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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Inter-Domain Routing S. Previdi, Ed. 3 Internet-Draft P. Psenak 4 Intended status: Standards Track C. Filsfils 5 Expires: May 3, 2017 Cisco Systems, Inc. 6 H. Gredler 7 RtBrick Inc. 8 M. Chen 9 Huawei Technologies 10 J. Tantsura 11 Individual 12 October 30, 2016 14 BGP Link-State extensions for Segment Routing 15 draft-gredler-idr-bgp-ls-segment-routing-ext-04 17 Abstract 19 Segment Routing (SR) allows for a flexible definition of end-to-end 20 paths within IGP topologies by encoding paths as sequences of 21 topological sub-paths, called "segments". These segments are 22 advertised by the link-state routing protocols (IS-IS, OSPF and 23 OSPFv3). 25 This draft defines extensions to the BGP Link-state address-family in 26 order to carry segment information via BGP. 28 Requirements Language 30 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 31 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 32 document are to be interpreted as described in RFC 2119 [RFC2119]. 34 Status of This Memo 36 This Internet-Draft is submitted in full conformance with the 37 provisions of BCP 78 and BCP 79. 39 Internet-Drafts are working documents of the Internet Engineering 40 Task Force (IETF). Note that other groups may also distribute 41 working documents as Internet-Drafts. The list of current Internet- 42 Drafts is at http://datatracker.ietf.org/drafts/current/. 44 Internet-Drafts are draft documents valid for a maximum of six months 45 and may be updated, replaced, or obsoleted by other documents at any 46 time. It is inappropriate to use Internet-Drafts as reference 47 material or to cite them other than as "work in progress." 48 This Internet-Draft will expire on May 3, 2017. 50 Copyright Notice 52 Copyright (c) 2016 IETF Trust and the persons identified as the 53 document authors. All rights reserved. 55 This document is subject to BCP 78 and the IETF Trust's Legal 56 Provisions Relating to IETF Documents 57 (http://trustee.ietf.org/license-info) in effect on the date of 58 publication of this document. Please review these documents 59 carefully, as they describe your rights and restrictions with respect 60 to this document. Code Components extracted from this document must 61 include Simplified BSD License text as described in Section 4.e of 62 the Trust Legal Provisions and are provided without warranty as 63 described in the Simplified BSD License. 65 Table of Contents 67 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 68 2. BGP-LS Extensions for Segment Routing . . . . . . . . . . . . 5 69 2.1. Node Attributes TLVs . . . . . . . . . . . . . . . . . . 5 70 2.1.1. SR-Capabilities TLV . . . . . . . . . . . . . . . . . 5 71 2.1.2. SR-Algorithm TLV . . . . . . . . . . . . . . . . . . 6 72 2.1.3. SR Local Block TLV . . . . . . . . . . . . . . . . . 7 73 2.1.4. SRMS Preference TLV . . . . . . . . . . . . . . . . . 7 74 2.2. Link Attribute TLVs . . . . . . . . . . . . . . . . . . . 8 75 2.2.1. Adjacency SID TLV . . . . . . . . . . . . . . . . . . 9 76 2.2.2. LAN Adjacency SID TLV . . . . . . . . . . . . . . . . 9 77 2.3. Prefix Attribute TLVs . . . . . . . . . . . . . . . . . . 10 78 2.3.1. Prefix-SID TLV . . . . . . . . . . . . . . . . . . . 11 79 2.3.2. IPv6 Prefix-SID TLV . . . . . . . . . . . . . . . . . 12 80 2.3.3. IGP Prefix Attributes TLV . . . . . . . . . . . . . . 13 81 2.3.4. Source Router Identifier (Source Router-ID) TLV . . . 14 82 2.3.5. Range TLV . . . . . . . . . . . . . . . . . . . . . . 14 83 2.3.6. Binding SID TLV . . . . . . . . . . . . . . . . . . . 15 84 2.3.7. Binding SID SubTLVs . . . . . . . . . . . . . . . . . 16 85 2.4. Equivalent IS-IS Segment Routing TLVs/Sub-TLVs . . . . . 22 86 2.5. Equivalent OSPF/OSPFv3 Segment Routing TLVs/Sub-TLVs . . 23 87 3. Procedures . . . . . . . . . . . . . . . . . . . . . . . . . 25 88 3.1. Advertisement of a IS-IS Prefix SID TLV . . . . . . . . . 25 89 3.2. Advertisement of a OSPF/OSPFv3 Prefix-SID TLV . . . . . . 25 90 3.3. Advertisement of a range of prefix-to-SID mappings in 91 OSPF . . . . . . . . . . . . . . . . . . . . . . . . . . 26 92 3.4. Advertisement of a range of IS-IS SR bindings . . . . . . 26 93 3.5. Advertisement of a path and its attributes from IS-IS 94 protocol . . . . . . . . . . . . . . . . . . . . . . . . 26 95 3.6. Advertisement of a path and its attributes from 96 OSPFv2/OSPFv3 protocol . . . . . . . . . . . . . . . . . 27 97 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 27 98 4.1. TLV/Sub-TLV Code Points Summary . . . . . . . . . . . . . 27 99 5. Manageability Considerations . . . . . . . . . . . . . . . . 28 100 5.1. Operational Considerations . . . . . . . . . . . . . . . 28 101 5.1.1. Operations . . . . . . . . . . . . . . . . . . . . . 28 102 6. Security Considerations . . . . . . . . . . . . . . . . . . . 29 103 7. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 29 104 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 29 105 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 29 106 9.1. Normative References . . . . . . . . . . . . . . . . . . 29 107 9.2. Informative References . . . . . . . . . . . . . . . . . 30 108 9.3. URIs . . . . . . . . . . . . . . . . . . . . . . . . . . 31 109 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 34 111 1. Introduction 113 Segment Routing (SR) allows for a flexible definition of end-to-end 114 paths by combining sub-paths called "segments". A segment can 115 represent any instruction, topological or service-based. A segment 116 can have a local semantic to an SR node or global within a domain. 117 Within IGP topologies an SR path is encoded as a sequence of 118 topological sub-paths, called "IGP segments". These segments are 119 advertised by the link-state routing protocols (IS-IS, OSPF and 120 OSPFv3). 122 Two types of IGP segments are defined, Prefix segments and Adjacency 123 segments. Prefix segments, by default, represent an ECMP-aware 124 shortest-path to a prefix, as per the state of the IGP topology. 125 Adjacency segments represent a hop over a specific adjacency between 126 two nodes in the IGP. A prefix segment is typically a multi-hop path 127 while an adjacency segment, in most of the cases, is a one-hop path. 128 [I-D.ietf-spring-segment-routing]. 130 When Segment Routing is enabled in a IGP domain, segments are 131 advertised in the form of Segment Identifiers (SIDs). The IGP link- 132 state routing protocols have been extended to advertise SIDs and 133 other SR-related information. IGP extensions are described in: IS-IS 134 [I-D.ietf-isis-segment-routing-extensions], OSPFv2 135 [I-D.ietf-ospf-segment-routing-extensions] and OSPFv3 136 [I-D.ietf-ospf-ospfv3-segment-routing-extensions]. Using these 137 extensions, Segment Routing can be enabled within an IGP domain. 