Bandwidth control method of a node device, a ring network and the protection path

A node apparatus in a ring network in which a protection path is provided that cycles around the ring network and transports a signal in a direction opposite to a signal transporting direction of the working path and in the event of a failure of the working path, a node apparatus adjacent to the failure loops back the signal flowing on the working path onto the protection path, the node apparatus comprising: allowable bandwidth storing unit which stores a maximum total bandwidth value, which represents the largest value among per-link total values of bandwidths that a plurality of working paths use on respective links connecting between the node apparatuses, as an allowable bandwidth for a shared path; and bandwidth control unit which controls the bandwidth of traffic flowing on the protection path, in accordance with the allowable bandwidth.