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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(See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Outdated reference: A later version (-13) exists of draft-ietf-bier-ping-07 == Outdated reference: A later version (-15) exists of draft-mirsky-mpls-p2mp-bfd-10 Summary: 0 errors (**), 0 flaws (~~), 3 warnings (==), 1 comment (--).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 Quan Xiong 3 Internet-Draft Greg Mirsky 4 Intended status: Standards Track ZTE Corporation 5 Expires: February 6, 2021 Fangwei Hu 6 Individual 7 Chang Liu 8 China Unicom 9 August 5, 2020 11 BIER BFD 12 draft-ietf-bier-bfd-00.txt 14 Abstract 16 Point to multipoint (P2MP) BFD is designed to verify multipoint 17 connectivity. This document specifies the application of P2MP BFD in 18 BIER network. 20 Status of This Memo 22 This Internet-Draft is submitted in full conformance with the 23 provisions of BCP 78 and BCP 79. 25 Internet-Drafts are working documents of the Internet Engineering 26 Task Force (IETF). Note that other groups may also distribute 27 working documents as Internet-Drafts. The list of current Internet- 28 Drafts is at https://datatracker.ietf.org/drafts/current/. 30 Internet-Drafts are draft documents valid for a maximum of six months 31 and may be updated, replaced, or obsoleted by other documents at any 32 time. It is inappropriate to use Internet-Drafts as reference 33 material or to cite them other than as "work in progress." 35 This Internet-Draft will expire on February 6, 2021. 37 Copyright Notice 39 Copyright (c) 2020 IETF Trust and the persons identified as the 40 document authors. All rights reserved. 42 This document is subject to BCP 78 and the IETF Trust's Legal 43 Provisions Relating to IETF Documents 44 (https://trustee.ietf.org/license-info) in effect on the date of 45 publication of this document. Please review these documents 46 carefully, as they describe your rights and restrictions with respect 47 to this document. Code Components extracted from this document must 48 include Simplified BSD License text as described in Section 4.e of 49 the Trust Legal Provisions and are provided without warranty as 50 described in the Simplified 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 . . . . . . . . . . . . 4 63 4.2.2. OSPF extension for BIER BFD . . . . . . . . . . . . . 5 64 5. Discriminators and Packet Demultiplexing . . . . . . . . . . 6 65 6. Active Tail in BIER BFD . . . . . . . . . . . . . . . . . . . 6 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 . . . . . . . . . . . . . . . . . . 8 72 9.3. BIER BFD Sub-sub-TLV . . . . . . . . . . . . . . . . . . 8 73 9.4. BIER BFD Sub-TLV . . . . . . . . . . . . . . . . . . . . 9 74 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 9 75 10.1. Normative References . . . . . . . . . . . . . . . . . . 9 76 10.2. Informative References . . . . . . . . . . . . . . . . . 10 77 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10 79 1. Introduction 81 Bit Index Explicit Replication (BIER) [RFC8279] provides the 82 forwarding of multicast data packets through a multicast domain. It 83 does so without requiring any explicit tree-building protocol and 84 without requiring intermediate nodes to maintain any per-flow state. 86 [RFC8562] defines a method of using Bidirectional Forwarding 87 Detection (BFD) to monitor and detect unicast failures between the 88 sender (head) and one or more receivers (tails) in multipoint or 89 multicast networks. [RFC8563] describes active tail extensions to 90 the BFD protocol for multipoint networks. 92 This document describes the procedures for using such mode of BFD 93 protocol to monitor connectivity between a multipoint sender, Bit- 94 Forwarding Ingress Router (BFIR), and a set of one or more multipoint 95 receivers, Bit-Forwarding Egress Routers (BFERs). The BIER BFD only 96 supports the unidirectional multicast. This document defines the use 97 of P2MP BFD as per [RFC8562], and active tail as per [RFC8563] for 98 BIER-specific domain. 100 2. Conventions used in this document 102 2.1. Terminology 104 This document uses the acronyms defined in [RFC8279] along with the 105 following: 107 BFD: Bidirectional Forwarding Detection. 109 OAM: Operations, Administration, and Maintenance. 111 P2MP: Point to Multi-Point. 