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Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Outdated reference: A later version (-12) exists of draft-ietf-lsr-ospf-prefix-originator-00 ** Obsolete normative reference: RFC 7752 (Obsoleted by RFC 9552) == Outdated reference: A later version (-21) exists of draft-ietf-isis-sr-yang-05 == Outdated reference: A later version (-30) exists of draft-ietf-ospf-sr-yang-07 == Outdated reference: A later version (-30) exists of draft-ietf-spring-sr-yang-12 Summary: 1 error (**), 0 flaws (~~), 5 warnings (==), 1 comment (--). 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: December 1, 2019 C. Filsfils 6 Cisco Systems, Inc. 7 H. Gredler 8 RtBrick Inc. 9 M. Chen 10 Huawei Technologies 11 May 30, 2019 13 BGP Link-State extensions for Segment Routing 14 draft-ietf-idr-bgp-ls-segment-routing-ext-15 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 document defines extensions to the BGP Link-state address-family 25 in 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 December 1, 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 . . . . . . . . . . . . . . . . . . 8 74 2.1.4. SR Local Block TLV . . . . . . . . . . . . . . . . . 8 75 2.1.5. SRMS Preference TLV . . . . . . . . . . . . . . . . . 10 76 2.2. Link Attribute TLVs . . . . . . . . . . . . . . . . . . . 11 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 semantic within a 104 domain. Within IGP topologies, an SR path is encoded as a sequence 105 of 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 denotes 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) can collect 181 SR information from across an SR domain (as described in [RFC8402]) 182 and construct the end-to-end path (with its associated SIDs) that 183 need to be applied to an incoming packet to achieve the desired end- 184 to-end forwarding. The SR domain may be comprised of a single AS or 185 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: Variable. Either 3 or 4 depending whether the value is 252 encoded as a label or as 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) and the 4 leftmost 256 bits are set to 0. If length is set to 4, then the value 257 represents a 32 bit SID (the total TLV size is 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 1 | 286 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 287 | SID/Label sub-TLV 1 (variable) // 288 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 290 ... 292 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 293 | Range Size N | 294 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 295 | SID/Label sub-TLV N (variable) // 296 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 298 Figure 3: SR Capabilities TLV Format 300 Where: 302 Type: 1034 304 Length: Variable. Minimum length is 12. 306 Flags: 1 octet of flags as defined in 307 [I-D.ietf-isis-segment-routing-extensions] for IS-IS. The flags 308 are not currently defined for OSPFv2 and OSPFv3 and SHOULD be set 309 to 0 and MUST be ignored on receipt. 311 Reserved: 1 octet that SHOULD be set to 0 and MUST be ignored on 312 receipt. 314 One or more entries, each of which have the following format: 316 Range Size: 3 octet with a non-zero value indicating the number 317 of labels in the range. 319 SID/Label sub-TLV (as defined in Section 2.1.1) which encodes 320 the first label in the range. Since the SID/Label sub-TLV is 321 used to indicate the first label of the SRGB range, only label 322 encoding is valid under the SR Capabilities TLV. 324 2.1.3. SR Algorithm TLV 326 The SR Algorithm TLV is used in order to advertise the SR Algorithms 327 supported by the node. This information is derived from the protocol 328 specific advertisements. 330 o IS-IS, as defined by the SR-Algorithm sub-TLV in 331 [I-D.ietf-isis-segment-routing-extensions]. 333 o OSPFv2/OSPFv3, as defined by the SR-Algorithm TLV in 334 [I-D.ietf-ospf-segment-routing-extensions]. OSPFv3 leverages the 335 same TLV as defined for OSPFv2. 337 The SR Algorithm TLV has the following format: 339 0 1 2 3 340 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 1 341 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 342 | Type | Length | 343 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 344 | Algorithm 1 | Algorithm... | Algorithm N | 345 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 347 Figure 4: SR Algorithm TLV Format 349 Where: 351 Type: 1035 353 Length: Variable. Minimum length is 1 and maximum can be 256. 355 Algorithm: One or more fields of 1 octet each identifying the 356 algorithm. 358 2.1.4. SR Local Block TLV 360 The SR Local Block (SRLB) TLV contains the range(s) of labels the 361 node has reserved for local SIDs. Local SIDs are used, e.g., in IGP 362 (IS-IS, OSPF) for Adjacency-SIDs, and may also be allocated by 363 components other than IGP protocols. As an example, an application 364 or a controller may instruct a node to allocate a specific local SID. 365 Therefore, in order for such applications or controllers to know the 366 range of local SIDs available, it is required that the node 367 advertises its SRLB. 369 This information is derived from the protocol specific 370 advertisements. 372 o IS-IS, as defined by the SR Local Block sub-TLV in 373 [I-D.ietf-isis-segment-routing-extensions]. 