NETWORK DEVICE, ROUTER DEVICE, SWITCHING METHOD USED THEREFOR, PROGRAM THEREOF, AND RECORDING MEDIUM

摘要

PROBLEM TO BE SOLVED: To provide a router device capable of switching fast to a route where a transfer packet is not looped when a link or an adjacent router device enters a down state.

SOLUTION: If a fault detector 132 detects a fault of the link or adjacent device during routing processing by a packet transfer part 12 for transfer to one of links 31 to 3n based upon route information previously calculated by a main route calculation part 112 and stored in a main route table 122, a high-speed switching part 13 performs immediate switching to an alternative route which is previously calculated by an alternative route calculation part 113 for an assumed fault place and stored in alternative route tables 1311 to 131n. The alternative route calculation part 113 decides whether alternative routes for the assumed fault place are looped by a looped route decision part 114 and stores only alternative routes which are not looped in the alternative route tables 1311 to 131n. Further, when completion of route update is received from another router device after the elapse of a certain time after fault occurrence, an alternative route which is decided as a looped route is added to the main route table 122.

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