139 +------------+ 140 | Consumer | 141 +------------+ 142 ^ 143 | 144 v 145 +-------------------+ 146 | BGP Speaker | +-----------+ 147 | (Route-Reflector) | | Consumer | 148 +-------------------+ +-----------+ 149 ^ ^ ^ ^ 150 | | | | 151 +---------------+ | +-------------------+ | 152 | | | | 153 v v v v 154 +-----------+ +-----------+ +-----------+ 155 | BGP | | BGP | | BGP | 156 | Speaker | | Speaker | . . . | Speaker | 157 +-----------+ +-----------+ +-----------+ 158 ^ ^ ^ 159 | | | 160 IGP IGP IGP 162 Figure 1: Link State info collection 164 Segment Routing (SR) allows advertisement of single or multi-hop 165 paths. The flooding scope for the IGP extensions for Segment routing 166 is IGP area-wide. Consequently, the contents of a Link State 167 Database (LSDB) or a Traffic Engineering Database (TED) has the scope 168 of an IGP area and therefore, by using the IGP alone it is not enough 169 to construct segments across multiple IGP Area or AS boundaries. 171 In order to address the need for applications that require 172 topological visibility across IGP areas, or even across Autonomous 173 Systems (AS), the BGP-LS address-family/sub-address-family have been 174 defined to allow BGP to carry Link-State information. The BGP 175 Network Layer Reachability Information (NLRI) encoding format for 176 BGP-LS and a new BGP Path Attribute called the BGP-LS attribute are 177 defined in [RFC7752]. The identifying key of each Link-State object, 178 namely a node, link, or prefix, is encoded in the NLRI and the 179 properties of the object are encoded in the BGP-LS attribute. 180 Figure Figure 1 describes a typical deployment scenario. In each IGP 181 area, one or more nodes are configured with BGP-LS. These BGP 182 speakers form an IBGP mesh by connecting to one or more route- 183 reflectors. This way, all BGP speakers (specifically the route- 184 reflectors) obtain Link-State information from all IGP areas (and 185 from other ASes from EBGP peers). An external component connects to 186 the route-reflector to obtain this information (perhaps moderated by 187 a policy regarding what information is or isn't advertised to the 188 external component). 190 This document describes extensions to BGP-LS to advertise the SR 191 information. An external component (e.g., a controller) then can 192 collect SR information in the "northbound" direction across IGP areas 193 or ASes and construct the end-to-end path (with its associated SIDs) 194 that need to be applied to an incoming packet to achieve the desired 195 end-to-end forwarding. 197 2. BGP-LS Extensions for Segment Routing 199 This document defines IGP SR extensions BGP-LS TLVs and Sub-TLVs. 200 Section 2.4 and Section 2.5 illustrates the equivalent TLVs and Sub- 201 TLVs in IS-IS, OSPF and OSPFv3 protocols. 203 BGP-LS [RFC7752] defines the BGP-LS NLRI that can be a Node NLRI, a 204 Link NLRI or a Prefix NLRI. The corresponding BGP-LS attribute is a 205 Node Attribute, a Link Attribute or a Prefix Attribute. BGP-LS 206 [RFC7752] defines the TLVs that map link-state information to BGP-LS 207 NLRI and the BGP-LS attribute. This document adds additional BGP-LS 208 attribute TLVs in order to encode SR information. 210 2.1. Node Attributes TLVs 212 The following Node Attribute TLVs are defined: 214 +----------------+-----------------+----------+---------------+ 215 | TLV Code Point | Description | Length | Section | 216 +----------------+-----------------+----------+---------------+ 217 | 1034 | SR Capabilities | variable | Section 2.1.1 | 218 | 1035 | SR Algorithm | variable | Section 2.1.2 | 219 | 1036 | SR Local Block | variable | Section 2.1.3 | 220 | 1037 | SRMS Preference | variable | Section 2.1.4 | 221 +----------------+-----------------+----------+---------------+ 223 Table 1: Node Attribute TLVs 225 These TLVs can ONLY be added to the Node Attribute associated with 226 the Node NLRI that originates the corresponding SR TLV. 228 2.1.1. SR-Capabilities TLV 230 The SR Capabilities sub-TLV has following format: 232 0 1 2 3 233 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 1 234 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 235 | Type | Length | 236 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 237 | Flags | RESERVED | 238 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 240 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 241 | Range Size | 242 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 243 // SID/Label Sub-TLV (variable) // 244 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 246 Type: TBD, suggested value 1034. 248 Length: Variable. 250 Flags: 1 octet of flags as defined in 251 [I-D.ietf-isis-segment-routing-extensions] and 252 [I-D.ietf-ospf-ospfv3-segment-routing-extensions]. 254 One or more entries, each of which have the following format: 256 Range Size: 3 octet value indicating the number of labels in 257 the range. 259 SID/Label sub-TLV (as defined in Section 2.3.7.2). 261 2.1.2. SR-Algorithm TLV 263 The SR-Algorithm TLV has the following format: 265 0 1 2 3 266 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 1 267 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 268 | Type | Length | 269 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 270 | Algorithm 1 | Algorithm... | Algorithm N | | 271 +- -+ 272 | | 273 + + 275 where: 277 Type: TBD, suggested value 1035. 279 Length: Variable. 281 Algorithm: 1 octet identifying the algorithm. 283 2.1.3. SR Local Block TLV 285 The SR Local Block (SRLB) Sub-TLV contains the range of labels the 286 node has reserved for local SIDs. Local SIDs are used, e.g., in IGP 287 (IS-IS, OSPF) for Adjacency-SIDs, and may also be allocated by other 288 components than IGP protocols. As an example, an application or a 289 controller may instruct a node to allocate a specific local SID. 290 Therefore, in order for such applications or controllers to know the 291 range of local SIDs available, it is required that the node 292 advertises its SRLB. 294 The SRLB TLV has the following format: 296 0 1 2 3 297 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 1 298 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 299 | Type | Length | 300 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 301 | Flags | RESERVED | 302 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 304 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 305 | Range Size | 306 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 307 // SID/Label Sub-TLV (variable) // 308 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 310 Type: TBD, suggested value 1036. 312 Length: Variable. 314 Flags: 1 octet of flags. None are defined at this stage. 316 One or more entries, each of which have the following format: 318 Range Size: 3 octet value indicating the number of labels in 319 the range. 