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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 BIER Z. Zhang 3 Internet-Draft ZTE Corporation 4 Intended status: Standards Track Z. Zhang, Ed. 5 Expires: August 26, 2021 Juniper Networks 6 I. Wijnands 7 Individual 8 M. Mishra 9 Cisco Systems 10 H. Bidgoli 11 Nokia 12 G. Mishra, Ed. 13 Verizon 14 February 22, 2021 16 Supporting BIER in IPv6 Networks (BIERin6) 17 draft-zhang-bier-bierin6-09 19 Abstract 21 BIER is a new architecture for the forwarding of multicast data 22 packets without requiring per-flow state inside the network. This 23 document describes how the existing BIER encapsulation specified in 24 RFC 8296 works in an IPv6 non-MPLS network, referred to as BIERin6. 25 Specifically, like in an IPv4 network, BIER can work over L2 links 26 directly or over tunnels. In case of IPv6 tunneling, a new IP "Next 27 Header" type is to be assigned for BIER. 29 Requirements Language 31 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 32 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 33 "OPTIONAL" in this document are to be interpreted as described in BCP 34 14 [RFC2119] [RFC8174] when, and only when, they appear in all 35 capitals, as shown here. 37 Status of This Memo 39 This Internet-Draft is submitted in full conformance with the 40 provisions of BCP 78 and BCP 79. 42 Internet-Drafts are working documents of the Internet Engineering 43 Task Force (IETF). Note that other groups may also distribute 44 working documents as Internet-Drafts. The list of current Internet- 45 Drafts is at https://datatracker.ietf.org/drafts/current/. 47 Internet-Drafts are draft documents valid for a maximum of six months 48 and may be updated, replaced, or obsoleted by other documents at any 49 time. It is inappropriate to use Internet-Drafts as reference 50 material or to cite them other than as "work in progress." 52 This Internet-Draft will expire on August 26, 2021. 54 Copyright Notice 56 Copyright (c) 2021 IETF Trust and the persons identified as the 57 document authors. All rights reserved. 59 This document is subject to BCP 78 and the IETF Trust's Legal 60 Provisions Relating to IETF Documents 61 (https://trustee.ietf.org/license-info) in effect on the date of 62 publication of this document. Please review these documents 63 carefully, as they describe your rights and restrictions with respect 64 to this document. Code Components extracted from this document must 65 include Simplified BSD License text as described in Section 4.e of 66 the Trust Legal Provisions and are provided without warranty as 67 described in the Simplified BSD License. 69 Table of Contents 71 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 72 1.1. BIER over L2/Tunnels . . . . . . . . . . . . . . . . . . 3 73 1.2. Considerations of Requirements for BIER in IPv6 Networks 3 74 2. IPv6 Header . . . . . . . . . . . . . . . . . . . . . . . . . 5 75 2.1. IPv6 Options Considerations . . . . . . . . . . . . . . . 5 76 3. BIER Header . . . . . . . . . . . . . . . . . . . . . . . . . 6 77 4. IPv6 Encapsulation Advertisement . . . . . . . . . . . . . . 6 78 4.1. Format . . . . . . . . . . . . . . . . . . . . . . . . . 6 79 4.2. Inter-area prefix redistribution . . . . . . . . . . . . 7 80 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7 81 6. Security Considerations . . . . . . . . . . . . . . . . . . . 7 82 7. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 7 83 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 7 84 8.1. Normative References . . . . . . . . . . . . . . . . . . 8 85 8.2. Informative References . . . . . . . . . . . . . . . . . 8 86 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10 88 1. Introduction 90 BIER [RFC8279] is a new architecture for the forwarding of multicast 91 data packets. It provides optimal forwarding through a "multicast 92 domain" and it does not precondition construction of a multicast 93 distribution tree, nor does it require intermediate nodes to maintain 94 any per-flow state. 