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'I-D.ietf-bier-non-mpls-bift-encoding') Summary: 2 errors (**), 0 flaws (~~), 4 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Internet Engineering Task Force S. Dhanaraj, Ed. 3 Internet-Draft Huawei 4 Intended status: Standards Track IJ. Wijnands 5 Expires: May 27, 2019 P. Psenak 6 Cisco Systems, Inc. 7 G. Yan 8 J. Xie 9 Huawei 10 November 23, 2018 12 ISIS Extensions for BIER in Non-MPLS Networks 13 draft-dhanaraj-bier-isis-non-mpls-extensions-00 15 Abstract 17 Bit Index Explicit Replication (BIER) [RFC8279] is an architecture 18 that provides multicast forwarding through a "BIER domain" without 19 requiring intermediate routers to maintain multicast related per-flow 20 state. BIER can be supported in MPLS and non-MPLS networks. The 21 common BIER header format and encapsulation for MPLS and non-MPLS 22 networks is specified in [RFC8296]. 24 BIER in Ethernet encapsulation is an example of BIER encapsulation in 25 non-MPLS networks. 27 [RFC8401] specifies the required extensions to the IS-IS [RFC1195] 28 protocol for the distribution of BIER sub-domain information 29 including the Sub-sub-TLV required to support BIER in MPLS 30 encapsulation for MPLS networks. 32 This document specifies the required extensions to the IS-IS 33 [RFC1195] protocol for supporting BIER in non-MPLS networks using 34 BIER in Ethernet encapsulation. 36 Status of This Memo 38 This Internet-Draft is submitted in full conformance with the 39 provisions of BCP 78 and BCP 79. 41 Internet-Drafts are working documents of the Internet Engineering 42 Task Force (IETF). Note that other groups may also distribute 43 working documents as Internet-Drafts. The list of current Internet- 44 Drafts is at https://datatracker.ietf.org/drafts/current/. 46 Internet-Drafts are draft documents valid for a maximum of six months 47 and may be updated, replaced, or obsoleted by other documents at any 48 time. It is inappropriate to use Internet-Drafts as reference 49 material or to cite them other than as "work in progress." 51 This Internet-Draft will expire on May 27, 2019. 53 Copyright Notice 55 Copyright (c) 2018 IETF Trust and the persons identified as the 56 document authors. All rights reserved. 58 This document is subject to BCP 78 and the IETF Trust's Legal 59 Provisions Relating to IETF Documents 60 (https://trustee.ietf.org/license-info) in effect on the date of 61 publication of this document. Please review these documents 62 carefully, as they describe your rights and restrictions with respect 63 to this document. Code Components extracted from this document must 64 include Simplified BSD License text as described in Section 4.e of 65 the Trust Legal Provisions and are provided without warranty as 66 described in the Simplified BSD License. 68 Table of Contents 70 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 71 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 72 2.1. Requirements Language . . . . . . . . . . . . . . . . . . 4 73 3. Procedure and Packet Formats . . . . . . . . . . . . . . . . 4 74 3.1. BIER Ethernet Encapsulation Sub-sub TLV . . . . . . . . . 5 75 4. Security Considerations . . . . . . . . . . . . . . . . . . . 6 76 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7 77 5.1. IS-IS sub-sub-TLVs for BIER Info sub-TLV Registry . . . . 7 78 6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 7 79 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 7 80 7.1. Normative References . . . . . . . . . . . . . . . . . . 7 81 7.2. Informative References . . . . . . . . . . . . . . . . . 8 82 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9 84 1. Introduction 86 Bit Index Explicit Replication (BIER) [RFC8279] is an architecture 87 that provides multicast forwarding through a "BIER domain" without 88 requiring intermediate routers to maintain multicast related per-flow 89 state. BIER can be supported in MPLS and non-MPLS networks. The 90 common BIER header format and encapsulation for MPLS and non-MPLS 91 networks is specified in [RFC8296]. 