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Cisco ME 3400 Ethernet Access Switch Software Configuration Guide
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Chapter 21 Configuring IGMP Snooping and MVR
Configuring IGMP Snooping
Beginning in privileged EXEC mode, follow these steps to enable the IGMP configurable-leave timer:
Use the no ip igmp snooping last-member-query-interval global configuration command to globally
reset the IGMP leave timer to the default setting.
Use the no ip igmp snooping vlan vlan-id last-member-query-interval global configuration
command to remove the configured IGMP leave-time setting from the specified VLAN.
Configuring TCN-Related Commands
These sections describe how to control flooded multicast traffic during a TCN event:
• Controlling the Multicast Flooding Time After a TCN Event, page 21-10
• Recovering from Flood Mode, page 21-11
• Disabling Multicast Flooding During a TCN Event, page 21-11

Controlling the Multicast Flooding Time After a TCN Event

You can control the time that multicast traffic is flooded after a TCH event by using the ip igmp
snooping tcn flood query count global configuration command. This command configures the number
of general queries for which multicast data traffic is flooded after a TCN event. Some examples of TCN
events are the client changed its location and the receiver is on same port that was blocked but is now
forwarding, and a port went down without sending a leave message.
If you set the TCN flood query count to 1 by using the ip igmp snooping tcn flood query count
command, the flooding stops after receiving one general query. If you set the count to 7, the flooding of
multicast traffic due to the TCN event lasts until 7 general queries are received. Groups are relearned
based on the general queries received during the TCN event.
Command Purpose
Step 1 configure terminal Enter global configuration mode.
Step 2 ip igmp snooping
last-member-query-interval time Configure the IGMP leave timer globally. The range is 100 to
32768 milliseconds. The default is 1000 seconds.
Step 3 ip igmp snooping vlan vlan-id
last-member-query-interval time (Optional) Configure the IGMP leave time on the VLAN interface. The
range is 100 to 32768 milliseconds.
Note Configuring the leave time on a VLAN overrides the globally
configured timer.
Step 4 end Return to privileged EXEC mode.
Step 5 show ip igmp snooping (Optional) Display the configured IGMP leave time.
Step 6 copy running-config startup-config (Optional) Save your entries in the configuration file.