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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: August 13, 2017 Cisco Systems, Inc. 6 H. Gredler 7 RtBrick Inc. 8 M. Chen 9 Huawei Technologies 10 J. Tantsura 11 Individual 12 February 9, 2017 14 BGP Link-State extensions for Segment Routing 15 draft-ietf-idr-bgp-ls-segment-routing-ext-01 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 August 13, 2017. 50 Copyright Notice 52 Copyright (c) 2017 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. Implementation Status . . . . . . . . . . . . . . . . . . . . 27 98 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 28 99 5.1. TLV/Sub-TLV Code Points Summary . . . . . . . . . . . . . 28 100 6. Manageability Considerations . . . . . . . . . . . . . . . . 29 101 6.1. Operational Considerations . . . . . . . . . . . . . . . 29 102 6.1.1. Operations . . . . . . . . . . . . . . . . . . . . . 29 103 7. Security Considerations . . . . . . . . . . . . . . . . . . . 30 104 8. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 30 105 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 30 106 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 30 107 10.1. Normative References . . . . . . . . . . . . . . . . . . 30 108 10.2. Informative References . . . . . . . . . . . . . . . . . 31 109 10.3. URIs . . . . . . . . . . . . . . . . . . . . . . . . . . 32 110 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 35 112 1. Introduction 114 Segment Routing (SR) allows for a flexible definition of end-to-end 115 paths by combining sub-paths called "segments". A segment can 116 represent any instruction, topological or service-based. A segment 117 can have a local semantic to an SR node or global within a domain. 118 Within IGP topologies an SR path is encoded as a sequence of 119 topological sub-paths, called "IGP segments". These segments are 120 advertised by the link-state routing protocols (IS-IS, OSPF and 121 OSPFv3). 123 Two types of IGP segments are defined, Prefix segments and Adjacency 124 segments. Prefix segments, by default, represent an ECMP-aware 125 shortest-path to a prefix, as per the state of the IGP topology. 126 Adjacency segments represent a hop over a specific adjacency between 127 two nodes in the IGP. A prefix segment is typically a multi-hop path 128 while an adjacency segment, in most of the cases, is a one-hop path. 129 [I-D.ietf-spring-segment-routing]. 131 When Segment Routing is enabled in a IGP domain, segments are 132 advertised in the form of Segment Identifiers (SIDs). The IGP link- 133 state routing protocols have been extended to advertise SIDs and 134 other SR-related information. IGP extensions are described in: IS-IS 135 [I-D.ietf-isis-segment-routing-extensions], OSPFv2 136 [I-D.ietf-ospf-segment-routing-extensions] and OSPFv3 137 [I-D.ietf-ospf-ospfv3-segment-routing-extensions]. Using these 138 extensions, Segment Routing can be enabled within an IGP domain. 140 +------------+ 141 | Consumer | 142 +------------+ 143 ^ 144 | 145 v 146 +-------------------+ 147 | BGP Speaker | +-----------+ 148 | (Route-Reflector) | | Consumer | 149 +-------------------+ +-----------+ 150 ^ ^ ^ ^ 151 | | | | 152 +---------------+ | +-------------------+ | 153 | | | | 154 v v v v 155 +-----------+ +-----------+ +-----------+ 156 | BGP | | BGP | | BGP | 157 | Speaker | | Speaker | . . . | Speaker | 158 +-----------+ +-----------+ +-----------+ 159 ^ ^ ^ 160 | | | 161 IGP IGP IGP 163 Figure 1: Link State info collection 165 Segment Routing (SR) allows advertisement of single or multi-hop 166 paths. The flooding scope for the IGP extensions for Segment routing 167 is IGP area-wide. Consequently, the contents of a Link State 168 Database (LSDB) or a Traffic Engineering Database (TED) has the scope 169 of an IGP area and therefore, by using the IGP alone it is not enough 170 to construct segments across multiple IGP Area or AS boundaries. 172 In order to address the need for applications that require 173 topological visibility across IGP areas, or even across Autonomous 174 Systems (AS), the BGP-LS address-family/sub-address-family have been 175 defined to allow BGP to carry Link-State information. The BGP 176 Network Layer Reachability Information (NLRI) encoding format for 177 BGP-LS and a new BGP Path Attribute called the BGP-LS attribute are 178 defined in [RFC7752]. The identifying key of each Link-State object, 179 namely a node, link, or prefix, is encoded in the NLRI and the 180 properties of the object are encoded in the BGP-LS attribute. 181 Figure Figure 1 describes a typical deployment scenario. In each IGP 182 area, one or more nodes are configured with BGP-LS. These BGP 183 speakers form an IBGP mesh by connecting to one or more route- 184 reflectors. This way, all BGP speakers (specifically the route- 185 reflectors) obtain Link-State information from all IGP areas (and 186 from other ASes from EBGP peers). An external component connects to 187 the route-reflector to obtain this information (perhaps moderated by 188 a policy regarding what information is or isn't advertised to the 189 external component). 191 This document describes extensions to BGP-LS to advertise the SR 192 information. An external component (e.g., a controller) then can 193 collect SR information in the "northbound" direction across IGP areas 194 or ASes and construct the end-to-end path (with its associated SIDs) 195 that need to be applied to an incoming packet to achieve the desired 196 end-to-end forwarding. 198 2. BGP-LS Extensions for Segment Routing 200 This document defines IGP SR extensions BGP-LS TLVs and Sub-TLVs. 201 Section 2.4 and Section 2.5 illustrates the equivalent TLVs and Sub- 202 TLVs in IS-IS, OSPF and OSPFv3 protocols. 204 BGP-LS [RFC7752] defines the BGP-LS NLRI that can be a Node NLRI, a 205 Link NLRI or a Prefix NLRI. The corresponding BGP-LS attribute is a 206 Node Attribute, a Link Attribute or a Prefix Attribute. BGP-LS 207 [RFC7752] defines the TLVs that map link-state information to BGP-LS 208 NLRI and the BGP-LS attribute. This document adds additional BGP-LS 209 attribute TLVs in order to encode SR information. 