RFC 1469 (rfc1469) - Page 1 of 4

IP Multicast over Token-Ring Local Area Networks

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Network Working Group                                        T. Pusateri
Request for Comments: 1469                                    Consultant
                                                               June 1993


            IP Multicast over Token-Ring Local Area Networks

Status of this Memo

   This RFC specifies an IAB standards track protocol for the Internet
   community, and requests discussion and suggestions for improvements.
   Please refer to the current edition of the "IAB Official Protocol
   Standards" for the standardization state and status of this protocol.
   Distribution of this memo is unlimited.

Abstract

   This document specifies a method for the transmission of IP multicast
   datagrams over Token-Ring Local Area Networks.  Although an interim
   solution has emerged and is currently being used, it is the intention
   of this document to specify a more efficient means of transmission
   using an assigned Token-Ring functional address.

Introduction

   IP multicasting provides a means of transmitting IP datagrams to a
   group of hosts.  A group IP address is used as the destination
   address in the IP datagram as documented in STD 5, RFC 1112 [1].
   These group addresses, also referred to as Class D addresses, fall in
   the range from 224.0.0.0 to 239.255.255.255.  A standard method of
   mapping IP multicast addresses to media types such as ethernet and
   fddi exist in [1] and RFC 1188 [2].  This document attempts to define
   the mapping for an IP multicast address to the corresponding Token-
   Ring MAC address.

Background

   The Token-Ring Network Architecture Reference [3] provides several
   types of addressing mechanisms.  These include both individual
   (unicast) and group addresses (multicast).  A special subtype of
   group addresses are called functional addresses and are indicated by
   a bit in the destination MAC address.  They were designed for widely
   used functions such as ring monitoring, NETBIOS, Bridge, and Lan
   Manager frames.  There are a limited number of functional addresses,
   31 in all, and therefore several unrelated functions must share the
   same functional address.





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