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Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Outdated reference: A later version (-13) exists of draft-ietf-bier-ping-07 == Outdated reference: A later version (-07) exists of draft-ietf-mpls-p2mp-bfd-01 Summary: 0 errors (**), 0 flaws (~~), 3 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 BIER WG Q. Xiong 3 Internet-Draft ZTE Corporation 4 Intended status: Standards Track G. Mirsky 5 Expires: 6 November 2022 Ericsson 6 F. Hu 7 Individual 8 C. Liu 9 China Unicom 10 5 May 2022 12 BIER BFD 13 draft-ietf-bier-bfd-02 15 Abstract 17 Point to multipoint (P2MP) BFD is designed to verify multipoint 18 connectivity. This document specifies the application of P2MP BFD in 19 BIER network. 21 Status of This Memo 23 This Internet-Draft is submitted in full conformance with the 24 provisions of BCP 78 and BCP 79. 26 Internet-Drafts are working documents of the Internet Engineering 27 Task Force (IETF). Note that other groups may also distribute 28 working documents as Internet-Drafts. The list of current Internet- 29 Drafts is at https://datatracker.ietf.org/drafts/current/. 31 Internet-Drafts are draft documents valid for a maximum of six months 32 and may be updated, replaced, or obsoleted by other documents at any 33 time. It is inappropriate to use Internet-Drafts as reference 34 material or to cite them other than as "work in progress." 36 This Internet-Draft will expire on 6 November 2022. 38 Copyright Notice 40 Copyright (c) 2022 IETF Trust and the persons identified as the 41 document authors. All rights reserved. 43 This document is subject to BCP 78 and the IETF Trust's Legal 44 Provisions Relating to IETF Documents (https://trustee.ietf.org/ 45 license-info) in effect on the date of publication of this document. 46 Please review these documents carefully, as they describe your rights 47 and restrictions with respect to this document. Code Components 48 extracted from this document must include Revised BSD License text as 49 described in Section 4.e of the Trust Legal Provisions and are 50 provided without warranty as described in the Revised BSD License. 52 Table of Contents 54 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 55 2. Conventions used in this document . . . . . . . . . . . . . . 3 56 2.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3 57 2.2. Requirements Language . . . . . . . . . . . . . . . . . . 3 58 3. BIER BFD Encapsulation . . . . . . . . . . . . . . . . . . . 3 59 4. BIER BFD Session Bootstrapping . . . . . . . . . . . . . . . 3 60 4.1. BIER OAM Bootstrapping . . . . . . . . . . . . . . . . . 4 61 4.2. IGP Protocol Bootstrapping . . . . . . . . . . . . . . . 4 62 4.2.1. IS-IS Extension for BIER BFD . . . . . . . . . . . . 5 63 4.2.2. OSPF Extension for BIER BFD . . . . . . . . . . . . . 6 64 5. Discriminators and Packet Demultiplexing . . . . . . . . . . 7 65 6. Active Tail in BIER BFD . . . . . . . . . . . . . . . . . . . 7 66 6.1. Unsolicited Head Notification Mode . . . . . . . . . . . 7 67 7. Security Considerations . . . . . . . . . . . . . . . . . . . 8 68 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 8 69 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 70 9.1. BIER OAM Message Type . . . . . . . . . . . . . . . . . . 8 71 9.2. BFD Discriminator TLV . . . . . . . . . . . . . . . . . . 9 72 9.3. BIER BFD Sub-sub-TLV . . . . . . . . . . . . . . . . . . 9 73 9.4. BIER BFD Sub-TLV . . . . . . . . . . . . . . . . . . . . 9 74 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 9 75 10.1. Normative References . . . . . . . . . . . . . . . . . . 10 76 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 11 78 1. Introduction 80 Bit Index Explicit Replication (BIER) [RFC8279] provides the 81 forwarding of multicast data packets through a multicast domain. It 82 does so without requiring any explicit tree-building protocol and 83 without requiring intermediate nodes to maintain any per-flow state. 