211 2.1. Node Attributes TLVs 213 The following Node Attribute TLVs are defined: 215 +----------------+-----------------+----------+---------------+ 216 | TLV Code Point | Description | Length | Section | 217 +----------------+-----------------+----------+---------------+ 218 | 1034 | SR Capabilities | variable | Section 2.1.1 | 219 | 1035 | SR Algorithm | variable | Section 2.1.2 | 220 | 1036 | SR Local Block | variable | Section 2.1.3 | 221 | 1037 | SRMS Preference | variable | Section 2.1.4 | 222 +----------------+-----------------+----------+---------------+ 224 Table 1: Node Attribute TLVs 226 These TLVs can ONLY be added to the Node Attribute associated with 227 the Node NLRI that originates the corresponding SR TLV. 229 2.1.1. SR-Capabilities TLV 231 The SR Capabilities sub-TLV has following format: 233 0 1 2 3 234 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 1 235 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 236 | Type | Length | 237 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 238 | Flags | RESERVED | 239 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 241 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 242 | Range Size | 243 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 244 // SID/Label Sub-TLV (variable) // 245 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 247 Type: TBD, suggested value 1034. 249 Length: Variable. 251 Flags: 1 octet of flags as defined in 252 [I-D.ietf-isis-segment-routing-extensions] and 253 [I-D.ietf-ospf-ospfv3-segment-routing-extensions]. 255 One or more entries, each of which have the following format: 257 Range Size: 3 octet value indicating the number of labels in 258 the range. 260 SID/Label sub-TLV (as defined in Section 2.3.7.2). 262 2.1.2. SR-Algorithm TLV 264 The SR-Algorithm TLV has the following format: 266 0 1 2 3 267 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 268 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 269 | Type | Length | 270 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 271 | Algorithm 1 | Algorithm... | Algorithm N | | 272 +- -+ 273 | | 274 + + 276 where: 278 Type: TBD, suggested value 1035. 280 Length: Variable. 282 Algorithm: 1 octet identifying the algorithm. 284 2.1.3. SR Local Block TLV 286 The SR Local Block (SRLB) Sub-TLV contains the range of labels the 287 node has reserved for local SIDs. Local SIDs are used, e.g., in IGP 288 (IS-IS, OSPF) for Adjacency-SIDs, and may also be allocated by other 289 components than IGP protocols. As an example, an application or a 290 controller may instruct a node to allocate a specific local SID. 291 Therefore, in order for such applications or controllers to know the 292 range of local SIDs available, it is required that the node 293 advertises its SRLB. 295 The SRLB TLV has the following format: 297 0 1 2 3 298 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 1 299 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 300 | Type | Length | 301 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 302 | Flags | RESERVED | 303 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 305 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 306 | Range Size | 307 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 308 // SID/Label Sub-TLV (variable) // 309 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 311 Type: TBD, suggested value 1036. 313 Length: Variable. 315 Flags: 1 octet of flags. None are defined at this stage. 317 One or more entries, each of which have the following format: 319 Range Size: 3 octet value indicating the number of labels in 320 the range. 322 SID/Label sub-TLV (as defined in Section 2.3.7.2). 324 2.1.4. SRMS Preference TLV 326 The Segment Routing Mapping Server (SRMS) Preference sub-TLV is used 327 in order to associate a preference with SRMS advertisements from a 328 particular source. 330 The SRMS Preference sub-TLV has following format: 332 0 1 2 3 333 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 1 334 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 335 | Type | Length | 336 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 337 | Preference | 338 +-+-+-+-+-+-+-+-+ 340 Type: TBD, suggested value 1037. 342 Length: 1. 344 Preference: 1 octet. Unsigned 8 bit SRMS preference. 346 The use of the SRMS Preference TLV is defined in 347 [I-D.ietf-isis-segment-routing-extensions]. 349 2.2. Link Attribute TLVs 351 The following Link Attribute TLVs are are defined: 353 +-----------+----------------------------+----------+---------------+ 354 | TLV Code | Description | Length | Section | 355 | Point | | | | 356 +-----------+----------------------------+----------+---------------+ 357 | 1099 | Adjacency Segment | variable | Section 2.2.1 | 358 | | Identifier (Adj-SID) TLV | | | 359 | 1100 | LAN Adjacency Segment | variable | Section 2.2.2 | 360 | | Identifier (Adj-SID) TLV | | | 361 +-----------+----------------------------+----------+---------------+ 363 Table 2: Link Attribute TLVs 365 These TLVs can ONLY be added to the Link Attribute associated with 366 the link whose local node originates the corresponding TLV. 368 For a LAN, normally a node only announces its adjacency to the IS-IS 369 pseudo-node (or the equivalent OSPF Designated and Backup Designated 370 Routers)[I-D.ietf-isis-segment-routing-extensions]. The LAN 371 Adjecency Segment TLV allows a node to announce adjacencies to all 372 other nodes attached to the LAN in a single instance of the BGP-LS 373 Link NLRI. Without this TLV, the corresponding BGP-LS link NLRI 374 would need to be originated for each additional adjacency in order to 375 advertise the SR TLVs for these neighbor adjacencies. 377 2.2.1. Adjacency SID TLV 379 The Adjacency SID (Adj-SID) 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 | Weight | Reserved | 387 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 388 | SID/Label/Index (variable) | 389 +---------------------------------------------------------------+ 391 where: 393 Type: TBD, suggested value 1099. 395 Length: Variable. 397 Flags. 1 octet field of following flags as defined in 398 [I-D.ietf-isis-segment-routing-extensions], 399 [I-D.ietf-ospf-segment-routing-extensions] and 400 [I-D.ietf-ospf-ospfv3-segment-routing-extensions]. 402 Weight: Weight used for load-balancing purposes. 404 SID/Index/Label: Label or index value depending on the flags 405 setting as defined in [I-D.ietf-isis-segment-routing-extensions], 406 [I-D.ietf-ospf-segment-routing-extensions] and 407 [I-D.ietf-ospf-ospfv3-segment-routing-extensions]. 