Patent ID: 8432913

Claim:
A relay device in a network system where communication between a plurality of networks is relayed by a plurality of relay devices, comprising: a plurality of network interfaces that are respectively connected to networks with adjacent relay devices; a current routing table storage unit that stores a routing table where a destination and a next transfer destination being any adjacent relay device are associated; a route control unit that, when a failure occurs in a link or another relay device in the network system, updates the routing table stored in the current routing table storage unit and, upon update, acquires inhibit target route information on a route that generates a micro-loop in the routing table after update; an inhibit target table that stores the inhibit target route information; an inhibit control unit that, on condition that route update in an adjacent relay device is completed, deletes a route in which the adjacent relay device is set as a next transfer destination from the inhibit target table; and a transfer processing unit that determines a transfer route of a packet based on the routing table stored in the current routing table storage unit and, on condition that the determined transfer route of the packet is not registered in the inhibit target table, executes transfer of the packet.