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Cisco Systems IntelligentGigabit Ethernet Switch Modules for the IBMBladeCenter, Software Configuration Guide
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Chapter14 Configuring IGMP Snooping and MVR
Configuring IGMP Filtering and Thrott ling
•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 n ext 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 forwar ding 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.
Command Purpose
Step1 configure terminal Enter global configuration mode.
Step2 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.
Step3 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.
Step4 end Return to privileged EXEC mode.
Step5 show running-config interface
interface-id
Verify the configuration.
Step6 copy running-config startup-config (Optional) Save your entries in the configuration file.