321 SID/Label sub-TLV (as defined in Section 2.3.7.2). 323 2.1.4. SRMS Preference TLV 325 The Segment Routing Mapping Server (SRMS) Preference sub-TLV is used 326 in order to associate a preference with SRMS advertisements from a 327 particular source. 329 The SRMS Preference sub-TLV has 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 | Preference | 335 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 337 Type: TBD, suggested value 1037. 339 Length: 1. 341 Preference: 1 octet. Unsigned 8 bit SRMS preference. 343 The use of the SRMS Preference TLV is defined in 344 [I-D.ietf-isis-segment-routing-extensions]. 346 2.2. Link Attribute TLVs 348 The following Link Attribute TLVs are are defined: 350 +-----------+----------------------------+----------+---------------+ 351 | TLV Code | Description | Length | Section | 352 | Point | | | | 353 +-----------+----------------------------+----------+---------------+ 354 | 1099 | Adjacency Segment | variable | Section 2.2.1 | 355 | | Identifier (Adj-SID) TLV | | | 356 | 1100 | LAN Adjacency Segment | variable | Section 2.2.2 | 357 | | Identifier (Adj-SID) TLV | | | 358 +-----------+----------------------------+----------+---------------+ 360 Table 2: Link Attribute TLVs 362 These TLVs can ONLY be added to the Link Attribute associated with 363 the link whose local node originates the corresponding TLV. 365 For a LAN, normally a node only announces its adjacency to the IS-IS 366 pseudo-node (or the equivalent OSPF Designated and Backup Designated 367 Routers)[I-D.ietf-isis-segment-routing-extensions]. The LAN 368 Adjecency Segment TLV allows a node to announce adjacencies to all 369 other nodes attached to the LAN in a single instance of the BGP-LS 370 Link NLRI. Without this TLV, the corresponding BGP-LS link NLRI 371 would need to be originated for each additional adjacency in order to 372 advertise the SR TLVs for these neighbor adjacencies. 374 2.2.1. Adjacency SID TLV 376 The Adjacency SID (Adj-SID) TLV has the following format: 378 0 1 2 3 379 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 1 380 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 381 | Type | Length | 382 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 383 | Flags | Weight | Reserved | 384 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 385 | SID/Label/Index (variable) | 386 +---------------------------------------------------------------+ 388 where: 390 Type: TBD, suggested value 1099. 392 Length: Variable. 394 Flags. 1 octet field of following flags as defined in 395 [I-D.ietf-isis-segment-routing-extensions], 396 [I-D.ietf-ospf-segment-routing-extensions] and 397 [I-D.ietf-ospf-ospfv3-segment-routing-extensions]. 399 Weight: Weight used for load-balancing purposes. 401 SID/Index/Label: Label or index value depending on the flags 402 setting as defined in [I-D.ietf-isis-segment-routing-extensions], 403 [I-D.ietf-ospf-segment-routing-extensions] and 404 [I-D.ietf-ospf-ospfv3-segment-routing-extensions]. 406 2.2.2. LAN Adjacency SID TLV 408 The LAN Adjacency SID (LAN-Adj-SID-SID) has the following format: 410 0 1 2 3 411 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 1 412 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 413 | Type | Length | 414 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 415 | Flags | Weight | Reserved | 416 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 418 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 419 | OSPF Neighbor ID / IS-IS System-ID | 420 + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 421 | | 422 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 424 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 425 | SID/Label/Index (variable) | 426 +---------------------------------------------------------------+ 428 where: 430 Type: TBD, suggested value 1100. 432 Length: Variable. 434 Flags. 1 octet field of following flags as defined in 435 [I-D.ietf-isis-segment-routing-extensions], 436 [I-D.ietf-ospf-segment-routing-extensions] and 437 [I-D.ietf-ospf-ospfv3-segment-routing-extensions]. 439 Weight: Weight used for load-balancing purposes. 441 SID/Index/Label: Label or index value depending on the flags 442 setting as defined in [I-D.ietf-isis-segment-routing-extensions], 443 [I-D.ietf-ospf-segment-routing-extensions] and 444 [I-D.ietf-ospf-ospfv3-segment-routing-extensions]. 446 2.3. Prefix Attribute TLVs 448 The following Prefix Attribute TLVs and Sub-TLVs are defined: 450 +----------------+-----------------------+----------+---------------+ 451 | TLV Code Point | Description | Length | Section | 452 +----------------+-----------------------+----------+---------------+ 453 | 1158 | Prefix SID | variable | Section 2.3.1 | 454 | 1159 | Range | variable | Section 2.3.5 | 455 | 1160 | Binding SID | variable | Section 2.3.6 | 456 | 1169 | IPv6 Prefix SID | variable | Section 2.3.2 | 457 | 1170 | IGP Prefix Attributes | variable | Section 2.3.3 | 458 | 1171 | Source Router-ID | variable | Section 2.3.4 | 459 +----------------+-----------------------+----------+---------------+ 461 Table 3: Prefix Attribute TLVs 463 +------------+-------------------------+----------+-----------------+ 464 | TLV Code | Description | Length | Section | 465 | Point | | | | 466 +------------+-------------------------+----------+-----------------+ 467 | 1161 | SID/Label TLV | variable | Section 2.3.7.2 | 468 | 1162 | ERO Metric TLV | 4 octets | Section 2.3.7.3 | 469 | 1163 | IPv4 ERO TLV | 8 octets | Section 2.3.7.4 | 470 | 1164 | IPv6 ERO TLV | 20 | Section 2.3.7.5 | 471 | | | octets | | 472 | 1165 | Unnumbered Interface ID | 12 | Section 2.3.7.6 | 473 | | ERO TLV | | | 474 | 1166 | IPv4 Backup ERO TLV | 8 octets | Section 2.3.7.7 | 475 | 1167 | IPv6 Backup ERO TLV | 10 | Section 2.3.7.8 | 476 | | | octets | | 477 | 1168 | Unnumbered Interface ID | 12 | Section 2.3.7.9 | 478 | | Backup ERO TLV | | | 479 +------------+-------------------------+----------+-----------------+ 481 Table 4: Prefix Attribute - Binding SID Sub-TLVs 483 2.3.1. Prefix-SID TLV 485 The Prefix-SID TLV can ONLY be added to the Prefix Attribute whose 486 local node in the corresponding Prefix NLRI is the node that 487 originates the corresponding SR TLV. 489 The Prefix-SID has the following format: 491 0 1 2 3 492 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 1 493 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 494 | Type | Length | 495 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 496 | Flags | Algorithm | Reserved | 497 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 498 | SID/Index/Label (variable) | 499 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 501 where: 503 Type: TBD, suggested value 1158. 