375 o OSPFv2/OSPFv3, as defined by the SR Local Block TLV in 376 [I-D.ietf-ospf-segment-routing-extensions]. OSPFv3 leverages the 377 same TLV as defined for OSPFv2. 379 The SRLB TLV has the following format: 381 0 1 2 3 382 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 1 383 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 384 | Type | Length | 385 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 386 | Flags | Reserved | 387 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 389 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 390 | Range Size 1 | 391 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 392 | SID/Label sub-TLV 1 (variable) // 393 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 395 ... 397 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 398 | Range Size N | 399 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 400 | SID/Label sub-TLV N (variable) // 401 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 403 Figure 5: SRLB TLV Format 405 Where: 407 Type: 1036 409 Length: Variable. Minimum length is 12. 411 Flags: 1 octet of flags. The flags are as defined in 412 [I-D.ietf-isis-segment-routing-extensions] for IS-IS. The flags 413 are not currently defined for OSPFv2 and OSPFv3 and SHOULD be set 414 to 0 and MUST be ignored on receipt. 416 Reserved: 1 octet that SHOULD be set to 0 and MUST be ignored on 417 receipt. 419 One or more entries, each of which have the following format: 421 Range Size: 3 octet value indicating the number of labels in 422 the range. 424 SID/Label sub-TLV (as defined in Section 2.1.1) which encodes 425 the first label in the range. Since the SID/Label sub-TLV is 426 used to indicate the first label of the SRLB range, only label 427 encoding is valid under the SR Local Block TLV. 429 2.1.5. SRMS Preference TLV 431 The Segment Routing Mapping Server (SRMS) Preference TLV is used in 432 order to associate a preference with SRMS advertisements from a 433 particular source. [I-D.ietf-spring-segment-routing-ldp-interop] 434 specifies the SRMS functionality along with SRMS preference of the 435 node advertising the SRMS Prefix-to-SID Mapping ranges. 437 This information is derived from the protocol specific 438 advertisements. 440 o IS-IS, as defined by the SRMS Preference sub-TLV in 441 [I-D.ietf-isis-segment-routing-extensions]. 443 o OSPFv2/OSPFv3, as defined by the SRMS Preference TLV in 444 [I-D.ietf-ospf-segment-routing-extensions]. OSPFv3 leverages the 445 same TLV as defined for OSPFv2. 447 The SRMS Preference TLV has the following format: 449 0 1 2 3 450 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 1 451 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 452 | Type | Length | 453 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 454 | Preference | 455 +-+-+-+-+-+-+-+-+ 457 Figure 6: SRMS Preference TLV Format 459 Where: 461 Type: 1037 463 Length: 1. 465 Preference: 1 octet carrying a unsigned 8 bit SRMS preference. 467 2.2. Link Attribute TLVs 469 The following Link Attribute TLVs are are defined: 471 +------+-----------------------+---------------+ 472 | Type | Description | Section | 473 +------+-----------------------+---------------+ 474 | 1099 | Adjacency SID TLV | Section 2.2.1 | 475 | 1100 | LAN Adjacency SID TLV | Section 2.2.2 | 476 | 1172 | L2 Bundle Member TLV | Section 2.2.3 | 477 +------+-----------------------+---------------+ 479 Table 2: Link Attribute TLVs 481 These TLVs should only be added to the BGP-LS Attribute associated 482 with the Link NLRI describing the link of the IGP node that is 483 originating the corresponding IGP TLV/sub-TLV described below. 485 2.2.1. Adjacency SID TLV 487 The Adjacency SID TLV is used in order to advertise information 488 related to an Adjacency SID. This information is derived from Adj- 489 SID sub-TLV of IS-IS [I-D.ietf-isis-segment-routing-extensions], 490 OSPFv2 [I-D.ietf-ospf-segment-routing-extensions] and OSPFv3 491 [I-D.ietf-ospf-ospfv3-segment-routing-extensions]. 493 The Adjacency SID TLV has the following format: 495 0 1 2 3 496 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 1 497 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 498 | Type | Length | 499 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 500 | Flags | Weight | Reserved | 501 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 502 | SID/Label/Index (variable) // 503 +---------------------------------------------------------------+ 505 Figure 7: Adjacency SID TLV Format 507 Where: 509 Type: 1099 511 Length: Variable. Either 7 or 8 depending on Label or Index 512 encoding of the SID 513 Flags. 1 octet value which should be set as: 515 * IS-IS Adj-SID flags are defined in 516 [I-D.ietf-isis-segment-routing-extensions]. 518 * OSPFv2 Adj-SID flags are defined in 519 [I-D.ietf-ospf-segment-routing-extensions]. 521 * OSPFv3 Adj-SID flags are defined in 522 [I-D.ietf-ospf-segment-routing-extensions]. 524 Weight: 1 octet carrying the weight used for load-balancing 525 purposes. 527 Reserved: 2 octets that SHOULD be set to 0 and MUST be ignored on 528 receipt. 530 SID/Index/Label: 532 * IS-IS: Label or index value as defined in 533 [I-D.ietf-isis-segment-routing-extensions]. 535 * OSPFv2: Label or index value as defined in 536 [I-D.ietf-ospf-segment-routing-extensions]. 538 * OSPFv3: Label or index value as defined in 539 [I-D.ietf-ospf-ospfv3-segment-routing-extensions]. 