the atm interface circuit 155 of this module the atm interface circuit 155 removes the routing information and then applies the cell to the clad circuit 154 the latter disassembles the entered atm cell into a frame as indicated at in fig6 b and successively outputs frames to the fast bus 151 via the buffer 153 each of the fr interface circuits 141 142 performs monitoring to determine whether the port address pa of a frame coincides with its own port address if coincidence is found then the fr interface circuit receives the frame as a result the frame is received by the fr interface circuit 141 on the basis of the identifier c d the fr interface circuit 141 distinguishes between a data frame and a control information frame in the case of a control information frame the fr interface circuit 141 executes processing in accordance with command cm if the frame is a data frame the fr interface circuit 141 sends the data frame to the local fast bus in this case the frame is the control information frame and the command cm is a command for registering logical path information therefore the processor 165 fig5 of the fr interface circuit 141 registers the logical path information that follows the command in the logical path setting table lpt it should be noted that if a value identical with that of the dlci of the received control information frame has been registered in the table lpt the value is overwritten to.