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Catalyst 3750 SwitchSoftware Configuration Guide
OL-8550-09
Chapter46 Configuring IP Multicast Routing
Configuring Optional IGMP Features
Default IGMP Configuration
Table46-4 shows the default IGMP configuration.
Configuring the Switch as a Member of a Group
You can configure the switch as a member of a multicast group and discover multicast reachability in a
network. If all the multicast-capable routers and multilayer switches that you administer are members of
a multicast group, pinging that group causes all these devices to respond. The devices respond to ICMP
echo-request packets addressed to a group of which they are members. Another example is the multicast
trace-route tools provided in the software.
Caution Performing this procedure might impact the CPU performance because the CPU receives all data traffic
for the group address.
Beginning in privileged EXEC mode, follow these steps to configure the switch to be a member of a
group. This procedure is optional.
To cancel membership in a group, use the no ip igmp join-group group-address interface configuration
command.
Table46-4 Default IGMP Configuration
Feature Default Setting
Multilayer switch as a member of a multicast group No group memberships are defined.
Access to multicast groups All groups are allowed on an interface.
IGMP version Version 2 on all interfaces.
IGMP host-query message interval 60 seconds on all interfaces.
IGMP query timeout 60 seconds on all interfaces.
IGMP maximum query response time 10 seconds on all interfaces.
Multilayer switch as a statically connected member Disabled.
Command Purpose
Step1 configure terminal Enter global configuration mode.
Step2 interface interface-id Specify the interface to be configured, and enter interface configuration
mode.
Step3 ip igmp join-group group-address Configure the switch to join a multicast group.
By default, no group memberships are defined.
For group-address, specify the multicast IP address in dotted decimal
notation.
Step4 end Return to privileged EXEC mode.
Step5 show ip igmp interface [interface-id] Verify your entries.
Step6 copy running-config startup-config (Optional) Save your entries in the configuration file.