Network Working Group Z. Albanna
Request for Comments: 3171 Juniper Networks
BCP: 51 K. Almeroth
Category: Best Current Practice UCSB
D. Meyer
Sprint
M. Schipper
IANA
August 2001
IANA Guidelines for IPv4 Multicast Address Assignments
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 (2001). All Rights Reserved.
Abstract
This memo provides guidance for the Internet Assigned Numbers
Authority (IANA) in assigning IPv4 multicast addresses.
1. Introduction
The Internet Assigned Numbers Authority (IANA) (www.iana.org) is
charged with allocating parameter values for fields in protocols
which have been designed, created or are maintained by the Internet
Engineering Task Force (IETF). RFC 2780 [RFC2780] provides the IANA
guidance in the assignment of parameters for fields in newly
developed protocols. This memo expands on section 4.4.2 of RFC 2780
and attempts to codify existing IANA practice used in the assignment
IPv4 multicast addresses.
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 [RFC2434]. The keywords MUST,
MUST NOT, MAY, OPTIONAL, REQUIRED, RECOMMENDED, SHALL, SHALL NOT,
SHOULD, SHOULD NOT are to be interpreted as defined in RFC 2119
[RFC2119].
Albanna, et al. Best Current Practice [Page 1]RFC 3171 IANA IPv4 Multicast Guidelines August 2001
In general, due to the relatively small size of the IPv4 multicast
addresses space, further assignment of IPv4 multicast address space
is recommended only in limited circumstances. Specifically, the IANA
should only assign addresses in those cases where the dynamic
selection (SDP/SAP), GLOP, SSM or Administratively Scoped address
spaces cannot be used. The guidelines described below are reflected
in http://www.iana.org/numbers.html.
2. Definition of Current Assignment Practice
Unlike IPv4 unicast address assignment, where blocks of addresses are
delegated to regional registries, IPv4 multicast addresses are
assigned directly by the IANA. Current assignments appear as follows
[IANA]:
224.0.0.0 - 224.0.0.255 (224.0.0/24) Local Network Control Block
224.0.1.0 - 224.0.1.255 (224.0.1/24) Internetwork Control Block
224.0.2.0 - 224.0.255.0 AD-HOC Block
224.1.0.0 - 224.1.255.255 (224.1/16) ST Multicast Groups
224.2.0.0 - 224.2.255.255 (224.2/16) SDP/SAP Block
224.252.0.0 - 224.255.255.255 DIS Transient Block
225.0.0.0 - 231.255.255.255 RESERVED
232.0.0.0 - 232.255.255.255 (232/8) Source Specific Multicast
Block
233.0.0.0 - 233.255.255.255 (233/8) GLOP Block
234.0.0.0 - 238.255.255.255 RESERVED
239.0.0.0 - 239.255.255.255 (239/8) Administratively Scoped
Block
The IANA generally assigns addresses from the Local Network Control,
Internetwork Control, and AD-HOC blocks. Assignment guidelines for
each of these blocks, as well as for the Source Specific Multicast,
GLOP and Administratively Scoped Blocks, are described below.
3. Local Network Control Block (224.0.0/24)
Addresses in the Local Network Control block are used for protocol
control traffic that is not forwarded off link. Examples of this
type of use include OSPFIGP All Routers (224.0.0.5) [RFC2328].
3.1. Assignment Guidelines
Pursuant to section 4.4.2 of RFC 2780 [RFC2780], assignments from the
Local Network Control block follow an Expert Review, IESG Approval or
Standards Action process. See [IANA] for the current set of
assignments.
Albanna, et al. Best Current Practice [Page 2]RFC 3171 IANA IPv4 Multicast Guidelines August 2001
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