Removing a Group-Port AssociationTo 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 modeip igmp fast-leave• View the configuration.INTERFACE VLAN modeshow configExample of Configuration Output After Removing a Group-Port AssociationDell(conf-if-vl-100)#show config!interface Vlan 100no ip addressip igmp snooping fast-leaveshutdownDell(conf-if-vl-100)#Disabling Multicast FloodingIf the switch receives a multicast packet that has an IP address of a group it has not learned (unregistered frame), the switch floodsthat 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 doesnot forward the frames on mrouter ports, even if they are present. Disable Layer 3 multicast (no ip multicast-routing) inorder to disable multicast flooding.• Configure the switch to only forward unregistered packets to ports on a VLAN that are connected to mrouter ports.CONFIGURATION modeno ip igmp snooping floodSpecifying a Port as Connected to a Multicast RouterTo statically specify or view a port in a VLAN, use the following commands.• Statically specify a port in a VLAN as connected to a multicast router.INTERFACE VLAN modeip igmp snooping mrouter• View the ports that are connected to multicast routers.EXEC Privilege mode.show ip igmp snooping mrouterConfiguring the Switch as QuerierTo configure the switch as a querier, use the following command.Hosts that do not support unsolicited reporting wait for a general query before sending a membership report. When the multicastsource and receivers are in the same VLAN, multicast traffic is not routed and so there is no querier. Configure the switch to be thequerier for a VLAN so that hosts send membership reports and the switch can generate a forwarding table by snooping.• Configure the switch to be the querier for a VLAN by first assigning an IP address to the VLAN interface.INTERFACE VLAN modeInternet Group Management Protocol (IGMP) 357
