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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: November 9, 2019 C. Filsfils 6 Cisco Systems, Inc. 7 H. Gredler 8 RtBrick Inc. 9 M. Chen 10 Huawei Technologies 11 May 8, 2019 13 BGP Link-State extensions for Segment Routing 14 draft-ietf-idr-bgp-ls-segment-routing-ext-14 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 November 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 . . . . . . . . . . . . . . . . . 10 76 2.2. Link Attribute TLVs . . . . . . . . . . . . . . . . . . . 10 77 2.2.1. Adjacency SID TLV . . . . . . . . . . . . . . . . . . 11 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 . . . . . . . . . . . . . . . . . . 16 81 2.3.1. Prefix SID TLV . . . . . . . . . . . . . . . . . . . 17 82 2.3.2. Prefix Attribute Flags TLV . . . . . . . . . . . . . 18 83 2.3.3. Source Router Identifier (Source Router-ID) TLV . . . 19 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 . 22 87 3. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 25 88 3.1. TLV/Sub-TLV Code Points Summary . . . . . . . . . . . . . 25 89 4. Manageability Considerations . . . . . . . . . . . . . . . . 25 90 5. Security Considerations . . . . . . . . . . . . . . . . . . . 26 91 6. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 27 92 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 28 93 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 28 94 8.1. Normative References . . . . . . . . . . . . . . . . . . 28 95 8.2. Informative References . . . . . . . . . . . . . . . . . 30 96 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 30 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. This information is derived from the protocol 226 specific advertisements. 228 o IS-IS, as defined by the SID/Label sub-TLV in 229 [I-D.ietf-isis-segment-routing-extensions]. 231 o OSPFv2/OSPFv3, as defined by the SID/Label sub-TLV in 232 [I-D.ietf-ospf-segment-routing-extensions] and 233 [I-D.ietf-ospf-ospfv3-segment-routing-extensions]. 235 The TLV and has the following format: 237 0 1 2 3 238 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 1 239 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 240 | Type | Length | 241 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 242 | SID/Label (variable) | 243 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 245 Figure 2: SID/Label sub-TLV Format 247 Where: 249 Type: 1161 251 Length: Either 3 or 4 depending whether the value is encoded as a 252 label or an index/SID. 254 SID/Label: If length is set to 3, then the 20 rightmost bits 255 represent a label (the total TLV size is 7). If length is set to 256 4, then the value represents a 32 bit SID (the total TLV size is 257 8). 259 2.1.2. SR Capabilities TLV 261 The SR Capabilities TLV is used in order to advertise the node's SR 262 Capabilities including its Segment Routing Global Base (SRGB) 263 range(s). In the case of IS-IS, the capabilities also include the 264 IPv4 and IPv6 support for the SR-MPLS forwarding plane. This 265 information is derived from the protocol specific advertisements. 267 o IS-IS, as defined by the SR Capabilities sub-TLV in 268 [I-D.ietf-isis-segment-routing-extensions]. 270 o OSPFv2/OSPFv3, as defined by the SID/Label Range TLV in 271 [I-D.ietf-ospf-segment-routing-extensions]. OSPFv3 leverages the 272 same TLV as defined for OSPFv2. 274 The SR Capabilities TLV has the following format: 276 0 1 2 3 277 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 1 278 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 279 | Type | Length | 280 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 281 | Flags | Reserved | 282 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 284 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 285 | Range Size | 286 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 287 // SID/Label sub-TLV (variable) // 288 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 290 Figure 3: SR Capabilities TLV Format 292 Where: 294 Type: 1034 296 Length: Variable. Minimum length is 12. 298 Flags: 1 octet of flags as defined in 299 [I-D.ietf-isis-segment-routing-extensions] for IS-IS. The flags 300 are not currently defined for OSPFv2 and OSPFv3 and SHOULD be set 301 to 0 and MUST be ignored on receipt. 303 Reserved: 1 octet that SHOULD be set to 0 and MUST be ignored on 304 receipt. 306 One or more entries, each of which have the following format: 308 Range Size: 3 octet with a non-zero value indicating the number 309 of labels in the range. 311 SID/Label sub-TLV (as defined in Section 2.1.1) which encodes 312 the first label in the range. Since the SID/Label sub-TLV is 313 used to indicate the first label of the SRGB range, only label 314 encoding is valid under the SR Capabilities TLV. 316 2.1.3. SR Algorithm TLV 318 The SR Algorithm TLV is used in order to advertise the SR Algorithms 319 supported by the node. This information is derived from the protocol 320 specific advertisements. 322 o IS-IS, as defined by the SR-Algorithm sub-TLV in 323 [I-D.ietf-isis-segment-routing-extensions]. 325 o OSPFv2/OSPFv3, as defined by the SR-Algorithm TLV in 326 [I-D.ietf-ospf-segment-routing-extensions]. OSPFv3 leverages the 327 same TLV as defined for OSPFv2. 