Bridge apparatus with entries reduced in filtering database and network using the same

A bridge apparatus includes a filtering database and a switch section. The filtering database stores sets of a source address of a transmission source bridge apparatus from which a frame has been transmitted and one of ports of the bridge apparatus through which the frame is received. The transmission source bridge apparatus address comprises a subnet ID, a node ID and a port ID, the subnet ID is an ID allocated to a subnet to which the transmission source bridge apparatus belongs, and the node ID is an ID allocated to the transmission source bridge apparatus. The port ID is an ID allocated to each of ports of the transmission source bridge apparatus. The switch section is connected with the ports of the bride apparatus and refers to the filtering database based on a destination address of a transmission frame to determine one port of the bridge apparatus as an output port from which the transmission frame is outputted, when the transmission frame is received through another of the ports of the bridge apparatus.