96 This document specifies non-MPLS BIER forwarding in an IPv6 [RFC8200] 97 environment, referred to as BIERin6, using non-MPLS BIER 98 encapsulation specified in [RFC8296]. 100 MPLS BIER forwarding in IPv6 is outside the scope of this document. 102 This document uses terminology defined in [RFC8279] and [RFC8296]. 104 1.1. BIER over L2/Tunnels 106 [RFC8296] defines the BIER encapsulation format in MPLS and non-MPLS 107 environment. In case of non-MPLS environment, a BIER packet is the 108 payload of an "outer" encapsulation, which has a "next header" 109 codepoint that is set to a value that means "non-MPLS BIER". This 110 "BIER over L2/Tunnel" model can be used as is in an IPv6 non-mpls 111 environment, and is referred to as BIERin6. 113 If a BFR needs to tunnel BIER packets to another BFR, e.g. per 114 [RFC8279] Section 6.9, while any type of tunnel will work, for best 115 efficiency native IPv6 encapsulation can be used with the destination 116 address being the downstream BFR and the Next Header field set to a 117 to-be-assigned value for "non-MPLS BIER". 119 +---------------+------------------------ 120 | IPv6 header | BIER header + data 121 | | 122 | Next Header = | 123 | BIER | 124 +---------------+------------------------ 126 Between two directly connected BFRs, a BIER header can directly 127 follow link layer header, e.g., an Ethernet header (with the 128 Ethertype set to 0xAB37). Optionally, IPv6 encapsulation can be used 129 even between directly connected BFRs (i.e. one-hop IPv6 tunneling) in 130 the following two cases: 132 o An operator mandates all traffic to be carried in IPv6. 134 o A BFR does not have BIER support in its "fast forwarding path" and 135 relies on "slow/software forwarding path", e.g. in environments 136 like [RFC7368] where high throughput multicast forwarding 137 performance is not critical. 139 1.2. Considerations of Requirements for BIER in IPv6 Networks 141 [draft-ietf-bier-ipv6-requirements] lists mandatory and optional 142 requirements for BIER in IPv6 Networks. As a solution based on the 143 BIER over L2/tunnel model [RFC8296], BIERin6 satisfies all the 144 mandatory requirements. 146 For the two optional requirements for fragmentation and Encapsulating 147 Security Payload (ESP), they can be satisfied by one of two ways: 149 o IPv6 based fragmentation/ESP: a BFIR encapsulates the payload in 150 IPv6 with fragmentation and/or ESP header, and then the IPv6 151 packets are treated as BIER payload. 153 o Generic Fragmentation/ESP 154 [I-D.zzhang-tsvwg-generic-transport-functions]: a BFIR does 155 generic fragmentation and/or ESP (without using IPv6 156 encapsulation) and the resulting packets are treated as BIER 157 payload. 159 Either way, the fragmentation/ESP is handled by a layer outside of 160 BIER and then the resulting packets are treated as BIER payload. 162 BIERin6 does support SRv6 based overlay services (e.g. MVPN/EVPN). 163 One of the following methods can be used (relevant overlay signaling 164 will be specified separately): 166 o An ingress PE (which is a BFIR) can encapsulate customer packets 167 with an IPv6 header (with optional fragmentation and ESP extension 168 headers). The destination address is a multicast locator plus the 169 Fucn/Arg portion that identifies the service. That IPv6 packet is 170 then treated as BIER payload. An egress PE (which is a BFER) uses 171 the standard SRv6 procedures to forward the IPv6 packet that is 172 exposed after the BIER header is decapsulated. 174 o Alternatively, since only the destination IPv6 address in the 175 above-mentioned IPv6 header is used for service delimiting 176 purpose, a new value can be assigned for the Proto field in the 177 BIER header to indicate that an IPv6 address (instead of an entire 178 IPv6 header) is added between the BIER header and original 179 payload. 