and MUST be ignored on 504 receipt. 506 SID/Index/Label: 508 * IS-IS: Label or index value as defined in 509 [I-D.ietf-isis-segment-routing-extensions], 511 * OSPFv2: Label or index value as defined in 512 [I-D.ietf-ospf-segment-routing-extensions], 514 * OSPFv3: Label or index value as defined in 515 [I-D.ietf-ospf-ospfv3-segment-routing-extensions], 517 The Flags and, as an extension, the SID/Index/Label fields of this 518 TLV need to be interpreted accordingly to the respective underlying 519 IS-IS, OSPFv2 or OSPFv3 protocol. The consumer of the BGP-LS 520 interested in this TLV information MUST check the Protocol-ID of the 521 BGP-LS Link NLRI and refer to the underlying protocol specification 522 in order to parse these fields. 524 2.2.2. LAN Adjacency SID TLV 526 For a LAN, normally a node only announces its adjacency to the IS-IS 527 pseudo-node (or the equivalent OSPF Designated and Backup Designated 528 Routers). The LAN Adjacency Segment TLV allows a node to announce 529 adjacencies to all other nodes attached to the LAN in a single 530 instance of the BGP-LS Link NLRI. Without this TLV, the 531 corresponding BGP-LS link NLRI would need to be originated for each 532 additional adjacency in order to advertise the SR TLVs for these 533 neighbor adjacencies. 535 This information is originated as in LAN Adj-SID sub-TLV of IS-IS 536 [I-D.ietf-isis-segment-routing-extensions], OSPFv2 537 [I-D.ietf-ospf-segment-routing-extensions] and OSPFv3 538 [I-D.ietf-ospf-ospfv3-segment-routing-extensions]. 540 The LAN Adjacency SID TLV has the following format: 542 0 1 2 3 543 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 1 544 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 545 | Type | Length | 546 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 547 | Flags | Weight | Reserved | 548 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 550 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 551 | OSPF Neighbor ID / IS-IS System-ID | 552 + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 553 | | 554 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 556 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 557 | SID/Label/Index (variable) | 558 +---------------------------------------------------------------+ 560 Figure 8: LAN Adjacency SID TLV Format 562 Where: 564 Type: 1100 566 Length: Variable. For IS-IS it would be 13 or 14 depending on 567 Label or Index encoding of the SID. For OSPF it would be 11 or 12 568 depending on Label or Index encoding of the SID. 570 Flags. 1 octet value which sould be parsed as: 572 * IS-IS LAN Adj-SID flags are defined in 573 [I-D.ietf-isis-segment-routing-extensions] section 2.2.2. 575 * OSPFv2 LAN Adj-SID flags are defined in 576 [I-D.ietf-ospf-segment-routing-extensions] section 6.2. 578 * OSPFv3 LAN Adj-SID flags are defined in 579 [I-D.ietf-ospf-segment-routing-extensions] section 7.3. 581 Weight: Weight used for load-balancing purposes. 583 Reserved: 2 octets that SHOULD be set to 0 and MUST be ignored on 584 receipt. 586 Neighbor ID: 6 octets for IS-IS for the System-ID and 4 octets for 587 OSPF for the OSPF Router-ID of the neighbor. 589 SID/Index/Label: 591 * IS-IS: Label or index value as defined in 592 [I-D.ietf-isis-segment-routing-extensions], 594 * OSPFv2: Label or index value as defined in 595 [I-D.ietf-ospf-segment-routing-extensions], 597 * OSPFv3: Label or index value as defined in 598 [I-D.ietf-ospf-ospfv3-segment-routing-extensions], 600 The Neighbor ID, Flags and, as an extension, the SID/Index/Label 601 fields of this TLV need to be interpreted accordingly to the 602 respective underlying IS-IS, OSPFv2 or OSPFv3 protocol. The consumer 603 of the BGP-LS interested in this TLV information MUST check the 604 Protocol-ID of the BGP-LS Link NLRI and refer to the underlying 605 protocol specification in order to parse these fields. 