541 The Flags and, as an extension, the SID/Index/Label fields of this 542 TLV are interpreted according to the respective underlying IS-IS, 543 OSPFv2 or OSPFv3 protocol. The Protocol-ID of the BGP-LS Link NLRI 544 is used to determine the underlying protocol specification for 545 parsing these fields. 547 2.2.2. LAN Adjacency SID TLV 549 For a LAN, normally a node only announces its adjacency to the IS-IS 550 pseudo-node (or the equivalent OSPF Designated and Backup Designated 551 Routers). The LAN Adjacency Segment TLV allows a node to announce 552 adjacencies to all other nodes attached to the LAN in a single 553 instance of the BGP-LS Link NLRI. Without this TLV, the 554 corresponding BGP-LS link NLRI would need to be originated for each 555 additional adjacency in order to advertise the SR TLVs for these 556 neighbor adjacencies. 558 This information is derived from LAN-Adj-SID sub-TLV of IS-IS 559 [I-D.ietf-isis-segment-routing-extensions] and LAN Adj-SID sub-TLV of 560 OSPFv2 [I-D.ietf-ospf-segment-routing-extensions] and OSPFv3 561 [I-D.ietf-ospf-ospfv3-segment-routing-extensions]. 563 The LAN Adjacency SID TLV has the following format: 565 0 1 2 3 566 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 1 567 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 568 | Type | Length | 569 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 570 | Flags | Weight | Reserved | 571 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 573 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 574 | OSPF Neighbor ID / IS-IS System-ID | 575 + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 576 | | 577 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 579 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 580 | SID/Label/Index (variable) // 581 +---------------------------------------------------------------+ 583 Figure 8: LAN Adjacency SID TLV Format 585 Where: 587 Type: 1100 589 Length: Variable. For IS-IS it would be 13 or 14 depending on 590 Label or Index encoding of the SID. For OSPF it would be 11 or 12 591 depending on Label or Index encoding of the SID. 593 Flags. 1 octet value which should be set as: 595 * IS-IS LAN Adj-SID flags are defined in 596 [I-D.ietf-isis-segment-routing-extensions]. 598 * OSPFv2 LAN Adj-SID flags are defined in 599 [I-D.ietf-ospf-segment-routing-extensions]. 601 * OSPFv3 LAN Adj-SID flags are defined in 602 [I-D.ietf-ospf-segment-routing-extensions]. 604 Weight: 1 octet carrying the weight used for load-balancing 605 purposes. 607 Reserved: 2 octets that SHOULD be set to 0 and MUST be ignored on 608 receipt. 610 Neighbor ID: 6 octets for IS-IS for the System-ID and 4 octets for 611 OSPF for the OSPF Router-ID of the neighbor. 613 SID/Index/Label: 615 * IS-IS: Label or index value as defined in 616 [I-D.ietf-isis-segment-routing-extensions]. 618 * OSPFv2: Label or index value as defined in 619 [I-D.ietf-ospf-segment-routing-extensions]. 621 * OSPFv3: Label or index value as defined in 622 [I-D.ietf-ospf-ospfv3-segment-routing-extensions]. 624 The Neighbor ID, Flags and, as an extension, the SID/Index/Label 625 fields of this TLV are interpreted according to the respective 626 underlying IS-IS, OSPFv2 or OSPFv3 protocol. The Protocol-ID of the 627 BGP-LS Link NLRI is used to determine the underlying protocol 628 specification for parsing these fields. 630 2.2.3. L2 Bundle Member Attribute TLV 632 The L2 Bundle Member Attribute TLV identifies an L2 Bundle Member 633 link which in turn is associated with a parent L3 link. The L3 link 634 is described by the Link NLRI defined in [RFC7752] and the L2 Bundle 635 Member Attribute TLV is associated with the Link NLRI. The TLV MAY 636 include sub-TLVs which describe attributes associated with the bundle 637 member. The identified bundle member represents a unidirectional 638 path from the originating router to the neighbor specified in the 639 parent L3 Link. Multiple L2 Bundle Member Attribute TLVs MAY be 640 associated with a Link NLRI. 642 This information is derived from L2 Bundle Member Attributes TLV of 643 IS-IS [I-D.ietf-isis-l2bundles]. The equivalent functionality has 644 not been specified as yet for OSPF. 646 The L2 Bundle Member Attribute TLV has the following format: 648 0 1 2 3 649 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 1 650 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 651 | Type | Length | 652 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 653 | L2 Bundle Member Descriptor | 654 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 655 | Link attribute sub-TLVs(variable) // 656 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 658 Figure 9: L2 Bundle Member Attributes TLV Format 660 Where: 662 Type: 1172 664 Length: Variable. 666 L2 Bundle Member Descriptor: 4 octets field that carries a Link 667 Local Identifier as defined in [RFC4202]. 669 Link attributes for L2 Bundle Member Links are advertised as sub-TLVs 670 of the L2 Bundle Member Attribute TLV. The sub-TLVs are identical to 671 existing BGP-LS TLVs as identified in the table below. 