Network Working Group M. Sivakumar Internet-Draft Juniper Networks Updates: 3376, 3810 (if approved) S. Venaas Intended status: Standards Track Cisco Systems, Inc. Expires: July 19, 2021 Z. Zhang ZTE Corporation H. Asaeda NICT January 15, 2021 IGMPv3/MLDv2 Message Extension draft-ietf-pim-igmp-mld-extension-03 Abstract IGMP and MLD protocols are extensible, but no extensions have been defined so far. This document provides a well-defined way of extending IGMP and MLD, using a list of TLVs (Type, Length and Value). Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at https://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on July 19, 2021. Copyright Notice Copyright (c) 2021 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect Sivakumar, et al. Expires July 19, 2021 [Page 1] Internet-Draft IGMPv3/MLDv2 message extension January 2021 to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Conventions used in this document . . . . . . . . . . . . . . 3 3. Extension Format . . . . . . . . . . . . . . . . . . . . . . 3 3.1. Multicast Listener Query Extension . . . . . . . . . . . 4 3.2. Version 2 Multicast Listener Report Extension . . . . . . 5 3.3. IGMP Membership Query Extension . . . . . . . . . . . . . 6 3.4. IGMP Version 3 Membership Report Extension . . . . . . . 7 4. Applicability and backwards compatibility . . . . . . . . . . 8 5. Security Considerations . . . . . . . . . . . . . . . . . . . 9 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 10 7.1. Normative References . . . . . . . . . . . . . . . . . . 10 7.2. Informative References . . . . . . . . . . . . . . . . . 10 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 11 1. Introduction In this document, we describe a generic method to extend IGMPv3 [RFC3376] and MLDv2 [RFC3810] messages to accommodate information other than what is contained in the current message formats. This is done by allowing a list of TLVs (Type, Length and Value) to be used in the Additional Data part of IGMPv3 and MLDv2 messages. This document defines a registry for such TLVs, while other documents will define the specific types and their values, and their semantics. The extension would only be used when at least one TLV is to be added to the message. This extension also applies to the lightweight versions of IGMPv3 and MLDv2 as defined in [RFC5790]. When this extension mechanism is used, it will make use of the entire Additional Data section defined in IGMPv3/MLDv2 for TLVs. The TLV scheme is flexible enough to provide for any future extensions. Additional Data is defined for query messages in IGMPv3 [RFC3376] Section 4.1.10 and MLDv2 [RFC3810] Section 5.1.12, and for report messages in IGMPv3 [RFC3376] Section 4.2.11 and MLDv2 [RFC3810] Section 5.2.11. One such TLV is being defined for use in BIER IGMP/MLD overlays [I-D.ietf-bier-mld]. This TLV provides BIER specific information that only will be processed by BIER routers. Sivakumar, et al. Expires July 19, 2021 [Page 2] Internet-Draft IGMPv3/MLDv2 message extension January 2021 2. Conventions used in this document The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here. 3. Extension Format A previously reserved bit in the IGMPv3 and MLDv2 headers is used to indicate whether this extension is used. When this extension is used, the Additional Data of IGMPv3 and MLDv2 messages would be formatted as follows. Note that this format contains a variable number of TLVs. It MUST contain at least one TLV. 0 1 2 3 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Extension Type 1 | Extension Length 1 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Extension Value 1 | . . . . . . +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Extension Type 2 | Extension Length 2 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Extension Value 2 | . . . . . . +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Extension Type n | Extension Length n | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Extension Value n | . . . . . . +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 1: Extension Format Extension Type: 2 octets. This identifies a particular Extension Type as defined in the IGMP/MLD Extension Type Registry. Extension Length: 2 octets. This specifies the length in octets of the following Extension Value field. Note that this value may be zero, in which case there is no Extension Value field present. Sivakumar, et al. Expires July 19, 2021 [Page 3] Internet-Draft IGMPv3/MLDv2 message extension January 2021 The next type field, if any, will come immediately after this length field. Extension Value: This field contains the value. The length and the contents of this field is according to the specification of the Extension Type as defined in the IGMP/MLD Extension Type Registry. The length MUST be as specified in the Extension Length field. There MUST be no data in the message after the last TLV. The TLVs are processed until the end of the message is reached. When processing the TLVs an implementation MUST keep track of how many octets are remaining in the message and stop TLV processing when there is no room for any further