Network Working Group                                          B. Fenner
Request for Comments: 3228                                 AT&T Research
BCP: 57                                                    February 2002
Category: Best Current Practice


                       IANA Considerations for
            IPv4 Internet Group Management Protocol (IGMP)

Status of this Memo

  This document specifies an Internet Best Current Practices for the
  Internet Community, and requests discussion and suggestions for
  improvements.  Distribution of this memo is unlimited.

Copyright Notice

  Copyright (C) The Internet Society (2002).  All Rights Reserved.

Abstract

  This memo requests that the IANA create a registry for fields in the
  IGMP (Internet Group Management Protocol) protocol header, and
  provides guidance for the IANA to use in assigning parameters for
  those fields.

Table of Contents

  1. Introduction. . . . . . . . . . . . . . . . . . . . . . . . .   1
  2. IANA Considerations for fields in the IPv4 IGMP header. . . .   2
  3. Assignments for testing and experimentation . . . . . . . . .   2
  4. Security Considerations . . . . . . . . . . . . . . . . . . .   2
  5. Normative References. . . . . . . . . . . . . . . . . . . . .   2
  6. Informative References. . . . . . . . . . . . . . . . . . . .   3
  7. Author's Address. . . . . . . . . . . . . . . . . . . . . . .   3
  8. Full Copyright Statement. . . . . . . . . . . . . . . . . . .   4

1.  Introduction

  This memo requests that the IANA create a registry for fields in the
  IGMP protocol header.

  The terms "Specification Required", "Expert Review", "IESG Approval",
  "IETF Consensus", and "Standards Action", are used in this memo to
  refer to the processes described in [2].






Fenner                   Best Current Practice                  [Page 1]

RFC 3228           IANA Considerations for IPv4 IGMP       February 2002


2.  IANA Considerations for fields in the IPv4 IGMP header

  The IPv4 IGMP header [1] contains the following fields that carry
  values assigned from IANA-managed name spaces: Type and Code.  Code
  field values are defined relative to a specific Type value.

  Values for the IPv4 IGMP Type fields are allocated using an IESG
  Approval or Standards Action processes.  Code Values for existing
  IPv4 IGMP Type fields are allocated using IESG Approval or Standards
  Action processes.  The policy for assigning Code values for new IPv4
  IGMP Types should be defined in the document defining the new Type
  value.

3.  Assignments for testing and experimentation

  Instead of suggesting temporary assignments as in [3], this document
  follows the lead of [4] and assigns a range of values for
  experimental use.  The IGMP Code values 240-255 inclusive (0xf0 -
  0xff) are reserved for protocol testing and experimentation.

  Systems should silently ignore IGMP messages with unknown Code
  values.

4.  Security Considerations

  Security analyzers such as firewalls and network intrusion detection
  monitors often rely on unambiguous interpretations of the fields
  described in this memo.  As new values for the fields are assigned,
  existing security analyzers that do not understand the new values may
  fail, resulting in either loss of connectivity if the analyzer
  declines to forward the unrecognized traffic, or loss of security if
  it does forward the traffic and the new values are used as part of an
  attack.  This vulnerability argues for high visibility (which the
  Standards Action and IETF Consensus processes ensure) for the
  assignments whenever possible.

5.  Normative References

  [1]   Fenner, W., "Internet Group Management Protocol, Version 2",
        RFC 2236, November 1997.

  [2]   Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA
        Considerations Section in RFCs", BCP 26, RFC 2434, October
        1998.







Fenner                   Best Current Practice                  [Page 2]

RFC 3228           IANA Considerations for IPv4 IGMP       February 2002


6.  Informative References

  [3]   Bradner, S. and V. Paxson, "IANA Allocation Guidelines For
        Values In the Internet Protocol and Related Headers", BCP 37,
        RFC 2780, March 2000.

  [4]   Narten, T., "Assigning Experimental and Testing Numbers
        Considered Useful", Work in Progress.

7.  Author's Address

        Bill Fenner
        AT&T Labs -- Research
        75 Willow Rd
        Menlo Park, CA 94025
        USA

        EMail: [email protected]

































Fenner                   Best Current Practice                  [Page 3]

RFC 3228           IANA Considerations for IPv4 IGMP       February 2002


8.  Full Copyright Statement

  Copyright (C) The Internet Society (2002).  All Rights Reserved.

  This document and translations of it may be copied and furnished to
  others, and derivative works that comment on or otherwise explain it
  or assist in its implementation may be prepared, copied, published
  and distributed, in whole or in part, without restriction of any
  kind, provided that the above copyright notice and this paragraph are
  included on all such copies and derivative works.  However, this
  document itself may not be modified in any way, such as by removing
  the copyright notice or references to the Internet Society or other
  Internet organizations, except as needed for the purpose of
  developing Internet standards in which case the procedures for
  copyrights defined in the Internet Standards process must be
  followed, or as required to translate it into languages other than
  English.

  The limited permissions granted above are perpetual and will not be
  revoked by the Internet Society or its successors or assigns.

  This document and the information contained herein is provided on an
  "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
  TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
  BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
  HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
  MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.

Acknowledgement

  Funding for the RFC Editor function is currently provided by the
  Internet Society.



















Fenner                   Best Current Practice                  [Page 4]