607 2.2.3. L2 Bundle Member Attribute TLV 609 The L2 Bundle Member Attribute TLV identifies an L2 Bundle Member 610 link which in turn is associated with a parent L3 link. The L3 link 611 is described by the Link NLRI defined in [RFC7752] and the L2 Bundle 612 Member Attribute TLV is associated with the Link NLRI. The TLV MAY 613 include sub-TLVs which describe attributes associated with the bundle 614 member. The identified bundle member represents a unidirectional 615 path from the originating router to the neighbor specified in the 616 parent L3 Link. Multiple L2 Bundle Member Attribute TLVs MAY be 617 associated with a Link NLRI. 619 This information is originated as in L2 Bundle Member Attributes TLV 620 of IS-IS [I-D.ietf-isis-l2bundles]. The equivalent functionality has 621 not been specified as yet for OSPF. 623 The L2 Bundle Member Attribute TLV has the following format: 625 0 1 2 3 626 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 1 627 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 628 | Type | Length | 629 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 631 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 632 | L2 Bundle Member Descriptor | 633 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 634 // Link attribute sub-TLVs(variable) // 635 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 637 Figure 9: L2 Bundle Member Attributes TLV Format 639 Where: 641 Type: 1172 643 Length: Variable. 645 L2 Bundle Member Descriptor: A Link Local Identifier as defined in 646 [RFC4202]. 648 Link attributes for L2 Bundle Member Links are advertised as sub-TLVs 649 of the L2 Bundle Member Attribute TLV. The sub-TLVs are identical to 650 existing BGP-LS TLVs as identified in the table below. 652 +-----------+----------------------------+--------------------------+ 653 | TLV Code | Description | Reference Document | 654 | Point | | | 655 +-----------+----------------------------+--------------------------+ 656 | 1088 | Administrative group | [RFC7752] | 657 | | (color) | | 658 | 1089 | Maximum link bandwidth | [RFC7752] | 659 | 1090 | Max. reservable link | [RFC7752] | 660 | | bandwidth | | 661 | 1091 | Unreserved bandwidth | [RFC7752] | 662 | 1092 | TE default metric | [RFC7752] | 663 | 1093 | Link protection type | [RFC7752] | 664 | 1099 | Adjacency Segment | Section 2.2.1 | 665 | | Identifier (Adj-SID) TLV | | 666 | 1100 | LAN Adjacency Segment | Section 2.2.2 | 667 | | Identifier (Adj-SID) TLV | | 668 | 1114 | Unidirectional link delay | [I-D.ietf-idr-te-pm-bgp] | 669 | 1115 | Min/Max Unidirectional | [I-D.ietf-idr-te-pm-bgp] | 670 | | link delay | | 671 | 1116 | Unidirectional Delay | [I-D.ietf-idr-te-pm-bgp] | 672 | | Variation | | 673 | 1117 | Unidirectional packet loss | [I-D.ietf-idr-te-pm-bgp] | 674 | 1118 | Unidirectional residual | [I-D.ietf-idr-te-pm-bgp] | 675 | | bandwidth | | 676 | 1119 | Unidirectional available | [I-D.ietf-idr-te-pm-bgp] | 677 | | bandwidth | | 678 | 1120 | Unidirectional bandwidth | [I-D.ietf-idr-te-pm-bgp] | 679 | | utilization | | 680 +-----------+----------------------------+--------------------------+ 682 Table 3: BGP-LS Attribute TLVs also used as sub-TLVs of L2 Bundle 683 Member Attribute TLV 685 2.3. Prefix Attribute TLVs 687 The following Prefix Attribute TLVs are defined: 689 +------+------------------------+---------------+ 690 | Type | Description | Section | 691 +------+------------------------+---------------+ 692 | 1158 | Prefix SID | Section 2.3.1 | 693 | 1159 | Range | Section 2.3.4 | 694 | 1170 | Prefix Attribute Flags | Section 2.3.2 | 695 | 1171 | Source Router-ID | Section 2.3.3 | 696 +------+------------------------+---------------+ 698 Table 4: Prefix Attribute TLVs 700 These TLVs should only be added to the BGP-LS Attribute associated 701 with the Prefix NLRI describing the prefix of the IGP node that is 702 originating the corresponding IGP TLV/sub-TLV described below. 704 2.3.1. Prefix SID TLV 706 The Prefix SID TLV is used in order to advertise information related 707 to a Prefix SID. This information is originated as in Prefix-SID 708 sub-TLV of IS-IS [I-D.ietf-isis-segment-routing-extensions], OSPFv2 709 [I-D.ietf-ospf-segment-routing-extensions] and OSPFv3 710 [I-D.ietf-ospf-ospfv3-segment-routing-extensions]. 