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].
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.
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: fenner@research.att.com
8. Full Copyright Statement
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