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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group J. Xie 3 Internet-Draft Huawei Technologies 4 Intended status: Standards Track L. Geng 5 Expires: January 2, 2020 China Mobile 6 M. McBride 7 Futurewei 8 R. Asati 9 Cisco 10 S. Dhanaraj 11 G. Yan 12 Y. Xia 13 Huawei 14 July 1, 2019 16 Encapsulation for BIER in Non-MPLS IPv6 Networks 17 draft-xie-bier-ipv6-encapsulation-02 19 Abstract 21 This document proposes a BIER IPv6 (BIERv6) encapsulation for Non- 22 MPLS IPv6 Networks using the IPv6 Destination Option extension 23 header. 25 Requirements Language 27 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 28 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 29 document are to be interpreted as described in [RFC2119] and 30 [RFC8174]. 32 Status of This Memo 34 This Internet-Draft is submitted in full conformance with the 35 provisions of BCP 78 and BCP 79. 37 Internet-Drafts are working documents of the Internet Engineering 38 Task Force (IETF). Note that other groups may also distribute 39 working documents as Internet-Drafts. The list of current Internet- 40 Drafts is at https://datatracker.ietf.org/drafts/current/. 42 Internet-Drafts are draft documents valid for a maximum of six months 43 and may be updated, replaced, or obsoleted by other documents at any 44 time. It is inappropriate to use Internet-Drafts as reference 45 material or to cite them other than as "work in progress." 47 This Internet-Draft will expire on January 2, 2020. 49 Copyright Notice 51 Copyright (c) 2019 IETF Trust and the persons identified as the 52 document authors. All rights reserved. 54 This document is subject to BCP 78 and the IETF Trust's Legal 55 Provisions Relating to IETF Documents 56 (https://trustee.ietf.org/license-info) in effect on the date of 57 publication of this document. Please review these documents 58 carefully, as they describe your rights and restrictions with respect 59 to this document. Code Components extracted from this document must 60 include Simplified BSD License text as described in Section 4.e of 61 the Trust Legal Provisions and are provided without warranty as 62 described in the Simplified BSD License. 64 Table of Contents 66 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 67 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 68 3. BIER IPv6 Encapsulation . . . . . . . . . . . . . . . . . . . 3 69 3.1. BIER Option in IPv6 Destination Options Header . . . . . 3 70 3.2. Multicast and Unicast Destination Address . . . . . . . . 6 71 3.3. BIERv6 Packet Format . . . . . . . . . . . . . . . . . . 8 72 4. BIERv6 Packet Processing . . . . . . . . . . . . . . . . . . 9 73 5. Security Considerations . . . . . . . . . . . . . . . . . . . 11 74 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11 75 6.1. BIER Option Type . . . . . . . . . . . . . . . . . . . . 11 76 6.2. BIER Multicast Address . . . . . . . . . . . . . . . . . 11 77 6.3. End.BIER Function . . . . . . . . . . . . . . . . . . . . 12 78 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 12 79 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 12 80 8.1. Normative References . . . . . . . . . . . . . . . . . . 12 81 8.2. Informative References . . . . . . . . . . . . . . . . . 13 82 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 13 84 1. Introduction 86 Bit Index Explicit Replication (BIER) [RFC8279] is an architecture 87 that provides optimal multicast forwarding without requiring 88 intermediate routers to maintain any per-flow state by using a 89 multicast-specific BIER header. 91 [RFC8296] defines a common BIER Header format for MPLS and Non-MPLS 92 networks. It has defined two types of encapsulation methods using 93 the common BIER Header, (1) BIER encapsulation in MPLS networks, 94 here-in after referred as MPLS BIER Header in this document and (2) 95 BIER encapsulation in Non-MPLS networks, here-in after referred as 96 Non-MPLS BIER Header in this document. [RFC8296] also assigned 97 Ethertype=0xAB37 for Non-MPLS BIER Header packets to be directly 98 carried over the Ethernet links. 