113 2.2. Requirements Language 115 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 116 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 117 "OPTIONAL" in this document are to be interpreted as described in BCP 118 14 [RFC2119] [RFC8174] when, and only when, they appear in all 119 capitals, as shown here. 121 3. BIER BFD Encapsulation 123 BIER BFD encapsulation uses the BIER OAM packet format defined in 124 [I-D.ietf-bier-ping]. The value of the Message Type field MUST be 125 set to BIER BFD (TBD1 by IANA ). BFD Control Packet, defined in 126 Section 4 [RFC5880] immediately follows the BIER OAM header. The 127 operation of Multipoint BFD with the BFD Control Packet is described 128 in [RFC8562]. 130 4. BIER BFD Session Bootstrapping 132 As defined in [RFC8562], BIER BFD session MAY be established to 133 monitor the state of the multipoint path. The BIER BFD session could 134 be created for each multipoint path and the set of BFERs over which 135 the BFIR is requested to run BIER BFD. The BFIR MUST advertise the 136 multipoint path and the value of My Discriminator associated with the 137 path to the set of BFERs. Bootstrapping a BIER BFD session MAY use 138 BIER OAM message Section 4.1 or the control plane Section 4.2. 140 The BIER BFD bootstrapping MUST be repeated when the value of this 141 discriminator being changed. 143 4.1. BIER OAM Bootstrapping 145 The BIER OAM could be used for bootstrapping the BIER BFD session. 146 The BFIR sends the BIER OAM Echo request message carrying a BFD 147 discriminator TLV which immediately follows the Target SI-Bitstring 148 TLV (section 3.3.2 [I-D.ietf-bier-ping]). 150 The Target SI-Bitstring TLV MUST be used to carry the set of BFER 151 information (including Sub-domain-id, Set ID, BS Len, Bitstring) for 152 the purpose of the session establishment. 154 The BFD discriminator TLV is a new TLV for BIER OAM TLV with the type 155 (TBD2 by IANA) and the length of 4. The value contains the 4-byte 156 local discriminator generated by BFIR for this session. This 157 discriminator MUST subsequently be used as the My Discriminator field 158 in the BIER BFD session packets sent by BFIR. The format is as 159 follows. 161 0 1 2 3 162 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 1 163 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 164 | Type=TBD2 | Length | 165 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 166 | My Discriminator | 167 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 169 Figure 1: BFD discriminator TLV 171 4.2. IGP protocol Bootstrapping 173 An alternative option to bootstrap the BIER BFD is to advertise the 174 BFD information in the control plane. This document defines a new 175 BIER BFD Sub-sub-TLV carried in IS-IS and OSPF protocol. 177 The BFIR generates the My Discriminator value for each multicast flow 178 and advertises it to the expecting BFERs which is indicated by the 179 Bitstring which is carried in BIER BFD sub-sub-TLV. The 180 corresponding BFERs SHOULD store the My Discriminator value for 181 packet Demultiplexing. 183 4.2.1. IS-IS extension for BIER BFD 185 The new BIER BFD Sub-sub-TLV is carried within the BIER Info sub-TLV 186 defined in [RFC8401]. The format is as follows. 188 0 1 2 3 189 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 1 190 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 191 | Type | Length | 192 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 193 | My Discriminator | 194 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 195 | RESERVED | BIFT-id | 196 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 197 | BitString (first 32 bits) ~ 198 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 199 ~ ~ 200 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 201 ~ BitString (last 32 bits) | 202 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 204 Figure 2: BIER BFD Sub-sub-TLV for IS-IS extension 206 Type: TBD3 by IANA. 208 Length: Length of the BIER BFD Sub-sub-TLV for IS-IS extension, in 209 bytes. 211 My Discriminator: A unique, nonzero discriminator value generated by 212 BFIR for each multipoint path. 214 The BitString field carries the set of BFR-IDs of BFER(s) that the 215 BFIR expects to establish the BIER BFD session. 217 The BIFT-id represents a particular Bit Index Forwarding Table (BIFT) 218 as per [RFC8279]. 