Igmp configuration, Igmp overview, Igmp versions – H3C Technologies H3C SecPath F1000-E User Manual
Page 35: Introduction to igmpv1
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IGMP Configuration
This chapter includes these sections:
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NOTE:
The term
router in this document refers to network routing devices running a routing protocol.
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 and adjacent multicast routers to establish and maintain
their multicast group memberships.
IGMP Versions
So far, there are three IGMP versions:
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IGMPv1 (documented in RFC 1112)
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IGMPv2 (documented in RFC 2236)
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IGMPv3 (documented in RFC 3376)
All IGMP versions support the Any-Source Multicast (ASM) model. In addition to support for the ASM
model, IGMPv3 can be directly deployed to implement the Source-Specific Multicast (SSM) model, while
IGMPv1 and IGMPv2 need to work with the IGMP SSM mapping function to implement the SSM model.
NOTE:
For more information about the ASM and SSM models, see
Multicast Overview of the IP Multicast Volume.
Introduction to IGMPv1
IGMPv1 manages multicast group memberships mainly based on the query and response mechanism.
On a subnet configured with multiple multicast routers, all the routers can hear IGMP membership report
messages (often referred to as reports) from hosts, but only one router is required to send IGMP query
messages (often referred to as queries). So, a querier election mechanism is used to determine 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.
NOTE:
For more information about DR, see
PIM Configuration in the IP Multicast Volume.