100 This document proposes a BIER IPv6 encapsulation for Non-MPLS IPv6 101 Networks, defining a method to carry the standard Non-MPLS BIER 102 header (as defined in [RFC8296]) in the native IPv6 header. A new 103 IPv6 Option type - BIER Option is defined to encode the standard Non- 104 MPLS BIER header and this newly defined BIER Option is carried under 105 the Destination Options header of the native IPv6 Header [RFC8200]. 107 This document details one of the proposed solutions for transporting 108 BIER packets in an IPv6 network. To better understand the overall 109 BIER IPv6 problem space, use cases and proposed solutions, refer to 110 [I-D.ietf-bier-ipv6-requirements]. 112 2. Terminology 114 Readers of this document are assumed to be familiar with the 115 terminology and concepts of the documents listed as Normative 116 References. 118 The following new terms are used throughout this document: 120 o BIERv6 - BIER IPv6. 122 o BIER Option - An Option type carried in IPv6 Destination Options 123 Header which includes the standard Non-MPLS BIER Header. 125 o BIERv6 Header - An IPv6 Header with BIER Option. 127 o BIERv6 Packet - An IPv6 packet with BIERv6 Header. Such an IPv6 128 packet typically carries the user multicast payload and is 129 forwarded by BFRs in the BIERv6 network towards the multicast 130 receivers. 132 o BIER Multicast Address - A well-known multicast address used as a 133 Destination Address in the BIERv6 Header to forward the packets to 134 other BFRs in BIERv6 network. 136 3. BIER IPv6 Encapsulation 138 3.1. BIER Option in IPv6 Destination Options Header 140 Destination Options Header and the Options that can be carried under 141 this extension header is defined in [RFC8200]. This document defines 142 a new Option type - BIER Option, to encode the Non-MPLS BIER header. 143 As specified in Section 4.2 [RFC8200], the BIER Option follows type- 144 length-value (TLV) encoding format and the standard Non-MPLS BIER 145 header [RFC8296] is encoded in the value portion of the BIER Option 146 TLV. 148 This BIER Option MUST be carried only inside the IPv6 Destination 149 Options header and MUST NOT be carried under the Hop-by-Hop Options 150 header. 152 Co-existence of Destination Options Header with BIER option TLV and 153 other IPv6 extension headers MUST confirm to the general requirements 154 defined in [RFC8200]. In addition to the requirements defined in 155 [RFC8200], this document requires that the Destination Options Header 156 with a BIER Option TLV MUST appear only after the Routing Header if 157 the Routing Header is present in the IPv6 Header. 159 The BIER Option is encoded in type-length-value (TLV) format as 160 follows: 162 0 1 2 3 163 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 1 164 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 165 | Next Header | Hdr Ext Len | Option Type | Option Length | 166 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 167 | | 168 ~ Non-MPLS BIER Header (defined in RFC8296) ~ 169 | | 170 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 172 Next Header 8-bit selector. Identifies the type of header 173 immediately following the Destination Options header. 175 Hdr Ext Len 8-bit unsigned integer. Length of the Destination 176 Options header in 8-octet units, not including the first 8 octets. 178 Option Type To be allocated by IANA. See section 6. 180 Option Length 8-bit unsigned integer. Length of the option, in 181 octets, excluding the Option Type and Option Length fields. 183 Non-MPLS BIER Header The Non-MPLS BIER Header defined in RFC8296. 184 Fields in the Non-MPLS BIER Header MUST be encoded as below. 186 BIFT-id: The BIFT-id is a domain-wide unique value in Non-MPLS 187 IPv6 encapsulation. See Section 2.2 of RFC 8296. 189 TC: SHOULD be set to binary value 000 upon transmission and MUST 190 be ignored upon. See Section 2.2 of RFC 8296. 192 S bit: SHOULD be set to 1 upon transmission, and MUST be ignored 193 upon reception. See Section 2.2 of RFC 8296. 195 TTL: MUST be set to 0 upon transmission, and MUST be ignored 196 upon reception. The function of TTL is replaced by the Hop 197 Limit field in IPv6 header. 199 Nibble: SHOULD be set to 0000 upon transmission, and MUST be 200 ignored upon reception. See Section 2.2 of RFC 8296. 202 Ver: MUST be set to 0 upon transmission, and MUST be discarded 203 when it is not 0 upon reception. See Section 2.2 of RFC 8296. 205 BSL: See Section 2.1.2 of RFC 8296. 207 Entropy: See Section 2.1.2 of RFC 8296. 