409 2.2.2. LAN Adjacency SID TLV 411 The LAN Adjacency SID (LAN-Adj-SID-SID) has the following format: 413 0 1 2 3 414 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 1 415 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 416 | Type | Length | 417 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 418 | Flags | Weight | Reserved | 419 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 421 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 422 | OSPF Neighbor ID / IS-IS System-ID | 423 + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 424 | | 425 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 427 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 428 | SID/Label/Index (variable) | 429 +---------------------------------------------------------------+ 431 where: 433 Type: TBD, suggested value 1100. 435 Length: Variable. 437 Flags. 1 octet field of following flags as defined in 438 [I-D.ietf-isis-segment-routing-extensions], 439 [I-D.ietf-ospf-segment-routing-extensions] and 440 [I-D.ietf-ospf-ospfv3-segment-routing-extensions]. 442 Weight: Weight used for load-balancing purposes. 444 SID/Index/Label: Label or index value depending on the flags 445 setting as defined in [I-D.ietf-isis-segment-routing-extensions], 446 [I-D.ietf-ospf-segment-routing-extensions] and 447 [I-D.ietf-ospf-ospfv3-segment-routing-extensions]. 449 2.3. Prefix Attribute TLVs 451 The following Prefix Attribute TLVs and Sub-TLVs are defined: 453 +----------------+-----------------------+----------+---------------+ 454 | TLV Code Point | Description | Length | Section | 455 +----------------+-----------------------+----------+---------------+ 456 | 1158 | Prefix SID | variable | Section 2.3.1 | 457 | 1159 | Range | variable | Section 2.3.5 | 458 | 1160 | Binding SID | variable | Section 2.3.6 | 459 | 1169 | IPv6 Prefix SID | variable | Section 2.3.2 | 460 | 1170 | IGP Prefix Attributes | variable | Section 2.3.3 | 461 | 1171 | Source Router-ID | variable | Section 2.3.4 | 462 +----------------+-----------------------+----------+---------------+ 464 Table 3: Prefix Attribute TLVs 466 +------------+-------------------------+----------+-----------------+ 467 | TLV Code | Description | Length | Section | 468 | Point | | | | 469 +------------+-------------------------+----------+-----------------+ 470 | 1161 | SID/Label TLV | variable | Section 2.3.7.2 | 471 | 1162 | ERO Metric TLV | 4 octets | Section 2.3.7.3 | 472 | 1163 | IPv4 ERO TLV | 8 octets | Section 2.3.7.4 | 473 | 1164 | IPv6 ERO TLV | 20 | Section 2.3.7.5 | 474 | | | octets | | 475 | 1165 | Unnumbered Interface ID | 12 | Section 2.3.7.6 | 476 | | ERO TLV | | | 477 | 1166 | IPv4 Backup ERO TLV | 8 octets | Section 2.3.7.7 | 478 | 1167 | IPv6 Backup ERO TLV | 10 | Section 2.3.7.8 | 479 | | | octets | | 480 | 1168 | Unnumbered Interface ID | 12 | Section 2.3.7.9 | 481 | | Backup ERO TLV | | | 482 +------------+-------------------------+----------+-----------------+ 484 Table 4: Prefix Attribute - Binding SID Sub-TLVs 486 2.3.1. Prefix-SID TLV 488 The Prefix-SID TLV can ONLY be added to the Prefix Attribute whose 489 local node in the corresponding Prefix NLRI is the node that 490 originates the corresponding SR TLV. 492 The Prefix-SID has the following format: 494 0 1 2 3 495 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 1 496 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 497 | Type | Length | 498 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 499 | Flags | Algorithm | Reserved | 500 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 501 | SID/Index/Label (variable) | 502 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 504 where: 506 Type: TBD, suggested value 1158. 508 Length: Variable 510 Algorithm: 1 octet value identify the algorithm. 512 SID/Index/Label: Label or index value depending on the flags 513 setting as defined in [I-D.ietf-isis-segment-routing-extensions], 514 [I-D.ietf-ospf-segment-routing-extensions] and 515 [I-D.ietf-ospf-ospfv3-segment-routing-extensions]. 517 The Prefix-SID TLV includes a Flags field. In the context of BGP-LS, 518 the Flags field format and the semantic of each individual flag MUST 519 be taken from the corresponding source protocol (i.e.: the protocol 520 of origin of the Prefix-SID being advertised in BGP-LS). 522 IS-IS Prefix-SID flags are defined in 523 [I-D.ietf-isis-segment-routing-extensions] section 2.1. 525 OSPF Prefix-SID flags are defined in 526 [I-D.ietf-ospf-segment-routing-extensions] section 5. 528 OSPFv3 Prefix-SID flags are defined in 529 [I-D.ietf-ospf-segment-routing-extensions] section 5. 531 2.3.2. IPv6 Prefix-SID TLV 533 The IPv6 Prefix-SID TLV can ONLY be added to the Prefix Attribute 534 whose local node in the corresponding Prefix NLRI is the node that 535 originates the corresponding SR TLV. 537 The IPv6 Prefix-SID has the following format: 539 0 1 2 3 540 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 1 541 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 542 | Type | Length | 543 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 544 | Flags | Algorithm | // 545 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ // 546 // Sub-TLVs // 547 // // 548 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 550 where: 552 Type: TBD, suggested value 1169. 554 Length: 3 + length of Sub-TLVs. 556 Flags: 2 octet field of flags. None of them is defined at this 557 stage. 559 Algorithm: 1 octet value identify the algorithm as defined in 560 [I-D.previdi-isis-ipv6-prefix-sid]. 562 Sub-TLVs: additional information encoded into the IPv6 Prefix-SID 563 Sub-TLV as defined in [I-D.previdi-isis-ipv6-prefix-sid]. 565 The IPv6 Prefix-SID TLV is defined in 566 [I-D.previdi-isis-ipv6-prefix-sid]. 568 2.3.3. IGP Prefix Attributes TLV 570 The IGP Prefix Attribute TLV carries IPv4/IPv6 prefix attribute flags 571 as defined in [RFC7684] and [RFC7794]. 573 The IGP Prefix Attribute TLV has the following format: 575 0 1 2 3 576 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 1 577 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 578 | Type | Length | 579 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 580 // Flags (variable) // 581 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 583 where: 585 Type: TBD, suggested value 1170. 587 Length: variable. 589 Flags: a variable length flag field (according to the length 590 field). Flags are routing protocol specific (OSPF and IS-IS). 591 OSPF flags are defined in [RFC7684] and IS-IS flags are defined in 592 [RFC7794]. The receiver of the BGP-LS update, when inspecting the 593 IGP Prefix Attribute TLV, MUST check the Protocol-ID of the NLRI 594 and refer to the protocol specification in order to parse the 595 flags. 597 2.3.4. Source Router Identifier (Source Router-ID) TLV 599 The Source Router-ID TLV contains the IPv4 or IPv6 Router-ID of the 600 originator as defined in [RFC7794]. While defined in the IS-IS 601 protocol, the Source Router-ID TLV may be used to carry the OSPF 602 Router-ID of the prefix originator. 