712 The Prefix SID TLV has the following format: 714 0 1 2 3 715 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 1 716 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 717 | Type | Length | 718 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 719 | Flags | Algorithm | Reserved | 720 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 721 | SID/Index/Label (variable) | 722 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 724 Figure 10: Prefix SID TLV Format 726 Where: 728 Type: 1158 730 Length: Variable, 7 or 8 depending on Label or Index encoding of 731 the SID 733 Flags: 1 octet value which sould be parsed as: 735 * IS-IS Prefix SID flags are defined in 736 [I-D.ietf-isis-segment-routing-extensions] section 2.1. 738 * OSPFv2 Prefix SID flags are defined in 739 [I-D.ietf-ospf-segment-routing-extensions] section 5. 741 * OSPFv3 Prefix SID flags are defined in 742 [I-D.ietf-ospf-segment-routing-extensions] section 5. 744 Algorithm: 1 octet value identify the algorithm. 746 Reserved: 2 octets that SHOULD be set to 0 and MUST be ignored on 747 receipt. 749 SID/Index/Label: 751 * IS-IS: Label or index value as defined in 752 [I-D.ietf-isis-segment-routing-extensions], 754 * OSPFv2: Label or index value as defined in 755 [I-D.ietf-ospf-segment-routing-extensions], 757 * OSPFv3: Label or index value as defined in 758 [I-D.ietf-ospf-ospfv3-segment-routing-extensions], 760 The Flags and, as an extension, the SID/Index/Label fields of this 761 TLV need to be interpreted accordingly to the respective underlying 762 IS-IS, OSPFv2 or OSPFv3 protocol. The consumer of the BGP-LS 763 interested in this TLV information MUST check the Protocol-ID of the 764 BGP-LS Prefix NLRI and refer to the underlying protocol specification 765 in order to parse these fields. 767 2.3.2. Prefix Attribute Flags TLV 769 The Prefix Attribute Flags TLV carries IPv4/IPv6 prefix attribute 770 flags information. These flags are defined for OSPFv2 in [RFC7684], 771 for OSPFv3 in [RFC5340] and for IS-IS in [RFC7794]. 773 The Prefix Attribute Flags TLV has the following format: 775 0 1 2 3 776 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 1 777 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 778 | Type | Length | 779 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 780 // Flags (variable) // 781 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 783 Figure 11: Prefix Attribute Flags TLV Format 785 Where: 787 Type: 1170 789 Length: variable. 791 Flags: a variable length flag field (according to the length 792 field). Flags are routing protocol specific and are to be parsed 793 as below: 795 * IS-IS flags correspond to the IPv4/IPv6 Extended Reachability 796 Attribute Flags defined in [RFC7794] 798 * OSPFv2 flags correspond to the Flags field of the OSPFv2 799 Extended Prefix TLV defined in [RFC7684] 801 * OSPFv3 flags map to the Prefix Options field defined in 802 [RFC5340] and extended via [RFC8362] 804 The Flags field of this TLV need to be interpreted accordingly to the 805 respective underlying IS-IS, OSPFv2 or OSPFv3 protocol. The consumer 806 of the BGP-LS interested in this TLV information MUST check the 807 Protocol-ID of the BGP-LS Prefix NLRI and refer to the underlying 808 protocol specification in order to parse this field. 810 2.3.3. Source Router Identifier (Source Router-ID) TLV 812 The Source Router-ID TLV contains the IPv4 or IPv6 Router-ID of the 813 originator of the Prefix. For IS-IS protocol this is as defined in 814 [RFC7794] IPv4 or IPv6 Router-ID of the originating router. For OSPF 815 protocol, this is as defined in [I-D.ietf-lsr-ospf-prefix-originator] 816 and is a 32 bit OSPF Router-ID of the originating router.. 