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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Networking Working Group R. Chen 3 Internet-Draft Zh. Zhang 4 Intended status: Standards Track ZTE Corporation 5 Expires: November 19, 2020 V. Govindan 6 IJ. Wijnands 7 Cisco 8 May 18, 2020 10 BGP Link-State extensions for BIER 11 draft-ietf-bier-bgp-ls-bier-ext-07 13 Abstract 15 Bit Index Explicit Replication (BIER) is an architecture that 16 provides optimal multicast forwarding through a "BIER domain" without 17 requiring intermediate routers to maintain any multicast related per- 18 flow state. BIER also does not require any explicit tree-building 19 protocol for its operation. A multicast data packet enters a BIER 20 domain at a "Bit-Forwarding Ingress Router" (BFIR), and leaves the 21 BIER domain at one or more "Bit-Forwarding Egress Routers" (BFERs). 22 The BFIR router adds a BIER header to the packet. The BIER header 23 contains a bitstring in which each bit represents exactly one BFER to 24 forward the packet to. The set of BFERs to which the multicast 25 packet needs to be forwarded is expressed by setting the bits that 26 correspond to those routers in the BIER header. 28 This document specifies extensions to the BGP Link-state address- 29 family in order to advertise BIER information. 31 Status of This Memo 33 This Internet-Draft is submitted in full conformance with the 34 provisions of BCP 78 and BCP 79. 36 Internet-Drafts are working documents of the Internet Engineering 37 Task Force (IETF). Note that other groups may also distribute 38 working documents as Internet-Drafts. The list of current Internet- 39 Drafts is at https://datatracker.ietf.org/drafts/current/. 41 Internet-Drafts are draft documents valid for a maximum of six months 42 and may be updated, replaced, or obsoleted by other documents at any 43 time. It is inappropriate to use Internet-Drafts as reference 44 material or to cite them other than as "work in progress." 46 This Internet-Draft will expire on November 19, 2020. 48 Copyright Notice 50 Copyright (c) 2020 IETF Trust and the persons identified as the 51 document authors. All rights reserved. 53 This document is subject to BCP 78 and the IETF Trust's Legal 54 Provisions Relating to IETF Documents 55 (https://trustee.ietf.org/license-info) in effect on the date of 56 publication of this document. Please review these documents 57 carefully, as they describe your rights and restrictions with respect 58 to this document. Code Components extracted from this document must 59 include Simplified BSD License text as described in Section 4.e of 60 the Trust Legal Provisions and are provided without warranty as 61 described in the Simplified BSD License. 63 Table of Contents 65 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 66 2. Conventions used in this document . . . . . . . . . . . . . . 3 67 3. BGP-LS Extensions for BIER . . . . . . . . . . . . . . . . . 3 68 3.1. Prefix Attributes TLVs . . . . . . . . . . . . . . . . . 3 69 3.1.1. The BIER information TLV . . . . . . . . . . . . . . 4 70 3.1.2. The BIER MPLS Encapsulation TLV . . . . . . . . . . . 5 71 3.1.3. The BIER Ethernet Encapsulation TLV . . . . . . . . . 6 72 4. Equivalent IS-IS BIER TLVs/Sub-TLVs . . . . . . . . . . . . . 7 73 5. Equivalent OSPFv2/OSPFV3 BIER TLVs/Sub-TLVs . . . . . . . . . 7 74 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 75 7. Security Considerations . . . . . . . . . . . . . . . . . . . 8 76 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 9 77 9. Normative references . . . . . . . . . . . . . . . . . . . . 9 78 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10 80 1. Introduction 82 Bit Index Explicit Replication (BIER) is an architecture that 83 provides optimal multicast forwarding through a "BIER domain" without 84 requiring intermediate routers to maintain any multicast related per- 85 flow state. BIER also does not require any explicit tree-building 86 protocol for its operation. A multicast data packet enters a BIER 87 domain at a "Bit-Forwarding Ingress Router" (BFIR), and leaves the 88 BIER domain at one or more "Bit-Forwarding Egress Routers" (BFERs). 