Patent ID: 7974192

Claim:
A method for forwarding multicast packets by a layer 2 module in a data switching device having a plurality of cooperating layer 2 modules, each module including at least one network interface for supporting directly connected multicast devices and an inter-module communication interface for communicating with remote modules, the method comprising: receiving, from a layer 2 module, one or more Internet Group Management Protocol (IGMP) messages at one or more of the network interfaces, the IGMP messages being layer 3 protocol messages; forwarding the one or more received IGMP messages to each remote module via the inter-module communication interface; snooping received IGMP messages at each module to determine that one or more network interfaces are associated with a particular multicast stream and maintaining the associated network interfaces in a forwarding interface list for the multicast stream, the forwarding interface list indicating all network interfaces and all remote modules that are associated with the multicast stream; receiving a multicast packet associated with the multicast stream from a network interface; and forwarding the multicast packet over the inter-module communication interface to each remote module having a network interface identified in the forwarding interface list.