TLVs. That is, TLV processing stops if there are less than 4 octets remaining in the message after a TLV is processed since there is not enough room for an additional minimal TLV. Also if a TLV has a length exceeding the remainder of the message, that TLV is ignored, and further TLV processing stops. IGMPv3 and MLDv2 messages are defined so that they can fit within the network MTU, in order to avoid fragmentation. When this extension mechanism is used, the number of Group Records in each Report message should be kept small enough that the entire message, including any extension TLVs can fit within the network MTU. 3.1. Multicast Listener Query Extension The MLD query format with extension is shown below. The E-bit MUST be set to 1 to indicate that the extension is present. Otherwise it MUST be 0. 0 1 2 3 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type = 130 | Code | Checksum | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Maximum Response Code | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | * * | | * Multicast Address * | | * * | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |E| Resv|S| QRV | QQIC | Number of Sources (N) | Sivakumar, et al. Expires July 19, 2021 [Page 4] Internet-Draft IGMPv3/MLDv2 message extension January 2021 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | * * | | * Source Address [1] * | | * * | | +- -+ | | * * | | * Source Address [2] * | | * * | | +- . -+ . . . . . . +- -+ | | * * | | * Source Address [N] * | | * * | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Extension | ~ ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 2: MLD Query Extension 3.2. Version 2 Multicast Listener Report Extension The MLD report format with extension is shown below. The E-bit MUST be set to 1 to indicate that the extension is present. Otherwise it MUST be 0. Sivakumar, et al. Expires July 19, 2021 [Page 5] Internet-Draft IGMPv3/MLDv2 message extension January 2021 0 1 2 3 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type = 143 | Reserved | Checksum | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |E| Reserved |Nr of Mcast Address Records (M)| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | . . . Multicast Address Record [1] . . . | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | . . . Multicast Address Record [2] . . . | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | . | . . . | . | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | . . . Multicast Address Record [M] . . . | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Extension | ~ ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 3: MLD Report Extension 3.3. IGMP Membership Query Extension The IGMP query format with the extension is shown below. The E-bit MUST be set to 1 to indicate that the extension is present. Otherwise it MUST be 0. Sivakumar, et al. Expires July 19, 2021 [Page 6] Internet-Draft IGMPv3/MLDv2 message extension January 2021 0 1 2 3 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type = 0x11 | Max Resp Code | Checksum | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Group Address | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |E| Resv|S| QRV | QQIC | Number of Sources (N) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Source Address [1] | +- -+ | Source Address [2] | +- . -+ . . . . . . +- -+ | Source Address [N] | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Extension | ~ ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 4: IGMP Query Extension 3.4. IGMP Version 3 Membership Report Extension The IGMP report format with the extension is shown below. The E-bit MUST be set to 1 to indicate that the extension is present. Otherwise it MUST be 0. Sivakumar, et al. Expires July 19, 2021 [Page 7] Internet-Draft IGMPv3/MLDv2 message extension January 2021 0 1 2 3 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type = 0x22 | Reserved | Checksum | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |E| Reserved | Number of Group Records (M) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | . . . Group Record [1] . . . | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | . . . Group Record [2] . . . | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | . | . . . | . | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | . . . Group Record [M] . . . | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Extension | ~ ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 5: IGMP Report Extension 4. Applicability and backwards compatibility IGMP and MLD implementations, host implementations in particular, rarely change, and it is expected to take a long time for them to support this extension mechanism. Also as new extensions are defined, it may take a long time before they are supported. Due to this, defining extensions should not be taken lightly, and it is crucial to consider backwards compatibility. Implementations that do not support this extension mechanism will simply ignore the extension, provided they are compliant with IGMPv3 and MLDv2 RFCs, which specify that additional data must be ignored, Sivakumar, et al. Expires July 19, 