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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 BIER R. Chen 3 Internet-Draft Z. Zhang 4 Intended status: Standards Track ZTE Corporation 5 Expires: 30 December 2022 V. Govindan 6 Cisco 7 IJ. Wijnands 8 Individual 9 Z. Zhang 10 Juniper Networks 11 28 June 2022 13 BGP Link-State extensions for BIER 14 draft-ietf-bier-bgp-ls-bier-ext-12 16 Abstract 18 Bit Index Explicit Replication (BIER) is an architecture that 19 provides optimal multicast forwarding through a "BIER domain" without 20 requiring intermediate routers to maintain any multicast related per- 21 flow state. BIER also does not require any explicit tree-building 22 protocol for its operation. A multicast data packet enters a BIER 23 domain at a "Bit-Forwarding Ingress Router" (BFIR), and leaves the 24 BIER domain at one or more "Bit-Forwarding Egress Routers" (BFERs). 25 The BFIR router adds a BIER header to the packet. The BIER header 26 contains a bitstring in which each bit represents exactly one BFER to 27 forward the packet to. The set of BFERs to which the multicast 28 packet needs to be forwarded is expressed by setting the bits that 29 correspond to those routers in the BIER header. 31 BGP Link-State (BGP-LS) enables the collection of various topology 32 informations from the network, and the topology informations are used 33 by the controller to calculate the fowarding tables and then 34 propagate them onto the BFRs(instead of having each node to calculate 35 on its own) and that can be for both inter-as and intra-as 36 situations. 38 This document specifies extensions to the BGP Link-state address- 39 family in order to advertise the BIER informations. 41 Status of This Memo 43 This Internet-Draft is submitted in full conformance with the 44 provisions of BCP 78 and BCP 79. 46 Internet-Drafts are working documents of the Internet Engineering 47 Task Force (IETF). Note that other groups may also distribute 48 working documents as Internet-Drafts. The list of current Internet- 49 Drafts is at https://datatracker.ietf.org/drafts/current/. 51 Internet-Drafts are draft documents valid for a maximum of six months 52 and may be updated, replaced, or obsoleted by other documents at any 53 time. It is inappropriate to use Internet-Drafts as reference 54 material or to cite them other than as "work in progress." 56 This Internet-Draft will expire on 30 December 2022. 58 Copyright Notice 60 Copyright (c) 2022 IETF Trust and the persons identified as the 61 document authors. All rights reserved. 63 This document is subject to BCP 78 and the IETF Trust's Legal 64 Provisions Relating to IETF Documents (https://trustee.ietf.org/ 65 license-info) in effect on the date of publication of this document. 66 Please review these documents carefully, as they describe your rights 67 and restrictions with respect to this document. Code Components 68 extracted from this document must include Revised BSD License text as 69 described in Section 4.e of the Trust Legal Provisions and are 70 provided without warranty as described in the Revised BSD License. 72 Table of Contents 74 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 75 2. Requirements Language . . . . . . . . . . . . . . . . . . . . 3 76 3. BGP-LS Extensions for BIER . . . . . . . . . . . . . . . . . 3 77 3.1. Prefix Attributes TLVs . . . . . . . . . . . . . . . . . 4 78 3.1.1. The BIER information TLV . . . . . . . . . . . . . . 4 79 3.1.2. The BIER MPLS Encapsulation TLV . . . . . . . . . . . 5 80 3.1.3. The BIER non-MPLS Encapsulation TLV . . . . . . . . . 6 81 4. Equivalent IS-IS BIER TLVs/Sub-TLVs . . . . . . . . . . . . . 7 82 5. Equivalent OSPFv2/OSPFV3 BIER TLVs/Sub-TLVs . . . . . . . . . 8 83 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 84 7. Security Considerations . . . . . . . . . . . . . . . . . . . 9 85 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 9 86 9. Normative References . . . . . . . . . . . . . . . . . . . . 9 87 10. Informative references . . . . . . . . . . . . . . . . . . . 