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Venaas 5 Intended status: Standards Track Cisco Systems, Inc. 6 Expires: July 19, 2021 Z. Zhang 7 ZTE Corporation 8 H. Asaeda 9 NICT 10 January 15, 2021 12 IGMPv3/MLDv2 Message Extension 13 draft-ietf-pim-igmp-mld-extension-03 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 19, 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. Applicability and backwards compatibility . . . . . . . . . . 8 64 5. Security Considerations . . . . . . . . . . . . . . . . . . . 9 65 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10 66 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 10 67 7.1. Normative References . . . . . . . . . . . . . . . . . . 10 68 7.2. Informative References . . . . . . . . . . . . . . . . . 10 69 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 11 71 1. Introduction 73 In this document, we describe a generic method to extend IGMPv3 74 [RFC3376] and MLDv2 [RFC3810] messages to accommodate information 75 other than what is contained in the current message formats. This is 76 done by allowing a list of TLVs (Type, Length and Value) to be used 77 in the Additional Data part of IGMPv3 and MLDv2 messages. This 78 document defines a registry for such TLVs, while other documents will 79 define the specific types and their values, and their semantics. The 80 extension would only be used when at least one TLV is to be added to 81 the message. This extension also applies to the lightweight versions 82 of IGMPv3 and MLDv2 as defined in [RFC5790]. 84 When this extension mechanism is used, it will make use of the entire 85 Additional Data section defined in IGMPv3/MLDv2 for TLVs. The TLV 86 scheme is flexible enough to provide for any future extensions. 88 Additional Data is defined for query messages in IGMPv3 [RFC3376] 89 Section 4.1.10 and MLDv2 [RFC3810] Section 5.1.12, and for report 90 messages in IGMPv3 [RFC3376] Section 4.2.11 and MLDv2 [RFC3810] 91 Section 5.2.11. 93 One such TLV is being defined for use in BIER IGMP/MLD overlays 94 [I-D.ietf-bier-mld]. This TLV provides BIER specific information 95 that only will be processed by BIER routers. 97 2. Conventions used in this document 99 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 100 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 101 "OPTIONAL" in this document are to be interpreted as described in BCP 102 14 [RFC2119] [RFC8174] when, and only when, they appear in all 103 capitals, as shown here. 105 3. Extension Format 107 A previously reserved bit in the IGMPv3 and MLDv2 headers is used to 108 indicate whether this extension is used. When this extension is 109 used, the Additional Data of IGMPv3 and MLDv2 messages would be 110 formatted as follows. Note that this format contains a variable 111 number of TLVs. It MUST contain at least one TLV. 113 0 1 2 3 114 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 1 115 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 116 | Extension Type 1 | Extension Length 1 | 117 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 118 | Extension Value 1 | 119 . . . 120 . . . 121 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 122 | Extension Type 2 | Extension Length 2 | 123 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 124 | Extension Value 2 | 125 . . . 126 . . . 127 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 128 | Extension Type n | Extension Length n | 129 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 130 | Extension Value n | 131 . . . 132 . . . 133 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 135 Figure 1: Extension Format 137 Extension Type: 2 octets. This identifies a particular Extension 138 Type as defined in the IGMP/MLD Extension Type Registry. 140 Extension Length: 2 octets. This specifies the length in octets 141 of the following Extension Value field. Note that this value may 142 be zero, in which case there is no Extension Value field present. 144 The next type field, if any, will come immediately after this 145 length field. 147 Extension Value: This field contains the value. The length and 148 the contents of this field is according to the specification of 149 the Extension Type as defined in the IGMP/MLD Extension Type 150 Registry. The length MUST be as specified in the Extension Length 151 field. 153 There MUST be no data in the message after the last TLV. The TLVs 154 are processed until the end of the message is reached. When 155 processing the TLVs an implementation MUST keep track of how many 156 octets are remaining in the message and stop TLV processing when 157 there is no room for any further TLVs. That is, TLV processing stops 158 if there are less than 4 octets remaining in the message after a TLV 159 is processed since there is not enough room for an additional minimal 160 TLV. Also if a TLV has a length exceeding the remainder of the 161 message, that TLV is ignored, and further TLV processing stops. 