RFC 2365 (rfc2365) - Page 1 of 8

Administratively Scoped IP Multicast

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Network Working Group                                           D. Meyer
Request for Comments: 2365                          University of Oregon
BCP: 23                                                        July 1998
Category: Best Current Practice


                  Administratively Scoped IP Multicast

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 (1998).  All Rights Reserved.

1. Abstract

   This document defines the "administratively scoped IPv4 multicast
   space" to be the range 239.0.0.0 to 239.255.255.255. In addition, it
   describes a simple set of semantics for the implementation of
   Administratively Scoped IP Multicast. Finally, it provides a mapping
   between the IPv6 multicast address classes [RFC 1884] and IPv4
   multicast address classes.

   This memo is a product of the MBONE Deployment Working Group (MBONED)
   in the Operations and Management Area of the Internet Engineering
   Task Force. Submit comments to [email protected]> or the author.

2. Acknowledgments

   Much of this memo is taken from "Administratively Scoped IP
   Multicast", Van Jacobson and Steve Deering, presented at the 30th
   IETF, Toronto, Canada, 25 July 1994. Steve Casner, Mark Handley and
   Dave Thaler have also provided insightful comments on earlier
   versions of this document.

3. Introduction

   Most current IP multicast implementations achieve some level of
   scoping by using the TTL field in the IP header. Typical MBONE
   (Multicast Backbone) usage has been to engineer TTL thresholds that
   confine traffic to some administratively defined topological region.
   The basic forwarding rule for interfaces with configured TTL
   thresholds is that a packet is not forwarded across the interface
   unless its remaining TTL is greater than the threshold.



Meyer                    Best Current Practice
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