505 Length: Variable 507 Algorithm: 1 octet value identify the algorithm. 509 SID/Index/Label: Label or index value depending on the flags 510 setting as defined in [I-D.ietf-isis-segment-routing-extensions], 511 [I-D.ietf-ospf-segment-routing-extensions] and 512 [I-D.ietf-ospf-ospfv3-segment-routing-extensions]. 514 The Prefix-SID TLV includes a Flags field. In the context of BGP-LS, 515 the Flags field format and the semantic of each individual flag MUST 516 be taken from the corresponding source protocol (i.e.: the protocol 517 of origin of the Prefix-SID being advertised in BGP-LS). 519 IS-IS Prefix-SID flags are defined in 520 [I-D.ietf-isis-segment-routing-extensions] section 2.1. 522 OSPF Prefix-SID flags are defined in 523 [I-D.ietf-ospf-segment-routing-extensions] section 5. 525 OSPFv3 Prefix-SID flags are defined in 526 [I-D.ietf-ospf-segment-routing-extensions] section 5. 528 2.3.2. IPv6 Prefix-SID TLV 530 The IPv6 Prefix-SID TLV can ONLY be added to the Prefix Attribute 531 whose local node in the corresponding Prefix NLRI is the node that 532 originates the corresponding SR TLV. 534 The IPv6 Prefix-SID has the following format: 536 0 1 2 3 537 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 1 538 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 539 | Type | Length | 540 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 541 | Flags | Algorithm | // 542 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ // 543 // Sub-TLVs // 544 // // 545 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 547 where: 549 Type: TBD, suggested value 1169. 551 Length: 3 + length of Sub-TLVs. 553 Flags: 2 octet field of flags. None of them is defined at this 554 stage. 556 Algorithm: 1 octet value identify the algorithm as defined in 557 [I-D.previdi-isis-ipv6-prefix-sid]. 559 Sub-TLVs: additional information encoded into the IPv6 Prefix-SID 560 Sub-TLV as defined in [I-D.previdi-isis-ipv6-prefix-sid]. 562 The IPv6 Prefix-SID TLV is defined in 563 [I-D.previdi-isis-ipv6-prefix-sid]. 565 2.3.3. IGP Prefix Attributes TLV 567 The IGP Prefix Attribute TLV carries IPv4/IPv6 prefix attribute flags 568 as defined in [RFC7684] and [RFC7794]. 570 The IGP Prefix Attribute TLV has the following format: 572 0 1 2 3 573 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 1 574 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 575 | Type | Length | 576 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 577 // Flags (variable) // 578 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 580 where: 582 Type: TBD, suggested value 1170. 584 Length: variable. 586 Flags: a variable length flag field (according to the length 587 field). Flags are routing protocol specific (OSPF and IS-IS). 588 OSPF flags are defined in [RFC7684] and IS-IS flags are defined in 589 [RFC7794]. The receiver of the BGP-LS update, when inspecting the 590 IGP Prefix Attribute TLV, MUST check the Protocol-ID of the NLRI 591 and refer to the protocol specification in order to parse the 592 flags. 594 2.3.4. Source Router Identifier (Source Router-ID) TLV 596 The Source Router-ID TLV contains the IPv4 or IPv6 Router-ID of the 597 originator as defined in [RFC7794]. While defined in the IS-IS 598 protocol, the Source Router-ID TLV may be used to carry the OSPF 599 Router-ID of the prefix originator. 601 The Source Router-ID TLV has the following format: 603 0 1 2 3 604 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 1 605 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 606 | Type | Length | 607 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 608 // IPv4/IPv6 Address (Router-ID) // 609 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 611 where: 613 Type: TBD, suggested value 1171. 615 Length: 4 or 16. 617 IPv4/IPv6 Address: 4 octet IPv4 address or 16 octet IPv6 address. 619 The semantic of the Source Router-ID TLV is defined in [RFC7794]. 621 2.3.5. Range TLV 623 The Range TLV can ONLY be added to the Prefix Attribute whose local 624 node in the corresponding Prefix NLRI is the node that originates the 625 corresponding SR TLV. 627 When the range TLV is used in order to advertise a path to a prefix 628 or a range of prefix-to-SID mappings, the Prefix-NLRI the Range TLV 629 is attached to MUST be advertised as a non-routing prefix where no 630 IGP metric TLV (TLV 1095) is attached. 632 The format of the Range TLV is as follows: 634 0 1 2 3 635 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 1 636 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 637 | Type | Length | 638 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 639 | Flags | RESERVED | Range Size | 640 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 641 // Sub-TLVs // 642 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 644 where: 646 Figure 2: Range TLV format 648 Type: 1159 650 Length is 4. 652 Flags: Only used when the source protocol is OSPF and defined in 653 [I-D.ietf-ospf-segment-routing-extensions] section 4 and 654 [I-D.ietf-ospf-ospfv3-segment-routing-extensions] section 4. 656 Range Size: 2 octets as defined in 657 [I-D.ietf-ospf-segment-routing-extensions] section 4. 659 Within the Range TLV, the following SubTLVs are may be present: 661 Binding SID TLV, defined in Section 2.3.6 663 Prefix-SID TLV, defined in Section 2.3.1 665 SID/Label TLV, defined in Section 2.3.7.2 667 2.3.6. Binding SID TLV 669 The Binding SID TLV can be used in two ways: 671 o as a sub-TLV of the Range TLV 673 o as a Prefix Attribute TLV 675 The format of the Binding SID TLV is as follows: 677 0 1 2 3 678 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 1 679 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 680 | Type | Length | 681 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 682 | Weight | Flags | RESERVED | 683 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 684 // SubTLVs (variable) // 685 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 687 where: 689 Figure 3: Binding SID Sub-TLV format 691 Type is 1160 693 Length is variable 695 Weight and Flags are mapped to Weight and Flags defined in 696 [I-D.ietf-isis-segment-routing-extensions] section 2.4, 697 [I-D.ietf-ospf-segment-routing-extensions] section 4 and 698 [I-D.ietf-ospf-ospfv3-segment-routing-extensions] section 4. 700 Sub-TLVs are defined in the following sections. 702 2.3.7. Binding SID SubTLVs 704 This section defines the Binding SID Sub-TLVs in BGP-LS to encode the 705 equivalent Sub-TLVs defined in 706 [I-D.ietf-isis-segment-routing-extensions], 707 [I-D.ietf-ospf-segment-routing-extensions] and 708 [I-D.ietf-ospf-ospfv3-segment-routing-extensions]. 