benes networks include an input stage having a plurality of input ports , an input connection stage configured to connect output signals of the input stage , an add connection stage configured to connect outputs of the input connection stage and to connect inputs of add ports corresponding in number to the number of the plurality of input ports , a drop connection stage configured to connect outputs of the add connection stage , to output some outputs to a next stage , and to output some outputs to drop ports , an output connection stage configured to connect the some outputs of the drop connection stage to an output side , and an output stage configured to output the outputs of the output connection stage to output ports .