818 The Source Router-ID TLV has the following format: 820 0 1 2 3 821 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 1 822 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 823 | Type | Length | 824 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 825 // 4 or 6 octet Router-ID // 826 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 828 Figure 12: Source Router-ID TLV Format 830 Where: 832 Type: 1171 834 Length: 4 or 16 in case of IS-IS and 4 in case of OSPF. 836 Router-ID: the IPv4 or IPv6 Router-ID in case of IS-IS and the 837 OSPF Router-ID in the case of OSPF. 839 2.3.4. Range TLV 841 The range TLV is used in order to advertise a range of prefix-to-SID 842 mappings as part of the Segment Routing Mapping Server (SRMS) 843 functionality [I-D.ietf-spring-segment-routing-ldp-interop], as 844 defined in the respective underlying IGP SR extensions 845 [I-D.ietf-ospf-segment-routing-extensions], 846 [I-D.ietf-ospf-ospfv3-segment-routing-extensions] and 847 [I-D.ietf-isis-segment-routing-extensions]. 849 A consumer of the BGP-LS information MUST NOT mis-interpret a Prefix 850 NLRI, that been advertised with a Range TLV associated with it on 851 account of an SRMS prefix-to-SID mapping in the underlying IGP, as a 852 normal routing prefix (i.e. prefix reachability) unless there is also 853 an IGP metric TLV (TLV 1095) attached to it. 855 The format of the Range TLV is as follows: 857 0 1 2 3 858 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 1 859 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 860 | Type | Length | 861 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 862 | Flags | Reserved | Range Size | 863 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 864 // sub-TLVs // 865 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 867 Figure 13: Range TLV Format 869 Where: 871 Type: 1159 873 Length: Variable, 11 or 12 depending on Label or Index encoding of 874 the SID 876 Flags: as defined in [I-D.ietf-ospf-segment-routing-extensions], 877 [I-D.ietf-ospf-ospfv3-segment-routing-extensions] and 878 [I-D.ietf-isis-segment-routing-extensions]. 880 Reserved: 1 octet that SHOULD be set to 0 and MUST be ignored on 881 receipt. 883 Range Size: 2 octets as defined in 884 [I-D.ietf-ospf-segment-routing-extensions]. 886 The Flags field of this TLV need to be interpreted accordingly to the 887 respective underlying IS-IS, OSPFv2 or OSPFv3 protocol. The consumer 888 of the BGP-LS interested in this TLV information MUST check the 889 Protocol-ID of the BGP-LS Prefix NLRI and refer to the underlying 890 protocol specification in order to parse this field. 892 Within the Range TLV, the prefix-to-SID mappings are advertised using 893 sub-TLVs as below: 895 Range TLV 896 Prefix-SID TLV (used as a sub-TLV in this context) 898 Where: 900 o The Range TLV is defined in Section 2.3.4. 902 o The Prefix-SID TLV (used as sub-TLV in this context) is defined in 903 Section 2.3.1. 905 The following sub-sections describe the procedures for mapping of 906 information from the underlying IGP protocols into the Range TLV. 908 2.3.4.1. Advertisement Procedure for OSPF 910 The OSPFv2/OSPFv3 Extended Prefix Range TLV is encoded in the Range 911 TLV. The flags of the Range TLV have the semantic mapped to the 912 definition in [I-D.ietf-ospf-segment-routing-extensions] section 4 or 913 [I-D.ietf-ospf-ospfv3-segment-routing-extensions] section 4. 915 Then the prefix-to-SID mapping from the OSPF Prefix SID sub-TLV is 916 encoded using the BGP-LS Prefix-SID TLV as defined in Section 2.3.1 917 with the flags set according to the definition in 918 [I-D.ietf-ospf-segment-routing-extensions] section 5 or 919 [I-D.ietf-ospf-ospfv3-segment-routing-extensions] section 5. 921 2.3.4.2. Advertisement Procedure for IS-IS 923 The IS-IS SID/Label Binding TLV, when used to signal mapping server 924 label bindings, is encoded in the Range TLV. The flags of the Range 925 TLV have the sematic mapped to the definition in 926 [I-D.ietf-isis-segment-routing-extensions] section 2.4.1. 928 Then the prefix-to-SID mappings from the IS-IS Prefix SID sub-TLV is 929 encoded using the BGP-LS Prefix-SID TLV as defined in Section 2.3.1 930 with the flags set according to the definition in 931 [I-D.ietf-isis-segment-routing-extensions] section 2.4.4.1. 