604 The Source Router-ID TLV has the following format: 606 0 1 2 3 607 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 1 608 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 609 | Type | Length | 610 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 611 // IPv4/IPv6 Address (Router-ID) // 612 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 614 where: 616 Type: TBD, suggested value 1171. 618 Length: 4 or 16. 620 IPv4/IPv6 Address: 4 octet IPv4 address or 16 octet IPv6 address. 622 The semantic of the Source Router-ID TLV is defined in [RFC7794]. 624 2.3.5. Range TLV 626 The Range TLV can ONLY be added to the Prefix Attribute whose local 627 node in the corresponding Prefix NLRI is the node that originates the 628 corresponding SR TLV. 630 When the range TLV is used in order to advertise a path to a prefix 631 or a range of prefix-to-SID mappings, the Prefix-NLRI the Range TLV 632 is attached to MUST be advertised as a non-routing prefix where no 633 IGP metric TLV (TLV 1095) is attached. 635 The format of the Range TLV is as follows: 637 0 1 2 3 638 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 1 639 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 640 | Type | Length | 641 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 642 | Flags | RESERVED | Range Size | 643 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 644 // Sub-TLVs // 645 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 647 where: 649 Figure 2: Range TLV format 651 Type: 1159 653 Length is 4. 655 Flags: Only used when the source protocol is OSPF and defined in 656 [I-D.ietf-ospf-segment-routing-extensions] section 4 and 657 [I-D.ietf-ospf-ospfv3-segment-routing-extensions] section 4. 659 Range Size: 2 octets as defined in 660 [I-D.ietf-ospf-segment-routing-extensions] section 4. 662 Within the Range TLV, the following SubTLVs are may be present: 664 Binding SID TLV, defined in Section 2.3.6 666 Prefix-SID TLV, defined in Section 2.3.1 668 SID/Label TLV, defined in Section 2.3.7.2 670 2.3.6. Binding SID TLV 672 The Binding SID TLV can be used in two ways: 674 o as a sub-TLV of the Range TLV 676 o as a Prefix Attribute TLV 678 The format of the Binding SID TLV is as follows: 680 0 1 2 3 681 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 1 682 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 683 | Type | Length | 684 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 685 | Weight | Flags | RESERVED | 686 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 687 // SubTLVs (variable) // 688 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 690 where: 692 Figure 3: Binding SID Sub-TLV format 694 Type is 1160 696 Length is variable 698 Weight and Flags are mapped to Weight and Flags defined in 699 [I-D.ietf-isis-segment-routing-extensions] section 2.4, 700 [I-D.ietf-ospf-segment-routing-extensions] section 4 and 701 [I-D.ietf-ospf-ospfv3-segment-routing-extensions] section 4. 703 Sub-TLVs are defined in the following sections. 705 2.3.7. Binding SID SubTLVs 707 This section defines the Binding SID Sub-TLVs in BGP-LS to encode the 708 equivalent Sub-TLVs defined in 709 [I-D.ietf-isis-segment-routing-extensions], 710 [I-D.ietf-ospf-segment-routing-extensions] and 711 [I-D.ietf-ospf-ospfv3-segment-routing-extensions]. 713 All ERO (Explicit Route Object) Sub-TLVs must immediately follow the 714 (SID)/Label Sub-TLV. 716 All Backup ERO Sub-TLVs must immediately follow the last ERO Sub-TLV. 718 2.3.7.1. Binding SID Prefix-SID Sub-TLV 720 When encoding IS-IS Mapping Server entries as defined in 721 [I-D.ietf-isis-segment-routing-extensions] the Prefix-SID TLV defined 722 in Section 2.3.1 is used as Sub-TLV in the Binding TLV. 724 2.3.7.2. SID/Label Sub-TLV 726 The SID/Label TLV has following format: 728 0 1 2 3 729 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 1 730 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 731 | Type | Length | 732 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 733 | SID/Label (variable) | 734 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 736 where: 738 Type: TBD, suggested value 1161. 740 Length: Variable, 3 or 4 bytes 742 SID/Label: If length is set to 3, then the 20 rightmost bits 743 represent a label. If length is set to 4, then the value 744 represents a 32 bit SID. 746 The receiving router MUST ignore the SID/Label Sub-TLV if the 747 length is other then 3 or 4. 749 2.3.7.3. ERO Metric Sub-TLV 751 The ERO Metric Sub-TLV has following format: 753 0 1 2 3 754 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 1 755 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 756 | Type | Length | 757 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 758 | Metric (4 octets) | 759 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 761 ERO Metric Sub-TLV format 763 where: 765 Type: TBD, suggested value 1162. 767 Length: Always 4 769 Metric: A 4 octet metric representing the aggregate IGP or TE path 770 cost. 772 2.3.7.4. IPv4 ERO Sub-TLV 774 The ERO Sub-TLV has following format: 776 0 1 2 3 777 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 1 778 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 779 | Type | Length | 780 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 781 | Flags | Reserved | 782 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 783 | IPv4 Address (4 octets) | 784 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 786 IPv4 ERO Sub-TLV format 788 where: 790 Type: TBD, suggested value 1163 792 Length: 8 octets 794 Flags: 1 octet of flags as defined in: 795 [I-D.ietf-isis-segment-routing-extensions], 796 [I-D.ietf-ospf-segment-routing-extensions] and 797 [I-D.ietf-ospf-ospfv3-segment-routing-extensions]. 799 IPv4 Address - the address of the explicit route hop. 801 2.3.7.5. IPv6 ERO Sub-TLV 803 The IPv6 ERO Sub-TLV has following format: 805 0 1 2 3 806 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 1 807 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 808 | Type | Length | 809 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 810 | Flags | Reserved | 811 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 812 | | 813 +- -+ 814 | | 815 +- IPv6 Address -+ 816 | | 817 +- -+ 818 | | 819 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 821 IPv6 ERO Sub-TLV format 823 where: 825 Type: TBD, suggested value 1164 827 Length: 20 octets 829 Flags: 1 octet of flags as defined in: 830 [I-D.ietf-isis-segment-routing-extensions], 831 [I-D.ietf-ospf-segment-routing-extensions] and 832 [I-D.ietf-ospf-ospfv3-segment-routing-extensions]. 