Bridge with reduced forwarding table using hierarchical addresses

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 is hierarchical and comprises a subnet ID, a node ID and a port ID, The filtering database is reduced by storing only one record per other subnet ID or other node ID, rather than one per individual address. The switch section is connected with the ports of the bridge 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. The reference is based on the subnet ID first, then the node ID if the destination is on the bridges own subnet, and then the port ID if it is on the bridges own node.