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Catalyst 2950 and Catalyst 2955 Switch Software Configuration Guide
OL-10101-02
Chapter 20 Configuring IGMP Snooping and MVR
Displaying IGMP Filtering and Throttling Configuration
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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.
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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 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.
Beginning in privileged EXEC mode, follow these steps to configure the throttling action when the
maximum number of entries is in the forwarding table:
To return to the default action of dropping the report, use the no ip igmp max-groups action interface
configuration command.
Displaying IGMP Filtering and Throttling Configuration
You can display IGMP profile characteristics, and you can display the IGMP profile and maximum group
configuration for all interfaces on the switch or for a specified interface. You can also display the IGMP
throttling configuration for all interfaces on the switch or for a specified interface.
Command Purpose
Step 1 configure terminal Enter global configuration mode.
Step 2 interface interface-id Enter interface configuration mode, and enter the physical interface to
configure. The interface can be a Layer 2 port that does not belong to an
EtherChannel group or an EtherChannel interface. The interface cannot
be a trunk port.
Step 3 ip igmp max-groups action {deny |
replace}
When an interface receives an IGMP report and the maximum number
of entries is in the forwarding table, specify the action that the interface
takes:
• deny—Drop the report.
• replace—Replace the existing group with the new group for which
the IGMP report was received.
Step 4 end Return to privileged EXEC mode.
Step 5 show running-config interface
interface-id
Verify the configuration.
Step 6 copy running-config startup-config (Optional) Save your entries in the configuration file.