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IANA Guidelines for IPv4 Multicast Address Assignments (RFC3171) Disclosure Number: IPCOM000005358D
Original Publication Date: 2001-Aug-01
Included in the Prior Art Database: 2001-Aug-31
Document File: 9 page(s) / 15K

Publishing Venue

Internet Society Requests For Comment (RFCs)

Related People

Z. Albanna: AUTHOR [+4]


This memo provides guidance for the Internet Assigned Numbers Authority (IANA) in assigning IPv4 multicast addresses.

This text was extracted from a ASCII Text document.
This is the abbreviated version, containing approximately 22% of the total text.

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.


This memo provides guidance for the Internet Assigned Numbers Authority (IANA) in assigning IPv4 multicast addresses.

1. Introduction

The Internet Assigned Numbers Authority (IANA) ( 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

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]: (224.0.0/24) Local Network Control Block (224.0.1/24) Internetwork Control Block AD-HOC Block (224.1/16) ST Multicast Groups (224.2/16) SDP/SAP Block DIS Transient Block RESERVED (232/8) Source Specific Multicast

Block (233/8) GLOP Block RESERVED (239/8) Administratively Scoped


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...