329 The SR Algorithm TLV has the following format: 331 0 1 2 3 332 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 1 333 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 334 | Type | Length | 335 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 336 | Algorithm 1 | Algorithm... | Algorithm N | | 337 +- -+ 338 | | 339 + + 341 Figure 4: SR Algorithm TLV Format 343 Where: 345 Type: 1035 347 Length: Variable. Minimum length is 1 and maximum can be 256. 349 Algorithm: 1 octet identifying the algorithm. 351 2.1.4. SR Local Block TLV 353 The SR Local Block (SRLB) TLV contains the range(s) of labels the 354 node has reserved for local SIDs. Local SIDs are used, e.g., in IGP 355 (IS-IS, OSPF) for Adjacency-SIDs, and may also be allocated by 356 components other than IGP protocols. As an example, an application 357 or a controller may instruct a node to allocate a specific local SID. 358 Therefore, in order for such applications or controllers to know the 359 range of local SIDs available, it is required that the node 360 advertises its SRLB. 362 This information is derived from the protocol specific 363 advertisements. 365 o IS-IS, as defined by the SR Local Block sub-TLV in 366 [I-D.ietf-isis-segment-routing-extensions]. 368 o OSPFv2/OSPFv3, as defined by the SR Local Block TLV in 369 [I-D.ietf-ospf-segment-routing-extensions]. OSPFv3 leverages the 370 same TLV as defined for OSPFv2. 372 The SRLB TLV has the following format: 374 0 1 2 3 375 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 1 376 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 377 | Type | Length | 378 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 379 | Flags | Reserved | 380 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 382 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 383 | Range Size | 384 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 385 // SID/Label sub-TLV (variable) // 386 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 388 Figure 5: SRLB TLV Format 390 Where: 392 Type: 1036 394 Length: Variable. Minimum length is 12. 396 Flags: 1 octet of flags. The flags are as defined in 397 [I-D.ietf-isis-segment-routing-extensions] for IS-IS. The flags 398 are not currently defined for OSPFv2 and OSPFv3 and SHOULD be set 399 to 0 and MUST be ignored on receipt. 401 Reserved: 1 octet that SHOULD be set to 0 and MUST be ignored on 402 receipt. 404 One or more entries, each of which have the following format: 406 Range Size: 3 octet value indicating the number of labels in 407 the range. 409 SID/Label sub-TLV (as defined in Section 2.1.1) which encodes 410 the first label in the range. Since the SID/Label sub-TLV is 411 used to indicate the first label of the SRLB range, only label 412 encoding is valid under the SR Local Block TLV. 414 2.1.5. SRMS Preference TLV 416 The Segment Routing Mapping Server (SRMS) Preference TLV is used in 417 order to associate a preference with SRMS advertisements from a 418 particular source. [I-D.ietf-spring-segment-routing-ldp-interop] 419 specifies the SRMS functionality along with SRMS preference of the 420 node advertising the SRMS Prefix-to-SID Mapping ranges. 422 This information is derived from the protocol specific 423 advertisements. 425 o IS-IS, as defined by the SRMS Preference sub-TLV in 426 [I-D.ietf-isis-segment-routing-extensions]. 428 o OSPFv2/OSPFv3, as defined by the SRMS Preference TLV in 429 [I-D.ietf-ospf-segment-routing-extensions]. OSPFv3 leverages the 430 same TLV as defined for OSPFv2. 432 The SRMS Preference TLV has the following format: 434 0 1 2 3 435 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 1 436 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 437 | Type | Length | 438 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 439 | Preference | 440 +-+-+-+-+-+-+-+-+ 442 Figure 6: SRMS Preference TLV Format 444 Where: 446 Type: 1037 448 Length: 1. 450 Preference: 1 octet. Unsigned 8 bit SRMS preference. 452 2.2. Link Attribute TLVs 454 The following Link Attribute TLVs are are defined: 456 +------+-----------------------+---------------+ 457 | Type | Description | Section | 458 +------+-----------------------+---------------+ 459 | 1099 | Adjacency SID TLV | Section 2.2.1 | 460 | 1100 | LAN Adjacency SID TLV | Section 2.2.2 | 461 | 1172 | L2 Bundle Member TLV | Section 2.2.3 | 462 +------+-----------------------+---------------+ 464 Table 2: Link Attribute TLVs 466 These TLVs should only be added to the BGP-LS Attribute associated 467 with the Link NLRI describing the link of the IGP node that is 468 originating the corresponding IGP TLV/sub-TLV described below. 470 2.2.1. Adjacency SID TLV 472 The Adjacency SID TLV is used in order to advertise information 473 related to an Adjacency SID. This information is derived from Adj- 474 SID sub-TLV of IS-IS [I-D.ietf-isis-segment-routing-extensions], 475 OSPFv2 [I-D.ietf-ospf-segment-routing-extensions] and OSPFv3 476 [I-D.ietf-ospf-ospfv3-segment-routing-extensions]. 478 The Adjacency SID TLV has the following format: 480 0 1 2 3 481 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 1 482 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 483 | Type | Length | 484 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 485 | Flags | Weight | Reserved | 486 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 487 | SID/Label/Index (variable) | 488 +---------------------------------------------------------------+ 490 Figure 7: Adjacency SID TLV Format 492 Where: 494 Type: 1099 496 Length: Variable, 7 or 8 depending on Label or Index encoding of 497 the SID 499 Flags. 