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Venaas 5 Intended status: Standards Track Cisco Systems, Inc. 6 Expires: July 25, 2021 Z. Zhang 7 ZTE Corporation 8 H. Asaeda 9 NICT 10 January 21, 2021 12 IGMPv3/MLDv2 Message Extension 13 draft-ietf-pim-igmp-mld-extension-04 15 Abstract 17 IGMP and MLD protocols are extensible, but no extensions have been 18 defined so far. This document provides a well-defined way of 19 extending IGMP and MLD, using a list of TLVs (Type, Length and 20 Value). 22 Status of This Memo 24 This Internet-Draft is submitted in full conformance with the 25 provisions of BCP 78 and BCP 79. 27 Internet-Drafts are working documents of the Internet Engineering 28 Task Force (IETF). Note that other groups may also distribute 29 working documents as Internet-Drafts. The list of current Internet- 30 Drafts is at https://datatracker.ietf.org/drafts/current/. 32 Internet-Drafts are draft documents valid for a maximum of six months 33 and may be updated, replaced, or obsoleted by other documents at any 34 time. It is inappropriate to use Internet-Drafts as reference 35 material or to cite them other than as "work in progress." 37 This Internet-Draft will expire on July 25, 2021. 39 Copyright Notice 41 Copyright (c) 2021 IETF Trust and the persons identified as the 42 document authors. All rights reserved. 44 This document is subject to BCP 78 and the IETF Trust's Legal 45 Provisions Relating to IETF Documents 46 (https://trustee.ietf.org/license-info) in effect on the date of 47 publication of this document. Please review these documents 48 carefully, as they describe your rights and restrictions with respect 49 to this document. Code Components extracted from this document must 50 include Simplified BSD License text as described in Section 4.e of 51 the Trust Legal Provisions and are provided without warranty as 52 described in the Simplified BSD License. 54 Table of Contents 56 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 57 2. Conventions used in this document . . . . . . . . . . . . . . 3 58 3. Extension Format . . . . . . . . . . . . . . . . . . . . . . 3 59 3.1. Multicast Listener Query Extension . . . . . . . . . . . 4 60 3.2. Version 2 Multicast Listener Report Extension . . . . . . 5 61 3.3. IGMP Membership Query Extension . . . . . . . . . . . . . 6 62 3.4. IGMP Version 3 Membership Report Extension . . . . . . . 7 63 4. Processing the extension . . . . . . . . . . . . . . . . . . 8 64 5. Applicability and backwards compatibility . . . . . . . . . . 9 65 6. Security Considerations . . . . . . . . . . . . . . . . . . . 10 66 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10 67 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 10 68 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 11 69 9.1. Normative References . . . . . . . . . . . . . . . . . . 11 70 9.2. Informative References . . . . . . . . . . . . . . . . . 11 71 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 11 73 1. Introduction 75 In this document, we describe a generic method to extend IGMPv3 76 [RFC3376] and MLDv2 [RFC3810] messages to accommodate information 77 other than what is contained in the current message formats. This is 78 done by allowing a list of TLVs (Type, Length and Value) to be used 79 in the Additional Data part of IGMPv3 and MLDv2 messages. This 80 document defines a registry for such TLVs, while other documents will 81 define the specific types and their values, and their semantics. The 82 extension would only be used when at least one TLV is to be added to 83 the message. This extension also applies to the lightweight versions 84 of IGMPv3 and MLDv2 as defined in [RFC5790]. 86 When this extension mechanism is used, it replaces the Additional 87 Data section defined in IGMPv3/MLDv2 for TLVs. 89 Additional Data is defined for query messages in IGMPv3 [RFC3376] 90 Section 4.1.10 and MLDv2 [RFC3810] Section 5.1.12, and for report 91 messages in IGMPv3 [RFC3376] Section 4.2.11 and MLDv2 [RFC3810] 92 Section 5.2.11. 94 One such TLV is being defined for use in BIER IGMP/MLD overlays 95 [I-D.ietf-bier-mld]. This TLV provides BIER specific information 96 that only will be processed by BIER routers. 