673 +-------------+------------------------------------+----------------+ 674 | TLV Code | Description | Reference | 675 | Point | | Document | 676 +-------------+------------------------------------+----------------+ 677 | 1088 | Administrative group (color) | [RFC7752] | 678 | 1089 | Maximum link bandwidth | [RFC7752] | 679 | 1090 | Max. reservable link bandwidth | [RFC7752] | 680 | 1091 | Unreserved bandwidth | [RFC7752] | 681 | 1092 | TE default metric | [RFC7752] | 682 | 1093 | Link protection type | [RFC7752] | 683 | 1099 | Adjacency Segment Identifier (Adj- | Section 2.2.1 | 684 | | SID) TLV | | 685 | 1100 | LAN Adjacency Segment Identifier | Section 2.2.2 | 686 | | (Adj-SID) TLV | | 687 | 1114 | Unidirectional link delay | [RFC8571] | 688 | 1115 | Min/Max Unidirectional link delay | [RFC8571] | 689 | 1116 | Unidirectional Delay Variation | [RFC8571] | 690 | 1117 | Unidirectional packet loss | [RFC8571] | 691 | 1118 | Unidirectional residual bandwidth | [RFC8571] | 692 | 1119 | Unidirectional available bandwidth | [RFC8571] | 693 | 1120 | Unidirectional bandwidth | [RFC8571] | 694 | | utilization | | 695 +-------------+------------------------------------+----------------+ 697 Table 3: BGP-LS Attribute TLVs also used as sub-TLVs of L2 Bundle 698 Member Attribute TLV 700 2.3. Prefix Attribute TLVs 702 The following Prefix Attribute TLVs are defined: 704 +------+------------------------+---------------+ 705 | Type | Description | Section | 706 +------+------------------------+---------------+ 707 | 1158 | Prefix SID | Section 2.3.1 | 708 | 1159 | Range | Section 2.3.4 | 709 | 1170 | Prefix Attribute Flags | Section 2.3.2 | 710 | 1171 | Source Router-ID | Section 2.3.3 | 711 +------+------------------------+---------------+ 713 Table 4: Prefix Attribute TLVs 715 These TLVs should only be added to the BGP-LS Attribute associated 716 with the Prefix NLRI describing the prefix of the IGP node that is 717 originating the corresponding IGP TLV/sub-TLV described below. 719 2.3.1. Prefix SID TLV 721 The Prefix SID TLV is used in order to advertise information related 722 to a Prefix SID. This information is derived from Prefix-SID sub-TLV 723 of IS-IS [I-D.ietf-isis-segment-routing-extensions] and the Prefix 724 SID sub-TLV of OSPFv2 [I-D.ietf-ospf-segment-routing-extensions] and 725 OSPFv3 [I-D.ietf-ospf-ospfv3-segment-routing-extensions]. 727 The Prefix SID TLV has the following format: 729 0 1 2 3 730 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 1 731 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 732 | Type | Length | 733 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 734 | Flags | Algorithm | Reserved | 735 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 736 | SID/Index/Label (variable) // 737 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 739 Figure 10: Prefix SID TLV Format 741 Where: 743 Type: 1158 745 Length: Variable. 7 or 8 depending on Label or Index encoding of 746 the SID 748 Flags: 1 octet value which should be set as: 750 * IS-IS Prefix SID flags are defined in 751 [I-D.ietf-isis-segment-routing-extensions]. 753 * OSPFv2 Prefix SID flags are defined in 754 [I-D.ietf-ospf-segment-routing-extensions]. 756 * OSPFv3 Prefix SID flags are defined in 757 [I-D.ietf-ospf-segment-routing-extensions]. 759 Algorithm: 1 octet value identify the algorithm. 761 Reserved: 2 octets that SHOULD be set to 0 and MUST be ignored on 762 receipt. 764 SID/Index/Label: 766 * IS-IS: Label or index value as defined in 767 [I-D.ietf-isis-segment-routing-extensions]. 769 * OSPFv2: Label or index value as defined in 770 [I-D.ietf-ospf-segment-routing-extensions]. 772 * OSPFv3: Label or index value as defined in 773 [I-D.ietf-ospf-ospfv3-segment-routing-extensions]. 775 The Flags and, as an extension, the SID/Index/Label fields of this 776 TLV are interpreted according to the respective underlying IS-IS, 777 OSPFv2 or OSPFv3 protocol. The Protocol-ID of the BGP-LS Prefix NLRI 778 is used to determine the underlying protocol specification for 779 parsing these fields. 781 2.3.2. Prefix Attribute Flags TLV 783 The Prefix Attribute Flags TLV carries IPv4/IPv6 prefix attribute 784 flags information. These flags are defined for OSPFv2 in [RFC7684], 785 for OSPFv3 in [RFC5340] and for IS-IS in [RFC7794]. 787 The Prefix Attribute Flags TLV has the following format: 789 0 1 2 3 790 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 1 791 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 792 | Type | Length | 793 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 794 | Flags (variable) // 795 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 797 Figure 11: Prefix Attribute Flags TLV Format 799 Where: 801 Type: 1170 803 Length: Variable. 805 Flags: a variable length flag field (according to the length 806 field). Flags are routing protocol specific and are to be set as 807 below: 809 * IS-IS flags correspond to the IPv4/IPv6 Extended Reachability 810 Attribute Flags defined in [RFC7794] 812 * OSPFv2 flags correspond to the Flags field of the OSPFv2 813 Extended Prefix TLV defined in [RFC7684] 815 * OSPFv3 flags map to the Prefix Options field defined in 816 [RFC5340] and extended via [RFC8362] 818 The Flags field of this TLV is interpreted according to the 819 respective underlying IS-IS, OSPFv2 or OSPFv3 protocol. The 820 Protocol-ID of the BGP-LS Prefix NLRI is used to determine the 821 underlying protocol specification for parsing this field. 