1 octet value which should be set as: 501 * IS-IS Adj-SID flags are defined in 502 [I-D.ietf-isis-segment-routing-extensions]. 504 * OSPFv2 Adj-SID flags are defined in 505 [I-D.ietf-ospf-segment-routing-extensions]. 507 * OSPFv3 Adj-SID flags are defined in 508 [I-D.ietf-ospf-segment-routing-extensions]. 510 Weight: Weight used for load-balancing purposes. 512 Reserved: 2 octets that SHOULD be set to 0 and MUST be ignored on 513 receipt. 515 SID/Index/Label: 517 * IS-IS: Label or index value as defined in 518 [I-D.ietf-isis-segment-routing-extensions]. 520 * OSPFv2: Label or index value as defined in 521 [I-D.ietf-ospf-segment-routing-extensions]. 523 * OSPFv3: Label or index value as defined in 524 [I-D.ietf-ospf-ospfv3-segment-routing-extensions]. 526 The Flags and, as an extension, the SID/Index/Label fields of this 527 TLV need to be interpreted accordingly to the respective underlying 528 IS-IS, OSPFv2 or OSPFv3 protocol. The Protocol-ID of the BGP-LS Link 529 NLRI should be used to determine the underlying protocol 530 specification for parsing these fields. 532 2.2.2. LAN Adjacency SID TLV 534 For a LAN, normally a node only announces its adjacency to the IS-IS 535 pseudo-node (or the equivalent OSPF Designated and Backup Designated 536 Routers). The LAN Adjacency Segment TLV allows a node to announce 537 adjacencies to all other nodes attached to the LAN in a single 538 instance of the BGP-LS Link NLRI. Without this TLV, the 539 corresponding BGP-LS link NLRI would need to be originated for each 540 additional adjacency in order to advertise the SR TLVs for these 541 neighbor adjacencies. 543 This information is derived from LAN-Adj-SID sub-TLV of IS-IS 544 [I-D.ietf-isis-segment-routing-extensions] and LAN Adj-SID sub-TLV of 545 OSPFv2 [I-D.ietf-ospf-segment-routing-extensions] and OSPFv3 546 [I-D.ietf-ospf-ospfv3-segment-routing-extensions]. 548 The LAN Adjacency SID TLV has the following format: 550 0 1 2 3 551 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 1 552 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 553 | Type | Length | 554 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 555 | Flags | Weight | Reserved | 556 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 558 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 559 | OSPF Neighbor ID / IS-IS System-ID | 560 + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 561 | | 562 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 564 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 565 | SID/Label/Index (variable) | 566 +---------------------------------------------------------------+ 568 Figure 8: LAN Adjacency SID TLV Format 570 Where: 572 Type: 1100 574 Length: Variable. For IS-IS it would be 13 or 14 depending on 575 Label or Index encoding of the SID. For OSPF it would be 11 or 12 576 depending on Label or Index encoding of the SID. 578 Flags. 1 octet value which should be set as: 580 * IS-IS LAN Adj-SID flags are defined in 581 [I-D.ietf-isis-segment-routing-extensions]. 583 * OSPFv2 LAN Adj-SID flags are defined in 584 [I-D.ietf-ospf-segment-routing-extensions]. 586 * OSPFv3 LAN Adj-SID flags are defined in 587 [I-D.ietf-ospf-segment-routing-extensions]. 589 Weight: Weight used for load-balancing purposes. 591 Reserved: 2 octets that SHOULD be set to 0 and MUST be ignored on 592 receipt. 594 Neighbor ID: 6 octets for IS-IS for the System-ID and 4 octets for 595 OSPF for the OSPF Router-ID of the neighbor. 597 SID/Index/Label: 599 * IS-IS: Label or index value as defined in 600 [I-D.ietf-isis-segment-routing-extensions]. 602 * OSPFv2: Label or index value as defined in 603 [I-D.ietf-ospf-segment-routing-extensions]. 605 * OSPFv3: Label or index value as defined in 606 [I-D.ietf-ospf-ospfv3-segment-routing-extensions]. 608 The Neighbor ID, Flags and, as an extension, the SID/Index/Label 609 fields of this TLV need to be interpreted accordingly to the 610 respective underlying IS-IS, OSPFv2 or OSPFv3 protocol. The 611 Protocol-ID of the BGP-LS Link NLRI should be used to determine the 612 underlying protocol specification for parsing these fields. 614 2.2.3. L2 Bundle Member Attribute TLV 616 The L2 Bundle Member Attribute TLV identifies an L2 Bundle Member 617 link which in turn is associated with a parent L3 link. The L3 link 618 is described by the Link NLRI defined in [RFC7752] and the L2 Bundle 619 Member Attribute TLV is associated with the Link NLRI. The TLV MAY 620 include sub-TLVs which describe attributes associated with the bundle 621 member. The identified bundle member represents a unidirectional 622 path from the originating router to the neighbor specified in the 623 parent L3 Link. Multiple L2 Bundle Member Attribute TLVs MAY be 624 associated with a Link NLRI. 626 This information is derived from L2 Bundle Member Attributes TLV of 627 IS-IS [I-D.ietf-isis-l2bundles]. The equivalent functionality has 628 not been specified as yet for OSPF. 630 The L2 Bundle Member Attribute TLV has the following format: 632 0 1 2 3 633 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 1 634 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 635 | Type | Length | 636 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 638 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 639 | L2 Bundle Member Descriptor | 640 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 641 // Link attribute sub-TLVs(variable) // 642 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 644 Figure 9: L2 Bundle Member Attributes TLV Format 646 Where: 648 Type: 1172 650 Length: Variable. 