834 IPv6 Address - the address of the explicit route hop. 836 2.3.7.6. Unnumbered Interface ID ERO Sub-TLV 838 The Unnumbered Interface-ID ERO Sub-TLV has following format: 840 0 1 2 3 841 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 1 842 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 843 | Type | Length | 844 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 845 | Flags | Reserved | 846 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 847 // Router ID (IPv4, 4 octet or IPv6, 16 octets) // 848 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 849 | Interface ID | 850 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 852 where: 854 Unnumbered Interface ID ERO Sub-TLV format 856 Type: TBD, suggested value 1165. 858 Length: Variable (12 for IPv4 Router-ID or 24 for IPv6 Router-ID). 860 Flags: 1 octet of flags as defined in: 861 [I-D.ietf-isis-segment-routing-extensions], 862 [I-D.ietf-ospf-segment-routing-extensions] and 863 [I-D.ietf-ospf-ospfv3-segment-routing-extensions]. 865 Router-ID: Router-ID of the next-hop. 867 Interface ID: is the identifier assigned to the link by the router 868 specified by the Router-ID. 870 2.3.7.7. IPv4 Backup ERO Sub-TLV 872 The IPv4 Backup ERO Sub-TLV has following format: 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 | 880 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 881 | IPv4 Address (4 octets) | 882 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 884 IPv4 Backup ERO Sub-TLV format 886 where: 888 Type: TBD, suggested value 1166. 890 Length: 8 octets 892 Flags: 1 octet of flags as defined in: 893 [I-D.ietf-isis-segment-routing-extensions], 894 [I-D.ietf-ospf-segment-routing-extensions] and 895 [I-D.ietf-ospf-ospfv3-segment-routing-extensions]. 897 IPv4 Address: Address of the explicit route hop. 899 2.3.7.8. IPv6 Backup ERO Sub-TLV 901 The IPv6 Backup ERO Sub-TLV has following format: 903 0 1 2 3 904 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 1 905 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 906 | Type | Length | 907 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 908 | Flags | Reserved | 909 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 910 | | 911 +- -+ 912 | | 913 +- IPv6 Address -+ 914 | | 915 +- -+ 916 | | 917 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 919 IPv6 Backup ERO Sub-TLV format 921 where: 923 Type: TBD, suggested value 1167. 925 Length: 8 octets 927 Flags: 1 octet of flags as defined in: 928 [I-D.ietf-isis-segment-routing-extensions], 929 [I-D.ietf-ospf-segment-routing-extensions] and 930 [I-D.ietf-ospf-ospfv3-segment-routing-extensions]. 932 IPv6 Address: Address of the explicit route hop. 934 2.3.7.9. Unnumbered Interface ID Backup ERO Sub-TLV 936 The Unnumbered Interface-ID Backup ERO Sub-TLV has following format: 938 0 1 2 3 939 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 1 940 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 941 | Type | Length | 942 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 943 | Flags | Reserved | 944 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 945 // Router ID (IPv4, 4 octet or IPv6, 16 octets) // 946 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 947 | Interface ID | 948 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 950 Unnumbered Interface ID Backup ERO Sub-TLV format 952 where: 954 Type: TBD, suggested value 1168. 956 Length: Variable (12 for IPv4 Router-ID or 24 for IPv6 Router-ID). 958 Flags: 1 octet of flags as defined in: 959 [I-D.ietf-isis-segment-routing-extensions], 960 [I-D.ietf-ospf-segment-routing-extensions] and 961 [I-D.ietf-ospf-ospfv3-segment-routing-extensions]. 963 Router-ID: Router-ID of the next-hop. 965 Interface ID: Identifier assigned to the link by the router 966 specified by the Router-ID. 968 2.4. Equivalent IS-IS Segment Routing TLVs/Sub-TLVs 970 This section illustrate the IS-IS Segment Routing Extensions TLVs and 971 Sub-TLVs mapped to the ones defined in this document. 973 The following table, illustrates for each BGP-LS TLV, its equivalence 974 in IS-IS. 976 +-----------+------------------------------+----------+-------------+ 977 | TLV Code | Description | Length | IS-IS TLV | 978 | Point | | | /Sub-TLV | 979 +-----------+------------------------------+----------+-------------+ 980 | 1034 | SR Capabilities | variable | 2 [1] | 981 | 1035 | SR Algorithm | variable | 19 [2] | 982 | 1099 | Adjacency Segment Identifier | variable | 31 [3] | 983 | | (Adj-SID) TLV | | | 984 | 1100 | LAN Adjacency Segment | variable | 32 [4] | 985 | | Identifier (LAN-Adj-SID) TLV | | | 986 | 1158 | Prefix SID | variable | 3 [5] | 987 | 1160 | Binding SID | variable | 149 [6] | 988 | 1161 | SID/Label TLV | variable | 1 [7] | 989 | 1162 | ERO Metric TLV | 4 octets | 10 [8] | 990 | 1163 | IPv4 ERO TLV | 5 octets | 11 [9] | 991 | 1164 | IPv6 ERO TLV | 17 | 12 [10] | 992 | | | octets | | 993 | 1165 | Unnumbered Interface ID ERO | variable | 13 [11] | 994 | | TLV | | | 995 | 1166 | IPv4 Backup ERO TLV | 5 octets | 14 [12] | 996 | 1167 | IPv6 Backup ERO TLV | 17 | 15 [13] | 997 | | | octets | | 998 | 1168 | Unnumbered Interface ID | variable | 16 [14] | 999 | | Backup ERO TLV | | | 1000 | 1169 | IPv6 Prefix SID | variable | 5 [15] | 1001 | 1170 | IGP Prefix Attributes | variable | 4 [16] | 1002 | 1171 | Source Router ID | variable | 11/12 [17] | 1003 +-----------+------------------------------+----------+-------------+ 1005 Table 5: IS-IS Segment Routing Extensions TLVs/Sub-TLVs 1007 2.5. Equivalent OSPF/OSPFv3 Segment Routing TLVs/Sub-TLVs 1009 This section illustrate the OSPF and OSPFv3 Segment Routing 1010 Extensions TLVs and Sub-TLVs mapped to the ones defined in this 1011 document. 1013 The following table, illustrates for each BGP-LS TLV, its equivalence 1014 in OSPF and OSPFv3. 