10 88 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 11 90 1. Introduction 92 Bit Index Explicit Replication (BIER) is an architecture that 93 provides optimal multicast forwarding through a "BIER domain" without 94 requiring intermediate routers to maintain any multicast related per- 95 flow state. BIER also does not require any explicit tree-building 96 protocol for its operation. A multicast data packet enters a BIER 97 domain at a "Bit-Forwarding Ingress Router" (BFIR), and leaves the 98 BIER domain at one or more "Bit-Forwarding Egress Routers" (BFERs). 99 The BFIR router adds a BIER header to the packet. The BIER header 100 contains a bitstring in which each bit represents exactly one BFER to 101 forward the packet to. The set of BFERs to which the multicast 102 packet needs to be forwarded are expressed by setting the bits that 103 correspond to those routers in the BIER header. 105 The BGP-LS address-family/sub-address-family have been defined to 106 allow BGP to carry Link-State informations. This document specifies 107 extensions to the BGP Link-state address-family in order to advertise 108 BIER-specific informations, Similar to BGP-LS Advertisement of IGP 109 Traffic Engineering Performance Metric Extensions([RFC8571]). An 110 external component (e.g., a controller/a PCE(see [RFC4655] for PCE- 111 Based Architecture ,[RFC5440] for PCEP and [RFC5376] for Inter-AS 112 Requirements for the PCEP.))then can learn the BIER informations in 113 the "northbound" direction and calculate BIRT/BIFT and then propagate 114 them onto BFRs (instead of having each BFR to calculate on its own), 115 and that can be for both inter-as and intra-as situations. 117 2. Requirements Language 119 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 120 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 121 document are to be interpreted as described in RFC 2119 [RFC2119]. 123 3. BGP-LS Extensions for BIER 125 [RFC8279] defines the BFR - A router that supports BIER is known as a 126 "Bit-Forwarding Router"(BFR), and each BFR MUST be assigned a "BFR- 127 Prefix". A BFR's Prefix MUST be an IP address (either IPv4 or IPv6) 128 of the BFR, and MUST be unique and routable within the BIER domain as 129 described in section 2 of [RFC8279], and then external component 130 (e.g., a controller) need to collect BIER informations of BIER 131 routers are associated with the BFR-Prefix in the "northbound" 132 direction within the BIER domain. 134 Given that the BIER informations are associated with the prefix, the 135 Prefix Attribute TLV [RFC7752] can be used to carry the BIER 136 informations. A new Prefix Attribute TLVs are defined for the 137 encoding of BIER informations. 139 3.1. Prefix Attributes TLVs 141 The following Prefix Attribute TLVs are defined: 143 +======+=============================+===============+ 144 | Type | Description | Section | 145 +======+=============================+===============+ 146 | TBD1 | BIER information | section 3.1.1 | 147 +------+-----------------------------+---------------+ 148 | TBD2 | BIER MPLS Encapsulation | section 3.1.2 | 149 +------+-----------------------------+---------------+ 150 | TBD3 | BIER non-MPLS Encapsulation | section 3.1.3 | 151 +------+-----------------------------+---------------+ 153 Table 1: The new Prefix Attribute TLVs 155 3.1.1. The BIER information TLV 157 A new Prefix Attribute TLV (defined in [RFC7752] is defined for 158 distributing BIER informations. The new TLV is called the BIER 159 information TLV. The BIER information TLV may appear multiple times. 161 The following BIER information TLV is defined: 163 0 1 2 3 164 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 1 165 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 166 | Type | Length | 167 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 168 | sub-domain-id | MT-ID | BFR-id | 169 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 170 | BAR | IPA | Reserved | 171 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 173 Figure 1 175 Type: A 2-octet field with value TBD, see IANA Considerations 176 section. 178 Length: 2 octets. 