Patent ID: 7616634

Claim:
A gateway device for connecting a multicast-supported network to a multicast-unsupported layer 2 (L2) network, comprising: an interface to the multicast-supported network; an interface to the L2 network; translation pattern information storage means for storing plural records of translation pattern information each consisting of a multicast IP address and a MAC address; first type data request packet processing means for assembling, when receiving a multicast request packet from the multicast-supported network as a first type data request packet for requesting distribution target data to be distributed from another multicast-supported network, a second type data request packet in which a destination MAC address of the first type data request packet is translated into a MAC address of a second gateway device, capable of transmitting, over the L2 network, multicast data packets in response to the first type data request packet, and transmitting the second type data request packet over the L2 network; second type data request packet processing means for storing, when receiving a second type data request packet from the L2 network, in said translation pattern information storage means, a record of translation pattern information consisting of a multicast IP address set in the second type data request packet and a MAC address of a third gateway device transmitting the second type data request packet, and for assembling a packet in which a destination MAC address of the second data type request packet is translated into a multicast MAC address associated with the multicast IP address set in the second type data request packet, and transmitting the address-translated packet over the multicast-supported network; data packet processing means for assembling, when receiving a multicast data packet as the multicast packet of distribution target data from the multicast-supported network and if a record of translation pattern information in said translation pattern information storage means contains an IP address coincident with a destination multicast IP address of the multicast data packet, a L2-network packet in which a destination multicast MAC address of the multicast data packet is translated into a MAC address corresponds to the multicast IP address contained in the record of translation pattern information, and transmitting the L2-network packet over the L2 network; and L2-network data packet processing means for assembling, when receiving an L2-network data packet from the L2 network, a packet in which a destination MAC address of the L2-network data packet is translated into a multicast MAC address associated with a multicast IP address set in the L2-network data packet, and transmitting the address-translated packet over the multicast-supported network.