METHOD FOR DETECTING FAILURE LINK BASED ON PATH CONTROL PROTOCOL, NODE DEVICE AND PROGRAM

PROBLEM TO BE SOLVED: To provide a method, etc., for detecting a failure link with a small computational quantity and in real time by monitoring an UPDATE based on a BGP (Border Gateway Protocol) in a normal sequence. SOLUTION: This node device has a path list record table for recording a preceding path list constituted of the continuity of AS (Autonomous System) numbers of relayed node devices for each prefix of an UPDATE (Announce), and a path-number record table for recording the number of paths for each link between node devices. Upon receiving the UPDATE (Announce), the node device determines whether the path list of the UPDATE (Announce) coincides with the preceding path list in an address of the same transmission source recorded in the path list record table. When the path list does not coincide with the preceding path list, the path list record table is updated with a new path list, the number of paths of the new link is increased with respect to the path-number record table, and the number of paths of the old link is decreased. A link of which the number of paths is changed to zero is determined as a failure link. COPYRIGHT: (C)2010,JPO&INPIT