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, 25, 2021                                          Z. Zhang
                                                         ZTE Corporation
                                                               H. Asaeda
                                                                    NICT
                                                        January 15, 21, 2021

                     IGMPv3/MLDv2 Message Extension
                  draft-ietf-pim-igmp-mld-extension-03
                  draft-ietf-pim-igmp-mld-extension-04

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
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   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on July 19, 25, 2021.

Copyright Notice

   Copyright (c) 2021 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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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.  Processing the extension  . . . . . . . . . . . . . . . . . .   8
   5.  Applicability and backwards compatibility . . . . . . . . . .   8
   5.   9
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   9
   6.  10
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  10
   7.
   8.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  10
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  10
     7.1.  11
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .  10
     7.2.  11
     9.2.  Informative References  . . . . . . . . . . . . . . . . .  10  11
   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 replaces 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.

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.  If this
      is not the first TLV, it will follow immediately after the end of
      the previous Extension Value field, or immediately after the
      previous Extension Length field if the previous Extension Length
      was zero.  There is no alignment or padding.

      Extension Length: 2 octets.  This specifies the length in octets
      of the following Extension Value field.  Note that this value  The length may be zero, in which case there is no Extension Value field present.

      The next type field, zero if any, will come immediately after this
      length field.
      no value is needed.

      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)     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                                                               |
       *                                                               *
       |                                                               |
       *                       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.

        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.

        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.

        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.  Processing the extension

   How to validate and process a specific type will be defined in the
   respective type specifications, but prior to validating and
   processing each of the types, the following general validation MUST
   be done.

   First one MUST check that the E-bit is set, otherwise this
   specification does not apply.  There MUST be no data in the IP
   payload after the last TLV.  To check this, one will need to walk
   through each of The TLVs until there are less than four octets left
   in the IP payload.  If there are any octets left, validation failed.

   The walk also stops and validation fails if a TLV has a length
   exceeding the remainder of the IP payload.  For this validation, one
   only examines the content of the Extension Length fields.

   If the validation failed, the entire Additional Data field MUST be
   ignored as specified in IGMPv3 [RFC3376] and MLDv2 [RFC3810].

   If the validation succeeded, one will proceed examining each of the
   specified types and perform validation and processing of the
   respective types.  Unsupported types MUST be ignored; type validation
   and processing proceeds as if they were not present.

5.  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,
   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.

6.  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.

   The respective types defined using this extension may impact security
   and this MUST be considered as part of the respective specifications.

6.

7.  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.

8.  Acknowledgements

   The authors thank Ian Duncan, Leonard Giuliano, Jake Holland and
   Zhaohui Zhang for reviewing the document and providing valuable
   feedback.

9.  References

7.1.

9.1.  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,
              <https://www.rfc-editor.org/info/rfc2119>.

   [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,
              <https://www.rfc-editor.org/info/rfc3376>.

   [RFC3810]  Vida, R., Ed. and L. Costa, Ed., "Multicast Listener
              Discovery Version 2 (MLDv2) for IPv6", RFC 3810,
              DOI 10.17487/RFC3810, June 2004,
              <https://www.rfc-editor.org/info/rfc3810>.

   [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,
              <https://www.rfc-editor.org/info/rfc8126>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

7.2.

9.2.  Informative References

   [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,
              <https://www.rfc-editor.org/info/rfc5790>.

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

   Hitoshi Asaeda
   National Institute of Information and
       Communications Technology
   4-2-1 Nukui-Kitamachi
   Koganei, Tokyo  184-8795
   Japan

   Email: asaeda@nict.go.jp