93 As stated in [RFC8296], the encapsulation of Initial Four Octets in 94 BIER header for MPLS and non-MPLS networks are different. In 95 particular, the first 20-bits of the BIER header (referred as BIFT- 96 id) is a "MPLS Label" in case of MPLS networks and is a "domain-wide- 97 unique-value" representing the combination of SD-BSL-SI in case of 98 non-MPLS networks. 100 BIER in Ethernet encapsulation is an example of BIER encapsulation in 101 non-MPLS networks. 103 BIER in Ethernet encapsulation(BIER-ETH): 104 Ethernet header is immediately followed by the BIER header. In 105 this type of encapsulation, the EtherType field in the Ethernet 106 header is set to 0xAB37 which is assigned by IEEE for non-MPLS 107 BIER packets as stated in [RFC8279]. 109 Processing and forwarding of multicast packets using the BIER-ETH 110 encapsulation requires special software and hardware capabilities. 111 The BFRs supporting this encapsulation type MUST advertise this 112 capability (along with the other required parameters specific to the 113 encapsulation) to the other routers in BIER domain. This 114 advertisement, for example, will enable the other BFRs in the BIER 115 domain in deciding, whether to include or exclude the advertising 116 router from the BAR and/or IPA algorithm while computing the 117 multicast path for a specific encapsulation type. 119 [RFC8401] specifies the required extensions to the IS-IS [RFC1195] 120 protocol for the distribution of BIER sub-domain information 121 including the Sub-sub-TLVs required to support BIER in MPLS 122 encapsulation for MPLS networks. 124 This document specifies the required extensions to the IS-IS 125 [RFC1195] protocol for supporting BIER in non-MPLS networks using 126 BIER in Ethernet encapsulation. 128 Support for other encapsulation types are outside the scope of this 129 document. In case of multiple encapsulation types supported by a BFR 130 in a BIER sub-domain, the selection of a encapsulation type to be 131 used for a BIER sub-domain is outside the scope of this document. 133 2. Terminology 135 Some of the terminology specified in [RFC8279] is replicated here and 136 extended by necessary definitions: 138 BIER: Bit Index Explicit Replication 139 (The overall architecture of forwarding multicast using a Bit 140 Position). 142 BIER-MPLS: BIER in MPLS encapsulation. 144 (Encapsulation of BIER header inside MPLS header in MPLS 145 networks). 147 BIER-ETH: BIER in Ethernet encapsulation. 148 (Encapsulation of BIER header inside Ethernet header 149 (EtherType=0xAB37) in non-MPLS networks). 151 BFR: Bit Forwarding Router (A router that participates in Bit Index 152 Multipoint Forwarding). A BFR is identified by a unique BFR- 153 prefix in a BIER domain. 155 BIFT: Bit Index Forwarding Table used to forward the BIER packets in 156 a domain. 158 BAR: BIER Algorithm. Used to calculate underlay nexthops 159 as defined by the BAR value. 161 IPA: IGP Algorithm. May be used to modify, enhance or replace the 162 calculation of underlay paths as defined by the BAR value 164 2.1. Requirements Language 166 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 167 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 168 "OPTIONAL" in this document are to be interpreted as described in BCP 169 14 [RFC2119] [RFC8174] when, and only when, they appear in all 170 capitals, as shown here. 172 3. Procedure and Packet Formats 174 BIER Info sub-TLV defined in [RFC8401] is used to advertise the sub- 175 domain id, and other associated parameters of the sub-domain like 176 BFR-id, MT, BAR, IPA. 178 This document introduces new sub-sub-TLVs under BIER Info sub-TLV to 179 advertise the encapsulation capability and other associated 180 parameters of the encapsulation. 