Adding an interface to a multicast group
You can manually add an interface to a multicast group. This is useful in the following cases:
- Hosts attached to the interface are unable to add themselves as members of the group using IGMP.
- There are no members for the group attached to the interface.
When you manually add an interface to a multicast group, the device forwards multicast packets for the group but does not itself accept packets for the group.
You can manually add a multicast group to individual ports only. If the port is a member of a virtual routing and forwarding (VRF) interface, you must add the ports to the group individually.
To manually add a port to a multicast group, enter a command such as the following at the configuration level for the port.
Device(config-if-e10000-1/1/1)# ip igmp static-group 224.2.2.2
This command adds port 1/1 to multicast group 224.2.2.2.
To add a port that is a member of a VRF interface to a multicast group, enter a command such as the following at the configuration level for the virtual routing interface.
Device(config-vif-1)# ip igmp static-group 224.2.2.2 ethernet 1/4/2
This command adds port 1/4/2 in VRF interface 1 to multicast group 224.2.2.2.
Syntax: [no] ip igmp static-group ip-addr [ ethernet unit/slot//port ]
The ip-addr variable specifies the group number.
The ethernet unit/slot/port parameter specifies the port number. Use this parameter if the port is a member of a VRF interface, and you are entering this command at the configuration level for the VRF interface.
Manually added groups are included in the group information displayed by the following commands:
- show ip igmp group
- show ip pim group
To display static multicast groups in the default VRF, enter the following command.
device# show ip igmp static
Group Address Interface Port List
----------------------------------
224.2.2.2 v1 ethe 1/4/2
Syntax: show ip igmp [ vrf vrf_name ] static
The vrf parameter allows you to display static IGMP groups for the VRF instance specified by the vrf_name variable.