Administrator Guide

• IGMP snooping is not supported on the default VLAN interface.
• Flooding of unregistered multicast traffic is enabled by default.
• Queries are not accepted from the server side ports and are only accepted from the uplink LAG.
• Reports and Leaves are flooded by default to the uplink LAG irrespective of whether it is an mrouter port
or not.
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. To disable multicast flooding on all VLAN
ports, enter the
no ip igmp snooping flood command in global configuration mode.
When multicast flooding is disabled, unregistered multicast data traffic is forwarded to only multicast router
ports on all VLANs. If there is no multicast router port in a VLAN, unregistered multicast data traffic is dropped.
Displaying IGMP Information
Use the show commands from the below table, to display information on IGMP. If you specify a group
address or interface:
• Enter a group address in dotted decimal format; for example, 225.0.0.0.
• Enter an interface in one of the following formats: tengigabitethernet slot/port, port-channel
port-channel-number, or vlan vlan-number.
Displaying IGMP Information
Command
Output
show ip igmp
snooping
groups [group-
address
[detail] |
detail |
interface
[group-address
[detail]]
Displays information on IGMP groups.
show ip igmp
snooping
interface
[
interface]
Displays IGMP information on IGMP-enabled interfaces.
show ip igmp
snooping
mrouter [vlan
vlan-number]
Displays information on IGMP-enabled multicast router (mrouter) interfaces.
clear ip igmp
snooping
groups [group-
Clears IGMP information for group addresses and IGMP-enabled interfaces.
Internet Group Management Protocol (IGMP) 397