1016 +------------+-----------------------------+----------+-------------+ 1017 | TLV Code | Description | Length | OSPF TLV | 1018 | Point | | | /Sub-TLV | 1019 +------------+-----------------------------+----------+-------------+ 1020 | 1034 | SR Capabilities | variable | 9 [18] | 1021 | 1035 | SR Algorithm | variable | 8 [19] | 1022 | 1099 | Adjacency Segment | variable | 2 [20] | 1023 | | Identifier (Adj-SID) TLV | | | 1024 | 1100 | LAN Adjacency Segment | variable | 3 [21] | 1025 | | Identifier (Adj-SID) TLV | | | 1026 | 1158 | Prefix SID | variable | 2 [22] | 1027 | 1161 | SID/Label TLV | variable | 1 [23] | 1028 | 1162 | ERO Metric TLV | 4 octets | 8 [24] | 1029 | 1163 | IPv4 ERO TLV | 8 octets | 4 [25] | 1030 | 1165 | Unnumbered Interface ID ERO | 12 | 5 [26] | 1031 | | TLV | octets | | 1032 | 1166 | IPv4 Backup ERO TLV | 8 octets | 6 [27] | 1033 | 1167 | Unnumbered Interface ID | 12 | 7 [28] | 1034 | | Backup ERO TLV | octets | | 1035 | 1167 | Unnumbered Interface ID | 12 | 7 [29] | 1036 | | Backup ERO TLV | octets | | 1037 +------------+-----------------------------+----------+-------------+ 1039 Table 6: OSPF Segment Routing Extensions TLVs/Sub-TLVs 1041 +------------+----------------------------+----------+--------------+ 1042 | TLV Code | Description | Length | OSPFv3 TLV | 1043 | Point | | | /Sub-TLV | 1044 +------------+----------------------------+----------+--------------+ 1045 | 1034 | SR Capabilities | variable | 9 [30] | 1046 | 1035 | SR Algorithm | variable | 8 [31] | 1047 | 1099 | Adjacency Segment | variable | 5 [32] | 1048 | | Identifier (Adj-SID) TLV | | | 1049 | 1100 | LAN Adjacency Segment | variable | 6 [33] | 1050 | | Identifier (Adj-SID) TLV | | | 1051 | 1158 | Prefix SID | variable | 4 [34] | 1052 | 1161 | SID/Label TLV | variable | 3 [35] | 1053 | 1162 | ERO Metric TLV | 4 octets | 8 [36] | 1054 | 1163 | IPv4 ERO TLV | 8 octets | 9 [37] | 1055 | 1164 | IPv6 ERO TLV | 20 | 8 [38] | 1056 | | | octets | | 1057 | 1165 | Unnumbered Interface ID | 12 | 11 [39] | 1058 | | ERO TLV | octets | | 1059 | 1166 | IPv4 Backup ERO TLV | 8 octets | 12 [40] | 1060 | 1167 | IPv6 Backup ERO TLV | 20 | 13 [41] | 1061 | | | octets | | 1062 | 1167 | Unnumbered Interface ID | 12 | 14 [42] | 1063 | | Backup ERO TLV | octets | | 1064 +------------+----------------------------+----------+--------------+ 1066 Table 7: OSPFv3 Segment Routing Extensions TLVs/Sub-TLVs 1068 3. Procedures 1070 The following sections describe the different operations for the 1071 propagation of SR TLVs into BGP-LS. 1073 3.1. Advertisement of a IS-IS Prefix SID TLV 1075 The advertisement of a IS-IS Prefix SID TLV has following rules: 1077 The IS-IS Prefix-SID is encoded in the BGP-LS Prefix Attribute 1078 Prefix-SID as defined in Section 2.3.1. The flags in the Prefix- 1079 SID TLV have the semantic defined in 1080 [I-D.ietf-isis-segment-routing-extensions] section 2.1. 1082 3.2. Advertisement of a OSPF/OSPFv3 Prefix-SID TLV 1084 The advertisement of a OSPF/OSPFv3 Prefix-SID TLV has following 1085 rules: 1087 The OSPF (or OSPFv3) Prefix-SID is encoded in the BGP-LS Prefix 1088 Attribute Prefix-SID as defined in Section 2.3.1. The flags in 1089 the Prefix-SID TLV have the semantic defined in 1090 [I-D.ietf-ospf-segment-routing-extensions] section 5 or 1091 [I-D.ietf-ospf-ospfv3-segment-routing-extensions] section 5. 1093 3.3. Advertisement of a range of prefix-to-SID mappings in OSPF 1095 The advertisement of a range of prefix-to-SID mappings in OSPF has 1096 following rules: 1098 The OSPF/OSPFv3 Extended Prefix Range TLV is encoded in the BGP-LS 1099 Prefix Attribute Range TLV as defined in Section 2.3.5. The flags 1100 of the Range TLV have the semantic mapped to the definition in 1101 [I-D.ietf-ospf-segment-routing-extensions] section 4 or 1102 [I-D.ietf-ospf-ospfv3-segment-routing-extensions] section 4. The 1103 Prefix-SID from the original OSPF Prefix SID Sub-TLV is encoded 1104 using the BGP-LS Prefix Attribute Prefix-SID as defined in 1105 Section 2.3.1 with the flags set according to the definition in 1106 [I-D.ietf-ospf-segment-routing-extensions] section 5 or 1107 [I-D.ietf-ospf-ospfv3-segment-routing-extensions] section 5. 1109 3.4. Advertisement of a range of IS-IS SR bindings 1111 The advertisement of a range of IS-IS SR bindings has following 1112 rules: 1114 In IS-IS the Mapping Server binding ranges are advertised using 1115 the Binding TLV. The IS-IS Binding TLV is encoded in the BGP-LS 1116 Prefix Attribute Range TLV as defined in Section 2.3.5 using the 1117 Binding Sub-TLV as defined in Section 2.3.6. The flags in the 1118 Range TLV are all set to zero on transmit and ignored on 1119 reception. The range value from the original IS-IS Binding TLV is 1120 encoded in the Range TLV "Range" field. 1122 3.5. Advertisement of a path and its attributes from IS-IS protocol 1124 The advertisement of a Path and its attributes is described in 1125 [I-D.ietf-isis-segment-routing-extensions] section 2.4 and has 1126 following rules: 1128 The original Binding SID TLV (from IS-IS) is encoded into the BGP- 1129 LS Range TLV defined in Section 2.3.5 using the Binding Sub-TLV as 1130 defined in Section 2.3.6. The set of Sub-TLVs from the original 1131 IS-IS Binding TLV are encoded as Sub-TLVs of the BGP-LS Binding 1132 TLV as defined in Section 2.3.6. This includes the SID/Label TLV 1133 defined in Section 2.3. 1135 3.6. Advertisement of a path and its attributes from OSPFv2/OSPFv3 1136 protocol 1138 The advertisement of a Path and its attributes is described in 1139 [I-D.ietf-ospf-segment-routing-extensions] section 6 and 1140 [I-D.ietf-ospf-ospfv3-segment-routing-extensions] section 6 and has 1141 following rules: 1143 Advertisement of a path for a single prefix: the original Binding 1144 SID TLV (from OSPFv2/OSPFv3) is encoded into the BGP-LS Prefix 1145 Attribute Binding TLV as defined in Section 2.3.6. The set of 1146 Sub-TLVs from the original OSPFv2/OSPFv3 Binding TLV are encoded 1147 as Sub-TLVs of the BGP-LS Binding TLV as defined in Section 2.3.6. 1148 This includes the SID/Label TLV defined in Section 2.3. 1150 Advertisement of an SR path for range of prefixes: the OSPF/OSPFv3 1151 Extended Prefix Range TLV is encoded in the BGP-LS Prefix 1152 Attribute Range TLV as defined in Section 2.3.5. The original 1153 OSPFv2/OSPFv3 Binding SID TLV is encoded into the BGP-LS Binding 1154 Sub-TLV as defined in Section 2.3.6. The set of Sub-TLVs from the 1155 original OSPFv2/OSPFv3 Binding TLV are encoded as Sub-TLVs of the 1156 BGP-LS Binding TLV as defined in Section 2.3.6. This includes the 1157 SID/Label TLV defined in Section 2.3. 1159 4. Implementation Status 1161 Note to RFC Editor: Please remove this section prior to publication, 1162 as well as the reference to RFC 7942. 1164 This section records the status of known implementations of the 1165 protocol defined by this specification at the time of posting of this 1166 Internet-Draft, and is based on a proposal described in [RFC7942]. 