710 All ERO (Explicit Route Object) Sub-TLVs must immediately follow the 711 (SID)/Label Sub-TLV. 713 All Backup ERO Sub-TLVs must immediately follow the last ERO Sub-TLV. 715 2.3.7.1. Binding SID Prefix-SID Sub-TLV 717 When encoding IS-IS Mapping Server entries as defined in 718 [I-D.ietf-isis-segment-routing-extensions] the Prefix-SID TLV defined 719 in Section 2.3.1 is used as Sub-TLV in the Binding TLV. 721 2.3.7.2. SID/Label Sub-TLV 723 The SID/Label TLV has following format: 725 0 1 2 3 726 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 1 727 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 728 | Type | Length | 729 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 730 | SID/Label (variable) | 731 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 733 where: 735 Type: TBD, suggested value 1161. 737 Length: Variable, 3 or 4 bytes 739 SID/Label: If length is set to 3, then the 20 rightmost bits 740 represent a label. If length is set to 4, then the value 741 represents a 32 bit SID. 743 The receiving router MUST ignore the SID/Label Sub-TLV if the 744 length is other then 3 or 4. 746 2.3.7.3. ERO Metric Sub-TLV 748 The ERO Metric Sub-TLV has following format: 750 0 1 2 3 751 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 1 752 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 753 | Type | Length | 754 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 755 | Metric (4 octets) | 756 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 758 ERO Metric Sub-TLV format 760 where: 762 Type: TBD, suggested value 1162. 764 Length: Always 4 766 Metric: A 4 octet metric representing the aggregate IGP or TE path 767 cost. 769 2.3.7.4. IPv4 ERO Sub-TLV 771 The ERO Sub-TLV has following format: 773 0 1 2 3 774 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 1 775 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 776 | Type | Length | 777 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 778 | Flags | Reserved | 779 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 780 | IPv4 Address (4 octets) | 781 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 783 IPv4 ERO Sub-TLV format 785 where: 787 Type: TBD, suggested value 1163 789 Length: 8 octets 791 Flags: 1 octet of flags as defined in: 792 [I-D.ietf-isis-segment-routing-extensions], 793 [I-D.ietf-ospf-segment-routing-extensions] and 794 [I-D.ietf-ospf-ospfv3-segment-routing-extensions]. 796 IPv4 Address - the address of the explicit route hop. 798 2.3.7.5. IPv6 ERO Sub-TLV 800 The IPv6 ERO Sub-TLV has following format: 802 0 1 2 3 803 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 1 804 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 805 | Type | Length | 806 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 807 | Flags | Reserved | 808 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 809 | | 810 +- -+ 811 | | 812 +- IPv6 Address -+ 813 | | 814 +- -+ 815 | | 816 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 818 IPv6 ERO Sub-TLV format 820 where: 822 Type: TBD, suggested value 1164 824 Length: 20 octets 826 Flags: 1 octet of flags as defined in: 827 [I-D.ietf-isis-segment-routing-extensions], 828 [I-D.ietf-ospf-segment-routing-extensions] and 829 [I-D.ietf-ospf-ospfv3-segment-routing-extensions]. 831 IPv6 Address - the address of the explicit route hop. 833 2.3.7.6. Unnumbered Interface ID ERO Sub-TLV 835 The Unnumbered Interface-ID ERO Sub-TLV has following format: 837 0 1 2 3 838 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 1 839 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 840 | Type | Length | 841 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 842 | Flags | Reserved | 843 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 844 // Router ID (IPv4, 4 octet or IPv6, 16 octets) // 845 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 846 | Interface ID | 847 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 849 where: 851 Unnumbered Interface ID ERO Sub-TLV format 853 Type: TBD, suggested value 1165. 855 Length: Variable (12 for IPv4 Router-ID or 24 for IPv6 Router-ID). 857 Flags: 1 octet of flags as defined in: 858 [I-D.ietf-isis-segment-routing-extensions], 859 [I-D.ietf-ospf-segment-routing-extensions] and 860 [I-D.ietf-ospf-ospfv3-segment-routing-extensions]. 862 Router-ID: Router-ID of the next-hop. 864 Interface ID: is the identifier assigned to the link by the router 865 specified by the Router-ID. 867 2.3.7.7. IPv4 Backup ERO Sub-TLV 869 The IPv4 Backup ERO Sub-TLV has following format: 871 0 1 2 3 872 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 1 873 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 874 | Type | Length | 875 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 876 | Flags | Reserved | 877 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 878 | IPv4 Address (4 octets) | 879 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 881 IPv4 Backup ERO Sub-TLV format 883 where: 885 Type: TBD, suggested value 1166. 887 Length: 8 octets 889 Flags: 1 octet of flags as defined in: 890 [I-D.ietf-isis-segment-routing-extensions], 891 [I-D.ietf-ospf-segment-routing-extensions] and 892 [I-D.ietf-ospf-ospfv3-segment-routing-extensions]. 894 IPv4 Address: Address of the explicit route hop. 896 2.3.7.8. IPv6 Backup ERO Sub-TLV 898 The IPv6 Backup ERO Sub-TLV has following format: 900 0 1 2 3 901 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 1 902 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 903 | Type | Length | 904 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 905 | Flags | Reserved | 906 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 907 | | 908 +- -+ 909 | | 910 +- IPv6 Address -+ 911 | | 912 +- -+ 913 | | 914 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 916 IPv6 Backup ERO Sub-TLV format 918 where: 920 Type: TBD, suggested value 1167. 922 Length: 8 octets 924 Flags: 1 octet of flags as defined in: 925 [I-D.ietf-isis-segment-routing-extensions], 926 [I-D.ietf-ospf-segment-routing-extensions] and 927 [I-D.ietf-ospf-ospfv3-segment-routing-extensions]. 929 IPv6 Address: Address of the explicit route hop. 931 2.3.7.9. Unnumbered Interface ID Backup ERO Sub-TLV 933 The Unnumbered Interface-ID Backup ERO Sub-TLV has following format: 935 0 1 2 3 936 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 1 937 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 938 | Type | Length | 939 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 940 | Flags | Reserved | 941 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 942 // Router ID (IPv4, 4 octet or IPv6, 16 octets) // 943 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 944 | Interface ID | 945 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 947 Unnumbered Interface ID Backup ERO Sub-TLV format 949 where: 951 Type: TBD, suggested value 1168. 953 Length: Variable (12 for IPv4 Router-ID or 24 for IPv6 Router-ID). 