Configuring Igmp; Overview; Igmp Versions; Igmpv1 Overview - HP MSR ASM Configuration Manual

Configuring IGMP

Overview

As a TCP/IP protocol responsible for IP multicast group member management, the IGMP is used by IP
hosts and adjacent multicast routers to establish and maintain their multicast group memberships.

IGMP versions

IGMPv1 (documented in RFC 1 1 12)
•
• IGMPv2 (documented in RFC 2236)
IGMPv3 (documented in RFC 3376)
•
All IGMP versions support the ASM model. In addition to the ASM model, IGMPv3 can directly
implement the SSM model. IGMPv1 and IGMPv2 must work with the IGMP SSM mapping function to
implement the SSM model. For more information about the ASM and SSM models, see "Multicast
overview."

IGMPv1 overview

IGMPv1 manages multicast group memberships based on the query and response mechanism.
All multicast routers on the same subnet can get IGMP membership report messages (often called
"reports") from hosts, but the subnet needs only one router to act as the IGMP querier to send IGMP
query messages (often called "queries"). The querier election mechanism determines which router acts
as the IGMP querier on the subnet.
In IGMPv1, the designated router (DR) elected by the working multicast routing protocol (such as PIM)
serves as the IGMP querier. For more information about DR, see "Configuring PIM."
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