163 IGMPv3 and MLDv2 messages are defined so that they can fit within the 164 network MTU, in order to avoid fragmentation. When this extension 165 mechanism is used, the number of Group Records in each Report message 166 should be kept small enough that the entire message, including any 167 extension TLVs can fit within the network MTU. 169 3.1. Multicast Listener Query Extension 171 The MLD query format with extension is shown below. The E-bit MUST 172 be set to 1 to indicate that the extension is present. Otherwise it 173 MUST be 0. 175 0 1 2 3 176 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 1 177 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 178 | Type = 130 | Code | Checksum | 179 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 180 | Maximum Response Code | Reserved | 181 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 182 | | 183 * * 184 | | 185 * Multicast Address * 186 | | 187 * * 188 | | 189 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 190 |E| Resv|S| QRV | QQIC | Number of Sources (N) | 191 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 192 | | 193 * * 194 | | 195 * Source Address [1] * 196 | | 197 * * 198 | | 199 +- -+ 200 | | 201 * * 202 | | 203 * Source Address [2] * 204 | | 205 * * 206 | | 207 +- . -+ 208 . . . 209 . . . 210 +- -+ 211 | | 212 * * 213 | | 214 * Source Address [N] * 215 | | 216 * * 217 | | 218 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 219 | Extension | 220 ~ ~ 221 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 223 Figure 2: MLD Query Extension 225 3.2. Version 2 Multicast Listener Report Extension 227 The MLD report format with extension is shown below. The E-bit MUST 228 be set to 1 to indicate that the extension is present. Otherwise it 229 MUST be 0. 231 0 1 2 3 232 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 1 233 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 234 | Type = 143 | Reserved | Checksum | 235 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 236 |E| Reserved |Nr of Mcast Address Records (M)| 237 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 238 | | 239 . . 240 . Multicast Address Record [1] . 241 . . 242 | | 243 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 244 | | 245 . . 246 . Multicast Address Record [2] . 247 . . 248 | | 249 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 250 | . | 251 . . . 252 | . | 253 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 254 | | 255 . . 256 . Multicast Address Record [M] . 257 . . 258 | | 259 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 260 | Extension | 261 ~ ~ 262 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 264 Figure 3: MLD Report Extension 266 3.3. IGMP Membership Query Extension 268 The IGMP query format with the extension is shown below. The E-bit 269 MUST be set to 1 to indicate that the extension is present. 270 Otherwise it MUST be 0. 272 0 1 2 3 273 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 1 274 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 275 | Type = 0x11 | Max Resp Code | Checksum | 276 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 277 | Group Address | 278 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 279 |E| Resv|S| QRV | QQIC | Number of Sources (N) | 280 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 281 | Source Address [1] | 282 +- -+ 283 | Source Address [2] | 284 +- . -+ 285 . . . 286 . . . 287 +- -+ 288 | Source Address [N] | 289 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 290 | Extension | 291 ~ ~ 292 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 294 Figure 4: IGMP Query Extension 296 3.4. IGMP Version 3 Membership Report Extension 298 The IGMP report format with the extension is shown below. The E-bit 299 MUST be set to 1 to indicate that the extension is present. 300 Otherwise it MUST be 0. 302 0 1 2 3 303 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 1 304 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 305 | Type = 0x22 | Reserved | Checksum | 306 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 307 |E| Reserved | Number of Group Records (M) | 308 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 309 | | 310 . . 311 . Group Record [1] . 312 . . 313 | | 314 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 315 | | 316 . . 317 . Group Record [2] . 318 . . 319 | | 320 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 321 | . | 322 . . . 323 | . | 324 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 325 | | 326 . . 327 . Group Record [M] . 328 . . 329 | | 330 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 331 | Extension | 332 ~ ~ 333 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 335 Figure 5: IGMP Report Extension 337 4. Applicability and backwards compatibility 339 IGMP and MLD implementations, host implementations in particular, 340 rarely change, and it is expected to take a long time for them to 341 support this extension mechanism. Also as new extensions are 342 defined, it may take a long time before they are supported. Due to 343 this, defining extensions should not be taken lightly, and it is 344 crucial to consider backwards compatibility. 