1167 The description of implementations in this section is intended to 1168 assist the IETF in its decision processes in progressing drafts to 1169 RFCs. Please note that the listing of any individual implementation 1170 here does not imply endorsement by the IETF. Furthermore, no effort 1171 has been spent to verify the information presented here that was 1172 supplied by IETF contributors. This is not intended as, and must not 1173 be construed to be, a catalog of available implementations or their 1174 features. Readers are advised to note that other implementations may 1175 exist. 1177 According to [RFC7942], "this will allow reviewers and working groups 1178 to assign due consideration to documents that have the benefit of 1179 running code, which may serve as evidence of valuable experimentation 1180 and feedback that have made the implemented protocols more mature. 1181 It is up to the individual working groups to use this information as 1182 they see fit". 1184 Several early implementations exist and will be reported in detail in 1185 a forthcoming version of this document. For purposes of early 1186 interoperability testing, when no FCFS code point was available, 1187 implementations have made use of the values described in Table 8. 1189 It will ease implementation interoperability and deployment if the 1190 value could be preserved also due to the large amount of codepoints 1191 this draft requires. However, when IANA-assigned values are 1192 available, implementations will be updated to use them. 1194 5. IANA Considerations 1196 This document requests assigning code-points from the registry for 1197 BGP-LS attribute TLVs based on table Table 8. 1199 5.1. TLV/Sub-TLV Code Points Summary 1201 This section contains the global table of all TLVs/Sub-TLVs defined 1202 in this document. 1204 +-----------+--------------------------+----------+-----------------+ 1205 | TLV Code | Description | Length | Section | 1206 | Point | | | | 1207 +-----------+--------------------------+----------+-----------------+ 1208 | 1034 | SR Capabilities | variable | Section 2.1.1 | 1209 | 1035 | SR Algorithm | variable | Section 2.1.2 | 1210 | 1036 | SR Local Block | variable | Section 2.1.3 | 1211 | 1037 | SRMS Preference | variable | Section 2.1.4 | 1212 | 1099 | Adjacency Segment | variable | Section 2.2.1 | 1213 | | Identifier (Adj-SID) TLV | | | 1214 | 1100 | LAN Adjacency Segment | variable | Section 2.2.2 | 1215 | | Identifier (Adj-SID) TLV | | | 1216 | 1158 | Prefix SID | variable | Section 2.3.1 | 1217 | 1159 | Range | variable | Section 2.3.5 | 1218 | 1160 | Binding SID | variable | Section 2.3.6 | 1219 | 1161 | SID/Label TLV | variable | Section 2.3.7.2 | 1220 | 1162 | ERO Metric TLV | 4 octets | 1 [43] | 1221 | 1163 | IPv4 ERO TLV | 8 octets | 1 [44] | 1222 | 1164 | IPv6 ERO TLV | 20 | 1 [45] | 1223 | | | octets | | 1224 | 1165 | Unnumbered Interface ID | 12 | 1 [46] | 1225 | | ERO TLV | octets | | 1226 | 1166 | IPv4 Backup ERO TLV | 8 octets | 1 [47] | 1227 | 1167 | IPv6 Backup ERO TLV | 20 | 1 [48] | 1228 | | | octets | | 1229 | 1168 | Unnumbered Interface ID | 12 | 1 [49] | 1230 | | Backup ERO TLV | octets | | 1231 | 1169 | IPv6 Prefix SID | variable | Section 2.3.2 | 1232 | 1170 | IGP Prefix Attributes | variable | Section 2.3.3 | 1233 | 1171 | Source Router-ID | variable | Section 2.3.4 | 1234 +-----------+--------------------------+----------+-----------------+ 1236 Table 8: Summary Table of TLV/Sub-TLV Codepoints 1238 6. Manageability Considerations 1240 This section is structured as recommended in [RFC5706]. 1242 6.1. Operational Considerations 1244 6.1.1. Operations 1246 Existing BGP and BGP-LS operational procedures apply. No additional 1247 operation procedures are defined in this document. 1249 7. Security Considerations 1251 Procedures and protocol extensions defined in this document do not 1252 affect the BGP security model. See the 'Security Considerations' 1253 section of [RFC4271] for a discussion of BGP security. Also refer to 1254 [RFC4272] and [RFC6952] for analysis of security issues for BGP. 1256 8. Contributors 1258 The following people have substantially contributed to the editing of 1259 this document: 1261 Acee Lindem 1262 Cisco Systems 1263 Email: acee@cisco.com 1265 Saikat Ray 1266 Individual 1267 Email: raysaikat@gmail.com 1269 9. Acknowledgements 1271 The authors would like to thank Les Ginsberg and Ketan Jivan 1272 Talaulikar for their review of this document. 1274 10. References 1276 10.1. Normative References 1278 [I-D.ietf-isis-segment-routing-extensions] 1279 Previdi, S., Filsfils, C., Bashandy, A., Gredler, H., 1280 Litkowski, S., Decraene, B., and j. jefftant@gmail.com, 1281 "IS-IS Extensions for Segment Routing", draft-ietf-isis- 1282 segment-routing-extensions-09 (work in progress), October 1283 2016. 1285 [I-D.ietf-ospf-ospfv3-segment-routing-extensions] 1286 Psenak, P., Previdi, S., Filsfils, C., Gredler, H., 1287 Shakir, R., Henderickx, W., and J. Tantsura, "OSPFv3 1288 Extensions for Segment Routing", draft-ietf-ospf-ospfv3- 1289 segment-routing-extensions-07 (work in progress), October 1290 2016. 1292 [I-D.ietf-ospf-segment-routing-extensions] 1293 Psenak, P., Previdi, S., Filsfils, C., Gredler, H., 1294 Shakir, R., Henderickx, W., and J. Tantsura, "OSPF 1295 Extensions for Segment Routing", draft-ietf-ospf-segment- 1296 routing-extensions-10 (work in progress), October 2016. 1298 [I-D.previdi-isis-ipv6-prefix-sid] 1299 Previdi, S., Ginsberg, L., and C. Filsfils, "Segment 1300 Routing IPv6 Prefix-SID", draft-previdi-isis-ipv6-prefix- 1301 sid-03 (work in progress), November 2016. 1303 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 1304 Requirement Levels", BCP 14, RFC 2119, 1305 DOI 10.17487/RFC2119, March 1997, 1306 . 1308 [RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A 1309 Border Gateway Protocol 4 (BGP-4)", RFC 4271, 1310 DOI 10.17487/RFC4271, January 2006, 1311 . 1313 [RFC7684] Psenak, P., Gredler, H., Shakir, R., Henderickx, W., 1314 Tantsura, J., and A. Lindem, "OSPFv2 Prefix/Link Attribute 1315 Advertisement", RFC 7684, DOI 10.17487/RFC7684, November 1316 2015, . 1318 [RFC7752] Gredler, H., Ed., Medved, J., Previdi, S., Farrel, A., and 1319 S. Ray, "North-Bound Distribution of Link-State and 1320 Traffic Engineering (TE) Information Using BGP", RFC 7752, 1321 DOI 10.17487/RFC7752, March 2016, 1322 . 1324 [RFC7794] Ginsberg, L., Ed., Decraene, B., Previdi, S., Xu, X., and 1325 U. Chunduri, "IS-IS Prefix Attributes for Extended IPv4 1326 and IPv6 Reachability", RFC 7794, DOI 10.17487/RFC7794, 1327 March 2016, . 1329 10.2. Informative References 1331 [I-D.ietf-spring-segment-routing] 1332 Filsfils, C., Previdi, S., Decraene, B., Litkowski, S., 1333 and R. Shakir, "Segment Routing Architecture", draft-ietf- 1334 spring-segment-routing-10 (work in progress), November 1335 2016. 