89 The BFIR router adds a BIER header to the packet. The BIER header 90 contains a bitstring in which each bit represents exactly one BFER to 91 forward the packet to. The set of BFERs to which the multicast 92 packet needs to be forwarded is expressed by setting the bits that 93 correspond to those routers in the BIER header. 95 When BIER is enabled in an IGP domain, BIER-related information will 96 be advertised via IGP link-state routing protocols. IGP extensions 97 are described in: ISIS[[RFC8401]],OSPFv2[[RFC8444]] and 98 OSPFv3[[I-D.ietf-bier-ospfv3-extensions]].The contents of a Link 99 State Database (LSDB) or of an IGP's Traffic Engineering Database 100 (TED) has the scope of an IGP area and therefore, by using the IGP 101 alone it is not enough to construct segments across multiple IGP Area 102 or AS boundaries. 104 In order to satisfy the need for applications that require 105 topological visibility across one area or Autonomous System (AS). 106 This document specifies extensions to the BGP Link-state address- 107 family in order to advertise BIER-specific. An external component 108 (e.g., a controller) then can collect BIER information in the 109 "northbound" direction within the BIER domain. 111 2. Conventions used in this document 113 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 114 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 115 document are to be interpreted as described in RFC2119. 117 3. BGP-LS Extensions for BIER 119 [RFC8279] defines the BFR - A router that supports BIER is known as a 120 "Bit-Forwarding Router"(BFR), and each BFR MUST be assigned a "BFR- 121 Prefix". A BFR's BFR-Prefix MUST be an IP address (either IPv4 or 122 IPv6) of the BFR, and MUST be unique and routable within the BIER 123 domain as described in section 2 of [RFC8279], and then external 124 component (e.g., a controller) need to collect BIER information of 125 BIER routers are associated with the BFR-Prefix in the "northbound" 126 direction within the BIER domain. 128 Given that the BIER information is associated with the prefix, the 129 Prefix Attribute TLV [RFC7752] can be used to carry the BIER 130 information. A new Prefix Attribute TLVs are defined for the 131 encoding of BIER information. 133 3.1. Prefix Attributes TLVs 135 The following Prefix Attribute TLVs are defined: 137 +------+---------------------------+---------------+ 138 | Type | Description | Section | 139 +------+---------------------------+---------------+ 140 | TBD |BIER information | Section 3.1.1 | 141 | TBD |BIER MPLS Encapsulation | Section 3.1.2 | 142 | TBD |BIER Ethernet Encapsulation| Section 3.1.2 | 143 +------+---------------------------+---------------+ 145 Table 1:The new Prefix Attribute TLVs 147 3.1.1. The BIER information TLV 149 A new Prefix Attribute TLV (defined in [RFC7752] is defined for 150 distributing BIER information. The new TLV is called the BIER TLV. 151 The BIER information TLVs may appear multiple times. 153 The following BIER information TLV is defined: 155 0 1 2 3 156 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 1 157 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 158 | Type | Length | 159 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 160 | BAR | IPA | subdomain-id | 161 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 162 | BFR-id | 163 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 164 | Sub-TLVs (variable) | 165 +- -+ 166 | | 168 Figure 2: The BIER information TLV 170 Type: 2 octet field with value TBD, see IANA Considerations section. 172 Length: 2 octet. 174 Reserved: MUST be 0 on transmission, ignored on reception. May be 175 used in future versions. 