85 [RFC8562] defines a method of using Bidirectional Forwarding 86 Detection (BFD) to monitor and detect unicast failures between the 87 sender (head) and one or more receivers (tails) in multipoint or 88 multicast networks. [RFC8563] describes active tail extensions to 89 the BFD protocol for multipoint networks. 91 This document describes the procedures for using such mode of BFD 92 protocol to monitor connectivity between a multipoint sender, Bit- 93 Forwarding Ingress Router (BFIR), and a set of one or more multipoint 94 receivers, Bit-Forwarding Egress Routers (BFERs). The BIER BFD only 95 supports the unidirectional multicast. This document defines the use 96 of P2MP BFD as per [RFC8562], and active tail as per [RFC8563] for 97 BIER-specific domain. 99 2. Conventions used in this document 101 2.1. Terminology 103 This document uses the acronyms defined in [RFC8279] along with the 104 following: 106 BFD: Bidirectional Forwarding Detection. 108 OAM: Operations, Administration, and Maintenance. 110 P2MP: Point to Multi-Point. 112 2.2. Requirements Language 114 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 115 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 116 "OPTIONAL" in this document are to be interpreted as described in BCP 117 14 [RFC2119] [RFC8174] when, and only when, they appear in all 118 capitals, as shown here. 120 3. BIER BFD Encapsulation 122 BIER BFD encapsulation uses the BIER OAM packet format defined in 123 [I-D.ietf-bier-ping]. The value of the Message Type field MUST be 124 set to BIER BFD (TBD1 will be assigned by IANA Section 9.1). BFD 125 Control packet, defined in Section 4 [RFC5880], immediately follows 126 the BIER OAM header. The operation of Multipoint BFD with the BFD 127 Control Packet is described in [RFC8562]. 129 4. BIER BFD Session Bootstrapping 131 As defined in [RFC8562], a BIER BFD session MAY be established to 132 monitor the state of the multipoint path. The BIER BFD session could 133 be created for each multipoint path and the set of BFERs over which 134 the BFIR is requested to run BIER BFD. The BFIR MUST advertise the 135 multipoint path and the value of My Discriminator associated with the 136 path to the set of BFERs. Bootstrapping a BIER BFD session MAY use 137 BIER OAM message Section 4.1 or the control plane Section 4.2. 139 The BIER BFD bootstrapping MUST be repeated when the value of this 140 discriminator being changed. 142 4.1. BIER OAM Bootstrapping 144 The BIER OAM could be used for bootstrapping the BIER BFD session. 145 The BFIR sends the BIER OAM Echo request message carrying a BFD 146 discriminator TLV which immediately follows the Target SI-Bitstring 147 TLV (section 3.3.2 [I-D.ietf-bier-ping]). 149 The Target SI-Bitstring TLV MUST be used to carry the set of BFER 150 information (including Sub-domain-id, Set ID, BS Len, Bitstring) for 151 the purpose of the session establishment. 153 Figure 1 displays the format of BFD Discriminator TLV. 155 0 1 2 3 156 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 1 157 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 158 | Type = TBD2 | Length | 159 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 160 | My Discriminator | 161 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 163 Figure 1: BFD Discriminator TLV 165 where: 167 * Type indicates BFD Discriminator TLV. The value (TBD2) is to be 168 allocated by IANA (Section 9.2). 170 * Length MUST be set to 4. 