User's Manual
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Chapter 73 IGMP Configuration
73.1 IGMP
Overview
Internet Group Management Protocol (IGMP) is a protocol used to manage multicast group members. IGMP
is an asymmetric protocol, containing the host side and the switch side. At the host side, the IGMP protocol
regulates how the host, the multicast group member, reports the multicast group it belongs to and how the host
responds to the query message from the switch. At the switch side, the IGMP protocol regulates how the IGMP-
supported switch learns the multicast group member ID of the hosts in the local network and how to modify
the stored multicast group member information according to the report message from the host.
Since our switches support the IGMP Router protocol, the multicast routing protocol can be provided with the
information about the multicast group members in the current network and the switch decides whether to
forward the multicast message. In a word, to enable the switch support the multicast process of the IP message,
the switch need be configured to support the multicast routing protocol and the IGMP Router protocol. Currently,
MY COMPANY' switches support the IGMP Router protocol and version 3 IGMP, the latest version.
There is no independent startup commands for IGMP. The function of the IGMP-Router protocol is started up
through the multicast routing protocol.
73.2 IGMP Configuration
The commands to configure the attributes of the IGMP-Router mainly are the commands to adjust the IGMP
parameters. The following is to describe these commands. For details about these commands, refer to
explanation documents relative to the IGMP commands.
73.3 Changing Current IGMP Version
Up to now, the IGMP protocol has three formal versions. The corresponding RFCs are RFC1112, RFC2236
and RFC3376. IGMP V1 supports only the function to record the multicast group members. IGMP V2 can query
the designated multicast group member, generates the leave message when an IGMP host leaves a multicast
group, and shortens the change delay of the group member. IGMP V3 has additional functions to update and
maintain the multicast group member IDs which correspond to the source host addresses. The IGMP Router
protocol of IGMP V3 is fully compatible with the host side of IGMP V1 and IGMP V2. MY COMPANY’s switch
software supports the IGMP Router protocols of the three IGMP versions.
You can configure the IGMP-Router function at different interfaces (the multicast routing protocol configured
on different interfaces can start up the IGMP-Router function) and different versions of IGMP can be run on
different interfaces.
Note that a multicast switch can start up the IGMP-Router function on only one of the ports that
connect the same network.
Run the following command in interface configuration mode to change the version of the IGMP-Router protocol
on a port:
Command Purpose