98 2. Conventions used in this document 100 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 101 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 102 "OPTIONAL" in this document are to be interpreted as described in BCP 103 14 [RFC2119] [RFC8174] when, and only when, they appear in all 104 capitals, as shown here. 106 3. Extension Format 108 A previously reserved bit in the IGMPv3 and MLDv2 headers is used to 109 indicate whether this extension is used. When this extension is 110 used, the Additional Data of IGMPv3 and MLDv2 messages would be 111 formatted as follows. Note that this format contains a variable 112 number of TLVs. It MUST contain at least one TLV. 114 0 1 2 3 115 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 1 116 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 117 | Extension Type 1 | Extension Length 1 | 118 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 119 | Extension Value 1 | 120 . . . 121 . . . 122 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 123 | Extension Type 2 | Extension Length 2 | 124 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 125 | Extension Value 2 | 126 . . . 127 . . . 128 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 129 | Extension Type n | Extension Length n | 130 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 131 | Extension Value n | 132 . . . 133 . . . 134 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 136 Figure 1: Extension Format 138 Extension Type: 2 octets. This identifies a particular Extension 139 Type as defined in the IGMP/MLD Extension Type Registry. If this 140 is not the first TLV, it will follow immediately after the end of 141 the previous Extension Value field, or immediately after the 142 previous Extension Length field if the previous Extension Length 143 was zero. There is no alignment or padding. 145 Extension Length: 2 octets. This specifies the length in octets 146 of the following Extension Value field. The length may be zero if 147 no value is needed. 149 Extension Value: This field contains the value. The length and 150 the contents of this field is according to the specification of 151 the Extension Type as defined in the IGMP/MLD Extension Type 152 Registry. The length MUST be as specified in the Extension Length 153 field. 155 IGMPv3 and MLDv2 messages are defined so that they can fit within the 156 network MTU, in order to avoid fragmentation. When this extension 157 mechanism is used, the number of Group Records in each Report message 158 should be kept small enough that the entire message, including any 159 extension TLVs can fit within the network MTU. 161 3.1. Multicast Listener Query Extension 163 The MLD query format with extension is shown below. The E-bit MUST 164 be set to 1 to indicate that the extension is present. Otherwise it 165 MUST be 0. 167 0 1 2 3 168 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 1 169 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 170 | Type = 130 | Code | Checksum | 171 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 172 | Maximum Response Code | Reserved | 173 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 174 | | 175 * * 176 | | 177 * Multicast Address * 178 | | 179 * * 180 | | 181 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 182 |E| Resv|S| QRV | QQIC | Number of Sources (N) | 183 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 184 | | 185 * * 186 | | 187 * Source Address [1] * 188 | | 189 * * 190 | | 191 +- -+ 192 | | 193 * * 194 | | 195 * Source Address [2] * 196 | | 197 * * 198 | | 199 +- . -+ 200 . . . 201 . . . 202 +- -+ 203 | | 204 * * 205 | | 206 * Source Address [N] * 207 | | 208 * * 209 | | 210 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 211 | Extension | 212 ~ ~ 213 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 215 Figure 2: MLD Query Extension 217 3.2. Version 2 Multicast Listener Report Extension 219 The MLD report format with extension is shown below. The E-bit MUST 220 be set to 1 to indicate that the extension is present. Otherwise it 221 MUST be 0. 223 0 1 2 3 224 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 1 225 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 226 | Type = 143 | Reserved | Checksum | 227 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 228 |E| Reserved |Nr of Mcast Address Records (M)| 229 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 230 | | 231 . . 232 . Multicast Address Record [1] . 233 . . 234 | | 235 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 236 | | 237 . . 238 . Multicast Address Record [2] . 239 . . 240 | | 241 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 242 | . | 243 . . . 244 | . | 245 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 246 | | 247 . . 248 . Multicast Address Record [M] . 249 . . 250 | | 251 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 252 | Extension | 253 ~ ~ 254 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 256 Figure 3: MLD Report Extension 258 3.3. IGMP Membership Query Extension 260 The IGMP query format with the extension is shown below. The E-bit 261 MUST be set to 1 to indicate that the extension is present. 