652 L2 Bundle Member Descriptor: A Link Local Identifier as defined in 653 [RFC4202]. 655 Link attributes for L2 Bundle Member Links are advertised as sub-TLVs 656 of the L2 Bundle Member Attribute TLV. The sub-TLVs are identical to 657 existing BGP-LS TLVs as identified in the table below. 659 +-------------+------------------------------------+----------------+ 660 | TLV Code | Description | Reference | 661 | Point | | Document | 662 +-------------+------------------------------------+----------------+ 663 | 1088 | Administrative group (color) | [RFC7752] | 664 | 1089 | Maximum link bandwidth | [RFC7752] | 665 | 1090 | Max. reservable link bandwidth | [RFC7752] | 666 | 1091 | Unreserved bandwidth | [RFC7752] | 667 | 1092 | TE default metric | [RFC7752] | 668 | 1093 | Link protection type | [RFC7752] | 669 | 1099 | Adjacency Segment Identifier (Adj- | Section 2.2.1 | 670 | | SID) TLV | | 671 | 1100 | LAN Adjacency Segment Identifier | Section 2.2.2 | 672 | | (Adj-SID) TLV | | 673 | 1114 | Unidirectional link delay | [RFC8571] | 674 | 1115 | Min/Max Unidirectional link delay | [RFC8571] | 675 | 1116 | Unidirectional Delay Variation | [RFC8571] | 676 | 1117 | Unidirectional packet loss | [RFC8571] | 677 | 1118 | Unidirectional residual bandwidth | [RFC8571] | 678 | 1119 | Unidirectional available bandwidth | [RFC8571] | 679 | 1120 | Unidirectional bandwidth | [RFC8571] | 680 | | utilization | | 681 +-------------+------------------------------------+----------------+ 683 Table 3: BGP-LS Attribute TLVs also used as sub-TLVs of L2 Bundle 684 Member Attribute TLV 686 2.3. Prefix Attribute TLVs 688 The following Prefix Attribute TLVs are defined: 690 +------+------------------------+---------------+ 691 | Type | Description | Section | 692 +------+------------------------+---------------+ 693 | 1158 | Prefix SID | Section 2.3.1 | 694 | 1159 | Range | Section 2.3.4 | 695 | 1170 | Prefix Attribute Flags | Section 2.3.2 | 696 | 1171 | Source Router-ID | Section 2.3.3 | 697 +------+------------------------+---------------+ 699 Table 4: Prefix Attribute TLVs 701 These TLVs should only be added to the BGP-LS Attribute associated 702 with the Prefix NLRI describing the prefix of the IGP node that is 703 originating the corresponding IGP TLV/sub-TLV described below. 705 2.3.1. Prefix SID TLV 707 The Prefix SID TLV is used in order to advertise information related 708 to a Prefix SID. This information is derived from Prefix-SID sub-TLV 709 of IS-IS [I-D.ietf-isis-segment-routing-extensions] and the Prefix 710 SID sub-TLV of OSPFv2 [I-D.ietf-ospf-segment-routing-extensions] and 711 OSPFv3 [I-D.ietf-ospf-ospfv3-segment-routing-extensions]. 713 The Prefix SID TLV has the following format: 715 0 1 2 3 716 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 1 717 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 718 | Type | Length | 719 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 720 | Flags | Algorithm | Reserved | 721 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 722 | SID/Index/Label (variable) | 723 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 725 Figure 10: Prefix SID TLV Format 727 Where: 729 Type: 1158 731 Length: Variable, 7 or 8 depending on Label or Index encoding of 732 the SID 734 Flags: 1 octet value which should be set as: 736 * IS-IS Prefix SID flags are defined in 737 [I-D.ietf-isis-segment-routing-extensions]. 739 * OSPFv2 Prefix SID flags are defined in 740 [I-D.ietf-ospf-segment-routing-extensions]. 742 * OSPFv3 Prefix SID flags are defined in 743 [I-D.ietf-ospf-segment-routing-extensions]. 745 Algorithm: 1 octet value identify the algorithm. 747 Reserved: 2 octets that SHOULD be set to 0 and MUST be ignored on 748 receipt. 750 SID/Index/Label: 752 * IS-IS: Label or index value as defined in 753 [I-D.ietf-isis-segment-routing-extensions]. 755 * OSPFv2: Label or index value as defined in 756 [I-D.ietf-ospf-segment-routing-extensions]. 758 * OSPFv3: Label or index value as defined in 759 [I-D.ietf-ospf-ospfv3-segment-routing-extensions]. 761 The Flags and, as an extension, the SID/Index/Label fields of this 762 TLV need to be interpreted accordingly to the respective underlying 763 IS-IS, OSPFv2 or OSPFv3 protocol. The Protocol-ID of the BGP-LS 764 Prefix NLRI should be used to determine the underlying protocol 765 specification for parsing 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 set as 793 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 806 Protocol-ID of the BGP-LS Prefix NLRI should be used to determine the 807 underlying protocol specification for parsing these fields. 809 2.3.3. Source Router Identifier (Source Router-ID) TLV 811 The Source Router-ID TLV contains the IPv4 or IPv6 Router-ID of the 812 originator of the Prefix. For the IS-IS protocol this is derived 813 from the IPv4/IPv6 Source Router ID sub-TLV as defined in [RFC7794]. 814 For the OSPF protocol, this is derived from the Prefix Source Router- 815 ID sub-TLV as defined in [I-D.ietf-lsr-ospf-prefix-originator]. 