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Host extensions for IP multicasting (RFC1054)

IP.com Disclosure Number: IPCOM000001861D
Original Publication Date: 1988-May-01
Included in the Prior Art Database: 2000-Sep-12
Document File: 15 page(s) / 41K

Publishing Venue

Internet Society Requests For Comment (RFCs)

Related People

S.E. Deering: AUTHOR

Abstract

IP multicasting is defined as the transmission of an IP datagram to a "host group", a set of zero or more hosts identified by a single IP destination address. A multicast datagram is delivered to all members of its destination host group with the same "best-efforts" reliability as regular unicast IP datagrams, i.e., the datagram is not guaranteed to arrive intact at all members of the destination group or in the same order relative to other datagrams.

This text was extracted from a ASCII Text document.
This is the abbreviated version, containing approximately 7% of the total text.

Network Working Group S. Deering

Request for Comments: 1054 Stanford University

Obsoletes: RFC 988 May 1988

Host Extensions for IP Multicasting

1. STATUS OF THIS MEMO

This memo specifies the extensions required of a host implementation

of the Internet Protocol (IP) to support multicasting. It is

proposed as a standard for IP multicasting in the Internet. This

specification is a major revision of RFC-988; changes from RFC-988

are listed in an Appendix. Distribution of this memo is unlimited.

2. INTRODUCTION

IP multicasting is defined as the transmission of an IP datagram to a

"host group", a set of zero or more hosts identified by a single IP

destination address. A multicast datagram is delivered to all

members of its destination host group with the same "best-efforts"

reliability as regular unicast IP datagrams, i.e., the datagram is

not guaranteed to arrive intact at all members of the destination

group or in the same order relative to other datagrams.

The membership of a host group is dynamic; that is, hosts may join

and leave groups at any time. There is no restriction on the

location or number of members in a host group. A host may be a

member of more than one group at a time. A host need not be a member

of a group to send datagrams to it.

A host group may be permanent or transient. A permanent group has a

well-known, administratively assigned IP address. It is the address,

not the membership of the group, that is permanent; at any time a

permanent group may have any number of members, even zero. Those IP

multicast addresses that are not reserved for permanent groups are

available for dynamic assignment to transient groups which exist only

as long as they have members.

Internetwork forwarding of IP multicast datagrams is handled by

"multicast routers" which may be co-resident with, or separate from,

internet gateways. A host transmits an IP multicast datagram as a

local network multicast which reaches all immediately-neighboring

members of the destination host group. If the datagram has an IP

time-to-live greater than 1, the multicast router(s) attached to the

local network take responsibility for forwarding it towards all other

networks that have members of the destination group. On those other

member networks that are reachable within the IP time-to-live, an

attached multicast router completes delivery by transmitting the

datagram as a local multicast.

This memo specifies the extensions required of a host IP

implementation to support IP multicasting, where a "host" is any

internet host or gateway other than those acting as multicast

routers. The algorithms and protocols used within and between

multicast routers are transparent to hosts and will be specified in

separate documents. This memo also does not specify how local

net...