262 Otherwise it MUST be 0. 264 0 1 2 3 265 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 1 266 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 267 | Type = 0x11 | Max Resp Code | Checksum | 268 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 269 | Group Address | 270 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 271 |E| Resv|S| QRV | QQIC | Number of Sources (N) | 272 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 273 | Source Address [1] | 274 +- -+ 275 | Source Address [2] | 276 +- . -+ 277 . . . 278 . . . 279 +- -+ 280 | Source Address [N] | 281 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 282 | Extension | 283 ~ ~ 284 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 286 Figure 4: IGMP Query Extension 288 3.4. IGMP Version 3 Membership Report Extension 290 The IGMP report format with the extension is shown below. The E-bit 291 MUST be set to 1 to indicate that the extension is present. 292 Otherwise it MUST be 0. 294 0 1 2 3 295 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 1 296 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 297 | Type = 0x22 | Reserved | Checksum | 298 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 299 |E| Reserved | Number of Group Records (M) | 300 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 301 | | 302 . . 303 . Group Record [1] . 304 . . 305 | | 306 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 307 | | 308 . . 309 . Group Record [2] . 310 . . 311 | | 312 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 313 | . | 314 . . . 315 | . | 316 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 317 | | 318 . . 319 . Group Record [M] . 320 . . 321 | | 322 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 323 | Extension | 324 ~ ~ 325 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 327 Figure 5: IGMP Report Extension 329 4. Processing the extension 331 How to validate and process a specific type will be defined in the 332 respective type specifications, but prior to validating and 333 processing each of the types, the following general validation MUST 334 be done. 336 First one MUST check that the E-bit is set, otherwise this 337 specification does not apply. There MUST be no data in the IP 338 payload after the last TLV. To check this, one will need to walk 339 through each of The TLVs until there are less than four octets left 340 in the IP payload. If there are any octets left, validation failed. 342 The walk also stops and validation fails if a TLV has a length 343 exceeding the remainder of the IP payload. For this validation, one 344 only examines the content of the Extension Length fields. 346 If the validation failed, the entire Additional Data field MUST be 347 ignored as specified in IGMPv3 [RFC3376] and MLDv2 [RFC3810]. 349 If the validation succeeded, one will proceed examining each of the 350 specified types and perform validation and processing of the 351 respective types. Unsupported types MUST be ignored; type validation 352 and processing proceeds as if they were not present. 354 5. Applicability and backwards compatibility 356 IGMP and MLD implementations, host implementations in particular, 357 rarely change, and it is expected to take a long time for them to 358 support this extension mechanism. Also as new extensions are 359 defined, it may take a long time before they are supported. Due to 360 this, defining extensions should not be taken lightly, and it is 361 crucial to consider backwards compatibility. 363 Implementations that do not support this extension mechanism will 364 simply ignore the extension, provided they are compliant with IGMPv3 365 and MLDv2 RFCs, which specify that additional data must be ignored, 366 and behave as if the extension is not present. Implementations that 367 support this extension MUST behave as if it is not present if they 368 support none of the extension types in an IGMP/MLD message. If they 369 support at least one of the types, they will process the supported 370 types according to the respective type specifications, and ignore any 371 unsupported types. 373 It is possible that a new extension type only applies to queries, or 374 only to reports, or there may be other specific conditions for when 375 it is to be used. A document defining a new type MUST specify 376 clearly under what conditions the new type should be used, including 377 for which message types. It MUST also be considered what the 378 behavior should be if a message is not used in the defined manner, 379 e.g., if it is present in a query message, when it was only expected 380 to be used in reports. 