Communication device for automatically setting a router configuration and method of controlling the device

A communication device includes a first part transmitting information to and receiving information from an adjacent device, a second part managing address information of all mounting ports of the communication device, a first port of the adjacent device, and a network to be constructed, the first port being connected to the communication device, a third part automatically determining addresses for the mounting ports of the communication device and the first port of the adjacent device so that the addresses are not duplicated; and a fourth part managing address determination authority to determine the addresses.