182 A BIER sub-domain MAY support multiple BIER encapsulation types like 183 BIER-MPLS, BIER-ETH. Within a BIER sub-domain, it is very well 184 possible and allowable to share the same BFR-id for a BFR across 185 different encapsulation types. If the operator wishes to use 186 different BFR-id for different encapsulation types, then he MUST 187 provision different BIER sub-domain for each encapsulation type. 189 The selection of encapsulation type to be used by a BFIR or BFR for a 190 sub-domain could be a matter of local policy and is outside the scope 191 of this document. 193 As described in Section 2.2.1.1 of [RFC8296], In non-MPLS networks, a 194 BIFT-id MUST be assigned for every combination of that 195 is to be used in that network. Two possible means by which the BIFT- 196 ids are assigned for a are described in 197 [I-D.ietf-bier-non-mpls-bift-encoding]. 199 As an example, suppose a particular BIER domain contains a SD (SD 0), 200 supports two BSLs (256 and 512), and contains 1024 BFRs. A BFR that 201 is provisioned for above SD, and that supports both BSLs, would have 202 to advertise the following set of BIFT-id's: 204 BIFT-id 1: corresponding to SD 0, BSL 256, SI 0. 206 BIFT-id 2: corresponding to SD 0, BSL 256, SI 1. 208 BIFT-id 3: corresponding to SD 0, BSL 256, SI 2. 210 BIFT-id 4: corresponding to SD 0, BSL 256, SI 3. 212 BIFT-id 5: corresponding to SD 0, BSL 512, SI 0. 214 BIFT-id 6: corresponding to SD 0, BSL 512, SI 1. 216 In such case, a BFR MUST assign a contiguous range of BIFT-ids as, 218 BIFT-id range [1 to 4] correspond to . The first 219 BIFT-id in the range correspond to SI=0, the second correspond to 220 SI=1, and so on. 222 BIFT-id range [5 to 6] correspond to . The first 223 BIFT-id in the range correspond to SI=0, the second correspond to 224 SI=1. 226 3.1. BIER Ethernet Encapsulation Sub-sub TLV 228 This sub-sub-TLV carries the information for the BIER Ethernet 229 encapsulation including the BitString length supported for a certain 230 pair. 232 It is advertised within the BIER Info sub-TLV defined in [RFC8401] 233 which in-turn is carried within the TLVs 235, 237 [RFC5120] or TLVs 234 135 [RFC5305], or TLV 236 [RFC5308]. 236 This sub-sub-TLV MAY appear multiple times within a single BIER Info 237 sub-TLV. If the same BitString length is repeated in multiple BIER 238 Ethernet encapsulation sub-sub-TLVs inside the same BIER Info sub- 239 TLV, the BIER Info sub-TLV MUST be ignored. 241 0 1 2 3 242 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 1 243 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 244 | Type | Length | 245 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 246 | Max SI |BS Len | BIFT-id | 247 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 249 Type: 2 (suggested value - To be assigned by IANA). 251 Length: 4 253 Max SI: 1 octet. Maximum Set Identifier (Section 1 of [RFC8279]) 254 used in the encapsulation for this BIER subdomain for this BitString 255 length. The first BIFT-id is for SI=0, the second BIFT-id is for 256 SI=1, etc. If the BIFT-id associated with the Maximum Set Identifier 257 exceeds the 20-bit range, the sub-sub-TLV MUST be ignored.. 259 Local BitString Length (BS Len): 4 bits. Encoded bitstring length 260 as per [RFC8296]. 262 BIFT-id: 20 bits. First BIFT-id of the BIFT-id range. 264 The "BIFT-id range" is the set of 20-bit values beginning with the 265 BIFT-id and ending with (BIFT-id + (Max SI)). A unique BIFT-id range 266 is allocated for each BitString length and sub-domain-id. These BIFT- 267 id's are used for BIER forwarding as described in [RFC8279] and 268 [RFC8296]. 270 The size of the BIFT-id range is determined by the number of SI's 271 (Section 1 of [RFC8279]) that are used in the network. Each SI maps 272 to a single BIFT-id in the BIFT-id range: the first BIFT-id is for 273 SI=0, the second BIFT-id is for SI=1, etc. 275 If the BIFT-id associated with the Maximum Set Identifier exceeds 276 the 20-bit range, the BIER Ethernet Encapsulation Sub-sub-TLV 277 containing the error MUST be ignored. 