Patent ID: 7715390

Claim:
A packet relay device which is connected to a plurality of other packet relay devices via a multicast network and builds a multicast path of the multicast network according to a unicast path table, the packet relay device comprising: a plurality of line units for connecting lines to transmit and receive multicast packet; a multicast path information storage unit which stores as multicast path entries, a transmission source address of the multicast packet, a group address, an address of an upstream packet relay device in the relay of the multicast packet, and information indicating the line where the upstream packet relay device exists; and a path calculation unit for managing the multicast path information storage unit, wherein when the other packet relay devices constitute an Equal-cost Multipath, the path calculation unit selects as the upstream packet relay device in the multicast packet relay, the other packet relay device existing on the line with a least number of times stored as the multicast path entry among the lines where the other packet relay devices exist and stores the selected device in the multicast path information storage unit.