955 Flags: 1 octet of flags as defined in: 956 [I-D.ietf-isis-segment-routing-extensions], 957 [I-D.ietf-ospf-segment-routing-extensions] and 958 [I-D.ietf-ospf-ospfv3-segment-routing-extensions]. 960 Router-ID: Router-ID of the next-hop. 962 Interface ID: Identifier assigned to the link by the router 963 specified by the Router-ID. 965 2.4. Equivalent IS-IS Segment Routing TLVs/Sub-TLVs 967 This section illustrate the IS-IS Segment Routing Extensions TLVs and 968 Sub-TLVs mapped to the ones defined in this document. 970 The following table, illustrates for each BGP-LS TLV, its equivalence 971 in IS-IS. 973 +-----------+------------------------------+----------+-------------+ 974 | TLV Code | Description | Length | IS-IS TLV | 975 | Point | | | /Sub-TLV | 976 +-----------+------------------------------+----------+-------------+ 977 | 1034 | SR Capabilities | variable | 2 [1] | 978 | 1035 | SR Algorithm | variable | 19 [2] | 979 | 1099 | Adjacency Segment Identifier | variable | 31 [3] | 980 | | (Adj-SID) TLV | | | 981 | 1100 | LAN Adjacency Segment | variable | 32 [4] | 982 | | Identifier (LAN-Adj-SID) TLV | | | 983 | 1158 | Prefix SID | variable | 3 [5] | 984 | 1160 | Binding SID | variable | 149 [6] | 985 | 1161 | SID/Label TLV | variable | 1 [7] | 986 | 1162 | ERO Metric TLV | 4 octets | 10 [8] | 987 | 1163 | IPv4 ERO TLV | 5 octets | 11 [9] | 988 | 1164 | IPv6 ERO TLV | 17 | 12 [10] | 989 | | | octets | | 990 | 1165 | Unnumbered Interface ID ERO | variable | 13 [11] | 991 | | TLV | | | 992 | 1166 | IPv4 Backup ERO TLV | 5 octets | 14 [12] | 993 | 1167 | IPv6 Backup ERO TLV | 17 | 15 [13] | 994 | | | octets | | 995 | 1168 | Unnumbered Interface ID | variable | 16 [14] | 996 | | Backup ERO TLV | | | 997 | 1169 | IPv6 Prefix SID | variable | 5 [15] | 998 | 1170 | IGP Prefix Attributes | variable | 4 [16] | 999 | 1171 | Source Router ID | variable | 11/12 [17] | 1000 +-----------+------------------------------+----------+-------------+ 1002 Table 5: IS-IS Segment Routing Extensions TLVs/Sub-TLVs 1004 2.5. Equivalent OSPF/OSPFv3 Segment Routing TLVs/Sub-TLVs 1006 This section illustrate the OSPF and OSPFv3 Segment Routing 1007 Extensions TLVs and Sub-TLVs mapped to the ones defined in this 1008 document. 1010 The following table, illustrates for each BGP-LS TLV, its equivalence 1011 in OSPF and OSPFv3. 1013 +------------+-----------------------------+----------+-------------+ 1014 | TLV Code | Description | Length | OSPF TLV | 1015 | Point | | | /Sub-TLV | 1016 +------------+-----------------------------+----------+-------------+ 1017 | 1034 | SR Capabilities | variable | 9 [18] | 1018 | 1035 | SR Algorithm | variable | 8 [19] | 1019 | 1099 | Adjacency Segment | variable | 2 [20] | 1020 | | Identifier (Adj-SID) TLV | | | 1021 | 1100 | LAN Adjacency Segment | variable | 3 [21] | 1022 | | Identifier (Adj-SID) TLV | | | 1023 | 1158 | Prefix SID | variable | 2 [22] | 1024 | 1161 | SID/Label TLV | variable | 1 [23] | 1025 | 1162 | ERO Metric TLV | 4 octets | 8 [24] | 1026 | 1163 | IPv4 ERO TLV | 8 octets | 4 [25] | 1027 | 1165 | Unnumbered Interface ID ERO | 12 | 5 [26] | 1028 | | TLV | octets | | 1029 | 1166 | IPv4 Backup ERO TLV | 8 octets | 6 [27] | 1030 | 1167 | Unnumbered Interface ID | 12 | 7 [28] | 1031 | | Backup ERO TLV | octets | | 1032 | 1167 | Unnumbered Interface ID | 12 | 7 [29] | 1033 | | Backup ERO TLV | octets | | 1034 +------------+-----------------------------+----------+-------------+ 1036 Table 6: OSPF Segment Routing Extensions TLVs/Sub-TLVs 1038 +------------+----------------------------+----------+--------------+ 1039 | TLV Code | Description | Length | OSPFv3 TLV | 1040 | Point | | | /Sub-TLV | 1041 +------------+----------------------------+----------+--------------+ 1042 | 1034 | SR Capabilities | variable | 9 [30] | 1043 | 1035 | SR Algorithm | variable | 8 [31] | 1044 | 1099 | Adjacency Segment | variable | 5 [32] | 1045 | | Identifier (Adj-SID) TLV | | | 1046 | 1100 | LAN Adjacency Segment | variable | 6 [33] | 1047 | | Identifier (Adj-SID) TLV | | | 1048 | 1158 | Prefix SID | variable | 4 [34] | 1049 | 1161 | SID/Label TLV | variable | 3 [35] | 1050 | 1162 | ERO Metric TLV | 4 octets | 8 [36] | 1051 | 1163 | IPv4 ERO TLV | 8 octets | 9 [37] | 1052 | 1164 | IPv6 ERO TLV | 20 | 8 [38] | 1053 | | | octets | | 1054 | 1165 | Unnumbered Interface ID | 12 | 11 [39] | 1055 | | ERO TLV | octets | | 1056 | 1166 | IPv4 Backup ERO TLV | 8 octets | 12 [40] | 1057 | 1167 | IPv6 Backup ERO TLV | 20 | 13 [41] | 1058 | | | octets | | 1059 | 1167 | Unnumbered Interface ID | 12 | 14 [42] | 1060 | | Backup ERO TLV | octets | | 1061 +------------+----------------------------+----------+--------------+ 1063 Table 7: OSPFv3 Segment Routing Extensions TLVs/Sub-TLVs 1065 3. Procedures 1067 The following sections describe the different operations for the 1068 propagation of SR TLVs into BGP-LS. 1070 3.1. Advertisement of a IS-IS Prefix SID TLV 1072 The advertisement of a IS-IS Prefix SID TLV has following rules: 1074 The IS-IS Prefix-SID is encoded in the BGP-LS Prefix Attribute 1075 Prefix-SID as defined in Section 2.3.1. The flags in the Prefix- 1076 SID TLV have the semantic defined in 1077 [I-D.ietf-isis-segment-routing-extensions] section 2.1. 1079 3.2. Advertisement of a OSPF/OSPFv3 Prefix-SID TLV 1081 The advertisement of a OSPF/OSPFv3 Prefix-SID TLV has following 1082 rules: 1084 The OSPF (or OSPFv3) Prefix-SID is encoded in the BGP-LS Prefix 1085 Attribute Prefix-SID as defined in Section 2.3.1. The flags in 1086 the Prefix-SID TLV have the semantic defined in 1087 [I-D.ietf-ospf-segment-routing-extensions] section 5 or 1088 [I-D.ietf-ospf-ospfv3-segment-routing-extensions] section 5. 1090 3.3. Advertisement of a range of prefix-to-SID mappings in OSPF 1092 The advertisement of a range of prefix-to-SID mappings in OSPF has 1093 following rules: 1095 The OSPF/OSPFv3 Extended Prefix Range TLV is encoded in the BGP-LS 1096 Prefix Attribute Range TLV as defined in Section 2.3.5. The flags 1097 of the Range TLV have the semantic mapped to the definition in 1098 [I-D.ietf-ospf-segment-routing-extensions] section 4 or 1099 [I-D.ietf-ospf-ospfv3-segment-routing-extensions] section 4. The 1100 Prefix-SID from the original OSPF Prefix SID Sub-TLV is encoded 1101 using the BGP-LS Prefix Attribute Prefix-SID as defined in 1102 Section 2.3.1 with the flags set according to the definition in 1103 [I-D.ietf-ospf-segment-routing-extensions] section 5 or 1104 [I-D.ietf-ospf-ospfv3-segment-routing-extensions] section 5. 1106 3.4. Advertisement of a range of IS-IS SR bindings 1108 The advertisement of a range of IS-IS SR bindings has following 1109 rules: 1111 In IS-IS the Mapping Server binding ranges are advertised using 1112 the Binding TLV. The IS-IS Binding TLV is encoded in the BGP-LS 1113 Prefix Attribute Range TLV as defined in Section 2.3.5 using the 1114 Binding Sub-TLV as defined in Section 2.3.6. The flags in the 1115 Range TLV are all set to zero on transmit and ignored on 1116 reception. The range value from the original IS-IS Binding TLV is 1117 encoded in the Range TLV "Range" field. 