817 The Source Router-ID TLV has the following format: 819 0 1 2 3 820 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 1 821 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 822 | Type | Length | 823 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 824 // 4 or 6 octet Router-ID // 825 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 827 Figure 12: Source Router-ID TLV Format 829 Where: 831 Type: 1171 833 Length: 4 or 16 in case of IS-IS and 4 in case of OSPF. 835 Router-ID: the IPv4 or IPv6 Router-ID in case of IS-IS and the 836 OSPF Router-ID in the case of OSPF. 838 2.3.4. Range TLV 840 The Range TLV is used in order to advertise a range of prefix-to-SID 841 mappings as part of the Segment Routing Mapping Server (SRMS) 842 functionality [I-D.ietf-spring-segment-routing-ldp-interop], as 843 defined in the respective underlying IGP SR extensions 844 [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]. The information 848 advertised in the Range TLV is derived from the SID/Label Binding TLV 849 in the case of IS-IS and the OSPFv2/OSPFv3 Extended Prefix Range TLV 850 in the case of OSPFv2/OSPFv3. 852 A Prefix NLRI, that been advertised with a Range TLV, is considered 853 as a normal routing prefix (i.e. prefix reachability) unless there is 854 also an IGP metric TLV (TLV 1095) attached to it. 856 The format of the Range TLV is as follows: 858 0 1 2 3 859 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 1 860 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 861 | Type | Length | 862 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 863 | Flags | Reserved | Range Size | 864 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 865 // sub-TLVs // 866 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 868 Figure 13: Range TLV Format 870 Where: 872 Type: 1159 874 Length: Variable, 11 or 12 depending on Label or Index encoding of 875 the SID 877 Flags: 1 octet value which should be set as: 879 * IS-IS SID/Label Binding TLV flags are defined in 880 [I-D.ietf-isis-segment-routing-extensions]. 882 * OSPFv2 OSPF Extended Prefix Range TLV flags are defined in 883 [I-D.ietf-ospf-segment-routing-extensions]. 885 * OSPFv3 Extended Prefix Range TLV flags are defined in 886 [I-D.ietf-ospf-ospfv3-segment-routing-extensions]. 888 Reserved: 1 octet that SHOULD be set to 0 and MUST be ignored on 889 receipt. 891 Range Size: 2 octets as defined in 892 [I-D.ietf-ospf-segment-routing-extensions]. 894 The Flags field of this TLV need to be interpreted accordingly to the 895 respective underlying IS-IS, OSPFv2 or OSPFv3 protocol. The consumer 896 of the BGP-LS interested in this TLV information MUST check the 897 Protocol-ID of the BGP-LS Prefix NLRI and refer to the underlying 898 protocol specification in order to parse this field. 900 The prefix-to-SID mappings are advertised using sub-TLVs as below: 902 IS-IS: 903 SID/Label Range TLV 904 Prefix-SID sub-TLV 906 OSPFv2/OSPFv3: 907 OSPFv2/OSPFv3 Extended Prefix Range TLV 908 Prefix SID sub-TLV 910 BGP-LS: 911 Range TLV 912 Prefix-SID TLV (used as a sub-TLV in this context) 914 The prefix-to-SID mapping information for the BGP-LS Prefix-SID TLV 915 (used as sub-TLV in this context) is encoded as described in 916 Section 2.3.1. 918 2.4. Equivalent IS-IS Segment Routing TLVs/Sub-TLVs 920 This section illustrate the IS-IS Segment Routing Extensions TLVs and 921 sub-TLVs mapped to the ones defined in this document. 923 The following table, illustrates for each BGP-LS TLV, its equivalence 924 in IS-IS. 926 +------------+---------------+--------------------------------------+ 927 | Descriptio | IS-IS TLV | Reference | 928 | n | /sub-TLV | | 929 +------------+---------------+--------------------------------------+ 930 | SR Capabil | SR- | [I-D.ietf-isis-segment-routing-exten | 931 | ities | Capabilities | sions] | 932 | | sub-TLV (2) | | 933 | SR | SR-Algorithm | [I-D.ietf-isis-segment-routing-exten | 934 | Algorithm | sub-TLV (19) | sions] | 935 | SR Local | SR Local | [I-D.ietf-isis-segment-routing-exten | 936 | Block | Block sub-TLV | sions] | 937 | | (22) | | 938 | SRMS | SRMS | [I-D.ietf-isis-segment-routing-exten | 939 | Preference | Preference | sions] | 940 | | sub-TLV (19) | | 941 | Adjacency | Adj-SID sub- | [I-D.ietf-isis-segment-routing-exten | 942 | SID | TLV (31) | sions] | 943 | LAN | LAN-Adj-SID | [I-D.ietf-isis-segment-routing-exten | 944 | Adjacency | sub-TLV (32) | sions] | 945 | SID | | | 946 | Prefix SID | Prefix-SID | [I-D.ietf-isis-segment-routing-exten | 947 | | sub-TLV (3) | sions] | 948 | Range | SID/Label | [I-D.ietf-isis-segment-routing-exten | 949 | | Binding TLV | sions] | 950 | | (149) | | 951 | SID/Label | SID/Label | [I-D.ietf-isis-segment-routing-exten | 952 | | sub-TLV (1) | sions] | 953 | Prefix | Prefix | [RFC7794] | 954 | Attribute | Attributes | | 955 | Flags | Flags sub-TLV | | 956 | | (4) | | 957 | Source | IPv4/IPv6 | [RFC7794] | 958 | Router-ID | Source Router | | 959 | | ID sub-TLV | | 960 | | (11/12) | | 961 | L2 Bundle | L2 Bundle | [I-D.ietf-isis-l2bundles] | 962 | Member | Member | | 963 | Attributes | Attributes | | 964 | | TLV (25) | | 965 +------------+---------------+--------------------------------------+ 967 Table 5: IS-IS Segment Routing Extensions TLVs/Sub-TLVs 969 2.5. Equivalent OSPFv2/OSPFv3 Segment Routing TLVs/Sub-TLVs 971 This section illustrate the OSPFv2 and OSPFv3 Segment Routing 972 Extensions TLVs and sub-TLVs mapped to the ones defined in this 973 document. 