How can I enable IGMP Snooping in OpenWRT?

Question

I'm using OpenWRT on a TP-LINK TL-WR703N. I need to block large quantities of multicast data on the wired side from being transmitted on Wifi. I thought I could use IGMP Snooping for this, since I found a comment "starting from 2.6.34, the kernel has IGMP snooping feature for the software bridges (disabled by default in OpenWrt)" and my kernel is 3.6.11 running r34761, but I can't find anywhere that explains how to turn this feature on.

Solution

Finally got a response here:

echo "1" > /sys/devices/virtual/net/br-lan/bridge/multicast_snooping

or set it in file sysctl.conf