181 BIERin6 being a solution based on [RFC8279] [RFC8296], ECMP is 182 inherently supported by BFRs using the the 20-bit entropy field in 183 the BIER header for the load balancing hash. When a BIER packet is 184 transported over an IPv6 tunnel, the entropy value is copied into the 185 20-bit IPv6 Flow Label (instead of using local 5-tuple input key to a 186 hash function to locally generate the stateless 20-bit flow label) so 187 that routers along the tunnel can do ECMP based on Flow Labels. For 188 a router along the tunnel doing deep packet inspection for ECMP 189 purpose, if it understands BIER header it can go past the BIER header 190 to look for the 5-tuple input key to a hash function, otherwise it 191 stops at the BIER header. In either case the router will not mistake 192 the BIER header as an IP header so no misordering should happen. 194 BIER has its own OAM functions independent of those related to the 195 underlying links or tunnels. With BIERin6 following the "BIER over 196 L2/tunnel" model, IPv6 OAM function and BIER OAM functions are used 197 independently for their own purposes. 199 Specifically, BIERin6 works with all of the following OAM methods, or 200 any future methods that are based on the "BIER over L2/tunnel" model: 202 o BIER OAM specified in [I-D.ietf-bier-ping] 204 o BIER BFD specified in [I-D.ietf-bier-bfd] 206 o BIER Performance Measurement specified in [I-D.ietf-bier-pmmm-oam] 208 o BIER Path Maximum Transmission Unit Discovery specified in 209 [I-D.ietf-bier-path-mtu-discovery] 211 o BIER IOAM specified in [I-D.xzlnp-bier-ioam] 213 2. IPv6 Header 215 Whenever IPv6 encapsulation is used for BIER forwarding, The Next 216 Header field in the IPv6 Header (if there are no extension headers), 217 or the Next Header field in the last extension header is set to TBD, 218 indicating that the payload is a BIER packet. 220 If the neighbor is directly connected, The destination address in 221 IPv6 header SHOULD be the neighbor's link-local address on this 222 router's outgoing interface, the source destination address SHOULD be 223 this router's link-local address on the outgoing interface, and the 224 IPv6 TTL MUST be set to 1. Otherwise, the destination address SHOULD 225 be the BIER prefix of the BFR neighbor, the source address SHOULD be 226 this router's BIER prefix, and the TTL MUST be large enough to get 227 the packet to the BFR neighbor. 229 The "Flow label" field in the IPv6 packet SHOULD be copied from the 230 entropy field in the BIER encapsulation. 232 2.1. IPv6 Options Considerations 234 For directly connected BIER routers, IPv6 Hop-by-Hop or Destination 235 options are irrelevant and SHOULD NOT be inserted by BFIR on the 236 BIERin6 packet. In this case IPv6 header, Next Header field should 237 be set to TBD. Any IPv6 packet arriving on BFRs and BFERs, with 238 multiple extension header where the last extension header has a Next 239 Header field set to TBD, SHOULD be discard and the node should 240 transmit an ICMP Parameter Problem message to the source of the 241 packet (BFIR) with an ICMP code value of TBD10 ('invalid options for 242 BIERin6'). 244 This also indicates that for disjoint BIER routers using IPv6 245 encapsulation, there SHOULD NOT be any IPv6 Hop-by-Hop or Destination 246 options be present in a BIERin6 packet. In this case, if additional 247 traffic engineering is required, IPv6 tunneling (i.e. BIERin6 over 248 SRv6) can be implemented. 250 3. BIER Header 252 The BIER header MUST be encoded per Section 2.2 of [RFC8296]. 254 The BIFT-id is either encoded per 255 [I-D.ietf-bier-non-mpls-bift-encoding] or per advertised by BFRs, as 256 specified in [I-D.ietf-bier-lsr-ethernet-extensions]. 