Cisco WS-C3560E-48PD-SF Command Reference - Page 201

Chapter 2 Catalyst 3560 Switch Cisco IOS Commands ip igmp snooping tcn flood ip igmp snooping tcn flood Use the ip igmp snooping tcn flood interface configuration command to specify multicast flooding as the Internet Group Management Protocol (IGMP) snooping spanning-tree Topology Change Notification (TCN) behavior. Use the no form of this command to disable the multicast flooding. ip igmp snooping tcn flood no ip igmp snooping tcn flood Syntax Description This command has no arguments or keywords. Defaults Multicast flooding is enabled on an interface during a spanning-tree TCN event. Command Modes Interface configuration Command History Release 12.2(25)SEB Modification This command was introduced. Usage Guidelines When the switch receives a TCN, multicast traffic is flooded to all the ports until two general queries are received. If the switch has many ports with attached hosts that are subscribed to different multicast groups, the flooding might exceed the capacity of the link and cause packet loss. You can change the flooding query count by using the ip igmp snooping tcn flood query count count global configuration command. Examples This example shows how to disable the multicast flooding on an interface: Switch(config)# interface gigabitethernet0/2 Switch(config-if)# no ip igmp snooping tcn flood You can verify your settings by entering the show ip igmp snooping privileged EXEC command. Related Commands Command ip igmp snooping ip igmp snooping tcn show ip igmp snooping Description Enables IGMP snooping on the switch or on a VLAN. Configures the IGMP TCN behavior on the switch. Displays the IGMP snooping configuration of the switch or the VLAN. 78-16405-05 Catalyst 3560 Switch Command Reference 2-169