177 BAR: A 1 octet field encoding the BIER Algorithm, used to calculate 178 underlay paths to reach BFERs. Values are allocated from the "BIER 179 Algorithms" registry which is defined in [RFC8401]. 181 IPA: A 1 octet field encoding the IGP Algorithm, used to either 182 modify,enhance, or replace the calculation of underlay paths to reach 183 BFERs as defined by the BAR value. Values are from the IGP Algorithm 184 registry. 186 Subdomain-id: Unique value identifying the BIER sub-domain, 1 octet. 188 MT-ID: Multi-Topology ID that identifies the topology that is 189 associated with the BIER sub-domain.1 octet. 191 BFR-id: A 2 octet field encoding the BFR-id, as documented in 192 [RFC8279]. If the BFR-id is zero, it means, the advertising router 193 is not advertising any BIER-id.In some environment, BFR-id can be 194 configured by NMS, The BFR-id should be sent to a controller. 196 BS Length: A 1 octet field encoding the Bitstring length as per 197 [RFC8296]. 199 If the MT-ID value is outside of the values specified in [RFC4915], 200 the BIER Sub-TLV MUST be ignored. 202 3.1.2. The BIER MPLS Encapsulation TLV 204 The BIER MPLS Encapsulation TLV is used in order to advertise MPLS 205 specific information used for BIER. It MAY appear multiple times. 207 In some environment, each router allocates its labels, and advertises 208 it to the controller.That solution is simpler as the controller does 209 not need to deal with label allocation. If the controller has to 210 deal with Label allocation , there needs to be a (global) range 211 carved out such there are no conflicts. We can avoid all that by 212 having the router allocate the BIER Label range and advertise it to 213 the controller. 215 The following the BIER MPLS Encapsulation Sub-TLV is defined: 217 0 1 2 3 218 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 1 219 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 220 | Type | Length | 221 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 222 | Max SI | Label | 223 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 224 |BS Len | Reserved | 225 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 227 Figure 3: The BIER MPLS Encapsulation TLV 229 Type: 2 octet field with value TBD, see IANA Considerations section. 231 Length: 2 octet. 233 Max SI: A 1 octet field encoding the maximum Set Identifier(as 234 defined in [RFC8279]), used in the encapsulation for this BIER 235 subdomain for this BitString length. 237 Label: A 3 octet field, where the 20 rightmost bits represent the 238 first label in the label range. 240 BS Length: A 1 octet field encoding the Bitstring length as per 241 [RFC8296] 243 BS length in multiple BIER MPLS Encapsulation Sub-TLV inside the same 244 BIER Sub-TLV MUST NOT repeat, otherwise only the first BIER MPLS 245 Encapsulation Sub-TLV with such BS length MUST be used and any 246 subsequent BIER MPLS Encapsulation Sub-TLVs with the same BS length 247 MUST be ignored. 249 3.1.3. The BIER Ethernet Encapsulation TLV 251 The BIER Ethernet Encapsulation TLV is used in order to advertise 252 ethernet encapsulation capability and other associated parameters of 253 the encapsulation.It MAY appear multiple times. 255 The following the BIER Ethernet Encapsulation Sub-TLV is defined: 257 0 1 2 3 258 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 1 259 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 260 | Type | Length | 261 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 262 | Max SI | BIFT-id | 263 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 264 |BS Len | Reserved | 265 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 267 Figure 4: The BIER Ethernet Encapsulation TLV 269 Type:2 octet field with value TBD, see IANA Considerations section. 271 Length: 2 octet.. 273 Max SI:A 1 octet field encoding the maximum Set Identifier(as defined 274 in [RFC8279]), used in the encapsulation for this BIER subdomain for 275 this BitString length. 