823 2.3.3. Source Router Identifier (Source Router-ID) TLV 825 The Source Router-ID TLV contains the IPv4 or IPv6 Router-ID of the 826 originator of the Prefix. For the IS-IS protocol this is derived 827 from the IPv4/IPv6 Source Router ID sub-TLV as defined in [RFC7794]. 828 For the OSPF protocol, this is derived from the Prefix Source Router- 829 ID sub-TLV as defined in [I-D.ietf-lsr-ospf-prefix-originator]. 831 The Source Router-ID TLV has the following format: 833 0 1 2 3 834 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 1 835 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 836 | Type | Length | 837 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 838 | 4 or 6 octet Router-ID // 839 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 841 Figure 12: Source Router-ID TLV Format 843 Where: 845 Type: 1171 847 Length: Variable. 4 or 16 in case of IS-IS and 4 in case of OSPF. 849 Router-ID: the IPv4 or IPv6 Router-ID in case of IS-IS and the 850 OSPF Router-ID in the case of OSPF. 852 2.3.4. Range TLV 854 The Range TLV is used in order to advertise a range of prefix-to-SID 855 mappings as part of the Segment Routing Mapping Server (SRMS) 856 functionality [I-D.ietf-spring-segment-routing-ldp-interop], as 857 defined in the respective underlying IGP SR extensions 858 [I-D.ietf-ospf-segment-routing-extensions], 860 [I-D.ietf-ospf-ospfv3-segment-routing-extensions] and 861 [I-D.ietf-isis-segment-routing-extensions]. The information 862 advertised in the Range TLV is derived from the SID/Label Binding TLV 863 in the case of IS-IS and the OSPFv2/OSPFv3 Extended Prefix Range TLV 864 in the case of OSPFv2/OSPFv3. 866 A Prefix NLRI, that been advertised with a Range TLV, is considered a 867 normal routing prefix (i.e. prefix reachability) only when there is 868 also an IGP metric TLV (TLV 1095) associated it. Otherwise, it is 869 considered only as the first prefix in the range for prefix-to-SID 870 mapping advertisement. 872 The format of the Range TLV is as follows: 874 0 1 2 3 875 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 1 876 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 877 | Type | Length | 878 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 879 | Flags | Reserved | Range Size | 880 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 881 | sub-TLVs // 882 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 884 Figure 13: Range TLV Format 886 Where: 888 Type: 1159 890 Length: Variable. 11 or 12 depending on Label or Index encoding of 891 the SID 893 Flags: 1 octet value which should be set as: 895 * IS-IS SID/Label Binding TLV flags are defined in 896 [I-D.ietf-isis-segment-routing-extensions]. 898 * OSPFv2 OSPF Extended Prefix Range TLV flags are defined in 899 [I-D.ietf-ospf-segment-routing-extensions]. 901 * OSPFv3 Extended Prefix Range TLV flags are defined in 902 [I-D.ietf-ospf-ospfv3-segment-routing-extensions]. 904 Reserved: 1 octet that SHOULD be set to 0 and MUST be ignored on 905 receipt. 907 Range Size: 2 octets as defined in 908 [I-D.ietf-ospf-segment-routing-extensions]. 910 The Flags field of this TLV is interpreted according to the 911 respective underlying IS-IS, OSPFv2 or OSPFv3 protocol. The 912 Protocol-ID of the BGP-LS Prefix NLRI is used to determine the 913 underlying protocol specification for parsing this field. 915 The prefix-to-SID mappings are advertised using sub-TLVs as below: 917 IS-IS: 918 SID/Label Range TLV 919 Prefix-SID sub-TLV 921 OSPFv2/OSPFv3: 922 OSPFv2/OSPFv3 Extended Prefix Range TLV 923 Prefix SID sub-TLV 925 BGP-LS: 926 Range TLV 927 Prefix-SID TLV (used as a sub-TLV in this context) 929 The prefix-to-SID mapping information for the BGP-LS Prefix-SID TLV 930 (used as sub-TLV in this context) is encoded as described in 931 Section 2.3.1. 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 | SR- | [I-D.ietf-isis-segment-routing-exten | 946 | ities | Capabilities | sions] | 947 | | sub-TLV (2) | | 948 | SR | SR-Algorithm | [I-D.ietf-isis-segment-routing-exten | 949 | Algorithm | sub-TLV (19) | sions] | 950 | SR Local | SR Local | [I-D.ietf-isis-segment-routing-exten | 951 | Block | Block sub-TLV | sions] | 952 | | (22) | | 953 | SRMS | SRMS | [I-D.ietf-isis-segment-routing-exten | 954 | Preference | Preference | sions] | 955 | | sub-TLV (19) | | 956 | Adjacency | Adj-SID sub- | [I-D.ietf-isis-segment-routing-exten | 957 | SID | TLV (31) | sions] | 958 | LAN | LAN-Adj-SID | [I-D.ietf-isis-segment-routing-exten | 959 | Adjacency | sub-TLV (32) | sions] | 960 | SID | | | 961 | Prefix SID | Prefix-SID | [I-D.ietf-isis-segment-routing-exten | 962 | | sub-TLV (3) | sions] | 963 | Range | SID/Label | [I-D.ietf-isis-segment-routing-exten | 964 | | Binding TLV | sions] | 965 | | (149) | | 966 | SID/Label | SID/Label | [I-D.ietf-isis-segment-routing-exten | 967 | | sub-TLV (1) | sions] | 968 | Prefix | Prefix | [RFC7794] | 969 | Attribute | Attributes | | 970 | Flags | Flags sub-TLV | | 971 | | (4) | | 972 | Source | IPv4/IPv6 | [RFC7794] | 973 | Router-ID | Source Router | | 974 | | ID sub-TLV | | 975 | | (11/12) | | 976 | L2 Bundle | L2 Bundle | [I-D.ietf-isis-l2bundles] | 977 | Member | Member | | 978 | Attributes | Attributes | | 979 | | TLV (25) | | 980 +------------+---------------+--------------------------------------+ 982 Table 5: IS-IS Segment Routing Extensions TLVs/Sub-TLVs 984 2.5. Equivalent OSPFv2/OSPFv3 Segment Routing TLVs/Sub-TLVs 986 This section illustrate the OSPFv2 and OSPFv3 Segment Routing 987 Extensions TLVs and sub-TLVs mapped to the ones defined in this 988 document. 