180 Subdomain-id: Unique value identifying the BIER sub-domain, 1 octet. 182 MT-ID: Multi-Topology ID that identifies the topology that is 183 associated with the BIER sub-domain.1 octet. 185 BFR-id: A 2-octet field encoding the BFR-id, as documented in 186 [RFC8279]. If the BFR-id is zero, it means, the advertising router 187 is not advertising any BIER-id.In some environment, BFR-id can be 188 configured by NMS, The BFR-id should be sent to a controller. 190 BAR: A 1-octet field encoding the BIER Algorithm, used to calculate 191 underlay paths to reach BFERs. Values are allocated from the "BIER 192 Algorithms" registry which is defined in [RFC8401]. 194 IPA: A 1-octet field encoding the IGP Algorithm, used to either 195 modify,enhance, or replace the calculation of underlay paths to reach 196 BFERs as defined by the BAR value. Values are from the IGP Algorithm 197 registry. 199 Reserved: MUST be 0 on transmission, ignored on reception. May be 200 used in future versions. 202 If the MT-ID value is outside of the values specified in [RFC4915], 203 the BIER Sub-TLV MUST be ignored. 205 3.1.2. The BIER MPLS Encapsulation TLV 207 The BIER MPLS Encapsulation TLV is used in order to advertise MPLS 208 specific informations used for BIER. It MAY appear multiple times. 210 In some environment, each router allocates its labels, and advertises 211 it to the controller.That solution is simpler as the controller does 212 not need to deal with label allocation. If the controller has to 213 deal with Label allocation , there needs to be a (global) range 214 carved out such there are no conflicts. We can avoid all that by 215 having the router allocate the BIER Label range and advertise it to 216 the controller. 218 The following the BIER MPLS Encapsulation Sub-TLV is defined: 220 0 1 2 3 221 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 1 222 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 223 | Type | Length | 224 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 225 | Max SI | Label | 226 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 227 |BS Len | Reserved | 228 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 230 Figure 2 232 Type: A 2-octet field with value TBD, see IANA Considerations 233 section. 235 Length: 2 octets. 237 Max SI: A 1-octet field encoding the maximum Set Identifier(as 238 defined in [RFC8279]), used in the encapsulation for this BIER 239 subdomain for this BitString length. 241 Label: A 3-octet field, where the 20 rightmost bits represent the 242 first label in the label range. 244 BS Len: A 4-bit field field encoding the Bitstring length as per 245 [RFC8296]. 247 BS length in multiple BIER MPLS Encapsulation Sub-TLV inside the same 248 BIER Sub-TLV MUST NOT repeat, otherwise only the first BIER MPLS 249 Encapsulation Sub-TLV with such BS length MUST be used and any 250 subsequent BIER MPLS Encapsulation Sub-TLVs with the same BS length 251 MUST be ignored. 253 3.1.3. The BIER non-MPLS Encapsulation TLV 255 The BIER non-MPLS Encapsulation TLV is used in order to advertise 256 non-MPLS encapsulation(e.g. ethernet encapsulation ) capability and 257 other associated parameters of the encapsulation.It MAY appear 258 multiple times. 260 The following the BIER non-MPLS Encapsulation Sub-TLV is defined: 262 0 1 2 3 263 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 1 264 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 265 | Type | Length | 266 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 267 | Max SI | BIFT-id | 268 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 269 |BS Len | Reserved | 270 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 272 Figure 3 274 Type:A 2-octet field with value TBD, see IANA Considerations section. 276 Length: 2 octets. 278 Max SI:A 1-octet field encoding the maximum Set Identifier(as defined 279 in [RFC8279]), used in the encapsulation for this BIER subdomain for 280 this BitString length. 282 BIFT-id:A 3-octet field, where the 20 rightmost bits represent the 283 first BIFT-id in the BIFT-id range. The 4 leftmost bits MUST be 284 ignored. 