277 BIFT-id:A 3-octet field, where the 20 rightmost bits represent the 278 first BIFT-id in the BIFT-id range. The 4 leftmost bits MUST be 279 ignored. 281 The "BIFT-id range" is the set of 20-bit values beginning with the 282 BIFT-id and ending with (BIFT-id + (Max SI)). A unique BIFT-id range 283 is allocated for each BitString length and sub-domain-id. These 284 BIFT-id's are used for BIER forwarding as described in [RFC8279])and 285 [RFC8296]. 287 Local BitString Length (BS Len): A 4 bit field encoding the Bitstring 288 length as per [RFC8296]. 290 Reserved:SHOULD be set to 0 on transmission and MUST be ignored on 291 reception. 293 4. Equivalent IS-IS BIER TLVs/Sub-TLVs 295 This section illustrate the BIER TLVs mapped to the ones defined in 296 this document. 298 The following table, illustrates for each BGP-LS TLV, its equivalence 299 in IS-IS. 301 +--------------+---------------------------+------------------------------------------+ 302 | Descriptio | IS-IS TLV | Reference | 303 | n | /Sub-TLV | | 304 +--------------+---------------------------+------------------------------------------+ 305 | BIER | BIER Info Sub-TLV | [RFC8401] | 306 | information | | | 307 | | | | 308 | BIER MPLS |BIER MPLS Encapsulation | [RFC8401] | 309 | Encapsulation|Sub-Sub-TLV | | 310 | | | | 311 | BIER Ethernet| BIER Etherne Encapsulation| [I-D.ietf-bier-lsr-ethernet-extensions] | 312 | Encapsulation| Sub-Sub-TLV | | 313 +--------------+---------------------------+------------------------------------------+ 315 Table 2:IS-IS BIER Sub-TLVs/Sub-Sub-TLVs 317 5. Equivalent OSPFv2/OSPFV3 BIER TLVs/Sub-TLVs 319 This section illustrate the BIER TLVs mapped to the ones defined in 320 this document. 322 The following table, illustrates for each BGP-LS TLV, its equivalence 323 in OSPFv2/OSPFV3. 325 +--------------+----------------------------+-----------------------------------------+ 326 | Descriptio | OSPFv2/OSPFV3 sub-TLV | Reference | 327 | n | /Sub-Sub-TLV | | 328 +--------------+----------------------------+-----------------------------------------+ 329 | BIER | BIER Sub-TLV |[RFC8444] & | 330 | information | |[I-D. ietf-bier-ospfv3-extensions | 331 | | | | 332 | BIER MPLS |BIER MPLS Encapsulation |[RFC8444]& | 333 | Encapsulation|Sub-TLV |[I-D. ietf-bier-ospfv3-extensions | 334 | | | | 335 | BIER Ethernet| BIER Etherne Encapsulation |[I-D.ietf-bier-lsr-ethernet-extensions] | 336 | Encapsulation| Sub-TLV | | 337 +--------------+----------------------------+-----------------------------------------+ 339 Table 3: OSPFv2/OSPFV3 BIER TLVs/Sub-TLVs 341 6. IANA Considerations 343 This document requests assigning code-points from the registry for 344 the new Prefix Attribute TLVs. 346 +-------------------+----------------------------+-----------------+ 347 | TLV Code Point | Description | Value defined | 348 +-------------------+----------------------------+-----------------+ 349 | TBD | BIER information | this document | 350 +-------------------+----------------------------+-----------------+ 351 | TBD | BIER MPLS Encapsulation | this document | 352 +-------------------+----------------------------+-----------------+ 353 | TBD | BIER Etherne Encapsulation | this document | 354 +-------------------+----------------------------+-----------------+ 356 Table 4: The new Prefix Attribute TLV 358 7. Security Considerations 360 Procedures and protocol extensions defined in this document do not 361 affect the BGP security model. See the "Security 362 Considerations"section of [RFC4271] for a discussion of BGP security. 363 Also, refer to [RFC4272] and [RFC6952] for analyses of security 364 issues for BGP.Security considerations for acquiring and distributing 365 BGP-LS information are discussed in [RFC7752]. 