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Cisco Catalyst Blade Switch 3130 for Dell Software Configuration Guide
OL-13270-01
Chapter23 Configuring IGMP Snooping and MVR
Configuring IGMP Snooping
To return to the default query solicitation, use the no ip igmp snooping tcn query solicit global
configuration command.

Disabling Multicast Flooding During a TCN Event

When the switch receives a TCN, multicast traffic is flooded to all the ports until 2 general queries are
received. If the switch has many ports with attached hosts that are subscribed to different multicast
groups, this flooding might exceed the capacity of the l ink an d c ause pa cket l oss. You can use the ip
igmp snooping tcn flood interface configuration command to control this behavior.
Beginning in privileged EXEC mode, follow these steps to disable multicast flooding on an interface:
To re-enable multicast flooding on an interface, use the ip igmp snooping tcn flood interface
configuration command.
Configuring the IGMP Snooping Querier
Follow these guidelines when configuring the IGMP snooping querier:
•Configure the VLAN in global configuration mode.
•Configure an IP address on the VLAN interface. When enabled, the IGMP sn ooping queri er uses the
IP address as the query source address.
•If there is no IP address configured on the VLAN interface, the IGMP snooping querier tries to use
the configured global IP address for the IGMP querier. If there is no global IP address specif ied, th e
IGMP querier tries to use the VLAN switch virtual interface (SVI) IP address (if one exists). If there
is no SVI IP address, the switch uses the first available IP ad dress conf igured on the switch. The f irst
IP address available appears in the output of the show ip interface privileged EXEC command. The
IGMP snooping querier does not generate an IGMP genera l q uer y i f it ca nno t find an available IP
address on the switch.
•The IGMP snooping querier supports IGMP Versions 1 and 2.
•When administratively enabled, the IGMP snooping querier moves to the nonquerier state if it
detects the presence of a multicast router in the network.
Command Purpose
Step1 configure terminal Enter global configuration mode.
Step2 interface interface-id Specify the interface to be configured, and enter interface
configuration mode.
Step3 no ip igmp snooping tcn flood Disable the flooding of multicast traffic during a spanning-tree TCN
event.
By default, multicast flooding is enabled on an interface.
Step4 exit Return to privileged EXEC mode.
Step5 show ip igmp snooping Verify the TCN settings.
Step6 copy running-config startup-config (Optional) Save your entries in the configuration file.