975 The following table, illustrates for each BGP-LS TLV, its equivalence 976 in OSPFv2 and OSPFv3. 978 +------------+-------------+----------------------------------------+ 979 | Descriptio | OSPFv2 TLV | Reference | 980 | n | /sub-TLV | | 981 +------------+-------------+----------------------------------------+ 982 | SR Capabil | SID/Label | [I-D.ietf-ospf-segment-routing-extensi | 983 | ities | Range TLV | ons] | 984 | | (9) | | 985 | SR | SR- | [I-D.ietf-ospf-segment-routing-extensi | 986 | Algorithm | Algorithm | ons] | 987 | | TLV (8) | | 988 | SR Local | SR Local | [I-D.ietf-ospf-segment-routing-extensi | 989 | Block | Block TLV | ons] | 990 | | (14) | | 991 | SRMS | SRMS | [I-D.ietf-ospf-segment-routing-extensi | 992 | Preference | Preference | ons] | 993 | | TLV (15) | | 994 | Adjacency | Adj-SID | [I-D.ietf-ospf-segment-routing-extensi | 995 | SID | sub-TLV (2) | ons] | 996 | LAN | LAN Adj-SID | [I-D.ietf-ospf-segment-routing-extensi | 997 | Adjacency | sub-TLV (3) | ons] | 998 | SID | | | 999 | Prefix SID | Prefix SID | [I-D.ietf-ospf-segment-routing-extensi | 1000 | | sub-TLV (2) | ons] | 1001 | Range | OSPF | [I-D.ietf-ospf-segment-routing-extensi | 1002 | | Extended | ons] | 1003 | | Prefix | | 1004 | | Range TLV | | 1005 | | (2) | | 1006 | SID/Label | SID/Label | [I-D.ietf-ospf-segment-routing-extensi | 1007 | | sub-TLV (1) | ons] | 1008 | Prefix | Flags of | [RFC7684] | 1009 | Attribute | OSPFv2 | | 1010 | Flags | Extended | | 1011 | | Prefix TLV | | 1012 | | (1) | | 1013 | Source | Prefix | [I-D.ietf-lsr-ospf-prefix-originator] | 1014 | Router-ID | Source | | 1015 | | Router-ID | | 1016 | | sub-TLV | | 1017 | | (TBD) | | 1018 +------------+-------------+----------------------------------------+ 1020 Table 6: OSPFv2 Segment Routing Extensions TLVs/Sub-TLVs 1022 +-----------+------------+------------------------------------------+ 1023 | Descripti | OSPFv3 TLV | Reference | 1024 | on | /sub-TLV | | 1025 +-----------+------------+------------------------------------------+ 1026 | SR Capabi | SID/Label | [I-D.ietf-ospf-segment-routing-extension | 1027 | lities | Range TLV | s] | 1028 | | (9) | | 1029 | SR | SR- | [I-D.ietf-ospf-segment-routing-extension | 1030 | Algorithm | Algorithm | s] | 1031 | | TLV (8) | | 1032 | SR Local | SR Local | [I-D.ietf-ospf-segment-routing-extension | 1033 | Block | Block TLV | s] | 1034 | | (14) | | 1035 | SRMS Pref | SRMS | [I-D.ietf-ospf-segment-routing-extension | 1036 | erence | Preference | s] | 1037 | | TLV (15) | | 1038 | Adjacency | Adj-SID | [I-D.ietf-ospf-ospfv3-segment-routing-ex | 1039 | SID | sub-TLV | tensions] | 1040 | | (5) | | 1041 | LAN | LAN Adj- | [I-D.ietf-ospf-ospfv3-segment-routing-ex | 1042 | Adjacency | SID sub- | tensions] | 1043 | SID | TLV (6) | | 1044 | Prefix | Prefix SID | [I-D.ietf-ospf-ospfv3-segment-routing-ex | 1045 | SID | sub-TLV | tensions] | 1046 | | (4) | | 1047 | Range | OSPFv3 | [I-D.ietf-ospf-ospfv3-segment-routing-ex | 1048 | | Extended | tensions] | 1049 | | Prefix | | 1050 | | Range TLV | | 1051 | | (9) | | 1052 | SID/Label | SID/Label | [I-D.ietf-ospf-ospfv3-segment-routing-ex | 1053 | | sub-TLV | tensions] | 1054 | | (7) | | 1055 | Prefix | Prefix | [RFC8362] | 1056 | Attribute | Option | | 1057 | Flags | Fields of | | 1058 | | Prefix TLV | | 1059 | | types | | 1060 | | 3,5,6 | | 1061 | Source | Prefix | [I-D.ietf-lsr-ospf-prefix-originator] | 1062 | Router-ID | Source | | 1063 | | Router-ID | | 1064 | | sub-TLV | | 1065 | | (TBD) | | 1066 +-----------+------------+------------------------------------------+ 1068 Table 7: OSPFv3 Segment Routing Extensions TLVs/Sub-TLVs 1070 3. IANA Considerations 1072 Early allocation of codepoints has been done by IANA for this 1073 document from the registry "BGP-LS Node Descriptor, Link Descriptor, 1074 Prefix Descriptor, and Attribute TLVs" based on Table 8. The column 1075 "IS-IS TLV/Sub-TLV" defined in the registry does not require any 1076 value and should be left empty. 1078 3.1. TLV/Sub-TLV Code Points Summary 1080 This section contains the global table of all TLVs/sub-TLVs defined 1081 in this document. 1083 +----------------+-----------------------------+---------------+ 1084 | TLV Code Point | Description | Reference | 1085 +----------------+-----------------------------+---------------+ 1086 | 1034 | SR Capabilities | Section 2.1.2 | 1087 | 1035 | SR Algorithm | Section 2.1.3 | 1088 | 1036 | SR Local Block | Section 2.1.4 | 1089 | 1037 | SRMS Preference | Section 2.1.5 | 1090 | 1099 | Adjacency SID | Section 2.2.1 | 1091 | 1100 | LAN Adjacency SID | Section 2.2.2 | 1092 | 1158 | Prefix SID | Section 2.3.1 | 1093 | 1159 | Range | Section 2.3.4 | 1094 | 1161 | SID/Label | Section 2.1.1 | 1095 | 1170 | Prefix Attribute Flags | Section 2.3.2 | 1096 | 1171 | Source Router-ID | Section 2.3.3 | 1097 | 1172 | L2 Bundle Member Attributes | Section 2.2.3 | 1098 +----------------+-----------------------------+---------------+ 1100 Table 8: Summary Table of TLV/Sub-TLV Codepoints 1102 4. Manageability Considerations 1104 This section is structured as recommended in [RFC5706]. 