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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: May 2, 2020 V. Govindan 6 IJ. Wijnands 7 Cisco 8 October 30, 2019 10 BGP Link-State extensions for BIER 11 draft-ietf-bier-bgp-ls-bier-ext-06 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 May 2, 2020. 48 Copyright Notice 50 Copyright (c) 2019 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 4. Equivalent IS-IS BIER TLVs/Sub-TLVs . . . . . . . . . . . . . 6 72 5. Equivalent OSPFv2/OSPFV3 BIER TLVs/Sub-TLVs . . . . . . . . . 6 73 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7 74 7. Security Considerations . . . . . . . . . . . . . . . . . . . 7 75 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 8 76 9. Normative references . . . . . . . . . . . . . . . . . . . . 8 77 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9 79 1. Introduction 81 Bit Index Explicit Replication (BIER) is an architecture that 82 provides optimal multicast forwarding through a "BIER domain" without 83 requiring intermediate routers to maintain any multicast related per- 84 flow state. BIER also does not require any explicit tree-building 85 protocol for its operation. A multicast data packet enters a BIER 86 domain at a "Bit-Forwarding Ingress Router" (BFIR), and leaves the 87 BIER domain at one or more "Bit-Forwarding Egress Routers" (BFERs). 88 The BFIR router adds a BIER header to the packet. The BIER header 89 contains a bitstring in which each bit represents exactly one BFER to 90 forward the packet to. The set of BFERs to which the multicast 91 packet needs to be forwarded is expressed by setting the bits that 92 correspond to those routers in the BIER header. 94 When BIER is enabled in an IGP domain, BIER-related information will 95 be advertised via IGP link-state routing protocols. IGP extensions 96 are described in: ISIS[[RFC8401]],OSPFv2[[RFC8444]] and 97 OSPFv3[[I-D.ietf-bier-ospfv3-extensions]].The contents of a Link 98 State Database (LSDB) or of an IGP's Traffic Engineering Database 99 (TED) has the scope of an IGP area and therefore, by using the IGP 100 alone it is not enough to construct segments across multiple IGP Area 101 or AS boundaries. 103 In order to satisfy the need for applications that require 104 topological visibility across one area or Autonomous System (AS). 105 This document specifies extensions to the BGP Link-state address- 106 family in order to advertise BIER-specific. An external component 107 (e.g., a controller) then can collect BIER information in the 108 "northbound" direction within the BIER domain. 110 2. Conventions used in this document 112 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 113 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 114 document are to be interpreted as described in RFC2119. 116 3. BGP-LS Extensions for BIER 118 [RFC8279] defines the BFR - A router that supports BIER is known as a 119 "Bit-Forwarding Router"(BFR), and each BFR MUST be assigned a "BFR- 120 Prefix". A BFR's BFR-Prefix MUST be an IP address (either IPv4 or 121 IPv6) of the BFR, and MUST be unique and routable within the BIER 122 domain as described in section 2 of [RFC8279], and then external 123 component (e.g., a controller) need to collect BIER information of 124 BIER routers are associated with the BFR-Prefix in the "northbound" 125 direction within the BIER domain. 127 Given that the BIER information is associated with the prefix, the 128 Prefix Attribute TLV [RFC7752] can be used to carry the BIER 129 information. A new Prefix Attribute TLVs are defined for the 130 encoding of BIER information. 132 3.1. Prefix Attributes TLVs 134 The following Prefix Attribute TLVs are defined: 136 +------+-----------------------+---------------+ 137 | Type | Description | Section | 138 +------+-----------------------+---------------+ 139 | TBD |BIER information | Section 3.1.1 | 140 | TBD |BIER MPLS Encapsulation| Section 3.1.2 | 141 +------+-----------------------+---------------+ 143 Table 1:The new Prefix Attribute TLVs 145 3.1.1. The BIER information TLV 147 A new Prefix Attribute TLV (defined in [RFC7752] is defined for 148 distributing BIER information. The new TLV is called the BIER TLV. 149 The BIER information TLVs may appear multiple times. 151 The following BIER information TLV is defined: 153 0 1 2 3 154 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 1 155 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 156 | Type | Length | 157 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 158 | BAR | IPA | subdomain-id | 159 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 160 | BFR-id | 161 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 162 | Sub-TLVs (variable) | 163 +- -+ 164 | | 166 Figure 2: The BIER information TLV 168 Type: 2 octet field with value TBD, see IANA Considerations section. 