286 The "BIFT-id range" is the set of 20-bit values beginning with the 287 BIFT-id and ending with (BIFT-id + (Max SI)). A unique BIFT-id range 288 is allocated for each BitString length and sub-domain-id. These 289 BIFT-id's are used for BIER forwarding as described in [RFC8279])and 290 [RFC8296]. 292 Local BitString Length (BS Len): A 4-bit field encoding the Bitstring 293 length as per [RFC8296]. 295 Reserved:SHOULD be set to 0 on transmission and MUST be ignored on 296 reception. 298 4. Equivalent IS-IS BIER TLVs/Sub-TLVs 300 This section illustrates the IS-IS BIER Extensions Sub-TLVs/Sub-Sub- 301 TLVs mapped to the ones defined in this document. 303 The following table illustrates for each BGP-LS TLV, and its 304 equivalence in IS-IS. 306 +=============+=============+=======================================+ 307 | Description | IS-IS TLV/ | Reference | 308 | | Sub-TLV | | 309 +=============+=============+=======================================+ 310 | BIER | BIER info | [RFC8401] | 311 | information | Sub-TLV | | 312 +-------------+-------------+---------------------------------------+ 313 | BIER MPLS | BIER MPLS | [RFC8401] | 314 |Encapsulation|Encapsulation| | 315 | | Sub-Sub-TLV | | 316 +-------------+-------------+---------------------------------------+ 317 |BIER non-MPLS|BIER non-MPLS|[I-D.ietf-bier-lsr-non-mpls-extensions]| 318 |Encapsulation|Encapsulation| | 319 | | Sub-Sub-TLV | | 320 +-------------+-------------+---------------------------------------+ 322 Table 2: OIS-IS BIER Extensions Sub-TLVs/Sub-Sub-TLVs 324 5. Equivalent OSPFv2/OSPFV3 BIER TLVs/Sub-TLVs 326 This section illustrates the BIER Extensions TLVs/Sub-TLVs mapped to 327 the ones defined in this document. 329 The following table illustrates for each BGP-LS TLV, and its 330 equivalence in OSPFv2/OSPFV3. 332 +=============+=============+===========================================+ 333 | Description |OSPFv2/OSPFV3| Reference | 334 | | sub-TLV/Sub-| | 335 | | Sub-TLV | | 336 +=============+=============+===========================================+ 337 | BIER | BIER Sub-TLV|[RFC8444],[I-D.ietf-bier-ospfv3-extensions]| 338 | information | | | 339 +-------------+-------------+-------------------------------------------+ 340 | BIER MPLS | BIER MPLS |[RFC8444],[I-D.ietf-bier-ospfv3-extensions]| 341 |Encapsulation|Encapsulation| | 342 | | Sub-TLV | | 343 +-------------+-------------+-------------------------------------------+ 344 |BIER non-MPLS|BIER non-MPLS| [I-D.ietf-bier-lsr-non-mpls-extensions] | 345 |Encapsulation|Encapsulation| | 346 | | Sub-TLV | | 347 +-------------+-------------+-------------------------------------------+ 349 Table 3: OSPFv2/OSPFV3 BIER TLVs/Sub-TLVs 351 6. IANA Considerations 353 This document requests assigning code-points from the registry for 354 the new Prefix Attribute TLVs. 356 +================+=============================+===============+ 357 | TLV Code Point | Description | Value defined | 358 +================+=============================+===============+ 359 | TBD1 | BIER information | this document | 360 +----------------+-----------------------------+---------------+ 361 | TBD2 | BIER MPLS Encapsulation | this document | 362 +----------------+-----------------------------+---------------+ 363 | TBD3 | BIER non-MPLS Encapsulation | this document | 364 +----------------+-----------------------------+---------------+ 366 Table 4: The new Prefix Attribute TLVs 368 7. Security Considerations 370 Procedures and protocol extensions defined in this document do not 371 affect the BGP security model. See the "Security 372 Considerations"section of [RFC4271] for a discussion of BGP 373 security.Security considerations for acquiring and distributing BGP- 374 LS information are discussed in [RFC7752]. 