1119 3.5. Advertisement of a path and its attributes from IS-IS protocol 1121 The advertisement of a Path and its attributes is described in 1122 [I-D.ietf-isis-segment-routing-extensions] section 2.4 and has 1123 following rules: 1125 The original Binding SID TLV (from IS-IS) is encoded into the BGP- 1126 LS Range TLV defined in Section 2.3.5 using the Binding Sub-TLV as 1127 defined in Section 2.3.6. The set of Sub-TLVs from the original 1128 IS-IS Binding TLV are encoded as Sub-TLVs of the BGP-LS Binding 1129 TLV as defined in Section 2.3.6. This includes the SID/Label TLV 1130 defined in Section 2.3. 1132 3.6. Advertisement of a path and its attributes from OSPFv2/OSPFv3 1133 protocol 1135 The advertisement of a Path and its attributes is described in 1136 [I-D.ietf-ospf-segment-routing-extensions] section 6 and 1137 [I-D.ietf-ospf-ospfv3-segment-routing-extensions] section 6 and has 1138 following rules: 1140 Advertisement of a path for a single prefix: the original Binding 1141 SID TLV (from OSPFv2/OSPFv3) is encoded into the BGP-LS Prefix 1142 Attribute Binding TLV as defined in Section 2.3.6. The set of 1143 Sub-TLVs from the original OSPFv2/OSPFv3 Binding TLV are encoded 1144 as Sub-TLVs of the BGP-LS Binding TLV as defined in Section 2.3.6. 1145 This includes the SID/Label TLV defined in Section 2.3. 1147 Advertisement of an SR path for range of prefixes: the OSPF/OSPFv3 1148 Extended Prefix Range TLV is encoded in the BGP-LS Prefix 1149 Attribute Range TLV as defined in Section 2.3.5. The original 1150 OSPFv2/OSPFv3 Binding SID TLV is encoded into the BGP-LS Binding 1151 Sub-TLV as defined in Section 2.3.6. The set of Sub-TLVs from the 1152 original OSPFv2/OSPFv3 Binding TLV are encoded as Sub-TLVs of the 1153 BGP-LS Binding TLV as defined in Section 2.3.6. This includes the 1154 SID/Label TLV defined in Section 2.3. 1156 4. IANA Considerations 1158 This document requests assigning code-points from the registry for 1159 BGP-LS attribute TLVs based on table Table 8. 1161 4.1. TLV/Sub-TLV Code Points Summary 1163 This section contains the global table of all TLVs/Sub-TLVs defined 1164 in this document. 1166 +-----------+--------------------------+----------+-----------------+ 1167 | TLV Code | Description | Length | Section | 1168 | Point | | | | 1169 +-----------+--------------------------+----------+-----------------+ 1170 | 1034 | SR Capabilities | variable | Section 2.1.1 | 1171 | 1035 | SR Algorithm | variable | Section 2.1.2 | 1172 | 1036 | SR Local Block | variable | Section 2.1.3 | 1173 | 1037 | SRMS Preference | variable | Section 2.1.4 | 1174 | 1099 | Adjacency Segment | variable | Section 2.2.1 | 1175 | | Identifier (Adj-SID) TLV | | | 1176 | 1100 | LAN Adjacency Segment | variable | Section 2.2.2 | 1177 | | Identifier (Adj-SID) TLV | | | 1178 | 1158 | Prefix SID | variable | Section 2.3.1 | 1179 | 1159 | Range | variable | Section 2.3.5 | 1180 | 1160 | Binding SID | variable | Section 2.3.6 | 1181 | 1161 | SID/Label TLV | variable | Section 2.3.7.2 | 1182 | 1162 | ERO Metric TLV | 4 octets | 1 [43] | 1183 | 1163 | IPv4 ERO TLV | 8 octets | 1 [44] | 1184 | 1164 | IPv6 ERO TLV | 20 | 1 [45] | 1185 | | | octets | | 1186 | 1165 | Unnumbered Interface ID | 12 | 1 [46] | 1187 | | ERO TLV | octets | | 1188 | 1166 | IPv4 Backup ERO TLV | 8 octets | 1 [47] | 1189 | 1167 | IPv6 Backup ERO TLV | 20 | 1 [48] | 1190 | | | octets | | 1191 | 1168 | Unnumbered Interface ID | 12 | 1 [49] | 1192 | | Backup ERO TLV | octets | | 1193 | 1169 | IPv6 Prefix SID | variable | Section 2.3.2 | 1194 | 1170 | IGP Prefix Attributes | variable | Section 2.3.3 | 1195 | 1171 | Source Router-ID | variable | Section 2.3.4 | 1196 +-----------+--------------------------+----------+-----------------+ 1198 Table 8: Summary Table of TLV/Sub-TLV Codepoints 1200 5. Manageability Considerations 1202 This section is structured as recommended in [RFC5706]. 1204 5.1. Operational Considerations 1206 5.1.1. Operations 1208 Existing BGP and BGP-LS operational procedures apply. No additional 1209 operation procedures are defined in this document. 1211 6. Security Considerations 1213 Procedures and protocol extensions defined in this document do not 1214 affect the BGP security model. See the 'Security Considerations' 1215 section of [RFC4271] for a discussion of BGP security. Also refer to 1216 [RFC4272] and [RFC6952] for analysis of security issues for BGP. 1218 7. Contributors 1220 The following people have substantially contributed to the editing of 1221 this document: 1223 Acee Lindem 1224 Cisco Systems 1225 Email: acee@cisco.com 1227 Saikat Ray 1228 Individual 1229 Email: raysaikat@gmail.com 1231 8. Acknowledgements 1233 The authors would like to thank Les Ginsberg for the review of this 1234 document. 1236 9. References 1238 9.1. Normative References 1240 [I-D.ietf-isis-segment-routing-extensions] 1241 Previdi, S., Filsfils, C., Bashandy, A., Gredler, H., 1242 Litkowski, S., Decraene, B., and j. jefftant@gmail.com, 1243 "IS-IS Extensions for Segment Routing", draft-ietf-isis- 1244 segment-routing-extensions-08 (work in progress), October 1245 2016. 1247 [I-D.ietf-ospf-ospfv3-segment-routing-extensions] 1248 Psenak, P., Previdi, S., Filsfils, C., Gredler, H., 1249 Shakir, R., Henderickx, W., and J. Tantsura, "OSPFv3 1250 Extensions for Segment Routing", draft-ietf-ospf-ospfv3- 1251 segment-routing-extensions-07 (work in progress), October 1252 2016. 1254 [I-D.ietf-ospf-segment-routing-extensions] 1255 Psenak, P., Previdi, S., Filsfils, C., Gredler, H., 1256 Shakir, R., Henderickx, W., and J. Tantsura, "OSPF 1257 Extensions for Segment Routing", draft-ietf-ospf-segment- 1258 routing-extensions-10 (work in progress), October 2016. 1260 [I-D.previdi-isis-ipv6-prefix-sid] 1261 Previdi, S., Ginsberg, L., and C. Filsfils, "Segment 1262 Routing IPv6 Prefix-SID", draft-previdi-isis-ipv6-prefix- 1263 sid-02 (work in progress), May 2016. 1265 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 1266 Requirement Levels", BCP 14, RFC 2119, 1267 DOI 10.17487/RFC2119, March 1997, 1268 . 1270 [RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A 1271 Border Gateway Protocol 4 (BGP-4)", RFC 4271, 1272 DOI 10.17487/RFC4271, January 2006, 1273 . 1275 [RFC7684] Psenak, P., Gredler, H., Shakir, R., Henderickx, W., 1276 Tantsura, J., and A. Lindem, "OSPFv2 Prefix/Link Attribute 1277 Advertisement", RFC 7684, DOI 10.17487/RFC7684, November 1278 2015, . 1280 [RFC7752] Gredler, H., Ed., Medved, J., Previdi, S., Farrel, A., and 1281 S. Ray, "North-Bound Distribution of Link-State and 1282 Traffic Engineering (TE) Information Using BGP", RFC 7752, 1283 DOI 10.17487/RFC7752, March 2016, 1284 . 