172 * My Discriminator - four-octet long field. The value is the local 173 discriminator generated by BFIR for this session. This 174 discriminator MUST be used as the My Discriminator field n the 175 BIER BFD Control packets sent by the BFIR. 177 4.2. IGP Protocol Bootstrapping 179 An alternative option to bootstrap the BIER BFD is to advertise the 180 BFD information in the control plane. This document defines a new 181 BIER BFD Sub-sub-TLV carried in IGP protocol including IS-IS and 182 OSPF. 184 The BFIR generates the My Discriminator value for each multicast flow 185 and advertises it to the expecting BFERs, which is indicated by the 186 Bitstring and the BIFT-id, which is carried in BIER BFD sub-sub-TLV. 187 The corresponding BFERs SHOULD store the My Discriminator value for 188 packet Demultiplexing. 190 4.2.1. IS-IS Extension for BIER BFD 192 The new BIER BFD Sub-sub-TLV is carried within the BIER Info sub-TLV 193 defined in [RFC8401]. The format is displayed in Figure 2. 195 0 1 2 3 196 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 1 197 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 198 | Type = TBD3 | Length | 199 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 200 | My Discriminator | 201 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 202 | RESERVED | BIFT-id | 203 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 204 | BitString (first 32 bits) ~ 205 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 206 ~ ~ 207 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 208 ~ BitString (last 32 bits) | 209 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 211 Figure 2: BIER BFD Sub-sub-TLV for IS-IS Extension 213 where: 215 * Type indicates BIER BFD sub-sub-TLV. The value (TBD3) is to be 216 allocated by IANA (Section 9.3). 218 * Length is a two-octet field. The value is the length of the BIER 219 BFD Sub-sub-TLV for IS-IS extension, in octets 221 * My Discriminator is a four-octet long field. The value is a 222 unique, nonzero discriminator value generated by BFIR for each 223 multipoint path. This discriminator MUST be used as the My 224 Discriminator field n the BIER BFD Control packets sent by the 225 BFIR. 227 * BIFT-id is a two-octet field. The value represents a particular 228 Bit Index Forwarding Table (BIFT) as per [RFC8279]. 230 * BitString field carries the set of BFR-IDs of BFER(s) that the 231 BFIR expects to establish the BIER BFD session. 233 4.2.2. OSPF Extension for BIER BFD 235 The new BIER BFD Sub-TLV is a sub-TLV of the BIER Sub-TLV defined in 236 [RFC8444]. The format is displayed in Figure 3. 238 0 1 2 3 239 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 1 240 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 241 | Type = TBD4 | Length | 242 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 243 | My Discriminator | 244 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 245 | RESERVED | BIFT-id | 246 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 247 | BitString (first 32 bits) ~ 248 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 249 ~ ~ 250 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 251 ~ BitString (last 32 bits) | 252 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 254 Figure 3: BIER BFD Sub-TLV for OSPF extension 256 Figure 3: BIER BFD Sub-sub-TLV for IS-IS Extension 258 where: 260 * Type indicates BIER BFD sub-TLV. The value (TBD4) is to be 261 allocated by IANA (Section 9.4). 263 * Length is a two-octet field. The value is the length of the BIER 264 BFD sub-TLV for OSPF extension, in octets 266 * My Discriminator is a four-octet long field. The value is a 267 unique, nonzero discriminator value generated by BFIR for each 268 multipoint path. This discriminator MUST be used as the My 269 Discriminator field n the BIER BFD Control packets sent by the 270 BFIR. 272 * BIFT-id is a two-octet field. The value represents a particular 273 Bit Index Forwarding Table (BIFT) as per [RFC8279]. 275 * BitString field carries the set of BFR-IDs of BFER(s) that the 276 BFIR expects to establish the BIER BFD session. 