25
CONFIDENTIAL
26-Jan-04
© 2002 Procket Networks, Inc. All rights reserved.
Internet Group Membership(management) Protocol (IGMP)
•How hosts tell routers about group membership
•Routers solicit group membership from directly connected hosts
•RFC 1112 specifies version 1 of IGMP
• Supported on Windows 95
•RFC 2236 specifies version 2 of IGMP
• Supported on latest service pack for Windows, newer Windows releases, and most UNIX systems
•IGMP version 3 is specified in IETF draft
• RFC3376
• provides source include-list capabilities (SSM!)
• Support?
•FreeBSD patch, Linux patch, Window XP
•http://videolab.uoregon.edu
•
IGMP
   The primary purpose of IGMP is to permit hosts to commincate their desire to receive multicast traffic to the IP Multicast router(s) on the local network.  This, in turn, permits the IP Multicast router(s) to “Join” the specified multicast group and to begin forwarding the multicast traffic onto the network segment.

The initial specification for IGMP (v1) was documented in RFC 1112, “Host Extensions for IP Multicasting”.  Since that time, many problems and limitations with IGMPv1 have been discovered.  This has lead to the development of the IGMPv2 specification which was ratified in November, 1997 as RFC 2236.

Even before IGMPv2 had been ratified, work on the next generation of the IGMP protocol, IGMPv3, had already begun.  However, the IGMPv3 specification is still in the working stage and has not been implemented by any vendors.