1286 [RFC7794] Ginsberg, L., Ed., Decraene, B., Previdi, S., Xu, X., and 1287 U. Chunduri, "IS-IS Prefix Attributes for Extended IPv4 1288 and IPv6 Reachability", RFC 7794, DOI 10.17487/RFC7794, 1289 March 2016, . 1291 9.2. Informative References 1293 [I-D.ietf-spring-segment-routing] 1294 Filsfils, C., Previdi, S., Decraene, B., Litkowski, S., 1295 and R. Shakir, "Segment Routing Architecture", draft-ietf- 1296 spring-segment-routing-09 (work in progress), July 2016. 1298 [RFC4272] Murphy, S., "BGP Security Vulnerabilities Analysis", 1299 RFC 4272, DOI 10.17487/RFC4272, January 2006, 1300 . 1302 [RFC5706] Harrington, D., "Guidelines for Considering Operations and 1303 Management of New Protocols and Protocol Extensions", 1304 RFC 5706, DOI 10.17487/RFC5706, November 2009, 1305 . 1307 [RFC6952] Jethanandani, M., Patel, K., and L. Zheng, "Analysis of 1308 BGP, LDP, PCEP, and MSDP Issues According to the Keying 1309 and Authentication for Routing Protocols (KARP) Design 1310 Guide", RFC 6952, DOI 10.17487/RFC6952, May 2013, 1311 . 1313 9.3. URIs 1315 [1] http://tools.ietf.org/html/draft-ietf-isis-segment-routing- 1316 extensions-05#section-3.1 1318 [2] http://tools.ietf.org/html/draft-ietf-isis-segment-routing- 1319 extensions-05#section-3.2 1321 [3] http://tools.ietf.org/html/draft-ietf-isis-segment-routing- 1322 extensions-05#section-2.2.1 1324 [4] http://tools.ietf.org/html/draft-ietf-isis-segment-routing- 1325 extensions-05#section-2.2.2 1327 [5] http://tools.ietf.org/html/draft-ietf-isis-segment-routing- 1328 extensions-05#section-2.1 1330 [6] http://tools.ietf.org/html/draft-ietf-isis-segment-routing- 1331 extensions-05#section-2.4 1333 [7] http://tools.ietf.org/html/draft-ietf-isis-segment-routing- 1334 extensions-05#section-2.3 1336 [8] http://tools.ietf.org/html/draft-ietf-isis-segment-routing- 1337 extensions-05#section-2.4.7 1339 [9] http://tools.ietf.org/html/draft-ietf-isis-segment-routing- 1340 extensions-05#section-2.4.8 1342 [10] http://tools.ietf.org/html/draft-ietf-isis-segment-routing- 1343 extensions-05#section-2.4.9 1345 [11] http://tools.ietf.org/html/draft-ietf-isis-segment-routing- 1346 extensions-05#section-2.4.10 1348 [12] http://tools.ietf.org/html/draft-ietf-isis-segment-routing- 1349 extensions-05#section-2.4.11 1351 [13] http://tools.ietf.org/html/draft-ietf-isis-segment-routing- 1352 extensions-05#section-2.4.12 1354 [14] http://tools.ietf.org/html/draft-ietf-isis-segment-routing- 1355 extensions-05#section-2.4.13 1357 [15] http://tools.ietf.org/html/draft-previdi-isis-ipv6-prefix-sid-01 1359 [16] http://tools.ietf.org/html/RFC7794 1361 [17] http://tools.ietf.org/html/RFC7794 1363 [18] http://tools.ietf.org/html/draft-ietf-ospf-segment-routing- 1364 extensions-05#section-3.2 1366 [19] http://tools.ietf.org/html/draft-ietf-ospf-segment-routing- 1367 extensions-05#section-3.1 1369 [20] http://tools.ietf.org/html/draft-ietf-ospf-segment-routing- 1370 extensions-05#section-7.1 1372 [21] http://tools.ietf.org/html/draft-ietf-ospf-segment-routing- 1373 extensions-05#section-7.2 1375 [22] http://tools.ietf.org/html/draft-ietf-ospf-segment-routing- 1376 extensions-05#section-5 1378 [23] http://tools.ietf.org/html/draft-ietf-ospf-segment-routing- 1379 extensions-05#section-2.1 1381 [24] http://tools.ietf.org/html/draft-ietf-ospf-segment-routing- 1382 extensions-05#section-6.1 1384 [25] http://tools.ietf.org/html/draft-ietf-ospf-segment-routing- 1385 extensions-05#section-6.2.1 1387 [26] http://tools.ietf.org/html/draft-ietf-ospf-segment-routing- 1388 extensions-05#section-6.2.2 1390 [27] http://tools.ietf.org/html/draft-ietf-ospf-segment-routing- 1391 extensions-05#section-6.2.3 1393 [28] http://tools.ietf.org/html/draft-ietf-ospf-segment-routing- 1394 extensions-05#section-6.2.4 1396 [29] http://tools.ietf.org/html/draft-ietf-ospf-segment-routing- 1397 extensions-05#section-6.2.4 1399 [30] http://tools.ietf.org/html/draft-ietf-ospf-ospfv3-segment- 1400 routing-extensions-05#section-3.2 1402 [31] http://tools.ietf.org/html/draft-ietf-ospf-ospfv3-segment- 1403 routing-extensions-05#section-3.1 1405 [32] http://tools.ietf.org/html/draft-ietf-ospf-ospfv3-segment- 1406 routing-extensions-05#section-7.1 1408 [33] http://tools.ietf.org/html/draft-ietf-ospf-ospfv3-segment- 1409 routing-extensions-05#section-7.2 1411 [34] http://tools.ietf.org/html/draft-ietf-ospf-ospfv3-segment- 1412 routing-extensions-05#section-5 1414 [35] http://tools.ietf.org/html/draft-ietf-ospf-ospfv3-segment- 1415 routing-extensions-05#section-2.1 1417 [36] http://tools.ietf.org/html/draft-ietf-ospf-ospfv3-segment- 1418 routing-extensions-05#section-6.1 1420 [37] http://tools.ietf.org/html/draft-ietf-ospf-ospfv3-segment- 1421 routing-extensions-05#section-6.2.1 1423 [38] http://tools.ietf.org/html/draft-ietf-ospf-ospfv3-segment- 1424 routing-extensions-05#section-6.2.2 1426 [39] http://tools.ietf.org/html/draft-ietf-ospf-ospfv3-segment- 1427 routing-extensions-05#section-6.2.3 1429 [40] http://tools.ietf.org/html/draft-ietf-ospf-ospfv3-segment- 1430 routing-extensions-05#section-6.2.4 1432 [41] http://tools.ietf.org/html/draft-ietf-ospf-ospfv3-segment- 1433 routing-extensions-05#section-6.2.5 1435 [42] http://tools.ietf.org/html/draft-ietf-ospf-ospfv3-segment- 1436 routing-extensions-05#section-6.2.6 1438 [43] http://tools.ietf.org/html/draft-ietf-isis-segment-routing- 1439 extensions-05#section-2.4.7 1441 [44] http://tools.ietf.org/html/draft-ietf-isis-segment-routing- 1442 extensions-05#section-2.4.8 1444 [45] http://tools.ietf.org/html/draft-ietf-isis-segment-routing- 1445 extensions-05#section-2.4.9 1447 [46] http://tools.ietf.org/html/draft-ietf-isis-segment-routing- 1448 extensions-05#section-2.4.10 1450 [47] http://tools.ietf.org/html/draft-ietf-isis-segment-routing- 1451 extensions-05#section-2.4.11 1453 [48] http://tools.ietf.org/html/draft-ietf-isis-segment-routing- 1454 extensions-05#section-2.4.12 1456 [49] http://tools.ietf.org/html/draft-ietf-isis-segment-routing- 1457 extensions-05#section-2.4.13 1459 Authors' Addresses 1461 Stefano Previdi (editor) 1462 Cisco Systems, Inc. 1463 Via Del Serafico, 200 1464 Rome 00142 1465 Italy 1467 Email: sprevidi@cisco.com 1469 Peter Psenak 1470 Cisco Systems, Inc. 1471 Apollo Business Center 1472 Mlynske nivy 43 1473 Bratislava 821 09 1474 Slovakia 1476 Email: ppsenak@cisco.com 1478 Clarence Filsfils 1479 Cisco Systems, Inc. 1480 Brussels 1481 Belgium 1483 Email: cfilsfil@cisco.com 1485 Hannes Gredler 1486 RtBrick Inc. 1488 Email: hannes@rtbrick.com 1489 Mach(Guoyi) Chen 1490 Huawei Technologies 1491 Huawei Building, No. 156 Beiqing Rd. 1492 Beijing 100095 1493 China 1495 Email: mach.chen@huawei.com 1497 Jeff Tantsura 1498 Individual 1500 Email: jefftant@gmail.com