1106 The new protocol extensions introduced in this document augment the 1107 existing IGP topology information that is distributed via [RFC7752]. 1108 Procedures and protocol extensions defined in this document do not 1109 affect the BGP protocol operations and management other than as 1110 discussed in the Manageability Considerations section of [RFC7752]. 1111 Specifically, the malformed attribute tests for syntactic checks in 1112 the Fault Management section of [RFC7752] now encompass the new BGP- 1113 LS Attribute TLVs defined in this document. The semantic or content 1114 checking for the TLVs specified in this document and their 1115 association with the BGP-LS NLRI types or their BGP-LS Attribute is 1116 left to the consumer of the BGP-LS information (e.g. an application 1117 or a controller) and not the BGP protocol. 1119 A consumer of the BGP-LS information retrieves this information over 1120 a BGP-LS session (refer Section 1 and 2 of [RFC7752]). The handling 1121 of semantic or content errors by the consumer would be dictated by 1122 the nature of its application usage and hence is beyond the scope of 1123 this document. 1125 This document only introduces new Attribute TLVs and any syntactic 1126 error in them would result in only that specific attribute being 1127 discarded with an error log. The SR information introduced in BGP-LS 1128 by this specification, may be used by BGP-LS consumer applications 1129 like a SR path computation engine (PCE) to learn the SR capabilities 1130 of the nodes in the topology and the mapping of SR segments to those 1131 nodes. This can enable the SR PCE to perform path computations based 1132 on SR for traffic engineering use-cases and to steer traffic on paths 1133 different from the underlying IGP based distributed best path 1134 computation. Errors in the encoding or decoding of the SR 1135 information may result in the unavailability of such information to 1136 the SR PCE or incorrect information being made available to it. This 1137 may result in the SR PCE not being able to perform the desired SR 1138 based optimization functionality or to perform it in an unexpected or 1139 inconsistent manner. The handling of such errors by applications 1140 like SR PCE may be implementation specific and out of scope of this 1141 document. 1143 The extensions, specified in this document, do not introduce any new 1144 configuration or monitoring aspects in BGP or BGP-LS other than as 1145 discussed in [RFC7752]. The manageability aspects of the underlying 1146 SR features are covered by [I-D.ietf-spring-sr-yang], 1147 [I-D.ietf-isis-sr-yang] and [I-D.ietf-ospf-sr-yang]. 1149 5. Security Considerations 1151 The new protocol extensions introduced in this document augment the 1152 existing IGP topology information that is distributed via [RFC7752]. 1153 The Security Considerations section of [RFC7752] also applies to 1154 these extensions. The procedures and new TLVs defined in this 1155 document, by themselves, do not affect the BGP-LS security model 1156 discussed in [RFC7752]. 1158 The TLVs introduced in this document are used to propagate IGP 1159 defined information ([I-D.ietf-isis-segment-routing-extensions], 1160 [I-D.ietf-ospf-segment-routing-extensions] and 1161 [I-D.ietf-ospf-ospfv3-segment-routing-extensions]). These TLVs 1162 represent the SR information associated with the IGP node, link and 1163 prefix. The IGP instances originating these TLVs are assumed to 1164 support all the required security and authentication mechanisms (as 1165 described in [I-D.ietf-isis-segment-routing-extensions], 1166 [I-D.ietf-ospf-segment-routing-extensions] and 1168 [I-D.ietf-ospf-ospfv3-segment-routing-extensions]) in order to 1169 prevent any security issue when propagating the TLVs into BGP-LS. 1170 The advertisement of the link attribute information defined in this 1171 document presents no additional risk beyond that associated with the 1172 existing set of link attribute information already supported in 1173 [RFC7752]. 1175 BGP-LS SR extensions enable traffic engineering use-cases within the 1176 Segment Routing domain. SR operates within a trusted domain 1177 [RFC8402] and its security considerations also apply to BGP-LS 1178 sessions when carrying SR information. The SR traffic engineering 1179 policies using the SIDs advertised via BGP-LS are expected to be used 1180 entirely within this trusted SR domain (e.g. between multiple AS/ 1181 domains within a single provider network). Therefore, precaution is 1182 necessary to ensure that the SR information advertised via BGP-LS 1183 sessions is limited to consumers in a secure manner within this 1184 trusted SR domain. BGP peering sessions for address-families other 1185 than Link-State may be setup to routers outside the SR domain. The 1186 isolation of BGP-LS peering sessions is recommended to ensure that 1187 BGP-LS topology information (including the newly added SR 1188 information) is not advertised to an external BGP peering session 1189 outside the SR domain. 