A transfer path of a multicast packet is set to an output port, from among a plurality of outputs each associated with a plurality of input ports, which is specified to output the multicast packet. The number of completed path setting processes which is the number of processes for which path setting has been completed, is counted. It is determined whether or not the number of completed processes counted is identical with the number of processes for executing the multicast communication. When it is determined that the numbers are identical with each other, it is recognized that the transfer path setting of the multicast communication has been completed.