933 2.4. Equivalent IS-IS Segment Routing TLVs/Sub-TLVs 935 This section illustrate the IS-IS Segment Routing Extensions TLVs and 936 sub-TLVs mapped to the ones defined in this document. 938 The following table, illustrates for each BGP-LS TLV, its equivalence 939 in IS-IS. 941 +------------+------------+-----------------------------------------+ 942 | Descriptio | IS-IS TLV | Reference | 943 | n | /sub-TLV | | 944 +------------+------------+-----------------------------------------+ 945 | SR Capabil | 2 | draft-ietf-isis-segment-routing- | 946 | ities | | extensions section-3.1 | 947 | SR | 19 | draft-ietf-isis-segment-routing- | 948 | Algorithm | | extensions section-3.2 | 949 | SR Local | 22 | draft-ietf-isis-segment-routing- | 950 | Block | | extensions section-3.3 | 951 | SRMS | 19 | draft-ietf-isis-segment-routing- | 952 | Preference | | extensions section-3.2 | 953 | Adjacency | 31 | draft-ietf-isis-segment-routing- | 954 | SID | | extensions section-2.2.1 | 955 | LAN | 32 | draft-ietf-isis-segment-routing- | 956 | Adjacency | | extensions section-2.2.2 | 957 | SID | | | 958 | Prefix SID | 3 | draft-ietf-isis-segment-routing- | 959 | | | extensions section-2.1 | 960 | Range | 149 | draft-ietf-isis-segment-routing- | 961 | | | extensions section-2.4 | 962 | SID/Label | 1 | draft-ietf-isis-segment-routing- | 963 | | | extensions section-2.3 | 964 | Prefix | 4 | RFC7794 section-2.1 | 965 | Attribute | | | 966 | Flags | | | 967 | Source | 11/12 | RFC7794 section-2.2 | 968 | Router-ID | | | 969 | L2 Bundle | 25 | draft-ietf-isis-l2bundles section-2 | 970 | Member | | | 971 | Attributes | | | 972 +------------+------------+-----------------------------------------+ 974 Table 5: IS-IS Segment Routing Extensions TLVs/Sub-TLVs 976 2.5. Equivalent OSPFv2/OSPFv3 Segment Routing TLVs/Sub-TLVs 978 This section illustrate the OSPFv2 and OSPFv3 Segment Routing 979 Extensions TLVs and sub-TLVs mapped to the ones defined in this 980 document. 982 The following table, illustrates for each BGP-LS TLV, its equivalence 983 in OSPFv2 and OSPFv3. 985 +------------+------------+-----------------------------------------+ 986 | Descriptio | OSPFv2 TLV | Reference | 987 | n | /sub-TLV | | 988 +------------+------------+-----------------------------------------+ 989 | SR Capabil | 9 | draft-ietf-ospf-segment-routing- | 990 | ities | | extensions section-3.2 | 991 | SR | 8 | draft-ietf-ospf-segment-routing- | 992 | Algorithm | | extensions section-3.1 | 993 | SR Local | 14 | draft-ietf-ospf-segment-routing- | 994 | Block | | extensions section-3.3 | 995 | SRMS | 15 | draft-ietf-ospf-segment-routing- | 996 | Preference | | extensions section-3.4 | 997 | Adjacency | 2 | draft-ietf-ospf-segment-routing- | 998 | SID | | extensions section-6.1 | 999 | LAN | 3 | draft-ietf-ospf-segment-routing- | 1000 | Adjacency | | extensions section-6.2 | 1001 | SID | | | 1002 | Prefix SID | 2 | draft-ietf-ospf-segment-routing- | 1003 | | | extensions section-5 | 1004 | Range | 2 | draft-ietf-ospf-segment-routing- | 1005 | | | extensions section-4 | 1006 | SID/Label | 1 | draft-ietf-ospf-segment-routing- | 1007 | | | extensions section-2.1 | 1008 | Prefix | 4 | RFC7684 section-2.1 | 1009 | Attribute | | | 1010 | Flags | | | 1011 | Source | TBD | draft-ietf-lsr-ospf-prefix-originator | 1012 | Router-ID | | section-4 | 1013 +------------+------------+-----------------------------------------+ 1015 Table 6: OSPFv2 Segment Routing Extensions TLVs/Sub-TLVs 1017 +-----------+------------+------------------------------------------+ 1018 | Descripti | OSPFv3 TLV | Reference | 1019 | on | /sub-TLV | | 1020 +-----------+------------+------------------------------------------+ 1021 | SR Capabi | 9 | draft-ietf-ospf-ospfv3-segment-routing- | 1022 | lities | | extensions section-3.2 | 1023 | SR | 8 | draft-ietf-ospf-ospfv3-segment-routing- | 1024 | Algorithm | | extensions section-3.1 | 1025 | SR Local | 14 | draft-ietf-ospf-ospfv3-segment-routing- | 1026 | Block | | extensions section-3.3 | 1027 | SRMS Pref | 15 | draft-ietf-ospf-ospfv3-segment-routing- | 1028 | erence | | extensions section-3.4 | 1029 | Adjacency | 5 | draft-ietf-ospf-ospfv3-segment-routing- | 1030 | SID | | extensions section-6.1 | 1031 | LAN | 6 | draft-ietf-ospf-ospfv3-segment-routing- | 1032 | Adjacency | | extensions section-6.2 | 1033 | SID | | | 1034 | Prefix | 4 | draft-ietf-ospf-ospfv3-segment-routing- | 1035 | SID | | extensions section-5 | 1036 | Range | 9 | draft-ietf-ospf-ospfv3-segment-routing- | 1037 | | | extensions section-4 | 1038 | SID/Label | 7 | draft-ietf-ospf-ospfv3-segment-routing- | 1039 | | | extensions section-2.1 | 1040 | Prefix | 4 | RFC8362 section-3.1 | 1041 | Attribute | | | 1042 | Flags | | | 1043 | Source | TBD | draft-ietf-lsr-ospf-prefix-originator | 1044 | Router-ID | | section-4 | 1045 +-----------+------------+------------------------------------------+ 1047 Table 7: OSPFv3 Segment Routing Extensions TLVs/Sub-TLVs 1049 3. IANA Considerations 1051 Early allocation of codepoints has been done by IANA for this 1052 document from the registry "BGP-LS Node Descriptor, Link Descriptor, 1053 Prefix Descriptor, and Attribute TLVs" based on Table 8. The column 1054 "IS-IS TLV/Sub-TLV" defined in the registry does not require any 1055 value and should be left empty. 1057 3.1. TLV/Sub-TLV Code Points Summary 1059 This section contains the global table of all TLVs/sub-TLVs defined 1060 in this document. 1062 +----------------+-----------------------------+---------------+ 1063 | TLV Code Point | Description | Reference | 1064 +----------------+-----------------------------+---------------+ 1065 | 1034 | SR Capabilities | Section 2.1.2 | 1066 | 1035 | SR Algorithm | Section 2.1.3 | 1067 | 1036 | SR Local Block | Section 2.1.4 | 1068 | 1037 | SRMS Preference | Section 2.1.5 | 1069 | 1099 | Adjacency SID | Section 2.2.1 | 1070 | 1100 | LAN Adjacency SID | Section 2.2.2 | 1071 | 1158 | Prefix SID | Section 2.3.1 | 1072 | 1159 | Range | Section 2.3.4 | 1073 | 1161 | SID/Label | Section 2.1.1 | 1074 | 1170 | Prefix Attribute Flags | Section 2.3.2 | 1075 | 1171 | Source Router-ID | Section 2.3.3 | 1076 | 1172 | L2 Bundle Member Attributes | Section 2.2.3 | 1077 +----------------+-----------------------------+---------------+ 1079 Table 8: Summary Table of TLV/Sub-TLV Codepoints 1081 4. Manageability Considerations 1083 This section is structured as recommended in [RFC5706]. 1085 The new protocol extensions introduced in this document augment the 1086 existing IGP topology information that is distributed via [RFC7752]. 1087 Procedures and protocol extensions defined in this document do not 1088 affect the BGP protocol operations and management other than as 1089 discussed in the Manageability Considerations section of [RFC7752]. 1090 Specifically, the malformed attribute tests for syntactic checks in 1091 the Fault Management section of [RFC7752] now encompass the new BGP- 1092 LS Attribute TLVs defined in this document. The semantic or content 1093 checking for the TLVs specified in this document and their 1094 association with the BGP-LS NLRI types or their BGP-LS Attribute is 1095 left to the consumer of the BGP-LS information (e.g. an application 1096 or a controller) and not the BGP protocol. 1098 A consumer of the BGP-LS information retrieves this information from 1099 a BGP protocol component that is doing the signaling over a BGP-LS 1100 session, via some APIs or a data model (refer Section 1 and 2 of 1101 [RFC7752]). The handling of semantic or content errors by the 1102 consumer would be dictated by the nature of its application usage and 1103 hence is beyond the scope of this document. 