Abstract: A bridge device for connecting networks together via data link layers, that assigns input port numbers unique to each port, to headers of input memory access control packets. A content-addressable memory stores destination addresses and groups of port numbers corresponding to the destination addresses. A determiner such as a controller determines whether or not a destination address of a memory access control packet is stored in the memory and determines whether or not a port number corresponding to the destination address coincides with an input port number of the memory access control packet. Based on the determinations made by the determiner, a selector selects one of the following as an output port number: either a port number corresponding to the destination address, or a port number designating all ports other than the input port, or a port number not designating any ports. An output port number assigner assigns an output port number to a memory access control port.