209 OAM: See Section 2.1.2 of RFC 8296. 211 Rsv: See Section 2.1.2 of RFC 8296. 213 DSCP: SHOULD be set to binary value 000000 upon transmission and 214 MUST be ignored upon reception. In IPv6 BIER encapsulation, 215 uses highest 6-bit of Traffic Class field of IPv6 header to hold 216 a Differentiated Services Codepoint [RFC2474]. 218 Proto: SHOULD be set to 0 upon transmission and MUST be ignored 219 upon reception. In IPv6 BIER encapsulation, the functionality 220 of this 6-bit Proto field is replaced by the Next Header field 221 in Destination Options header, which is the last IPv6 extension 222 header, to indicate the BIER payload, which is also IPv6 223 payload. 225 For BIER Proto 1, indicating a Downstream-assigned MPLS 226 payload, use Next Header value 137. 228 For BIER Proto 2, indicating an Upstream-assigned MPLS 229 payload, there is no Next Header code currently. An 230 upstream-assigned MPLS label within the context of special 231 BFIR router, which in turn is represented by the BFIR-id and 232 the Sub-domain indirectly indicated by the BIFT-id in a BIER- 233 MPLS or BIER-ETH packet, can be replaced by an IPv6 source 234 address in a BIER IPv6 encapsulation packet in a direct 235 manner. In this case, use Next Header value 4 for IPv4 236 payload, or value 41 for IPv6 payload. 238 For BIER Proto 3, indicating an Ethernet payload, use Next 239 Header value 97. 241 For BIER Proto 4, indicating an IPv4 payload, use Next Header 242 value 4. 244 For BIER Proto 5, indicating a BIER-OAM payload, use Next 245 Header value 58. How the BIER-PING is supported with BIER 246 IPv6 encapsulation is outside the scope of this document. 248 For BIER Proto 6, indicating an IPv6 payload, use Next Header 249 value 41. 251 BFIR-id: See Section 2.1.2 of RFC 8296. 253 BitString: See Section 2.1.2 of RFC 8296. 255 3.2. Multicast and Unicast Destination Address 257 BIER is generally a hop-by-hop and one-to-many architecture, and thus 258 the IPv6 Destination Address (DA) being a Multicast Address is a 259 proper approach for both the two paradigms in BIERv6 encapsulation. 261 This document proposes to use multicast address FF0X::AB37 (to be 262 allocated and reserved by IANA - See Section 6.2) as the IPv6 263 destination address for the BIERv6 packets to be forwarded in the 264 BIER domain. 266 All the interfaces of the BFRs supporting the BIERv6 encapsulation 267 defined in this document MUST subscribe and listen to BIER multicast 268 address FF0X::AB37 belong to scopes [1, 2, 3, 4, 5, E] defined in 269 [RFC7346]. However it is RECOMMENDED to use Realm-Local scope (scope 270 value 3), that is FF03:AB37 as a destination address while forwarding 271 the BIERv6 packet, as this scope zone is exactly the BIERv6 Domain. 272 The use of other scopes is outside the scope of this document. 274 Use of a Unicast Address as a IPv6 Destination Address is permissible 275 and useful in certain cases. 277 1. Tunneling a BIERv6 packet over a non-BIER capable router. 279 2. Fast rerouting a BIERv6 packet using a unicast by-pass tunnel. 281 3. Forwarding a BIERv6 packet to one of the many BFR neighbors 282 connected on a LAN. 284 4. Connecting BIER domains, for example Data Center domains, in an 285 overlay manner. 287 The unicast address used in BIERv6 packet targeting a BFR SHOULD be 288 the IPv6 BFR-Prefix advertised from this BFR. When a BFR advertises 289 the BIER information with BIERv6 encapsulation capability, the IPv6 290 BFR-prefix of this BFR MUST be selected specifically for BIERv6 291 packet forwarding. Locally this "BIER Specific" IPv6 address is 292 initialized in FIB with a flag of "BIER specific handling", 293 represented as End.BIER function. For convenience, the indication in 294 FIB share the same space as SRv6 Endpoints Behaviors defined in 295 [I-D.ietf-spring-srv6-network-programming]. Apart from this sharing 296 of code space, there is nothing dependent on SRv6. The co-existance 297 of BIERv6 and SRv6 is outside the scope of this document. 299 BFR Prefix is used only in control plane in BIER MPLS encapsulation 300 but not used in data plane. While in BIERv6, BFR prefix is used in 301 both control plane and data plane. The "BIER Specific" IPv6 address 302 can be used for BIER MPLS in control plane too. So it is RECOMMENDED 303 to use a "BIER specific" IPv6 address as BFR prefix when deploying 304 BIER in IPv6 network from the scratch. One should be careful not use 305 the IPv6 address selected as BFR prefix for other purpose like BGP 306 session until the "BIER specific handling" can do more general 307 process. 