Disclosed is a router network which, regardless of the format used for a network, ensures that communication with another segment will be maintained, even though a fault may occur at a router. The router network includes a plurality of local area networks (LANs), furnished with routers for independent communication; wherein the plurality of local area networks communicate with each other using the Internet protocol (IP) or the Internet work packet protocol (IPX); wherein a network environment for a subordinate segment serviced by a specific router is established for a different router; and wherein when a fault occurs at the specific router, the different router is used as a proxy router to provide communication support for the subordinate segment of the specific router in accordance with the network environment which was set in advance.