170 Length: 2 octet. 172 Reserved: MUST be 0 on transmission, ignored on reception. May be 173 used in future versions. 175 BAR: A 1 octet field encoding the BIER Algorithm, used to calculate 176 underlay paths to reach BFERs. Values are allocated from the "BIER 177 Algorithms" registry which is defined in [RFC8401]. 179 IPA: A 1 octet field encoding the IGP Algorithm, used to either 180 modify,enhance, or replace the calculation of underlay paths to reach 181 BFERs as defined by the BAR value. Values are from the IGP Algorithm 182 registry. 184 Subdomain-id: Unique value identifying the BIER sub-domain, 1 octet. 186 MT-ID: Multi-Topology ID that identifies the topology that is 187 associated with the BIER sub-domain.1 octet. 189 BFR-id: A 2 octet field encoding the BFR-id, as documented in 190 [RFC8279]. If the BFR-id is zero, it means, the advertising router 191 is not advertising any BIER-id.In some environment, BFR-id can be 192 configured by NMS, The BFR-id should be sent to a controller. 194 BS Length: A 1 octet field encoding the Bitstring length as per 195 [RFC8296]. 197 If the MT-ID value is outside of the values specified in [RFC4915], 198 the BIER Sub-TLV MUST be ignored. 200 3.1.2. The BIER MPLS Encapsulation TLV 202 The BIER MPLS Encapsulation TLV is used in order to advertise MPLS 203 specific information used for BIER. It MAY appear multiple times. 205 In some environment, each router allocates its labels, and advertises 206 it to the controller.That solution is simpler as the controller does 207 not need to deal with label allocation. If the controller has to 208 deal with Label allocation , there needs to be a (global) range 209 carved out such there are no conflicts. We can avoid all that by 210 having the router allocate the BIER Label range and advertise it to 211 the controller. 213 The following the BIER MPLS Encapsulation Sub-TLV is defined: 215 0 1 2 3 216 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 1 217 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 218 | Type | Length | 219 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 220 | Max SI | Label | 221 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 222 |BS Len | Reserved | 223 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 225 Figure 3: The BIER MPLS Encapsulation TLV 227 Type: 2 octet field with value TBD, see IANA Considerations section. 229 Length: 2 octet. 231 Max SI: A 1 octet field encoding the maximum Set Identifier(as 232 defined in [RFC8279]), used in the encapsulation for this BIER 233 subdomain for this BitString length. 235 Label: A 3 octet field, where the 20 rightmost bits represent the 236 first label in the label range. 238 BS Length: A 1 octet field encoding the Bitstring length as per 239 [RFC8296] 241 BS length in multiple BIER MPLS Encapsulation Sub-TLV inside the same 242 BIER Sub-TLV MUST NOT repeat, otherwise only the first BIER MPLS 243 Encapsulation Sub-TLV with such BS length MUST be used and any 244 subsequent BIER MPLS Encapsulation Sub-TLVs with the same BS length 245 MUST be ignored. 247 4. Equivalent IS-IS BIER TLVs/Sub-TLVs 249 This section illustrate the BIER TLVs mapped to the ones defined in 250 this document. 252 The following table, illustrates for each BGP-LS TLV, its equivalence 253 in IS-IS. 255 +--------------+-------------------------+----------------------------------+ 256 | Descriptio | IS-IS TLV | Reference | 257 | n | /Sub-TLV | | 258 +--------------+-------------------------+----------------------------------+ 259 | BIER | BIER Info Sub-TLV | [RFC8401] | 260 | information | | | 261 | | | | 262 | BIER MPLS |BIER MPLS Encapsulation | [RFC8401] | 263 | Encapsulation|Sub-Sub-TLV | | 264 +--------------+-------------------------+----------------------------------+ 266 Table 2:IS-IS BIER Sub-TLVs/Sub-Sub-TLVs 268 5. Equivalent OSPFv2/OSPFV3 BIER TLVs/Sub-TLVs 270 This section illustrate the BIER TLVs mapped to the ones defined in 271 this document. 273 The following table, illustrates for each BGP-LS TLV, its equivalence 274 in OSPFv2/OSPFV3. 