309 The following is an example of configuring a BIER specific IPv6 310 address and using this address as BFR prefix: 312 # Config a BIER specific IPv6 address with 128-bit mask on loopback0. 313 interface loopback0 314 ipv6 address 2019::AB37 128 End.BIER 316 # Config the BIER-specific IPv6 address on loopback0 as BFR Prefix. 317 bier sub-domain 6 ipv6-underlay 318 bfr-prefix interface loopback0 320 The address used as "BIER specific" IPv6 address can be from inside 321 the scope of an SRv6 Locator or outside the scope of the SRv6 322 Locator(s) since it is a host prefix (128-bit prefix-length prefix). 324 Each "BIER specific" address can be used in one or many sub-domains 325 as BFR-prefix, such that it can be associated with one or many Multi- 326 Topologies (MTs) or algorithms. 328 More than one "BIER specific" address are also allowed as different 329 BFR-prefix of more than one sub-domain, as described in section 2 of 330 [RFC8279]. 332 The following is an example pseudo-code of the End.BIER function: 334 1. IF NH = 60 AND HopLimit > 0 ;;Ref1 335 2. IF (OptType1 = BIER) and (OptLength1 = HdrExtLen*8 + 4) ;;Ref2 336 3. Lookup the BIER Header inside the BIER option TLV. 337 4. Forward via the matched entry. 338 5. ELSE 339 6. Drop the packet. 340 7. ELSE IF Last_NH = ICMPv6 ;;Ref3 341 8. Send to CPU. 342 9. ELSE 343 10. Drop the packet. 345 Ref1: Destination options header follows the IPv6 header directly and 346 HopLimit is bigger than zero. 348 Ref2: The first TLV is BIER type and is the only one in Destination 349 options header. 351 Ref3: An ICMPv6 packet using End.BIER as destination address. 353 3.3. BIERv6 Packet Format 355 As a multicast packet enters the BIER domain in a Non-MPLS IPv6 356 network, the multicast packet will be encapsulated with BIERv6 357 Header. 359 Typically a BIERv6 header would contain the Destination Options 360 Header as the only Extensions Header besides IPv6 Header. However, 361 it is allowed and possible for other extension headers to appear 362 along with the Destination Options Header as long as the requirements 363 listed in section 3.1 of this document is met. 365 Format of the multicast packet with BIERv6 encapsulation carrying 366 only the Destination Options header is depicted in the below figure. 368 +---------------+--------------+------------ 369 | IPv6 header | Dest Options | X type of 370 | | Header with | multicast 371 | | BIER Option | packet 372 | | | 373 | Next Hdr = 60 | Nxt Hdr = X | 374 +---------------+--------------+------------ 376 Format of the multicast packet with BIERv6 encapsulation carrying 377 other extension headers along with Destination Options extension 378 header is required to follow general recommendations of [RFC8200] and 379 examples in other RFCs. [RFC6275] introduces how the order should be 380 when other extension headers carries along with Home address option 381 in a destination options header. Similar to this example, this 382 document requires the Destination Options Header carrying the BIER 383 option MUST be placed as follows: 385 o After the routing header, if that header is present 387 o Before the Fragment Header, if that header is present 389 o Before the AH Header or ESP Header, if either one of those headers 390 is present 392 Source Address field in the IPv6 header MUST be a routable IPv6 393 unicast address of the BFIR in any case. 395 BFIR encodes the Non-MPLS BIER header in the above mentioned 396 encapsulation format and forwards the BIERv6 packet to the nexthop 397 BFR following the local BIFT table. 399 BFRs in the IPv6 network, processes and replicates the packets 400 towards the BFERs using the local BIFT table. The bit-string field 401 in the Non-MPLS BIER header may be changed by the BFRs as they 402 replicate the packet. BFRs MUST follow the procedures defined in 403 section 3.1 as they modify the other fields in the Non-MPLS BIER 404 header. The source address in the IPv6 header MUST NOT be modified 405 by the BFRs. 407 4. BIERv6 Packet Processing 409 There is no BIER-specific processing, and all the 8 steps in section 410 6.5 of RFC8279 apply to BIERv6 packet processing. However, there are 411 some IPv6-specific processing procedures due to the base and general 412 procedures of IPv6. 