382 When defining new types, care must be taken to ensure that nodes that 383 support the type can co-exist with nodes that don't, on the same 384 subnet. There could be multiple routers where only some support the 385 extension, or multiple hosts where only some support the extension. 386 Or a router may support it and none of the hosts, or all hosts may 387 support it, but none of the routers. With multiple types being used, 388 it must also be considered that some hosts or routers may only 389 support some of the types, and potentially one node might support 390 only one type, and another node only another type. 392 Documents defining new types MUST have security considerations 393 relevant to the new types. They MUST also in addition to defining 394 the behavior of hosts and routers supporting the new types, consider 395 compatibility with hosts and routers on the same subnet that do not 396 support the new types. Further, they MUST consider whether there are 397 any dependencies or restrictions on combinations between the new 398 types and any pre-existing types. 400 This document defines an extension mechanism only for IGMPv3 and 401 MLDv2. Hence this mechanism would not apply if hosts or routers send 402 older version message. 404 6. Security Considerations 406 This document extends IGMP and MLD message formats, allowing for a 407 variable number of TLVs. Implementations must take care when parsing 408 the TLVs to not exceed the packet boundary, an attacker could 409 intentionally specify a TLV with a length exceeding the boundary. 411 An implementation could add a large number of minimal TLVs in a 412 message to increase the cost of processing the message to magnify a 413 Denial of Service attack. 415 The respective types defined using this extension may impact security 416 and this MUST be considered as part of the respective specifications. 418 7. IANA Considerations 420 A new registry called "IGMP/MLD Extension Types" should be created 421 with registration procedure "IETF Review" as defined in [RFC8126] 422 with this document as a reference. The registry should be common for 423 IGMP and MLD and can perhaps be added to the "Internet Group 424 Management Protocol (IGMP) Type Numbers" section. The initial 425 content of the registry should be as below. 427 Type Length Name Reference 428 -------------------------------------------------------------- 430 8. Acknowledgements 432 The authors thank Ian Duncan, Leonard Giuliano, Jake Holland and 433 Zhaohui Zhang for reviewing the document and providing valuable 434 feedback. 436 9. References 438 9.1. Normative References 440 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 441 Requirement Levels", BCP 14, RFC 2119, 442 DOI 10.17487/RFC2119, March 1997, 443 . 445 [RFC3376] Cain, B., Deering, S., Kouvelas, I., Fenner, B., and A. 446 Thyagarajan, "Internet Group Management Protocol, Version 447 3", RFC 3376, DOI 10.17487/RFC3376, October 2002, 448 . 450 [RFC3810] Vida, R., Ed. and L. Costa, Ed., "Multicast Listener 451 Discovery Version 2 (MLDv2) for IPv6", RFC 3810, 452 DOI 10.17487/RFC3810, June 2004, 453 . 455 [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for 456 Writing an IANA Considerations Section in RFCs", BCP 26, 457 RFC 8126, DOI 10.17487/RFC8126, June 2017, 458 . 460 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 461 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 462 May 2017, . 464 9.2. Informative References 466 [I-D.ietf-bier-mld] 467 Pfister, P., Wijnands, I., Venaas, S., Wang, C., Zhang, 468 Z., and M. Stenberg, "BIER Ingress Multicast Flow Overlay 469 using Multicast Listener Discovery Protocols", draft-ietf- 470 bier-mld-04 (work in progress), March 2020. 472 [RFC5790] Liu, H., Cao, W., and H. Asaeda, "Lightweight Internet 473 Group Management Protocol Version 3 (IGMPv3) and Multicast 474 Listener Discovery Version 2 (MLDv2) Protocols", RFC 5790, 475 DOI 10.17487/RFC5790, February 2010, 476 . 478 Authors' Addresses 479 Mahesh Sivakumar 480 Juniper Networks 481 64 Butler St 482 Milpitas CA 95035 483 USA 485 Email: sivakumar.mahesh@gmail.com 487 Stig Venaas 488 Cisco Systems, Inc. 489 Tasman Drive 490 San Jose CA 95134 491 USA 493 Email: stig@cisco.com 495 Zheng(Sandy) Zhang 496 ZTE Corporation 497 No. 50 Software Ave, Yuhuatai District 498 Nanjing 210000 499 China 501 Email: zhang.zheng@zte.com.cn 503 Hitoshi Asaeda 504 National Institute of Information and 505 Communications Technology 506 4-2-1 Nukui-Kitamachi 507 Koganei, Tokyo 184-8795 508 Japan 510 Email: asaeda@nict.go.jp