990 The following table, illustrates for each BGP-LS TLV, its equivalence 991 in OSPFv2 and OSPFv3. 993 +------------+-------------+----------------------------------------+ 994 | Descriptio | OSPFv2 TLV | Reference | 995 | n | /sub-TLV | | 996 +------------+-------------+----------------------------------------+ 997 | SR Capabil | SID/Label | [I-D.ietf-ospf-segment-routing-extensi | 998 | ities | Range TLV | ons] | 999 | | (9) | | 1000 | SR | SR- | [I-D.ietf-ospf-segment-routing-extensi | 1001 | Algorithm | Algorithm | ons] | 1002 | | TLV (8) | | 1003 | SR Local | SR Local | [I-D.ietf-ospf-segment-routing-extensi | 1004 | Block | Block TLV | ons] | 1005 | | (14) | | 1006 | SRMS | SRMS | [I-D.ietf-ospf-segment-routing-extensi | 1007 | Preference | Preference | ons] | 1008 | | TLV (15) | | 1009 | Adjacency | Adj-SID | [I-D.ietf-ospf-segment-routing-extensi | 1010 | SID | sub-TLV (2) | ons] | 1011 | LAN | LAN Adj-SID | [I-D.ietf-ospf-segment-routing-extensi | 1012 | Adjacency | sub-TLV (3) | ons] | 1013 | SID | | | 1014 | Prefix SID | Prefix SID | [I-D.ietf-ospf-segment-routing-extensi | 1015 | | sub-TLV (2) | ons] | 1016 | Range | OSPF | [I-D.ietf-ospf-segment-routing-extensi | 1017 | | Extended | ons] | 1018 | | Prefix | | 1019 | | Range TLV | | 1020 | | (2) | | 1021 | SID/Label | SID/Label | [I-D.ietf-ospf-segment-routing-extensi | 1022 | | sub-TLV (1) | ons] | 1023 | Prefix | Flags of | [RFC7684] | 1024 | Attribute | OSPFv2 | | 1025 | Flags | Extended | | 1026 | | Prefix TLV | | 1027 | | (1) | | 1028 | Source | Prefix | [I-D.ietf-lsr-ospf-prefix-originator] | 1029 | Router-ID | Source | | 1030 | | Router-ID | | 1031 | | sub-TLV | | 1032 | | (TBD) | | 1033 +------------+-------------+----------------------------------------+ 1035 Table 6: OSPFv2 Segment Routing Extensions TLVs/Sub-TLVs 1037 +-----------+------------+------------------------------------------+ 1038 | Descripti | OSPFv3 TLV | Reference | 1039 | on | /sub-TLV | | 1040 +-----------+------------+------------------------------------------+ 1041 | SR Capabi | SID/Label | [I-D.ietf-ospf-segment-routing-extension | 1042 | lities | Range TLV | s] | 1043 | | (9) | | 1044 | SR | SR- | [I-D.ietf-ospf-segment-routing-extension | 1045 | Algorithm | Algorithm | s] | 1046 | | TLV (8) | | 1047 | SR Local | SR Local | [I-D.ietf-ospf-segment-routing-extension | 1048 | Block | Block TLV | s] | 1049 | | (14) | | 1050 | SRMS Pref | SRMS | [I-D.ietf-ospf-segment-routing-extension | 1051 | erence | Preference | s] | 1052 | | TLV (15) | | 1053 | Adjacency | Adj-SID | [I-D.ietf-ospf-ospfv3-segment-routing-ex | 1054 | SID | sub-TLV | tensions] | 1055 | | (5) | | 1056 | LAN | LAN Adj- | [I-D.ietf-ospf-ospfv3-segment-routing-ex | 1057 | Adjacency | SID sub- | tensions] | 1058 | SID | TLV (6) | | 1059 | Prefix | Prefix SID | [I-D.ietf-ospf-ospfv3-segment-routing-ex | 1060 | SID | sub-TLV | tensions] | 1061 | | (4) | | 1062 | Range | OSPFv3 | [I-D.ietf-ospf-ospfv3-segment-routing-ex | 1063 | | Extended | tensions] | 1064 | | Prefix | | 1065 | | Range TLV | | 1066 | | (9) | | 1067 | SID/Label | SID/Label | [I-D.ietf-ospf-ospfv3-segment-routing-ex | 1068 | | sub-TLV | tensions] | 1069 | | (7) | | 1070 | Prefix | Prefix | [RFC8362] | 1071 | Attribute | Option | | 1072 | Flags | Fields of | | 1073 | | Prefix TLV | | 1074 | | types | | 1075 | | 3,5,6 | | 1076 | Source | Prefix | [I-D.ietf-lsr-ospf-prefix-originator] | 1077 | Router-ID | Source | | 1078 | | Router-ID | | 1079 | | sub-TLV | | 1080 | | (TBD) | | 1081 +-----------+------------+------------------------------------------+ 1083 Table 7: OSPFv3 Segment Routing Extensions TLVs/Sub-TLVs 1085 3. IANA Considerations 1087 Early allocation of codepoints has been done by IANA for this 1088 document from the registry "BGP-LS Node Descriptor, Link Descriptor, 1089 Prefix Descriptor, and Attribute TLVs" under the "BGP-LS Parameters" 1090 registry based on Table 8. The column "IS-IS TLV/Sub-TLV" defined in 1091 the registry does not require any value and should be left empty. 1093 3.1. TLV/Sub-TLV Code Points Summary 1095 This section contains the global table of all TLVs/sub-TLVs defined 1096 in this document. 1098 +----------------+-----------------------------+---------------+ 1099 | TLV Code Point | Description | Reference | 1100 +----------------+-----------------------------+---------------+ 1101 | 1034 | SR Capabilities | Section 2.1.2 | 1102 | 1035 | SR Algorithm | Section 2.1.3 | 1103 | 1036 | SR Local Block | Section 2.1.4 | 1104 | 1037 | SRMS Preference | Section 2.1.5 | 1105 | 1099 | Adjacency SID | Section 2.2.1 | 1106 | 1100 | LAN Adjacency SID | Section 2.2.2 | 1107 | 1158 | Prefix SID | Section 2.3.1 | 1108 | 1159 | Range | Section 2.3.4 | 1109 | 1161 | SID/Label | Section 2.1.1 | 1110 | 1170 | Prefix Attribute Flags | Section 2.3.2 | 1111 | 1171 | Source Router-ID | Section 2.3.3 | 1112 | 1172 | L2 Bundle Member Attributes | Section 2.2.3 | 1113 +----------------+-----------------------------+---------------+ 1115 Table 8: Summary Table of TLV/Sub-TLV Codepoints 1117 4. Manageability Considerations 1119 This section is structured as recommended in [RFC5706]. 1121 The new protocol extensions introduced in this document augment the 1122 existing IGP topology information that is distributed via [RFC7752]. 