1337 [RFC4272] Murphy, S., "BGP Security Vulnerabilities Analysis", 1338 RFC 4272, DOI 10.17487/RFC4272, January 2006, 1339 . 1341 [RFC5706] Harrington, D., "Guidelines for Considering Operations and 1342 Management of New Protocols and Protocol Extensions", 1343 RFC 5706, DOI 10.17487/RFC5706, November 2009, 1344 . 1346 [RFC6952] Jethanandani, M., Patel, K., and L. Zheng, "Analysis of 1347 BGP, LDP, PCEP, and MSDP Issues According to the Keying 1348 and Authentication for Routing Protocols (KARP) Design 1349 Guide", RFC 6952, DOI 10.17487/RFC6952, May 2013, 1350 . 1352 [RFC7942] Sheffer, Y. and A. Farrel, "Improving Awareness of Running 1353 Code: The Implementation Status Section", BCP 205, 1354 RFC 7942, DOI 10.17487/RFC7942, July 2016, 1355 . 1357 10.3. URIs 1359 [1] http://tools.ietf.org/html/draft-ietf-isis-segment-routing- 1360 extensions-05#section-3.1 1362 [2] http://tools.ietf.org/html/draft-ietf-isis-segment-routing- 1363 extensions-05#section-3.2 1365 [3] http://tools.ietf.org/html/draft-ietf-isis-segment-routing- 1366 extensions-05#section-2.2.1 1368 [4] http://tools.ietf.org/html/draft-ietf-isis-segment-routing- 1369 extensions-05#section-2.2.2 1371 [5] http://tools.ietf.org/html/draft-ietf-isis-segment-routing- 1372 extensions-05#section-2.1 1374 [6] http://tools.ietf.org/html/draft-ietf-isis-segment-routing- 1375 extensions-05#section-2.4 1377 [7] http://tools.ietf.org/html/draft-ietf-isis-segment-routing- 1378 extensions-05#section-2.3 1380 [8] http://tools.ietf.org/html/draft-ietf-isis-segment-routing- 1381 extensions-05#section-2.4.7 1383 [9] http://tools.ietf.org/html/draft-ietf-isis-segment-routing- 1384 extensions-05#section-2.4.8 1386 [10] http://tools.ietf.org/html/draft-ietf-isis-segment-routing- 1387 extensions-05#section-2.4.9 1389 [11] http://tools.ietf.org/html/draft-ietf-isis-segment-routing- 1390 extensions-05#section-2.4.10 1392 [12] http://tools.ietf.org/html/draft-ietf-isis-segment-routing- 1393 extensions-05#section-2.4.11 1395 [13] http://tools.ietf.org/html/draft-ietf-isis-segment-routing- 1396 extensions-05#section-2.4.12 1398 [14] http://tools.ietf.org/html/draft-ietf-isis-segment-routing- 1399 extensions-05#section-2.4.13 1401 [15] http://tools.ietf.org/html/draft-previdi-isis-ipv6-prefix-sid-01 1403 [16] http://tools.ietf.org/html/RFC7794 1405 [17] http://tools.ietf.org/html/RFC7794 1407 [18] http://tools.ietf.org/html/draft-ietf-ospf-segment-routing- 1408 extensions-05#section-3.2 1410 [19] http://tools.ietf.org/html/draft-ietf-ospf-segment-routing- 1411 extensions-05#section-3.1 1413 [20] http://tools.ietf.org/html/draft-ietf-ospf-segment-routing- 1414 extensions-05#section-7.1 1416 [21] http://tools.ietf.org/html/draft-ietf-ospf-segment-routing- 1417 extensions-05#section-7.2 1419 [22] http://tools.ietf.org/html/draft-ietf-ospf-segment-routing- 1420 extensions-05#section-5 1422 [23] http://tools.ietf.org/html/draft-ietf-ospf-segment-routing- 1423 extensions-05#section-2.1 1425 [24] http://tools.ietf.org/html/draft-ietf-ospf-segment-routing- 1426 extensions-05#section-6.1 1428 [25] http://tools.ietf.org/html/draft-ietf-ospf-segment-routing- 1429 extensions-05#section-6.2.1 1431 [26] http://tools.ietf.org/html/draft-ietf-ospf-segment-routing- 1432 extensions-05#section-6.2.2 1434 [27] http://tools.ietf.org/html/draft-ietf-ospf-segment-routing- 1435 extensions-05#section-6.2.3 1437 [28] http://tools.ietf.org/html/draft-ietf-ospf-segment-routing- 1438 extensions-05#section-6.2.4 1440 [29] http://tools.ietf.org/html/draft-ietf-ospf-segment-routing- 1441 extensions-05#section-6.2.4 1443 [30] http://tools.ietf.org/html/draft-ietf-ospf-ospfv3-segment- 1444 routing-extensions-05#section-3.2 1446 [31] http://tools.ietf.org/html/draft-ietf-ospf-ospfv3-segment- 1447 routing-extensions-05#section-3.1 1449 [32] http://tools.ietf.org/html/draft-ietf-ospf-ospfv3-segment- 1450 routing-extensions-05#section-7.1 1452 [33] http://tools.ietf.org/html/draft-ietf-ospf-ospfv3-segment- 1453 routing-extensions-05#section-7.2 1455 [34] http://tools.ietf.org/html/draft-ietf-ospf-ospfv3-segment- 1456 routing-extensions-05#section-5 1458 [35] http://tools.ietf.org/html/draft-ietf-ospf-ospfv3-segment- 1459 routing-extensions-05#section-2.1 1461 [36] http://tools.ietf.org/html/draft-ietf-ospf-ospfv3-segment- 1462 routing-extensions-05#section-6.1 1464 [37] http://tools.ietf.org/html/draft-ietf-ospf-ospfv3-segment- 1465 routing-extensions-05#section-6.2.1 1467 [38] http://tools.ietf.org/html/draft-ietf-ospf-ospfv3-segment- 1468 routing-extensions-05#section-6.2.2 1470 [39] http://tools.ietf.org/html/draft-ietf-ospf-ospfv3-segment- 1471 routing-extensions-05#section-6.2.3 1473 [40] http://tools.ietf.org/html/draft-ietf-ospf-ospfv3-segment- 1474 routing-extensions-05#section-6.2.4 1476 [41] http://tools.ietf.org/html/draft-ietf-ospf-ospfv3-segment- 1477 routing-extensions-05#section-6.2.5 1479 [42] http://tools.ietf.org/html/draft-ietf-ospf-ospfv3-segment- 1480 routing-extensions-05#section-6.2.6 1482 [43] http://tools.ietf.org/html/draft-ietf-isis-segment-routing- 1483 extensions-05#section-2.4.7 1485 [44] http://tools.ietf.org/html/draft-ietf-isis-segment-routing- 1486 extensions-05#section-2.4.8 1488 [45] http://tools.ietf.org/html/draft-ietf-isis-segment-routing- 1489 extensions-05#section-2.4.9 1491 [46] http://tools.ietf.org/html/draft-ietf-isis-segment-routing- 1492 extensions-05#section-2.4.10 1494 [47] http://tools.ietf.org/html/draft-ietf-isis-segment-routing- 1495 extensions-05#section-2.4.11 1497 [48] http://tools.ietf.org/html/draft-ietf-isis-segment-routing- 1498 extensions-05#section-2.4.12 1500 [49] http://tools.ietf.org/html/draft-ietf-isis-segment-routing- 1501 extensions-05#section-2.4.13 1503 Authors' Addresses 1505 Stefano Previdi (editor) 1506 Cisco Systems, Inc. 1507 Via Del Serafico, 200 1508 Rome 00142 1509 Italy 1511 Email: sprevidi@cisco.com 1513 Peter Psenak 1514 Cisco Systems, Inc. 1515 Apollo Business Center 1516 Mlynske nivy 43 1517 Bratislava 821 09 1518 Slovakia 1520 Email: ppsenak@cisco.com 1522 Clarence Filsfils 1523 Cisco Systems, Inc. 1524 Brussels 1525 Belgium 1527 Email: cfilsfil@cisco.com 1529 Hannes Gredler 1530 RtBrick Inc. 1532 Email: hannes@rtbrick.com 1533 Mach(Guoyi) Chen 1534 Huawei Technologies 1535 Huawei Building, No. 156 Beiqing Rd. 1536 Beijing 100095 1537 China 1539 Email: mach.chen@huawei.com 1541 Jeff Tantsura 1542 Individual 1544 Email: jefftant@gmail.com