276 +--------------+-------------------------+----------------------------------+ 277 | Descriptio | OSPFv2/OSPFV3 sub-TLV | Reference | 278 | n | /Sub-Sub-TLV | | 279 +--------------+-------------------------+----------------------------------+ 280 | BIER | BIER Sub-TLV |[RFC8444] & | 281 | information | |[I-D. ietf-bier-ospfv3-extensions | 282 | | | | 283 | BIER MPLS |BIER MPLS Encapsulation |[RFC8444]& | 284 | Encapsulation|Sub-TLV |[I-D. ietf-bier-ospfv3-extensions | 285 +--------------+-------------------------+----------------------------------+ 287 Table 3: OSPFv2/OSPFV3 BIER TLVs/Sub-TLVs 289 6. IANA Considerations 291 This document requests assigning code-points from the registry for 292 the new Prefix Attribute TLVs. 294 +-------------------+-------------------------+-----------------+ 295 | TLV Code Point | Description | Value defined | 296 +-------------------+-------------------------+-----------------+ 297 | TBD | BIER information | this document | 298 +-------------------+-------------------------+-----------------+ 299 | TBD | BIER MPLS Encapsulation | this document | 300 +-------------------+-------------------------+-----------------+ 302 Table 4: The new Prefix Attribute TLV 304 7. Security Considerations 306 Procedures and protocol extensions defined in this document do not 307 affect the BGP security model. See the "Security 308 Considerations"section of [RFC4271] for a discussion of BGP security. 309 Also, refer to [RFC4272] and [RFC6952] for analyses of security 310 issues for BGP.Security considerations for acquiring and distributing 311 BGP-LS information are discussed in [RFC7752]. 313 The TLVs introduced in this document are used to propagate the Bit 314 Index Explicit Replication (BIER) defined in [[RFC8401]], [[RFC8444]] 315 and [[I-D.ietf-bier-ospfv3-extensions]]. These TLVs represent the 316 bier information associated with the prefix. It is assumed that the 317 IGP instances originating these TLVs will support all the required 318 security and authentication mechanisms in [[RFC8401]], [[RFC8444]] 319 and [[I-D.ietf-bier-ospfv3-extensions]] in order to prevent any 320 security issues when propagating the TLVs into BGP-LS. The 321 advertisement of the link attribute information defined in this 322 document presents no additional risk beyond that associated with the 323 existing link attribute information already supported in [RFC7752]. 325 8. Acknowledgements 327 We would like to thank Peter Psenak (Cisco) and Ketan 328 Talaulikar(Cisco) for his comments and support of this work. 330 9. Normative references 332 [I-D.ietf-bier-ospfv3-extensions] 333 Psenak, P., Kumar, N., and I. Wijnands, "OSPFv3 Extensions 334 for BIER", draft-ietf-bier-ospfv3-extensions-00 (work in 335 progress), May 2019. 337 [RFC3630] Katz, D., Kompella, K., and D. Yeung, "Traffic Engineering 338 (TE) Extensions to OSPF Version 2", RFC 3630, 339 DOI 10.17487/RFC3630, September 2003, 340 . 342 [RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A 343 Border Gateway Protocol 4 (BGP-4)", RFC 4271, 344 DOI 10.17487/RFC4271, January 2006, 345 . 347 [RFC4272] Murphy, S., "BGP Security Vulnerabilities Analysis", 348 RFC 4272, DOI 10.17487/RFC4272, January 2006, 349 . 351 [RFC4915] Psenak, P., Mirtorabi, S., Roy, A., Nguyen, L., and P. 352 Pillay-Esnault, "Multi-Topology (MT) Routing in OSPF", 353 RFC 4915, DOI 10.17487/RFC4915, June 2007, 354 . 356 [RFC6952] Jethanandani, M., Patel, K., and L. Zheng, "Analysis of 357 BGP, LDP, PCEP, and MSDP Issues According to the Keying 358 and Authentication for Routing Protocols (KARP) Design 359 Guide", RFC 6952, DOI 10.17487/RFC6952, May 2013, 360 . 362 [RFC7752] Gredler, H., Ed., Medved, J., Previdi, S., Farrel, A., and 363 S. Ray, "North-Bound Distribution of Link-State and 364 Traffic Engineering (TE) Information Using BGP", RFC 7752, 365 DOI 10.17487/RFC7752, March 2016, 366 . 368 [RFC8279] Wijnands, IJ., Ed., Rosen, E., Ed., Dolganow, A., 369 Przygienda, T., and S. Aldrin, "Multicast Using Bit Index 370 Explicit Replication (BIER)", RFC 8279, 371 DOI 10.17487/RFC8279, November 2017, 372 . 374 [RFC8296] Wijnands, IJ., Ed., Rosen, E., Ed., Dolganow, A., 375 Tantsura, J., Aldrin, S., and I. Meilik, "Encapsulation 376 for Bit Index Explicit Replication (BIER) in MPLS and Non- 377 MPLS Networks", RFC 8296, DOI 10.17487/RFC8296, January 378 2018, . 380 [RFC8401] Ginsberg, L., Ed., Przygienda, T., Aldrin, S., and Z. 381 Zhang, "Bit Index Explicit Replication (BIER) Support via 382 IS-IS", RFC 8401, DOI 10.17487/RFC8401, June 2018, 383 . 385 [RFC8444] Psenak, P., Ed., Kumar, N., Wijnands, IJ., Dolganow, A., 386 Przygienda, T., Zhang, J., and S. Aldrin, "OSPFv2 387 Extensions for Bit Index Explicit Replication (BIER)", 388 RFC 8444, DOI 10.17487/RFC8444, November 2018, 389 . 391 Authors' Addresses 393 Ran Chen 394 ZTE Corporation 395 No.50 Software Avenue,Yuhuatai District 396 Nanjing, Jiangsu Province 210012 397 China 399 Phone: +86 025 88014636 400 Email: chen.ran@zte.com.cn 402 Zheng Zhang 403 ZTE Corporation 404 No.50 Software Avenue,Yuhuatai District 405 Nanjing, Jiangsu Province 210012 406 China 408 Email: zhang.zheng@zte.com.cn 410 Vengada Prasad Govindan 411 Cisco 413 Email: venggovi@cisco.com 414 IJsbrand Wijnands 415 Cisco 416 De Kleetlaan 6a 417 Diegem 1831 418 Belgium 420 Email: ice@cisco.com