Administrator Guide

Configuring IGMP Snooping
Configuring IGMP snooping is a one-step process. To enable, view, or disable IGMP snooping, use the following commands.
There is no specific configuration needed for IGMP snooping with virtual link trunking (VLT). For information about VLT
configurations, refer to Virtual Link Trunking (VLT).
● Enable IGMP snooping on a switch.
CONFIGURATION mode
ip igmp snooping enable
● View the configuration.
CONFIGURATION mode
show running-config
● Disable snooping on a VLAN.
INTERFACE VLAN mode
no ip igmp snooping
Related Configuration Tasks
● Specifying a Port as Connected to a Multicast Router
● Removing a Group-Port Association
● Disabling Multicast Flooding
● Configuring the Switch as Querier
Dell(conf)#ip igmp snooping enable
Dell(conf)#do show running-config igmp
ip igmp snooping enable
Dell(conf)#
Removing a Group-Port Association
To configure or view the remove a group-port association feature, use the following commands.
● Configure the switch to remove a group-port association after receiving an IGMP Leave message.
INTERFACE VLAN mode
ip igmp fast-leave
● View the configuration.
INTERFACE VLAN mode
show config
Dell(conf-if-vl-100)#show config
!
interface Vlan 100
no ip address
ip igmp snooping fast-leave
shutdown
Dell(conf-if-vl-100)#
Disabling Multicast Flooding
If the switch receives a multicast packet that has an IP address of a group it has not learned (unregistered frame), the switch
floods that packet out of all ports on the VLAN.
When you configure the no ip igmp snooping flood command, the system drops the packets immediately. The system
does not forward the frames on mrouter ports, even if they are present. Disable Layer 3 multicast (no ip multicast-
routing) in order to disable multicast flooding.
● Configure the switch to only forward unregistered packets to ports on a VLAN that are connected to mrouter ports.
CONFIGURATION mode
Internet Group Management Protocol (IGMP)
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