367 The TLVs introduced in this document are used to propagate the Bit 368 Index Explicit Replication (BIER) defined in [[RFC8401]], [[RFC8444]] 369 , [[I-D.ietf-bier-ospfv3-extensions]] and 371 [[I-D.ietf-bier-lsr-ethernet-extensions]] . These TLVs represent the 372 bier information associated with the prefix. It is assumed that the 373 IGP instances originating these TLVs will support all the required 374 security and authentication mechanisms in [[RFC8401]], [[RFC8444]] 375 [[I-D.ietf-bier-ospfv3-extensions]] and 376 [[I-D.ietf-bier-lsr-ethernet-extensions]] in order to prevent any 377 security issues when propagating the TLVs into BGP-LS. The 378 advertisement of the link attribute information defined in this 379 document presents no additional risk beyond that associated with the 380 existing link attribute information already supported in [RFC7752]. 382 8. Acknowledgements 384 We would like to thank Peter Psenak (Cisco) and Ketan 385 Talaulikar(Cisco) for his comments and support of this work. 387 9. Normative references 389 [I-D.ietf-bier-lsr-ethernet-extensions] 390 Dhanaraj, S., Wijnands, I., Psenak, P., Zhang, Z., Yan, 391 G., and J. Xie, "LSR Extensions for BIER over Ethernet", 392 draft-ietf-bier-lsr-ethernet-extensions-01 (work in 393 progress), July 2019. 395 [I-D.ietf-bier-ospfv3-extensions] 396 Psenak, P., Kumar, N., and I. Wijnands, "OSPFv3 Extensions 397 for BIER", draft-ietf-bier-ospfv3-extensions-01 (work in 398 progress), November 2019. 400 [RFC3630] Katz, D., Kompella, K., and D. Yeung, "Traffic Engineering 401 (TE) Extensions to OSPF Version 2", RFC 3630, 402 DOI 10.17487/RFC3630, September 2003, 403 . 405 [RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A 406 Border Gateway Protocol 4 (BGP-4)", RFC 4271, 407 DOI 10.17487/RFC4271, January 2006, 408 . 410 [RFC4272] Murphy, S., "BGP Security Vulnerabilities Analysis", 411 RFC 4272, DOI 10.17487/RFC4272, January 2006, 412 . 414 [RFC4915] Psenak, P., Mirtorabi, S., Roy, A., Nguyen, L., and P. 415 Pillay-Esnault, "Multi-Topology (MT) Routing in OSPF", 416 RFC 4915, DOI 10.17487/RFC4915, June 2007, 417 . 419 [RFC6952] Jethanandani, M., Patel, K., and L. Zheng, "Analysis of 420 BGP, LDP, PCEP, and MSDP Issues According to the Keying 421 and Authentication for Routing Protocols (KARP) Design 422 Guide", RFC 6952, DOI 10.17487/RFC6952, May 2013, 423 . 425 [RFC7752] Gredler, H., Ed., Medved, J., Previdi, S., Farrel, A., and 426 S. Ray, "North-Bound Distribution of Link-State and 427 Traffic Engineering (TE) Information Using BGP", RFC 7752, 428 DOI 10.17487/RFC7752, March 2016, 429 . 431 [RFC8279] Wijnands, IJ., Ed., Rosen, E., Ed., Dolganow, A., 432 Przygienda, T., and S. Aldrin, "Multicast Using Bit Index 433 Explicit Replication (BIER)", RFC 8279, 434 DOI 10.17487/RFC8279, November 2017, 435 . 437 [RFC8296] Wijnands, IJ., Ed., Rosen, E., Ed., Dolganow, A., 438 Tantsura, J., Aldrin, S., and I. Meilik, "Encapsulation 439 for Bit Index Explicit Replication (BIER) in MPLS and Non- 440 MPLS Networks", RFC 8296, DOI 10.17487/RFC8296, January 441 2018, . 443 [RFC8401] Ginsberg, L., Ed., Przygienda, T., Aldrin, S., and Z. 444 Zhang, "Bit Index Explicit Replication (BIER) Support via 445 IS-IS", RFC 8401, DOI 10.17487/RFC8401, June 2018, 446 . 448 [RFC8444] Psenak, P., Ed., Kumar, N., Wijnands, IJ., Dolganow, A., 449 Przygienda, T., Zhang, J., and S. Aldrin, "OSPFv2 450 Extensions for Bit Index Explicit Replication (BIER)", 451 RFC 8444, DOI 10.17487/RFC8444, November 2018, 452 . 454 Authors' Addresses 456 Ran Chen 457 ZTE Corporation 458 No.50 Software Avenue,Yuhuatai District 459 Nanjing, Jiangsu Province 210012 460 China 462 Phone: +86 025 88014636 463 Email: chen.ran@zte.com.cn 464 Zheng Zhang 465 ZTE Corporation 466 No.50 Software Avenue,Yuhuatai District 467 Nanjing, Jiangsu Province 210012 468 China 470 Email: zhang.zheng@zte.com.cn 472 Vengada Prasad Govindan 473 Cisco 475 Email: venggovi@cisco.com 477 IJsbrand Wijnands 478 Cisco 479 De Kleetlaan 6a 480 Diegem 1831 481 Belgium 483 Email: ice@cisco.com