258 4. IPv6 Encapsulation Advertisement 260 When IPv6 encapsulation is not required between directly connected 261 BFRs, no signaling in addition to that specified in 262 [I-D.ietf-bier-lsr-ethernet-extensions] is needed. 264 Otherwise, a node that requires IPv6 encapsulation MUST advertise the 265 BIER IPv6 transportation sub-sub-sub-TLV/sub-sub-TLV according to 266 local configuration or policy in the BIER domain to request other 267 BFRs to always use IPv6 encapsulation. 269 In presence of multiple encapsulation possibilities hop-by-hop it is 270 a matter of local policy which encapsulation is imposed and the 271 receiving router MUST accept all encapsulations that it advertised. 273 4.1. Format 275 The BIER IPv6 transportation is a new sub-sub-TLV of BIER Ethernet 276 Encapsulation sub-TLV defined in OSPFv3, and a new sub-sub-sub-TLV of 277 BIER Ethernet Encapsulation sub-sub-TLV defined in ISIS, as per 278 [I-D.ietf-bier-lsr-ethernet-extensions]. 280 0 1 2 3 281 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 1 282 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 283 | Type | Length | 284 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 286 o Type: For OSPF, value TBD1 (prefer 1) is used to indicate it is 287 the IPv6 transportation sub-TLV. For ISIS, value TBD2 (prefer 1) 288 is used to indicate it is the IPv6 transportation sub-sub-TLV. 290 o Length: 0. 292 4.2. Inter-area prefix redistribution 294 When BFR-prefixes are advertised across IGP areas per 295 [I-D.ietf-bier-lsr-ethernet-extensions] or redistributed across 296 protocol boundaries per [I-D.ietf-bier-prefix-redistribute], the BIER 297 IPv6 transportation sub-sub-TLV or sub-sub-sub-TLV MAY be re- 298 advertised/re-distributed as well. 300 5. IANA Considerations 302 IANA is requested to assign a new "BIER" type for "Next Header" in 303 the "Assigned Internet Protocol Numbers" registry. 305 IANA is requested to assign a new "BIERin6" type for "invalid 306 options" in the "ICMP code value" registry. 308 IANA is requested to assign a new "IPv6 address" type in the "BIER 309 Next Protocol Identifiers" registry. 311 IANA is requested to assign a new "BIER IPv6 transportation Sub-sub- 312 TLV" type in the "OSPFv3 BIER Ethernet Encapsulation sub-TLV" 313 Registry. 315 IANA is requested to set up a new "BIER IPv6 transportation Sub-sub- 316 sub-TLV" type in the "IS-IS BIER Ethernet Encapsulation sub-sub-TLV" 317 Registry. 319 6. Security Considerations 321 General IPv6 and BIER security considerations apply. 323 7. Acknowledgement 325 The authors would like to thank Tony Przygienda, Nagendra Kumar for 326 their review and valuable comments. 328 8. References 329 8.1. Normative References 331 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 332 Requirement Levels", BCP 14, RFC 2119, 333 DOI 10.17487/RFC2119, March 1997, 334 . 336 [RFC6437] Amante, S., Carpenter, B., Jiang, S., and J. Rajahalme, 337 "IPv6 Flow Label Specification", RFC 6437, 338 DOI 10.17487/RFC6437, November 2011, 339 . 341 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 342 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 343 May 2017, . 345 [RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6 346 (IPv6) Specification", STD 86, RFC 8200, 347 DOI 10.17487/RFC8200, July 2017, 348 . 350 [RFC8279] Wijnands, IJ., Ed., Rosen, E., Ed., Dolganow, A., 351 Przygienda, T., and S. Aldrin, "Multicast Using Bit Index 352 Explicit Replication (BIER)", RFC 8279, 353 DOI 10.17487/RFC8279, November 2017, 354 . 356 [RFC8296] Wijnands, IJ., Ed., Rosen, E., Ed., Dolganow, A., 357 Tantsura, J., Aldrin, S., and I. Meilik, "Encapsulation 358 for Bit Index Explicit Replication (BIER) in MPLS and Non- 359 MPLS Networks", RFC 8296, DOI 10.17487/RFC8296, January 360 2018, . 362 [RFC8401] Ginsberg, L., Ed., Przygienda, T., Aldrin, S., and Z. 363 Zhang, "Bit Index Explicit Replication (BIER) Support via 364 IS-IS", RFC 8401, DOI 10.17487/RFC8401, June 2018, 365 . 