With IGMP Snooping enabled, the device (L2 switch) can make intelligent multicast forwarding (only) toward those hosts, i.e. IPSTBs etc., which request to join (as members of) a specific multicast group, i.e. an IPTV channel etc., within the broadcast domain (same PVC/VLAN). As a result, it significantly reduces traffic flooding upon interfaces which are not registered as receivers of specific multicast group.