1123 Procedures and protocol extensions defined in this document do not 1124 affect the BGP protocol operations and management other than as 1125 discussed in the Manageability Considerations section of [RFC7752]. 1126 Specifically, the malformed attribute tests for syntactic checks in 1127 the Fault Management section of [RFC7752] now encompass the new BGP- 1128 LS Attribute TLVs defined in this document. The semantic or content 1129 checking for the TLVs specified in this document and their 1130 association with the BGP-LS NLRI types or their BGP-LS Attribute is 1131 left to the consumer of the BGP-LS information (e.g. an application 1132 or a controller) and not the BGP protocol. 1134 A consumer of the BGP-LS information retrieves this information over 1135 a BGP-LS session (refer Section 1 and 2 of [RFC7752]). The handling 1136 of semantic or content errors by the consumer would be dictated by 1137 the nature of its application usage and hence is beyond the scope of 1138 this document. 1140 This document only introduces new Attribute TLVs and any syntactic 1141 error in them would result in only that specific attribute being 1142 discarded with an error log. The SR information introduced in BGP-LS 1143 by this specification, may be used by BGP-LS consumer applications 1144 like a SR path computation engine (PCE) to learn the SR capabilities 1145 of the nodes in the topology and the mapping of SR segments to those 1146 nodes. This can enable the SR PCE to perform path computations based 1147 on SR for traffic engineering use-cases and to steer traffic on paths 1148 different from the underlying IGP based distributed best path 1149 computation. Errors in the encoding or decoding of the SR 1150 information may result in the unavailability of such information to 1151 the SR PCE or incorrect information being made available to it. This 1152 may result in the SR PCE not being able to perform the desired SR 1153 based optimization functionality or to perform it in an unexpected or 1154 inconsistent manner. The handling of such errors by applications 1155 like SR PCE may be implementation specific and out of scope of this 1156 document. 1158 The extensions, specified in this document, do not introduce any new 1159 configuration or monitoring aspects in BGP or BGP-LS other than as 1160 discussed in [RFC7752]. The manageability aspects of the underlying 1161 SR features are covered by [I-D.ietf-spring-sr-yang], 1162 [I-D.ietf-isis-sr-yang] and [I-D.ietf-ospf-sr-yang]. 1164 5. Security Considerations 1166 The new protocol extensions introduced in this document augment the 1167 existing IGP topology information that is distributed via [RFC7752]. 1168 The Security Considerations section of [RFC7752] also applies to 1169 these extensions. The procedures and new TLVs defined in this 1170 document, by themselves, do not affect the BGP-LS security model 1171 discussed in [RFC7752]. 1173 The TLVs introduced in this document are used to propagate IGP 1174 defined information ([I-D.ietf-isis-segment-routing-extensions], 1175 [I-D.ietf-ospf-segment-routing-extensions] and 1176 [I-D.ietf-ospf-ospfv3-segment-routing-extensions]). These TLVs 1177 represent the SR information associated with the IGP node, link and 1178 prefix. The IGP instances originating these TLVs are assumed to 1179 support all the required security and authentication mechanisms (as 1180 described in [I-D.ietf-isis-segment-routing-extensions], 1181 [I-D.ietf-ospf-segment-routing-extensions] and 1183 [I-D.ietf-ospf-ospfv3-segment-routing-extensions]) in order to 1184 prevent any security issue when propagating the TLVs into BGP-LS. 1185 The advertisement of the link attribute information defined in this 1186 document presents no additional risk beyond that associated with the 1187 existing set of link attribute information already supported in 1188 [RFC7752]. 1190 BGP-LS SR extensions enable traffic engineering use-cases within the 1191 Segment Routing domain. SR operates within a trusted domain 1192 [RFC8402] and its security considerations also apply to BGP-LS 1193 sessions when carrying SR information. The SR traffic engineering 1194 policies using the SIDs advertised via BGP-LS are expected to be used 1195 entirely within this trusted SR domain (e.g. between multiple AS/ 1196 domains within a single provider network). Therefore, precaution is 1197 necessary to ensure that the SR information advertised via BGP-LS 1198 sessions is limited to consumers in a secure manner within this 1199 trusted SR domain. BGP peering sessions for address-families other 1200 than Link-State may be setup to routers outside the SR domain. The 1201 isolation of BGP-LS peering sessions is recommended to ensure that 1202 BGP-LS topology information (including the newly added SR 1203 information) is not advertised to an external BGP peering session 1204 outside the SR domain. 