279 4. Security Considerations 281 Security concerns for IS-IS are addressed in [RFC5304] and [RFC5310] 282 and the security concerns for IS-IS extensions for BIER are addressed 283 in [RFC8401]. 285 This document introduces new sub-sub-TLV for the already existing IS- 286 IS TLVs defined for distributing the BIER sub-domain information in 287 [RFC8401]. It does not introduce any new security risks to IS-IS. 289 5. IANA Considerations 291 The document requests new allocations from the IS-IS registries as 292 follows 294 5.1. IS-IS sub-sub-TLVs for BIER Info sub-TLV Registry 296 BIER Ethernet Encapsulation sub-sub-TLV: 2 (suggested) 298 6. Acknowledgments 300 The author wants to thank Jeffrey (Zhaohui) Zhang and Antonie 301 Przygienda for their comments and suggestions. 303 7. References 305 7.1. Normative References 307 [I-D.ietf-bier-non-mpls-bift-encoding] 308 Wijnands, I., Xu, X., and H. Bidgoli, "An Optional 309 Encoding of the BIFT-id Field in the non-MPLS BIER 310 Encapsulation", draft-ietf-bier-non-mpls-bift-encoding-01 311 (work in progress), October 2018. 313 [RFC1195] Callon, R., "Use of OSI IS-IS for routing in TCP/IP and 314 dual environments", RFC 1195, DOI 10.17487/RFC1195, 315 December 1990, . 317 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 318 Requirement Levels", BCP 14, RFC 2119, 319 DOI 10.17487/RFC2119, March 1997, 320 . 322 [RFC5120] Przygienda, T., Shen, N., and N. Sheth, "M-ISIS: Multi 323 Topology (MT) Routing in Intermediate System to 324 Intermediate Systems (IS-ISs)", RFC 5120, 325 DOI 10.17487/RFC5120, February 2008, 326 . 328 [RFC5304] Li, T. and R. Atkinson, "IS-IS Cryptographic 329 Authentication", RFC 5304, DOI 10.17487/RFC5304, October 330 2008, . 332 [RFC5305] Li, T. and H. Smit, "IS-IS Extensions for Traffic 333 Engineering", RFC 5305, DOI 10.17487/RFC5305, October 334 2008, . 336 [RFC5308] Hopps, C., "Routing IPv6 with IS-IS", RFC 5308, 337 DOI 10.17487/RFC5308, October 2008, 338 . 340 [RFC5310] Bhatia, M., Manral, V., Li, T., Atkinson, R., White, R., 341 and M. Fanto, "IS-IS Generic Cryptographic 342 Authentication", RFC 5310, DOI 10.17487/RFC5310, February 343 2009, . 345 [RFC7794] Ginsberg, L., Ed., Decraene, B., Previdi, S., Xu, X., and 346 U. Chunduri, "IS-IS Prefix Attributes for Extended IPv4 347 and IPv6 Reachability", RFC 7794, DOI 10.17487/RFC7794, 348 March 2016, . 350 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 351 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 352 May 2017, . 354 [RFC8279] Wijnands, IJ., Ed., Rosen, E., Ed., Dolganow, A., 355 Przygienda, T., and S. Aldrin, "Multicast Using Bit Index 356 Explicit Replication (BIER)", RFC 8279, 357 DOI 10.17487/RFC8279, November 2017, 358 . 360 [RFC8296] Wijnands, IJ., Ed., Rosen, E., Ed., Dolganow, A., 361 Tantsura, J., Aldrin, S., and I. Meilik, "Encapsulation 362 for Bit Index Explicit Replication (BIER) in MPLS and Non- 363 MPLS Networks", RFC 8296, DOI 10.17487/RFC8296, January 364 2018, . 366 [RFC8401] Ginsberg, L., Ed., Przygienda, T., Aldrin, S., and Z. 367 Zhang, "Bit Index Explicit Replication (BIER) Support via 368 IS-IS", RFC 8401, DOI 10.17487/RFC8401, June 2018, 369 . 371 7.2. Informative References 373 [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for 374 Writing an IANA Considerations Section in RFCs", BCP 26, 375 RFC 8126, DOI 10.17487/RFC8126, June 2017, 376 . 378 Authors' Addresses 380 Senthil Dhanaraj (editor) 381 Huawei 383 Email: senthil.dhanaraj.ietf@gmail.com 385 IJsbrand Wijnands 386 Cisco Systems, Inc. 388 Email: ice@cisco.com 390 Peter Psenak 391 Cisco Systems, Inc. 393 Email: ppsenak@cisco.com 395 Gang Yan 396 Huawei 398 Email: yangang@huawei.com 400 Jingrong Xie 401 Huawei 403 Email: xiejingrong@huawei.com