Routing device, communications system, and routing method

A communications system which includes a routing device included in a communication network capable of explicit routing which specifies resources included in a default path for each flow, the routing device comprising:

• a detour path detection unit that detects a detour path which enables estimation of temporary transmission quality which can be provided to a flow within a detour region when at least a portion of an explicit default path of the flow transmitted by the routing device is detoured via resources included in a default path of another flow;
• and
• a routing unit that routes data of the flow at least to either one of the detour path and the default path, based on a difference between transmission quality of the detour path detected by the detour path detection unit and transmission quality of the default path.

A routing method included in a communication network capable of explicit routing which specifies resources included in a default path for each flow, the routing method comprising the steps of:

• detecting a detour path which enables estimation of temporary transmission quality which can be provided to a flow within a detour region when at least a portion of an explicit default path of the flow transmitted by a routing device is detoured via resources included in a default path of another flow;
• and
• routing data of the flow at least to either one of the detour path and the default path, based on a difference between transmission quality of the detected detour path and transmission quality of the default path.