220 4.2.2. OSPF extension for BIER BFD 222 The new BIER BFD Sub-TLV is a sub-TLV of the BIER Sub-TLV defined in 223 [RFC8444]. The format is as follows. 225 0 1 2 3 226 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 1 227 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 228 | Type | Length | 229 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 230 | My Discriminator | 231 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 232 | RESERVED | BIFT-id | 233 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 234 | BitString (first 32 bits) ~ 235 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 236 ~ ~ 237 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 238 ~ BitString (last 32 bits) | 239 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 241 Figure 3: BIER BFD Sub-TLV for OSPF extension 243 Type: TBD4 by IANA. 245 Length: Length of the BIER BFD Sub-TLV for OSPF extension, in bytes. 247 Other fields in BIER BFD Sub-TLV is the same with section 4.2.1. 249 5. Discriminators and Packet Demultiplexing 251 As defined in [RFC8562], the BFIR sends BFD Control packets over the 252 multipoint path via the BIER BFD session with My Discriminator set to 253 the value assigned by the BFIR and the value of the Your 254 Discriminator set to zero. The set of BFERs MUST demultiplex BFD 255 packets based on a combination of the source address, My 256 Discriminator value. The source address is BFIR-id and BIER MPLS 257 Label (MPLS network) or BFIR-id and BIFT-id (Non-MPLS network) for 258 BIER BFD. My Discriminator value is advertised in BIER BFD 259 bootstrapping using one of the options described in Section 4. 261 6. Active Tail in BIER BFD 263 [RFC8563] defined an extension for Multipoint BFD, which allows the 264 head to discover the state of a multicast distribution tree for any 265 sub-set of tails. For BIER BFD in the active tail mode, the BFIR may 266 learn the state and connectivity of the BFERs through allowing the 267 BFERs to notify the BFIR. As per [RFC8563] provides detailed 268 information on how the BFIR can use multipoint Poll sequence message 269 or a combination of multicast and unicast Poll sequence messages to 270 determine the state of the multicast tree. Also, [RFC8563] describes 271 that a BFER can transmit an unsolicited unicast Poll sequence message 272 to the BFIR (note that a unicast message must be sent over a path 273 which is disjoint from the multicast distribution tree). 275 6.1. Unsolicited Head Notification Mode 277 [I-D.mirsky-mpls-p2mp-bfd] provides detailed information on using the 278 unsolicited notification method for P2MP MPLS LSP which is also 279 applicable to BIER. 281 In Section 5.2.1 [RFC8563] is noted that "the tail sends unsolicited 282 BFD packets in response to the detection of a multipoint path 283 failure" but without the specifics on the information in the packet 284 and frequency of transmissions. This document defines the procedure 285 of the active tail with unsolicited notifications for BIER as 286 specified below. 288 Upon detecting the failure, a BFER sends a BFD control packet with 289 the following settings: 291 o the Poll (P) bit is set; 293 o the Status (Sta) field set to Down value; 295 o the Diagnostic (Diag) field set to Control Detection Time Expired 296 value; 298 o the value of the Your Discriminator field is set to the value the 299 BFER has been using to demultiplex that BFD multipoint session; 301 o BFD Control packet is encapsulated in IP/UDP with the destination 302 IP address of the BFIR and the UDP destination port number set to 303 4784 per [RFC5883] 305 o the BFD Control packets are transmitted at the rate of one per 306 second until either the BFER receives valid for this BFD session 307 control packet with the Final (F) bit set from the BFIR or the 308 defect condition clears. 310 To improve the likelihood of notifying the BFIR of the failure, the 311 BFER SHOULD transmit three BFD Control packets defined above in short 312 succession. 314 A BFIR that has received the BFD Control packet, as described above, 315 sends the unicast IP/UDP encapsulated BFD control packet with the 316 Final (F) bit set to the BFER. 318 7. Security Considerations 320 For BIER OAM packet processing security considerations, see 321 [I-D.ietf-bier-ping]. 323 For general multipoint BFD security considerations, see [RFC8562]. 325 No additional security issues are raised in this document beyond 326 those that exist in the referenced BFD documents. 