Example of the show config Command
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.
On the MXL Switch, when you configure no ip igmp snooping flood, the system forwards the
frames on the mrouter ports for first 96 IGMP snooping-enabled VLANs. For all other VLANs, the
unregistered multicast packets are dropped.
Specifying a Port as Connected to a Multicast Router
To 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 mode
ip igmp snooping mrouter
View the ports that are connected to multicast routers.
EXEC Privilege mode.
show ip igmp snooping mrouter
Configuring the Switch as Querier
To 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 multicast source and receivers are in the same VLAN, multicast traffic is not routed and
so there is no querier. Configure the switch to be the querier 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 mode
ip igmp snooping querier
IGMP snooping querier does not start if there is a statically configured multicast router interface in
the VLAN.
The switch may lose the querier election if it does not have the lowest IP address of all potential
queriers on the subnet.
When enabled, IGMP snooping querier starts after one query interval in case no IGMP general
query (with IP SA lower than its VLAN IP address) is received on any of its VLAN members.
Internet Group Management Protocol (IGMP) 395