346 Implementations that do not support this extension mechanism will 347 simply ignore the extension, provided they are compliant with IGMPv3 348 and MLDv2 RFCs, which specify that additional data must be ignored, 349 and behave as if the extension is not present. Implementations that 350 support this extension MUST behave as if it is not present if they 351 support none of the extension types in an IGMP/MLD message. If they 352 support at least one of the types, they will process the supported 353 types according to the respective type specifications, and ignore any 354 unsupported types. 356 It is possible that a new extension type only applies to queries, or 357 only to reports, or there may be other specific conditions for when 358 it is to be used. A document defining a new type MUST specify 359 clearly under what conditions the new type should be used, including 360 for which message types. It MUST also be considered what the 361 behavior should be if a message is not used in the defined manner, 362 e.g., if it is present in a query message, when it was only expected 363 to be used in reports. 365 When defining new types, care must be taken to ensure that nodes that 366 support the type can co-exist with nodes that don't, on the same 367 subnet. There could be multiple routers where only some support the 368 extension, or multiple hosts where only some support the extension. 369 Or a router may support it and none of the hosts, or all hosts may 370 support it, but none of the routers. With multiple types being used, 371 it must also be considered that some hosts or routers may only 372 support some of the types, and potentially one node might support 373 only one type, and another node only another type. 375 Documents defining new types MUST have security considerations 376 relevant to the new types. They MUST also in addition to defining 377 the behavior of hosts and routers supporting the new types, consider 378 compatibility with hosts and routers on the same subnet that do not 379 support the new types. Further, they MUST consider whether there are 380 any dependencies or restrictions on combinations between the new 381 types and any pre-existing types. 383 This document defines an extension mechanism only for IGMPv3 and 384 MLDv2. Hence this mechanism would not apply if hosts or routers send 385 older version message. 387 5. Security Considerations 389 This document extends IGMP and MLD message formats, allowing for a 390 variable number of TLVs. Implementations must take care when parsing 391 the TLVs to not exceed the packet boundary, an attacker could 392 intentionally specify a TLV with a length exceeding the boundary. 394 An implementation could add a large number of minimal TLVs in a 395 message to increase the cost of processing the message to magnify a 396 Denial of Service attack. 398 The respective types defined using this extension may impact security 399 and this MUST be considered as part of the respective specifications. 401 6. IANA Considerations 403 A new registry called "IGMP/MLD Extension Types" should be created 404 with registration procedure "IETF Review" as defined in [RFC8126] 405 with this document as a reference. The registry should be common for 406 IGMP and MLD and can perhaps be added to the "Internet Group 407 Management Protocol (IGMP) Type Numbers" section. The initial 408 content of the registry should be as below. 410 Type Length Name Reference 411 -------------------------------------------------------------- 413 7. References 415 7.1. Normative References 417 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 418 Requirement Levels", BCP 14, RFC 2119, 419 DOI 10.17487/RFC2119, March 1997, 420 . 422 [RFC3376] Cain, B., Deering, S., Kouvelas, I., Fenner, B., and A. 423 Thyagarajan, "Internet Group Management Protocol, Version 424 3", RFC 3376, DOI 10.17487/RFC3376, October 2002, 425 . 427 [RFC3810] Vida, R., Ed. and L. Costa, Ed., "Multicast Listener 428 Discovery Version 2 (MLDv2) for IPv6", RFC 3810, 429 DOI 10.17487/RFC3810, June 2004, 430 . 432 [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for 433 Writing an IANA Considerations Section in RFCs", BCP 26, 434 RFC 8126, DOI 10.17487/RFC8126, June 2017, 435 . 437 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 438 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 439 May 2017, . 441 7.2. Informative References 443 [I-D.ietf-bier-mld] 444 Pfister, P., Wijnands, I., Venaas, S., Wang, C., Zhang, 445 Z., and M. Stenberg, "BIER Ingress Multicast Flow Overlay 446 using Multicast Listener Discovery Protocols", draft-ietf- 447 bier-mld-04 (work in progress), March 2020. 449 [RFC5790] Liu, H., Cao, W., and H. Asaeda, "Lightweight Internet 450 Group Management Protocol Version 3 (IGMPv3) and Multicast 451 Listener Discovery Version 2 (MLDv2) Protocols", RFC 5790, 452 DOI 10.17487/RFC5790, February 2010, 453 . 455 Authors' Addresses 457 Mahesh Sivakumar 458 Juniper Networks 459 64 Butler St 460 Milpitas CA 95035 461 USA 463 Email: sivakumar.mahesh@gmail.com 465 Stig Venaas 466 Cisco Systems, Inc. 467 Tasman Drive 468 San Jose CA 95134 469 USA 471 Email: stig@cisco.com 473 Zheng(Sandy) Zhang 474 ZTE Corporation 475 No. 50 Software Ave, Yuhuatai District 476 Nanjing 210000 477 China 479 Email: zhang.zheng@zte.com.cn 480 Hitoshi Asaeda 481 National Institute of Information and 482 Communications Technology 483 4-2-1 Nukui-Kitamachi 484 Koganei, Tokyo 184-8795 485 Japan 487 Email: asaeda@nict.go.jp