1105 This document only introduces new Attribute TLVs and any syntactic 1106 error in them would result in only that specific attribute being 1107 discarded with an error log. The SR information introduced in BGP-LS 1108 by this specification, may be used by BGP-LS consumer applications 1109 like a SR path computation engine (PCE) to learn the SR capabilities 1110 of the nodes in the topology and the mapping of SR segments to those 1111 nodes. This can enable the SR PCE to perform path computations based 1112 on SR for traffic engineering use-cases and to steer traffic on paths 1113 different from the underlying IGP based distributed best path 1114 computation. Errors in the encoding or decoding of the SR 1115 information may result in the unavailability of such information to 1116 the SR PCE or incorrect information being made available to it. This 1117 may result in the SR PCE not being able to perform the desired SR 1118 based optimization functionality or to perform it in an unexpected or 1119 inconsistent manner. The handling of such errors by applications 1120 like SR PCE may be implementation specific and out of scope of this 1121 document. 1123 The extensions, specified in this document, do not introduce any new 1124 configuration or monitoring aspects in BGP or BGP-LS other than as 1125 discussed in [RFC7752]. The manageability aspects of the underlying 1126 SR features are covered by [I-D.ietf-spring-sr-yang], 1127 [I-D.ietf-isis-sr-yang] and [I-D.ietf-ospf-sr-yang]. 1129 5. Security Considerations 1131 The new protocol extensions introduced in this document augment the 1132 existing IGP topology information that was distributed via [RFC7752]. 1133 The Security Considerations section of [RFC7752] also applies to 1134 these extensions. The procedures and new TLVs defined in this 1135 document, by themselves, do not affect the BGP-LS security model 1136 discussed in [RFC7752]. 1138 BGP-LS SR extensions enable traffic engineering use-cases within the 1139 Segment Routing domain. SR operates within a trusted domain (refer 1140 Security Considerations section in [RFC8402] for more detail) and its 1141 security considerations also apply to BGP-LS sessions when carrying 1142 SR information.The SR traffic engineering policies using the SIDs 1143 advertised via BGP-LS are expected to be used entirely within this 1144 trusted SR domain (e.g. between multiple AS/domains within a single 1145 provider network). Therefore, precaution is necessary to ensure that 1146 the SR information collected via BGP-LS is limited to specific 1147 controllers or applications in a secure manner within this SR domain. 1149 The isolation of BGP-LS peering sessions is also required to ensure 1150 that BGP-LS topology information (including the newly added SR 1151 information) is not advertised to an external BGP peering session 1152 outside an administrative domain. 1154 6. Contributors 1156 The following people have substantially contributed to the editing of 1157 this document: 1159 Peter Psenak 1160 Cisco Systems 1161 Email: ppsenak@cisco.com 1163 Les Ginsberg 1164 Cisco Systems 1165 Email: ginsberg@cisco.com 1167 Acee Lindem 1168 Cisco Systems 1169 Email: acee@cisco.com 1171 Saikat Ray 1172 Individual 1173 Email: raysaikat@gmail.com 1175 Jeff Tantsura 1176 Apstra Inc. 1177 Email: jefftant.ietf@gmail.com 1179 7. Acknowledgements 1181 The authors would like to thank Jeffrey Haas, Aijun Wang, Robert 1182 Raszuk and Susan Hares for their review of this document and their 1183 comments. The authors would also like to thank Alvaro Retana for his 1184 extensive review and comments which helped correct issues and improve 1185 the document. 1187 8. References 1189 8.1. Normative References 1191 [I-D.ietf-idr-te-pm-bgp] 1192 Ginsberg, L., Previdi, S., Wu, Q., Tantsura, J., and C. 1193 Filsfils, "BGP-LS Advertisement of IGP Traffic Engineering 1194 Performance Metric Extensions", draft-ietf-idr-te-pm- 1195 bgp-18 (work in progress), December 2018. 1197 [I-D.ietf-isis-l2bundles] 1198 Ginsberg, L., Bashandy, A., Filsfils, C., Nanduri, M., and 1199 E. Aries, "Advertising L2 Bundle Member Link Attributes in 1200 IS-IS", draft-ietf-isis-l2bundles-07 (work in progress), 1201 May 2017. 1203 [I-D.ietf-isis-segment-routing-extensions] 1204 Previdi, S., Ginsberg, L., Filsfils, C., Bashandy, A., 1205 Gredler, H., and B. Decraene, "IS-IS Extensions for 1206 Segment Routing", draft-ietf-isis-segment-routing- 1207 extensions-22 (work in progress), December 2018. 