Cisco Systems 3560 Manual De Usuario

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 a port can join.

Switch(config)# interface gigabitethernet0/2

Switch(config-if)# ip igmp max-groups 25

Switch(config-if)# end

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:

This restriction can be applied only to Layer 2 ports. 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. 

If you configure the throttling action as deny, the entries that were previously in the forwarding 
table are not removed but are aged out. After these entries are aged out and the maximum 
number of entries is in the forwarding table, the switch drops the next IGMP report received on 
the interface.

If you configure the throttling action as replace, the entries that were previously in the 
forwarding table are removed. When the maximum number of entries is in the forwarding table, 
the switch replaces a randomly selected entry with the received IGMP report.

To prevent the switch from removing the forwarding-table entries, you can configure the IGMP 
throttling action before an interface adds entries to the forwarding table.

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.

Return to privileged EXEC mode.

show running-config interface 
interface-id

Verify the configuration.

(Optional) Save your entries in the configuration file.