278 5. Discriminators and Packet Demultiplexing 280 As defined in [RFC8562], the BFIR sends BFD Control packets to the 281 set of BFERs over the multipoint path via the BIER BFD session with 282 My Discriminator is set to the value assigned by the BFIR, and the 283 value of the Your Discriminator is set to zero. The set of BFERs 284 MUST demultiplex BFD packets based on a combination of the source 285 address, My Discriminator value. The source address is BFIR-id and 286 BIER MPLS Label (MPLS network) or BFIR-id and BIFT-id (Non-MPLS 287 network) for BIER BFD. My Discriminator value is advertised in BIER 288 BFD bootstrapping using one of the options described in Section 4. 290 6. Active Tail in BIER BFD 292 [RFC8563] defined an extension for Multipoint BFD, which allows the 293 head to discover the state of a multicast distribution tree for any 294 sub-set of tails. For BIER BFD in the active tail mode, the BFIR may 295 learn the state and connectivity of the BFERs by allowing the BFERs 296 to notify the BFIR. As per [RFC8563] provides detailed information 297 on how the BFIR can use multipoint Poll sequence message or a 298 combination of multicast and unicast Poll sequence messages to 299 determine the state of the multicast tree. Also, [RFC8563] describes 300 that a BFER can transmit an unsolicited unicast Poll sequence message 301 to the BFIR (note that a unicast message must be sent over a path 302 which is disjoint from the multicast distribution tree). 304 6.1. Unsolicited Head Notification Mode 306 [I-D.ietf-mpls-p2mp-bfd] provides detailed information on using the 307 unsolicited notification method for P2MP MPLS LSP, which is also 308 applicable to BIER. 310 In Section 5.2.1 [RFC8563] is noted that "the tail sends unsolicited 311 BFD packets in response to the detection of a multipoint path 312 failure" but without the specifics on the information in the packet 313 and frequency of transmissions. This document defines the procedure 314 of the active tail with unsolicited notifications for BIER as 315 specified below. 317 Upon detecting the failure, a BFER sends a BFD control packet with 318 the following settings: 320 * the Poll (P) bit is set; 322 * the Status (Sta) field is set to Down value; 323 * the Diagnostic (Diag) field is set to Control Detection Time 324 Expired value; 326 * the value of the Your Discriminator field is set to the value the 327 BFER has been used to demultiplex that BFD multipoint session; 329 * BFD Control packet is encapsulated in IP/UDP with the destination 330 IP address of the BFIR and the UDP destination port number set to 331 4784 per [RFC5883] 333 * the BFD Control packets are transmitted at the rate of one per 334 second until either the BFER receives valid for this BFD session 335 control packet with the Final (F) bit is set from the BFIR or the 336 defect condition clears. 338 To improve the likelihood of notifying the BFIR of the failure, the 339 BFER SHOULD transmit three BFD Control packets defined above in short 340 succession. 342 A BFIR that has received the BFD Control packet, as described above, 343 sends the unicast IP/UDP encapsulated BFD control packet with the 344 Final (F) bit set to the BFER. 346 7. Security Considerations 348 For BIER OAM packet processing security considerations, see 349 [I-D.ietf-bier-ping]. 351 For general multipoint BFD security considerations, see [RFC8562]. 353 No additional security issues are raised in this document beyond 354 those that exist in the referenced BFD documents. 