Chapter 5 Igmp Configuration; Igmp Overview; Igmp Versions; Work Mechanism Of Igmpv1 - H3C S3610 Series Operation Manual

Operation Manual – Multicast Protocol
H3C S3610&S5510 Series Ethernet Switches

Chapter 5 IGMP Configuration

5.1 IGMP Overview

As a TCP/IP protocol responsible for IP multicast group member management, the
Internet Group Management Protocol (IGMP) is used by IP hosts to establish and
maintain their multicast group memberships to immediately neighboring multicast
routers.

5.1.1 IGMP Versions

So far, there are three IGMP versions:
IGMPv1 (described in RFC 1112)
IGMPv2 (described in RFC 2236)
IGMPv3 (described in RFC 3376)
All IGMP versions support the Any-Source Multicast (ASM) model. In addition, IGMPv3
provides strong support to the Source-Specific Multicast (SSM) model.

5.1.2 Work Mechanism of IGMPv1

IGMPv1 manages multicast groups mainly based on the query and response
mechanism.
Of multiple multicast routers on the same subnet, only one router is needed for sending
IGMP queries because all the routers can receive IGMP reports from hosts. So, a
querier election mechanism is required to determine which router will act as the IGMP
querier on the subnet.
In IGMPv1, the designated router (DR) elected by the Layer 3 multicast routing protocol
(such as PIM) serves as the IGMP querier.
For more information about a DR, refer to " PIM Configuration".
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Chapter 5 IGMP Configuration