1191 6. Contributors 1193 The following people have substantially contributed to the editing of 1194 this document: 1196 Peter Psenak 1197 Cisco Systems 1198 Email: ppsenak@cisco.com 1200 Les Ginsberg 1201 Cisco Systems 1202 Email: ginsberg@cisco.com 1204 Acee Lindem 1205 Cisco Systems 1206 Email: acee@cisco.com 1208 Saikat Ray 1209 Individual 1210 Email: raysaikat@gmail.com 1212 Jeff Tantsura 1213 Apstra Inc. 1214 Email: jefftant.ietf@gmail.com 1216 7. Acknowledgements 1218 The authors would like to thank Jeffrey Haas, Aijun Wang, Robert 1219 Raszuk and Susan Hares for their review of this document and their 1220 comments. The authors would also like to thank Alvaro Retana for his 1221 extensive review and comments which helped correct issues and improve 1222 the document. 1224 8. References 1226 8.1. Normative References 1228 [I-D.ietf-isis-l2bundles] 1229 Ginsberg, L., Bashandy, A., Filsfils, C., Nanduri, M., and 1230 E. Aries, "Advertising L2 Bundle Member Link Attributes in 1231 IS-IS", draft-ietf-isis-l2bundles-07 (work in progress), 1232 May 2017. 1234 [I-D.ietf-isis-segment-routing-extensions] 1235 Previdi, S., Ginsberg, L., Filsfils, C., Bashandy, A., 1236 Gredler, H., and B. Decraene, "IS-IS Extensions for 1237 Segment Routing", draft-ietf-isis-segment-routing- 1238 extensions-24 (work in progress), April 2019. 1240 [I-D.ietf-lsr-ospf-prefix-originator] 1241 Wang, A., Lindem, A., Dong, J., Talaulikar, K., and P. 1242 Psenak, "OSPF Extension for Prefix Originator", draft- 1243 ietf-lsr-ospf-prefix-originator-00 (work in progress), 1244 February 2019. 1246 [I-D.ietf-ospf-ospfv3-segment-routing-extensions] 1247 Psenak, P. and S. Previdi, "OSPFv3 Extensions for Segment 1248 Routing", draft-ietf-ospf-ospfv3-segment-routing- 1249 extensions-23 (work in progress), January 2019. 1251 [I-D.ietf-ospf-segment-routing-extensions] 1252 Psenak, P., Previdi, S., Filsfils, C., Gredler, H., 1253 Shakir, R., Henderickx, W., and J. Tantsura, "OSPF 1254 Extensions for Segment Routing", draft-ietf-ospf-segment- 1255 routing-extensions-27 (work in progress), December 2018. 1257 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 1258 Requirement Levels", BCP 14, RFC 2119, 1259 DOI 10.17487/RFC2119, March 1997, 1260 . 1262 [RFC4202] Kompella, K., Ed. and Y. Rekhter, Ed., "Routing Extensions 1263 in Support of Generalized Multi-Protocol Label Switching 1264 (GMPLS)", RFC 4202, DOI 10.17487/RFC4202, October 2005, 1265 . 1267 [RFC5340] Coltun, R., Ferguson, D., Moy, J., and A. Lindem, "OSPF 1268 for IPv6", RFC 5340, DOI 10.17487/RFC5340, July 2008, 1269 . 1271 [RFC7684] Psenak, P., Gredler, H., Shakir, R., Henderickx, W., 1272 Tantsura, J., and A. Lindem, "OSPFv2 Prefix/Link Attribute 1273 Advertisement", RFC 7684, DOI 10.17487/RFC7684, November 1274 2015, . 1276 [RFC7752] Gredler, H., Ed., Medved, J., Previdi, S., Farrel, A., and 1277 S. Ray, "North-Bound Distribution of Link-State and 1278 Traffic Engineering (TE) Information Using BGP", RFC 7752, 1279 DOI 10.17487/RFC7752, March 2016, 1280 . 1282 [RFC7794] Ginsberg, L., Ed., Decraene, B., Previdi, S., Xu, X., and 1283 U. Chunduri, "IS-IS Prefix Attributes for Extended IPv4 1284 and IPv6 Reachability", RFC 7794, DOI 10.17487/RFC7794, 1285 March 2016, . 1287 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 1288 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 1289 May 2017, . 1291 [RFC8362] Lindem, A., Roy, A., Goethals, D., Reddy Vallem, V., and 1292 F. Baker, "OSPFv3 Link State Advertisement (LSA) 1293 Extensibility", RFC 8362, DOI 10.17487/RFC8362, April 1294 2018, . 1296 [RFC8402] Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L., 1297 Decraene, B., Litkowski, S., and R. Shakir, "Segment 1298 Routing Architecture", RFC 8402, DOI 10.17487/RFC8402, 1299 July 2018, . 1301 [RFC8571] Ginsberg, L., Ed., Previdi, S., Wu, Q., Tantsura, J., and 1302 C. Filsfils, "BGP - Link State (BGP-LS) Advertisement of 1303 IGP Traffic Engineering Performance Metric Extensions", 1304 RFC 8571, DOI 10.17487/RFC8571, March 2019, 1305 . 1307 8.2. Informative References 1309 [I-D.ietf-isis-sr-yang] 1310 Litkowski, S., Qu, Y., Sarkar, P., Chen, I., and J. 1311 Tantsura, "YANG Data Model for IS-IS Segment Routing", 1312 draft-ietf-isis-sr-yang-05 (work in progress), March 2019. 1314 [I-D.ietf-ospf-sr-yang] 1315 Yeung, D., Qu, Y., Zhang, Z., Chen, I., and A. Lindem, 1316 "YANG Data Model for OSPF SR (Segment Routing) Protocol", 1317 draft-ietf-ospf-sr-yang-07 (work in progress), March 2019. 1319 [I-D.ietf-spring-segment-routing-ldp-interop] 1320 Bashandy, A., Filsfils, C., Previdi, S., Decraene, B., and 1321 S. Litkowski, "Segment Routing interworking with LDP", 1322 draft-ietf-spring-segment-routing-ldp-interop-15 (work in 1323 progress), September 2018. 1325 [I-D.ietf-spring-sr-yang] 1326 Litkowski, S., Qu, Y., Lindem, A., Sarkar, P., and J. 1327 Tantsura, "YANG Data Model for Segment Routing", draft- 1328 ietf-spring-sr-yang-12 (work in progress), February 2019. 1330 [RFC5706] Harrington, D., "Guidelines for Considering Operations and 1331 Management of New Protocols and Protocol Extensions", 1332 RFC 5706, DOI 10.17487/RFC5706, November 2009, 1333 . 1335 Authors' Addresses 1337 Stefano Previdi 1338 Huawei Technologies 1339 Rome 1340 Italy 1342 Email: stefano@previdi.net 1344 Ketan Talaulikar (editor) 1345 Cisco Systems, Inc. 1346 India 1348 Email: ketant@cisco.com 1349 Clarence Filsfils 1350 Cisco Systems, Inc. 1351 Brussels 1352 Belgium 1354 Email: cfilsfil@cisco.com 1356 Hannes Gredler 1357 RtBrick Inc. 1359 Email: hannes@rtbrick.com 1361 Mach(Guoyi) Chen 1362 Huawei Technologies 1363 Huawei Building, No. 156 Beiqing Rd. 1364 Beijing 100095 1365 China 1367 Email: mach.chen@huawei.com