376 The TLVs introduced in this document are used to propagate the Bit 377 Index Explicit Replication (BIER) defined in [[RFC8401]], [[RFC8444]] 378 , [[I-D.ietf-bier-ospfv3-extensions]] and 379 [[I-D.ietf-bier-lsr-non-mpls-extensions]] . These TLVs represent the 380 bier information associated with the prefix. It is assumed that the 381 IGP instances originating these TLVs will support all the required 382 security and authentication mechanisms in [[RFC8401]], [[RFC8444]] 383 [[I-D.ietf-bier-ospfv3-extensions]] and 384 [[I-D.ietf-bier-lsr-non-mpls-extensions]] in order to prevent any 385 security issues when propagating the TLVs into BGP-LS. The 386 advertisement of the link attribute information defined in this 387 document present no additional risk beyond that associated with the 388 existing link attribute informations already supported in [RFC7752]. 390 8. Acknowledgements 392 The authors thank Peter Psenak, Ketan Talaulikar, Gyan Mishra and 393 Benchong Xu and many others for their suggestions and comments. 395 9. Normative References 397 [I-D.ietf-bier-lsr-non-mpls-extensions] 398 Dhanaraj, S., Yan, G., Wijnands, I., Psenak, P., Zhang, 399 Z., and J. Xie, "LSR Extensions for BIER non-MPLS 400 Encapsulation", Work in Progress, Internet-Draft, draft- 401 ietf-bier-lsr-non-mpls-extensions-00, 1 March 2022, 402 . 405 [I-D.ietf-bier-ospfv3-extensions] 406 Psenak, P., Nainar, N. K., and I. Wijnands, "OSPFv3 407 Extensions for BIER", Work in Progress, Internet-Draft, 408 draft-ietf-bier-ospfv3-extensions-05, 19 November 2021, 409 . 412 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 413 Requirement Levels", BCP 14, RFC 2119, 414 DOI 10.17487/RFC2119, March 1997, 415 . 417 [RFC4655] Farrel, A., Vasseur, J.-P., and J. Ash, "A Path 418 Computation Element (PCE)-Based Architecture", RFC 4655, 419 DOI 10.17487/RFC4655, August 2006, 420 . 422 [RFC4915] Psenak, P., Mirtorabi, S., Roy, A., Nguyen, L., and P. 423 Pillay-Esnault, "Multi-Topology (MT) Routing in OSPF", 424 RFC 4915, DOI 10.17487/RFC4915, June 2007, 425 . 427 [RFC7752] Gredler, H., Ed., Medved, J., Previdi, S., Farrel, A., and 428 S. Ray, "North-Bound Distribution of Link-State and 429 Traffic Engineering (TE) Information Using BGP", RFC 7752, 430 DOI 10.17487/RFC7752, March 2016, 431 . 433 [RFC8279] Wijnands, IJ., Ed., Rosen, E., Ed., Dolganow, A., 434 Przygienda, T., and S. Aldrin, "Multicast Using Bit Index 435 Explicit Replication (BIER)", RFC 8279, 436 DOI 10.17487/RFC8279, November 2017, 437 . 439 [RFC8296] Wijnands, IJ., Ed., Rosen, E., Ed., Dolganow, A., 440 Tantsura, J., Aldrin, S., and I. Meilik, "Encapsulation 441 for Bit Index Explicit Replication (BIER) in MPLS and Non- 442 MPLS Networks", RFC 8296, DOI 10.17487/RFC8296, January 443 2018, . 445 [RFC8401] Ginsberg, L., Ed., Przygienda, T., Aldrin, S., and Z. 446 Zhang, "Bit Index Explicit Replication (BIER) Support via 447 IS-IS", RFC 8401, DOI 10.17487/RFC8401, June 2018, 448 . 450 [RFC8444] Psenak, P., Ed., Kumar, N., Wijnands, IJ., Dolganow, A., 451 Przygienda, T., Zhang, J., and S. Aldrin, "OSPFv2 452 Extensions for Bit Index Explicit Replication (BIER)", 453 RFC 8444, DOI 10.17487/RFC8444, November 2018, 454 . 456 [RFC8571] Ginsberg, L., Ed., Previdi, S., Wu, Q., Tantsura, J., and 457 C. Filsfils, "BGP - Link State (BGP-LS) Advertisement of 458 IGP Traffic Engineering Performance Metric Extensions", 459 RFC 8571, DOI 10.17487/RFC8571, March 2019, 460 . 462 10. Informative references 464 [RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A 465 Border Gateway Protocol 4 (BGP-4)", RFC 4271, 466 DOI 10.17487/RFC4271, January 2006, 467 . 469 [RFC5376] Bitar, N., Zhang, R., and K. Kumaki, "Inter-AS 470 Requirements for the Path Computation Element 471 Communication Protocol (PCECP)", RFC 5376, 472 DOI 10.17487/RFC5376, November 2008, 473 . 475 [RFC5440] Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation 476 Element (PCE) Communication Protocol (PCEP)", RFC 5440, 477 DOI 10.17487/RFC5440, March 2009, 478 . 480 Authors' Addresses 482 Ran Chen 483 ZTE Corporation 484 Nanjing 485 China 486 Email: chen.ran@zte.com.cn 488 Zheng Zhang 489 ZTE Corporation 490 Nanjing 491 China 492 Email: zhang.zheng@zte.com.cn 494 Vengada Prasad Govindan 495 Cisco 496 Email: venggovi@cisco.com 498 IJsbrand Wijnands 499 Individual 500 Email: ice@braindump.be 502 Zhaohui Zhang 503 Juniper Networks 504 Email: zzhang@juniper.net