20-24
Catalyst 2950 and Catalyst 2955 Switch Software Configuration Guide
OL-10101-02
Chapter 20 Configuring IGMP Snooping and MVR
Configuring IGMP Filtering and Throttling
Setting the Maximum Number of IGMP Groups
You can set the maximum number of IGMP groups that a Layer 2 interface can join by using the ip igmp
max-groups interface configuration command. Use the no form of this command to set the maximum
back to the default, which is no limit.
You can use this command on an logical EtherChannel interface but cannot use it on ports that belong to
an EtherChannel port group.
Beginning in privileged EXEC mode, follow these steps to set the maximum number of IGMP groups in
the forwarding table:
To remove the maximum group limitation and return to the default of no maximum, use the no ip igmp
max-groups interface configuration command.
This example shows how to limit to 25 the number of IGMP groups that an interface can join.
Switch(config)# interface
Switch(config-if)# ip igmp max-groups 25
Switch(config-if)# end
Configuring the IGMP Throttling Action
After you set the maximum number of IGMP groups that a Layer 2 interface can join, you can configure
an interface to replace the existing group with the new group for which the IGMP report was received
by using the ip igmp max-groups action replace interface configuration command. Use the no form of
this command to return to the default, which is to drop the IGMP join report.
Follow these guidelines when configuring the IGMP throttling action:
• You can use this command on a logical EtherChannel interface but cannot use it on ports that belong
to an EtherChannel port group.
• When the maximum group limitation is set to the default (no maximum), entering the ip igmp
max-groups action {deny | replace} command has no effect.
• If you configure the throttling action and set the maximum group limitation after an interface has
added multicast entries to the forwarding table, the forwarding-table entries are either aged out or
removed, depending on the throttling action.
Command Purpose
Step 1 configure terminal Enter global configuration mode.
Step 2 interface interface-id Enter interface configuration mode by entering the physical interface to
configure. The interface can be a Layer 2 port that does not belong to an
EtherChannel group or a EtherChannel interface.
Step 3 ip igmp max-groups number Set the maximum number of IGMP groups that the interface can join.
The range is 0 to 4294967294. The default is to have no maximum set.
Step 4 end Return to privileged EXEC mode.
Step 5 show running-configuration interface
interface-id
Verify the configuration.
Step 6 copy running-config startup-config (Optional) Save your entries in the configuration file.