IGMP/MLD snooping

configname: CONFIG_BRIDGE_IGMP_SNOOPING

Linux Kernel Configuration
└─>Networking support
└─>Networking options
└─>IGMP/MLD snooping
In linux kernel since version 2.6.34 (release Date: 2010-05-16)  
If you say Y here, then the Ethernet bridge will be able selectively
forward multicast traffic based on IGMP/MLD traffic received from
each port.

Say N to exclude this support and reduce the binary size.

If unsure, say Y.