1206 6. Contributors 1208 The following people have substantially contributed to the editing of 1209 this document: 1211 Peter Psenak 1212 Cisco Systems 1213 Email: ppsenak@cisco.com 1215 Les Ginsberg 1216 Cisco Systems 1217 Email: ginsberg@cisco.com 1219 Acee Lindem 1220 Cisco Systems 1221 Email: acee@cisco.com 1223 Saikat Ray 1224 Individual 1225 Email: raysaikat@gmail.com 1227 Jeff Tantsura 1228 Apstra Inc. 1229 Email: jefftant.ietf@gmail.com 1231 7. Acknowledgements 1233 The authors would like to thank Jeffrey Haas, Aijun Wang, Robert 1234 Raszuk and Susan Hares for their review of this document and their 1235 comments. The authors would also like to thank Alvaro Retana for his 1236 extensive review and comments which helped correct issues and improve 1237 the document. 1239 8. References 1241 8.1. Normative References 1243 [I-D.ietf-isis-l2bundles] 1244 Ginsberg, L., Bashandy, A., Filsfils, C., Nanduri, M., and 1245 E. Aries, "Advertising L2 Bundle Member Link Attributes in 1246 IS-IS", draft-ietf-isis-l2bundles-07 (work in progress), 1247 May 2017. 1249 [I-D.ietf-isis-segment-routing-extensions] 1250 Previdi, S., Ginsberg, L., Filsfils, C., Bashandy, A., 1251 Gredler, H., and B. Decraene, "IS-IS Extensions for 1252 Segment Routing", draft-ietf-isis-segment-routing- 1253 extensions-25 (work in progress), May 2019. 1255 [I-D.ietf-lsr-ospf-prefix-originator] 1256 Wang, A., Lindem, A., Dong, J., Talaulikar, K., and P. 1257 Psenak, "OSPF Extension for Prefix Originator", draft- 1258 ietf-lsr-ospf-prefix-originator-00 (work in progress), 1259 February 2019. 1261 [I-D.ietf-ospf-ospfv3-segment-routing-extensions] 1262 Psenak, P. and S. Previdi, "OSPFv3 Extensions for Segment 1263 Routing", draft-ietf-ospf-ospfv3-segment-routing- 1264 extensions-23 (work in progress), January 2019. 1266 [I-D.ietf-ospf-segment-routing-extensions] 1267 Psenak, P., Previdi, S., Filsfils, C., Gredler, H., 1268 Shakir, R., Henderickx, W., and J. Tantsura, "OSPF 1269 Extensions for Segment Routing", draft-ietf-ospf-segment- 1270 routing-extensions-27 (work in progress), December 2018. 1272 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 1273 Requirement Levels", BCP 14, RFC 2119, 1274 DOI 10.17487/RFC2119, March 1997, 1275 . 1277 [RFC4202] Kompella, K., Ed. and Y. Rekhter, Ed., "Routing Extensions 1278 in Support of Generalized Multi-Protocol Label Switching 1279 (GMPLS)", RFC 4202, DOI 10.17487/RFC4202, October 2005, 1280 . 1282 [RFC5340] Coltun, R., Ferguson, D., Moy, J., and A. Lindem, "OSPF 1283 for IPv6", RFC 5340, DOI 10.17487/RFC5340, July 2008, 1284 . 1286 [RFC7684] Psenak, P., Gredler, H., Shakir, R., Henderickx, W., 1287 Tantsura, J., and A. Lindem, "OSPFv2 Prefix/Link Attribute 1288 Advertisement", RFC 7684, DOI 10.17487/RFC7684, November 1289 2015, . 1291 [RFC7752] Gredler, H., Ed., Medved, J., Previdi, S., Farrel, A., and 1292 S. Ray, "North-Bound Distribution of Link-State and 1293 Traffic Engineering (TE) Information Using BGP", RFC 7752, 1294 DOI 10.17487/RFC7752, March 2016, 1295 . 1297 [RFC7794] Ginsberg, L., Ed., Decraene, B., Previdi, S., Xu, X., and 1298 U. Chunduri, "IS-IS Prefix Attributes for Extended IPv4 1299 and IPv6 Reachability", RFC 7794, DOI 10.17487/RFC7794, 1300 March 2016, . 1302 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 1303 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 1304 May 2017, . 1306 [RFC8362] Lindem, A., Roy, A., Goethals, D., Reddy Vallem, V., and 1307 F. Baker, "OSPFv3 Link State Advertisement (LSA) 1308 Extensibility", RFC 8362, DOI 10.17487/RFC8362, April 1309 2018, . 1311 [RFC8402] Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L., 1312 Decraene, B., Litkowski, S., and R. Shakir, "Segment 1313 Routing Architecture", RFC 8402, DOI 10.17487/RFC8402, 1314 July 2018, . 1316 [RFC8571] Ginsberg, L., Ed., Previdi, S., Wu, Q., Tantsura, J., and 1317 C. Filsfils, "BGP - Link State (BGP-LS) Advertisement of 1318 IGP Traffic Engineering Performance Metric Extensions", 1319 RFC 8571, DOI 10.17487/RFC8571, March 2019, 1320 . 1322 8.2. Informative References 1324 [I-D.ietf-isis-sr-yang] 1325 Litkowski, S., Qu, Y., Sarkar, P., Chen, I., and J. 1326 Tantsura, "YANG Data Model for IS-IS Segment Routing", 1327 draft-ietf-isis-sr-yang-05 (work in progress), March 2019. 1329 [I-D.ietf-ospf-sr-yang] 1330 Yeung, D., Qu, Y., Zhang, Z., Chen, I., and A. Lindem, 1331 "YANG Data Model for OSPF SR (Segment Routing) Protocol", 1332 draft-ietf-ospf-sr-yang-07 (work in progress), March 2019. 1334 [I-D.ietf-spring-segment-routing-ldp-interop] 1335 Bashandy, A., Filsfils, C., Previdi, S., Decraene, B., and 1336 S. Litkowski, "Segment Routing interworking with LDP", 1337 draft-ietf-spring-segment-routing-ldp-interop-15 (work in 1338 progress), September 2018. 1340 [I-D.ietf-spring-sr-yang] 1341 Litkowski, S., Qu, Y., Lindem, A., Sarkar, P., and J. 1342 Tantsura, "YANG Data Model for Segment Routing", draft- 1343 ietf-spring-sr-yang-12 (work in progress), February 2019. 1345 [RFC5706] Harrington, D., "Guidelines for Considering Operations and 1346 Management of New Protocols and Protocol Extensions", 1347 RFC 5706, DOI 10.17487/RFC5706, November 2009, 1348 . 1350 Authors' Addresses 1352 Stefano Previdi 1353 Huawei Technologies 1354 Rome 1355 Italy 1357 Email: stefano@previdi.net 1359 Ketan Talaulikar (editor) 1360 Cisco Systems, Inc. 1361 India 1363 Email: ketant@cisco.com 1364 Clarence Filsfils 1365 Cisco Systems, Inc. 1366 Brussels 1367 Belgium 1369 Email: cfilsfil@cisco.com 1371 Hannes Gredler 1372 RtBrick Inc. 1374 Email: hannes@rtbrick.com 1376 Mach(Guoyi) Chen 1377 Huawei Technologies 1378 Huawei Building, No. 156 Beiqing Rd. 1379 Beijing 100095 1380 China 1382 Email: mach.chen@huawei.com