414 On the overlay layer, when a multicast packet enters the BIER domain 415 in a Non-MPLS IPv6 network, the Ingress BFR (BFIR) encapsulates the 416 multicast packet with a BIERv6 Header, transforming it to a BIERv6 417 packet. The BIERv6 header includes an IPv6 header and IPv6 418 Destination Options Header within a standard Non-MPLS BIER header. 419 Source Address field in the IPv6 header MUST be set to a routable 420 IPv6 unicast address of the BFIR. Destination Address field in the 421 IPv6 header is set to a BIER multicast address, FF0X::AB37, if the 422 next-hop BFR is directly connected, or MAY be set to a unicast 423 address in case of the scenarios discussed in section 3.2. 425 On the BIER layer, upon receiving an BIERv6 packet, the BFR processes 426 the IPv6 header first. This is the general procedure of IPv6. 428 If the IPv6 Destination address is the BIER multicast address, a 429 'BIER Specific Handling' indication will be obtained by the preceding 430 Multicast DA lookup (MFIB lookup). The BIER option, if exists, will 431 be checked to decide which neighbor(s) to replicate the BIERv6 packet 432 to. 434 If the IPv6 Destination address is an IPv6 BFR-Prefix unicast address 435 of this BFR, a 'BIER Specific Handling' indication will be obtained 436 by the preceding Unicast DA lookup (FIB lookup). The BIER option, if 437 exists, will be checked to decide which neighbor(s) to replicate the 438 BIERv6 packet to. 440 It is a local behavior to handle the combination of extension 441 headers, options and the BIER option(s) in destination options header 442 when a 'BIER Specific Handling' indication is got by the preceding 443 MFIB or FIB lookup. Early deployment of BIERv6 may require there is 444 only one BIER option TLV in the destination options header followed 445 the IPv6 header. How other extension headers or more BIER option 446 TLVs in a BIERv6 packet is handled is outside the scope of this 447 document. 449 A packet having a 'BIER Specific Handling' indication but not having 450 a BIER option MAY be processed normally as normal multicast or 451 unicast forwarding procedures do, or MAY be dropped. 453 A packet not having a 'BIER Specific Handling' indication but having 454 a BIER option SHOULD be processed normally as normal multicast or 455 unicast forwarding procedures, which may be a behavior of drop, or 456 send to CPU, or other behaviors in existing implementations. 458 The Destination Address field in the IPv6 Header MUST change to the 459 nexthop BFR's BFR Prefix if Unicast address is used in BIERv6. 461 The Hop Limit field of IPv6 header MUST decrease by 1 when sending 462 packets to a BFR neighbor, while the TTL in the BIER header MUST be 463 unchanged. 465 The BitString in the BIER header in the Destination Options Header 466 may change when sending packets to a neighbor. Such change of 467 BitString MUST be aligned with the procedure defined in RFC8279. 468 Because of the requirement to change the content of the option when 469 forwarding BIERv6 packet, the BIER option type should have chg flag 1 470 per section 4.2 of RFC8200. 472 The procedures applies normally if a bit corresponding to the self 473 bfr-id is set in the bit-string field of the Non-MPLS BIER header of 474 the BIERv6 packet. The node is considered to be an Egress BFR (BFER) 475 in this case. The BFER removes the BIERv6 header, including the IPv6 476 header and the Destination Options header, and copies the packet to 477 the multicast flow overlay. The egress VRF of a packet may be 478 determined by a single MFIB lookup on the BFER using both the IPv6 SA 479 and IPv6 DA. 481 5. Security Considerations 483 A BIERv6 packet with a special IPv6 Destination Address, either 484 multicast or unicast, would be processed by BIER forwarding procedure 485 only when the 'BIER valid' flag has been obtained ahead of time in 486 the normal MFIB or FIB lookup of the IPv6 header. Otherwise the 487 packet with an IPv6 BIER Option will be dropped, as if the Option is 488 not recognize by the node. 490 An IPv6 packet with BIER multicast address FF0X::AB37 as destination 491 address, but does not carry IPv6 BIER Option will be dropped. 