1209 [I-D.ietf-lsr-ospf-prefix-originator] 1210 Wang, A., Lindem, A., Dong, J., Talaulikar, K., and P. 1211 Psenak, "OSPF Extension for Prefix Originator", draft- 1212 ietf-lsr-ospf-prefix-originator-00 (work in progress), 1213 February 2019. 1215 [I-D.ietf-ospf-ospfv3-segment-routing-extensions] 1216 Psenak, P. and S. Previdi, "OSPFv3 Extensions for Segment 1217 Routing", draft-ietf-ospf-ospfv3-segment-routing- 1218 extensions-23 (work in progress), January 2019. 1220 [I-D.ietf-ospf-segment-routing-extensions] 1221 Psenak, P., Previdi, S., Filsfils, C., Gredler, H., 1222 Shakir, R., Henderickx, W., and J. Tantsura, "OSPF 1223 Extensions for Segment Routing", draft-ietf-ospf-segment- 1224 routing-extensions-27 (work in progress), December 2018. 1226 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 1227 Requirement Levels", BCP 14, RFC 2119, 1228 DOI 10.17487/RFC2119, March 1997, 1229 . 1231 [RFC4202] Kompella, K., Ed. and Y. Rekhter, Ed., "Routing Extensions 1232 in Support of Generalized Multi-Protocol Label Switching 1233 (GMPLS)", RFC 4202, DOI 10.17487/RFC4202, October 2005, 1234 . 1236 [RFC5340] Coltun, R., Ferguson, D., Moy, J., and A. Lindem, "OSPF 1237 for IPv6", RFC 5340, DOI 10.17487/RFC5340, July 2008, 1238 . 1240 [RFC7684] Psenak, P., Gredler, H., Shakir, R., Henderickx, W., 1241 Tantsura, J., and A. Lindem, "OSPFv2 Prefix/Link Attribute 1242 Advertisement", RFC 7684, DOI 10.17487/RFC7684, November 1243 2015, . 1245 [RFC7752] Gredler, H., Ed., Medved, J., Previdi, S., Farrel, A., and 1246 S. Ray, "North-Bound Distribution of Link-State and 1247 Traffic Engineering (TE) Information Using BGP", RFC 7752, 1248 DOI 10.17487/RFC7752, March 2016, 1249 . 1251 [RFC7794] Ginsberg, L., Ed., Decraene, B., Previdi, S., Xu, X., and 1252 U. Chunduri, "IS-IS Prefix Attributes for Extended IPv4 1253 and IPv6 Reachability", RFC 7794, DOI 10.17487/RFC7794, 1254 March 2016, . 1256 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 1257 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 1258 May 2017, . 1260 [RFC8362] Lindem, A., Roy, A., Goethals, D., Reddy Vallem, V., and 1261 F. Baker, "OSPFv3 Link State Advertisement (LSA) 1262 Extensibility", RFC 8362, DOI 10.17487/RFC8362, April 1263 2018, . 1265 8.2. Informative References 1267 [I-D.ietf-isis-sr-yang] 1268 Litkowski, S., Qu, Y., Sarkar, P., Chen, I., and J. 1269 Tantsura, "YANG Data Model for IS-IS Segment Routing", 1270 draft-ietf-isis-sr-yang-04 (work in progress), June 2018. 1272 [I-D.ietf-ospf-sr-yang] 1273 Yeung, D., Qu, Y., Zhang, Z., Chen, I., and A. Lindem, 1274 "YANG Data Model for OSPF SR (Segment Routing) Protocol", 1275 draft-ietf-ospf-sr-yang-07 (work in progress), March 2019. 1277 [I-D.ietf-spring-segment-routing-ldp-interop] 1278 Bashandy, A., Filsfils, C., Previdi, S., Decraene, B., and 1279 S. Litkowski, "Segment Routing interworking with LDP", 1280 draft-ietf-spring-segment-routing-ldp-interop-15 (work in 1281 progress), September 2018. 1283 [I-D.ietf-spring-sr-yang] 1284 Litkowski, S., Qu, Y., Lindem, A., Sarkar, P., and J. 1285 Tantsura, "YANG Data Model for Segment Routing", draft- 1286 ietf-spring-sr-yang-12 (work in progress), February 2019. 1288 [RFC5706] Harrington, D., "Guidelines for Considering Operations and 1289 Management of New Protocols and Protocol Extensions", 1290 RFC 5706, DOI 10.17487/RFC5706, November 2009, 1291 . 1293 [RFC8402] Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L., 1294 Decraene, B., Litkowski, S., and R. Shakir, "Segment 1295 Routing Architecture", RFC 8402, DOI 10.17487/RFC8402, 1296 July 2018, . 1298 Authors' Addresses 1300 Stefano Previdi 1301 Huawei Technologies 1302 Rome 1303 Italy 1305 Email: stefano@previdi.net 1307 Ketan Talaulikar (editor) 1308 Cisco Systems, Inc. 1309 India 1311 Email: ketant@cisco.com 1313 Clarence Filsfils 1314 Cisco Systems, Inc. 1315 Brussels 1316 Belgium 1318 Email: cfilsfil@cisco.com 1320 Hannes Gredler 1321 RtBrick Inc. 1323 Email: hannes@rtbrick.com 1325 Mach(Guoyi) Chen 1326 Huawei Technologies 1327 Huawei Building, No. 156 Beiqing Rd. 1328 Beijing 100095 1329 China 1331 Email: mach.chen@huawei.com