2021 [Page 8] Internet-Draft IGMPv3/MLDv2 message extension January 2021 and behave as if the extension is not present. Implementations that support this extension MUST behave as if it is not present if they support none of the extension types in an IGMP/MLD message. If they support at least one of the types, they will process the supported types according to the respective type specifications, and ignore any unsupported types. It is possible that a new extension type only applies to queries, or only to reports, or there may be other specific conditions for when it is to be used. A document defining a new type MUST specify clearly under what conditions the new type should be used, including for which message types. It MUST also be considered what the behavior should be if a message is not used in the defined manner, e.g., if it is present in a query message, when it was only expected to be used in reports. When defining new types, care must be taken to ensure that nodes that support the type can co-exist with nodes that don't, on the same subnet. There could be multiple routers where only some support the extension, or multiple hosts where only some support the extension. Or a router may support it and none of the hosts, or all hosts may support it, but none of the routers. With multiple types being used, it must also be considered that some hosts or routers may only support some of the types, and potentially one node might support only one type, and another node only another type. Documents defining new types MUST have security considerations relevant to the new types. They MUST also in addition to defining the behavior of hosts and routers supporting the new types, consider compatibility with hosts and routers on the same subnet that do not support the new types. Further, they MUST consider whether there are any dependencies or restrictions on combinations between the new types and any pre-existing types. This document defines an extension mechanism only for IGMPv3 and MLDv2. Hence this mechanism would not apply if hosts or routers send older version message. 5. Security Considerations This document extends IGMP and MLD message formats, allowing for a variable number of TLVs. Implementations must take care when parsing the TLVs to not exceed the packet boundary, an attacker could intentionally specify a TLV with a length exceeding the boundary. An implementation could add a large number of minimal TLVs in a message to increase the cost of processing the message to magnify a Denial of Service attack. Sivakumar, et al. Expires July 19, 2021 [Page 9] Internet-Draft IGMPv3/MLDv2 message extension January 2021 The respective types defined using this extension may impact security and this MUST be considered as part of the respective specifications. 6. IANA Considerations A new registry called "IGMP/MLD Extension Types" should be created with registration procedure "IETF Review" as defined in [RFC8126] with this document as a reference. The registry should be common for IGMP and MLD and can perhaps be added to the "Internet Group Management Protocol (IGMP) Type Numbers" section. The initial content of the registry should be as below. Type Length Name Reference -------------------------------------------------------------- 7. References 7.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . [RFC3376] Cain, B., Deering, S., Kouvelas, I., Fenner, B., and A. Thyagarajan, "Internet Group Management Protocol, Version 3", RFC 3376, DOI 10.17487/RFC3376, October 2002, . [RFC3810] Vida, R., Ed. and L. Costa, Ed., "Multicast Listener Discovery Version 2 (MLDv2) for IPv6", RFC 3810, DOI 10.17487/RFC3810, June 2004, . [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for Writing an IANA Considerations Section in RFCs", BCP 26, RFC 8126, DOI 10.17487/RFC8126, June 2017, . [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, . 7.2. Informative References Sivakumar, et al. Expires July 19, 2021 [Page 10] Internet-Draft IGMPv3/MLDv2 message extension January 2021 [I-D.ietf-bier-mld] Pfister, P., Wijnands, I., Venaas, S., Wang, C., Zhang, Z., and M. Stenberg, "BIER Ingress Multicast Flow Overlay using Multicast Listener Discovery Protocols", draft-ietf- bier-mld-04 (work in progress), March 2020. [RFC5790] Liu, H., Cao, W., and H. Asaeda, "Lightweight Internet Group Management Protocol Version 3 (IGMPv3) and Multicast Listener Discovery Version 2 (MLDv2) Protocols", RFC 5790, DOI 10.17487/RFC5790, February 2010, . Authors' Addresses Mahesh Sivakumar Juniper Networks 64 Butler St Milpitas CA 95035 USA Email: sivakumar.mahesh@gmail.com Stig Venaas Cisco Systems, Inc. Tasman Drive San Jose CA 95134 USA Email: stig@cisco.com Zheng(Sandy) Zhang ZTE Corporation No. 50 Software Ave, Yuhuatai District Nanjing 210000 China Email: zhang.zheng@zte.com.cn Sivakumar, et al. Expires July 19, 2021 [Page 11] Internet-Draft IGMPv3/MLDv2 message extension January 2021 Hitoshi Asaeda National Institute of Information and Communications Technology 4-2-1 Nukui-Kitamachi Koganei, Tokyo 184-8795 Japan Email: asaeda@nict.go.jp Sivakumar, et al. Expires July 19, 2021 [Page 12]