493 6. IANA Considerations 495 6.1. BIER Option Type 497 Allocation is expected from IANA for a BIER Option Type codepoint 498 from the "Destination Options and Hop-by-Hop Options" sub-registry of 499 the "Internet Protocol Version 6 (IPv6) Parameters" registry. The 500 value 0x70 is suggested. 502 +-----------+-----+-----+-------+-------------+------------+ 503 | Hex Value | act | chg | rest | Description | Reference | 504 +-----------+-----+-----+-------+-------------+------------+ 505 | 0x70 | 01 | 1 | 10000 | BIER Option | This draft | 506 +-----------+-----+-----+-------+-------------+------------+ 508 Figure 1: IPv6 Option Type Suggested 510 6.2. BIER Multicast Address 512 Allocation is expected from IANA for a BIER Multicast Address from 513 the "Variable Scope Multicast Addresses" sub-registry of the "IPv6 514 Multicast Address Space Registry" registry. The address 'FF0X::AB37' 515 is suggested. 517 +-----------------------+---------------------+------------+ 518 | Address(es) | Description | Reference | 519 | | | | 520 +-----------------------+---------------------+------------+ 521 | FF0X:0:0:0:0:0:0:AB37 | ALL_BIER_FORWARDERS | This draft | 522 +-----------------------+---------------------+------------+ 524 Figure 2: Multicast Address Suggested 526 6.3. End.BIER Function 528 Allocation is expected from IANA for an End.BIER function codepoint 529 from the "SRv6 Endpoint Behaviors" sub-registry. The value 60 is 530 suggested. 532 +-------+--------+--------------------------+------------+ 533 | Value | Hex | Endpoint function | Reference | 534 +-------+--------+--------------------------+------------+ 535 | TBD | TBD | End.BIER | This draft | 536 +-------+--------+--------------------------+------------+ 538 Figure 3: End.BIER Function 540 7. Acknowledgements 542 The authors would like to thank Stig Venaas for his valuable 543 comments. Thanks IJsbrand Wijnands, Greg Shepherd, Tony Przygienda, 544 Toerless Eckert, Jeffrey Zhang for the helpful comments to improve 545 this document. 547 8. References 549 8.1. Normative References 551 [RFC6275] Perkins, C., Ed., Johnson, D., and J. Arkko, "Mobility 552 Support in IPv6", RFC 6275, DOI 10.17487/RFC6275, July 553 2011, . 555 [RFC7346] Droms, R., "IPv6 Multicast Address Scopes", RFC 7346, 556 DOI 10.17487/RFC7346, August 2014, 557 . 559 [RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6 560 (IPv6) Specification", STD 86, RFC 8200, 561 DOI 10.17487/RFC8200, July 2017, 562 . 564 [RFC8279] Wijnands, IJ., Ed., Rosen, E., Ed., Dolganow, A., 565 Przygienda, T., and S. Aldrin, "Multicast Using Bit Index 566 Explicit Replication (BIER)", RFC 8279, 567 DOI 10.17487/RFC8279, November 2017, 568 . 570 [RFC8296] Wijnands, IJ., Ed., Rosen, E., Ed., Dolganow, A., 571 Tantsura, J., Aldrin, S., and I. Meilik, "Encapsulation 572 for Bit Index Explicit Replication (BIER) in MPLS and Non- 573 MPLS Networks", RFC 8296, DOI 10.17487/RFC8296, January 574 2018, . 576 8.2. Informative References 578 [I-D.ietf-bier-ipv6-requirements] 579 McBride, M., Xie, J., Dhanaraj, S., and R. Asati, "BIER 580 IPv6 Requirements", draft-ietf-bier-ipv6-requirements-00 581 (work in progress), May 2019. 583 [I-D.ietf-spring-srv6-network-programming] 584 Filsfils, C., Camarillo, P., Leddy, J., 585 daniel.voyer@bell.ca, d., Matsushima, S., and Z. Li, "SRv6 586 Network Programming", draft-ietf-spring-srv6-network- 587 programming-00 (work in progress), April 2019. 589 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 590 Requirement Levels", BCP 14, RFC 2119, 591 DOI 10.17487/RFC2119, March 1997, 592 . 594 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 595 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 596 May 2017, . 598 Authors' Addresses 600 Jingrong Xie 601 Huawei Technologies 603 Email: xiejingrong@huawei.com 605 Liang Geng 606 China Mobile 607 Beijing 10053 609 Email: gengliang@chinamobile.com 611 Mike McBride 612 Futurewei 614 Email: mmcbride7@gmail.com 615 Rajiv Asati 616 Cisco 618 Email: rajiva@cisco.com 620 Senthil Dhanaraj 621 Huawei 623 Email: senthil.dhanaraj@huawei.com 625 Gang Yan 626 Huawei 628 Email: yangang@huawei.com 630 Yang Xia 631 Huawei 633 Email: yolanda.xia@huawei.com