356 8. Acknowledgements 358 The authors would like to thank the comments and suggestions from 359 Sandy Zhang, Jeffrey (Zhaohui) Zhang, Donald Eastlake 3rd. 361 9. IANA Considerations 363 9.1. BIER OAM Message Type 365 IANA is requested to assign a new type from the BIER OAM Message Type 366 registry as follows: 368 +=======+=============+=================+ 369 | Value | Description | Reference | 370 +=======+=============+=================+ 371 | TBD1 | BIER BFD | [this document] | 372 +-------+-------------+-----------------+ 374 Table 1 376 9.2. BFD Discriminator TLV 378 IANA is requested to assign a new type from the BIER OAM TLV registry 379 as follows: 381 +=======+=======================+=================+ 382 | Value | Description | Reference | 383 +=======+=======================+=================+ 384 | TBD2 | BFD discriminator TLV | [this document] | 385 +-------+-----------------------+-----------------+ 387 Table 2 389 9.3. BIER BFD Sub-sub-TLV 391 IANA is requested to assign a new BIER BFD Sub-sub-TLV within the 392 BIER Info sub-TLV registry is defined in [RFC8401] as follows: 394 +=======+======================+=================+ 395 | Value | Description | Reference | 396 +=======+======================+=================+ 397 | TBD3 | BIER BFD Sub-sub-TLV | [this document] | 398 +-------+----------------------+-----------------+ 400 Table 3 402 9.4. BIER BFD Sub-TLV 404 IANA is requested to assign a new BIER BFD Sub-TLV from the BIER Sub- 405 TLV registry is defined in [RFC8444] as follows: 407 +=======+==================+=================+ 408 | Value | Description | Reference | 409 +=======+==================+=================+ 410 | TBD4 | BIER BFD Sub-TLV | [this document] | 411 +-------+------------------+-----------------+ 413 Table 4 415 10. References 416 10.1. Normative References 418 [I-D.ietf-bier-ping] 419 Kumar, N., Pignataro, C., Akiya, N., Zheng, L., Chen, M., 420 and G. Mirsky, "BIER Ping and Trace", Work in Progress, 421 Internet-Draft, draft-ietf-bier-ping-07, 11 May 2020, 422 . 425 [I-D.ietf-mpls-p2mp-bfd] 426 Mirsky, G., Mishra, G., and D. E. 3rd, "BFD for Multipoint 427 Networks over Point-to-Multi-Point MPLS LSP", Work in 428 Progress, Internet-Draft, draft-ietf-mpls-p2mp-bfd-01, 10 429 February 2022, . 432 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 433 Requirement Levels", BCP 14, RFC 2119, 434 DOI 10.17487/RFC2119, March 1997, 435 . 437 [RFC5880] Katz, D. and D. Ward, "Bidirectional Forwarding Detection 438 (BFD)", RFC 5880, DOI 10.17487/RFC5880, June 2010, 439 . 441 [RFC5883] Katz, D. and D. Ward, "Bidirectional Forwarding Detection 442 (BFD) for Multihop Paths", RFC 5883, DOI 10.17487/RFC5883, 443 June 2010, . 445 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 446 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 447 May 2017, . 449 [RFC8279] Wijnands, IJ., Ed., Rosen, E., Ed., Dolganow, A., 450 Przygienda, T., and S. Aldrin, "Multicast Using Bit Index 451 Explicit Replication (BIER)", RFC 8279, 452 DOI 10.17487/RFC8279, November 2017, 453 . 455 [RFC8401] Ginsberg, L., Ed., Przygienda, T., Aldrin, S., and Z. 456 Zhang, "Bit Index Explicit Replication (BIER) Support via 457 IS-IS", RFC 8401, DOI 10.17487/RFC8401, June 2018, 458 . 460 [RFC8444] Psenak, P., Ed., Kumar, N., Wijnands, IJ., Dolganow, A., 461 Przygienda, T., Zhang, J., and S. Aldrin, "OSPFv2 462 Extensions for Bit Index Explicit Replication (BIER)", 463 RFC 8444, DOI 10.17487/RFC8444, November 2018, 464 . 466 [RFC8562] Katz, D., Ward, D., Pallagatti, S., Ed., and G. Mirsky, 467 Ed., "Bidirectional Forwarding Detection (BFD) for 468 Multipoint Networks", RFC 8562, DOI 10.17487/RFC8562, 469 April 2019, . 471 [RFC8563] Katz, D., Ward, D., Pallagatti, S., Ed., and G. Mirsky, 472 Ed., "Bidirectional Forwarding Detection (BFD) Multipoint 473 Active Tails", RFC 8563, DOI 10.17487/RFC8563, April 2019, 474 . 476 Authors' Addresses 478 Quan Xiong 479 ZTE Corporation 480 No.6 Huashi Park Rd 481 Wuhan 482 Hubei, 430223 483 China 484 Phone: +86 27 83531060 485 Email: xiong.quan@zte.com.cn 487 Greg Mirsky 488 Ericsson 489 Email: gregimirsky@gmail.com 491 Fangwei Hu 492 Individual 493 Email: hufwei@gmail.com 495 Chang Liu 496 China Unicom 497 No.9 Shouti Nanlu 498 Beijing 499 100048 500 China 501 Phone: +86-010-68799999-7294 502 Email: liuc131@chinaunicom.cn