367 8.2. Informative References 369 [I-D.ietf-bier-bar-ipa] 370 Zhang, Z., Przygienda, T., Dolganow, A., Bidgoli, H., 371 Wijnands, I., and A. Gulko, "BIER Underlay Path 372 Calculation Algorithm and Constraints", draft-ietf-bier- 373 bar-ipa-07 (work in progress), September 2020. 375 [I-D.ietf-bier-bfd] 376 Xiong, Q., Mirsky, G., hu, f., and C. Liu, "BIER BFD", 377 draft-ietf-bier-bfd-00 (work in progress), November 2020. 379 [I-D.ietf-bier-idr-extensions] 380 Xu, X., Chen, M., Patel, K., Wijnands, I., and T. 381 Przygienda, "BGP Extensions for BIER", draft-ietf-bier- 382 idr-extensions-07 (work in progress), September 2019. 384 [I-D.ietf-bier-ipv6-requirements] 385 McBride, M., Xie, J., Geng, X., Dhanaraj, S., Asati, R., 386 Zhu, Y., Mishra, G., and Z. Zhang, "BIER IPv6 387 Requirements", draft-ietf-bier-ipv6-requirements-09 (work 388 in progress), September 2020. 390 [I-D.ietf-bier-lsr-ethernet-extensions] 391 Dhanaraj, S., Yan, G., Wijnands, I., Psenak, P., Zhang, 392 Z., and J. Xie, "LSR Extensions for BIER over Ethernet", 393 draft-ietf-bier-lsr-ethernet-extensions-02 (work in 394 progress), December 2020. 396 [I-D.ietf-bier-non-mpls-bift-encoding] 397 Wijnands, I., Mishra, M., Xu, X., and H. Bidgoli, "An 398 Optional Encoding of the BIFT-id Field in the non-MPLS 399 BIER Encapsulation", draft-ietf-bier-non-mpls-bift- 400 encoding-03 (work in progress), November 2020. 402 [I-D.ietf-bier-ospfv3-extensions] 403 Psenak, P., Nainar, N., and I. Wijnands, "OSPFv3 404 Extensions for BIER", draft-ietf-bier-ospfv3-extensions-03 405 (work in progress), November 2020. 407 [I-D.ietf-bier-path-mtu-discovery] 408 Mirsky, G., Przygienda, T., and A. Dolganow, "Path Maximum 409 Transmission Unit Discovery (PMTUD) for Bit Index Explicit 410 Replication (BIER) Layer", draft-ietf-bier-path-mtu- 411 discovery-09 (work in progress), November 2020. 413 [I-D.ietf-bier-ping] 414 Nainar, N., Pignataro, C., Akiya, N., Zheng, L., Chen, M., 415 and G. Mirsky, "BIER Ping and Trace", draft-ietf-bier- 416 ping-07 (work in progress), May 2020. 418 [I-D.ietf-bier-pmmm-oam] 419 Mirsky, G., Zheng, L., Chen, M., and G. Fioccola, 420 "Performance Measurement (PM) with Marking Method in Bit 421 Index Explicit Replication (BIER) Layer", draft-ietf-bier- 422 pmmm-oam-09 (work in progress), December 2020. 424 [I-D.ietf-bier-prefix-redistribute] 425 Zhang, Z., Bo, W., Zhang, Z., Wijnands, I., and Y. Liu, 426 "BIER Prefix Redistribute", draft-ietf-bier-prefix- 427 redistribute-00 (work in progress), August 2020. 429 [I-D.xzlnp-bier-ioam] 430 Min, X., Zhang, Z., Liu, Y., Nainar, N., and C. Pignataro, 431 "Bit Index Explicit Replication (BIER) Encapsulation for 432 In-situ OAM (IOAM) Data", draft-xzlnp-bier-ioam-01 (work 433 in progress), January 2021. 435 [I-D.zhang-bier-babel-extensions] 436 Zhang, Z. and T. Przygienda, "BIER in BABEL", draft-zhang- 437 bier-babel-extensions-04 (work in progress), November 438 2020. 440 [I-D.zzhang-tsvwg-generic-transport-functions] 441 Zhang, Z., Bonica, R., and K. Kompella, "Generic Transport 442 Functions", draft-zzhang-tsvwg-generic-transport- 443 functions-00 (work in progress), November 2020. 445 [RFC7368] Chown, T., Ed., Arkko, J., Brandt, A., Troan, O., and J. 446 Weil, "IPv6 Home Networking Architecture Principles", 447 RFC 7368, DOI 10.17487/RFC7368, October 2014, 448 . 450 Authors' Addresses 452 Zheng(Sandy) Zhang 453 ZTE Corporation 455 EMail: zhang.zheng@zte.com.cn 457 Zhaohui Zhang (editor) 458 Juniper Networks 460 EMail: zzhang@juniper.net 462 IJsbrand Wijnands 463 Individual 465 EMail: ice@braindump.be 466 Mankamana Mishra 467 Cisco Systems 469 EMail: mankamis@cisco.com 471 Hooman Bidgoli 472 Nokia 474 EMail: hooman.bidgoli@nokia.com 476 Gyan Mishra (editor) 477 Verizon 479 EMail: gyan.s.mishra@verizon.com