RFC 3569 (rfc3569) - Page 1 of 14


An Overview of Source-Specific Multicast (SSM)



Alternative Format: Original Text Document



Network Working Group                              S. Bhattacharyya, Ed.
Request for Comments: 3569                                        Sprint
Category: Informational                                        July 2003


             An Overview of Source-Specific Multicast (SSM)

Status of this Memo

   This memo provides information for the Internet community.  It does
   not specify an Internet standard of any kind.  Distribution of this
   memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2003).  All Rights Reserved.

Abstract

   The purpose of this document is to provide an overview of
   Source-Specific Multicast (SSM) and issues related to its deployment.
   It discusses how the SSM service model addresses the challenges faced
   in inter-domain multicast deployment, changes needed to routing
   protocols and applications to deploy SSM and interoperability issues
   with current multicast service models.

1.  Introduction

   This document provides an overview of the Source-Specific Multicast
   (SSM) service and its deployment using the PIM-SM and IGMP/MLD
   protocols.  The network layer service provided by SSM is a "channel",
   identified by an SSM destination IP address (G) and a source IP
   address S.  An IPv4 address range has been reserved by IANA for use
   by the SSM service.  An SSM destination address range already exists
   for IPv6.  A source S transmits IP datagrams to an SSM destination
   address G.  A receiver can receive these datagrams by subscribing to
   the channel (Source, Group) or (S,G).  Channel subscription is
   supported by version 3 of the IGMP protocol for IPv4 and version2 of
   the MLD protocol for IPv6.  The interdomain tree for forwarding IP
   multicast datagrams is rooted at the source S, and is constructed
   using the PIM Sparse Mode [9] protocol.

   This document is not intended to be a standard for Source-Specific
   Multicast (SSM).  Instead, its goal is to serve as an introduction to
   SSM and its benefits for anyone interested in deploying SSM services.
   It provides an overview of SSM and how it solves a number of problems
   faced in the deployment of inter-domain multicast.  It outlines
   changes to protocols and applications both at end-hosts and routers



Bhattacharyya                Informational