328 8. Acknowledgements 330 The authors would like to thank the comments and suggestions from 331 Sandy Zhang, Jeffrey (Zhaohui) Zhang, Donald Eastlake 3rd. 333 9. IANA Considerations 335 9.1. BIER OAM Message Type 337 IANA is requested to assign a new type from the BIER OAM Message Type 338 registry as follows: 340 +--------+--------------+------------------+ 341 | Value | Description | Reference | 342 +--------+--------------+------------------+ 343 | TBD1 | BIER BFD | [this document] | 344 +--------+--------------+------------------+ 346 Table 1 348 9.2. BFD Discriminator TLV 350 IANA is requested to assign a new type from the BIER OAM TLV registry 351 as follows: 353 +--------+-----------------------+------------------+ 354 | Value | Description | Reference | 355 +--------+-----------------------+------------------+ 356 | TBD2 | BFD discriminator TLV | [this document] | 357 +--------+-----------------------+------------------+ 359 Table 2 361 9.3. BIER BFD Sub-sub-TLV 363 IANA is requested to assign a new BIER BFD Sub-sub-TLV within the 364 BIER Info sub-TLV registry defined in [RFC8401] as follows: 366 +--------+----------------------+------------------+ 367 | Value | Description | Reference | 368 +--------+----------------------+------------------+ 369 | TBD3 | BIER BFD Sub-sub-TLV | [this document] | 370 +--------+----------------------+------------------+ 372 Table 3 374 9.4. BIER BFD Sub-TLV 376 IANA is requested to assign a new BIER BFD Sub-TLV from the BIER Sub- 377 TLV registry defined in [RFC8444] as follows: 379 +--------+------------------+------------------+ 380 | Value | Description | Reference | 381 +--------+------------------+------------------+ 382 | TBD4 | BIER BFD Sub-TLV | [this document] | 383 +--------+------------------+------------------+ 385 Table 4 387 10. References 389 10.1. Normative References 391 [I-D.ietf-bier-ping] 392 Nainar, N., Pignataro, C., Akiya, N., Zheng, L., Chen, M., 393 and G. Mirsky, "BIER Ping and Trace", draft-ietf-bier- 394 ping-07 (work in progress), May 2020. 396 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 397 Requirement Levels", BCP 14, RFC 2119, 398 DOI 10.17487/RFC2119, March 1997, 399 . 401 [RFC5880] Katz, D. and D. Ward, "Bidirectional Forwarding Detection 402 (BFD)", RFC 5880, DOI 10.17487/RFC5880, June 2010, 403 . 405 [RFC5883] Katz, D. and D. Ward, "Bidirectional Forwarding Detection 406 (BFD) for Multihop Paths", RFC 5883, DOI 10.17487/RFC5883, 407 June 2010, . 409 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 410 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 411 May 2017, . 413 [RFC8279] Wijnands, IJ., Ed., Rosen, E., Ed., Dolganow, A., 414 Przygienda, T., and S. Aldrin, "Multicast Using Bit Index 415 Explicit Replication (BIER)", RFC 8279, 416 DOI 10.17487/RFC8279, November 2017, 417 . 419 [RFC8401] Ginsberg, L., Ed., Przygienda, T., Aldrin, S., and Z. 420 Zhang, "Bit Index Explicit Replication (BIER) Support via 421 IS-IS", RFC 8401, DOI 10.17487/RFC8401, June 2018, 422 . 424 [RFC8444] Psenak, P., Ed., Kumar, N., Wijnands, IJ., Dolganow, A., 425 Przygienda, T., Zhang, J., and S. Aldrin, "OSPFv2 426 Extensions for Bit Index Explicit Replication (BIER)", 427 RFC 8444, DOI 10.17487/RFC8444, November 2018, 428 . 430 [RFC8562] Katz, D., Ward, D., Pallagatti, S., Ed., and G. Mirsky, 431 Ed., "Bidirectional Forwarding Detection (BFD) for 432 Multipoint Networks", RFC 8562, DOI 10.17487/RFC8562, 433 April 2019, . 435 [RFC8563] Katz, D., Ward, D., Pallagatti, S., Ed., and G. Mirsky, 436 Ed., "Bidirectional Forwarding Detection (BFD) Multipoint 437 Active Tails", RFC 8563, DOI 10.17487/RFC8563, April 2019, 438 . 440 10.2. Informative References 442 [I-D.mirsky-mpls-p2mp-bfd] 443 Mirsky, G., "BFD for Multipoint Networks over Point-to- 444 Multi-Point MPLS LSP", draft-mirsky-mpls-p2mp-bfd-10 (work 445 in progress), April 2020. 447 Authors' Addresses 449 Quan Xiong 450 ZTE Corporation 451 No.6 Huashi Park Rd 452 Wuhan, Hubei 430223 453 China 455 Phone: +86 27 83531060 456 Email: xiong.quan@zte.com.cn 457 Greg Mirsky 458 ZTE Corporation 459 USA 461 Email: gregimirsky@gmail.com 463 Fangwei Hu 464 Individual 466 Email: hufwei@gmail.com 468 Chang Liu 469 China Unicom 470 No.9 Shouti Nanlu 471 Beijing 100048 472 China 474 Phone: +86-010-68799999-7294 475 Email: liuc131@chinaunicom.cn