Enabling drop-unknown filters

While IGMP snooping is enabled, the traffic will be forwarded only to joined ports. Configuring drop unknown filters, ensures that packets are not forwarded to ports where a request for the traffic stream has not been received.

This could either be a filter across all VLANs (vlan-shared) or per VLAN (vlan-exclusive). The default is vlan-shared.

Prerequisites

You must be in the configuration context, as indicated by the switch(config)# prompt.

Procedure

Globally enable dropping multicast data using the following command.

ip igmp snooping drop-unknown {vlan-shared | vlan-exclusive}

For example, the following command configures a shared VLAN filter on the switch:

switch# configure terminal
switch(config)# ip igmp snooping drop-unknown vlan-shared