Controller, a communication system, a communication method, and a storage medium for storing a communication program

A communication system comprising:

• a network including a plurality of nodes connected each other by a link;
• a monitoring unit that monitors parameter related to quality of wavelength paths through the nodes;
• a first degraded path detecting unit that detects a wavelength path as a first degraded path, whose quality is detected to be degraded, based on the parameter monitored;
• a correlation path computation unit that computes a correlation path which is correlated with the first degraded path;
• a second degraded path detecting unit that detects a degraded path as a second degraded path from the correlation path;
• and
• a failure localization unit that localizes a node or a link as a failure node or a failure link, wherein the node or the link are traversed by both of the first degraded path and the second degraded path.

A communication method comprising:

• detecting a wavelength path as a first degraded path, whose quality is detected to be degraded, based on received parameter of wavelength paths in a network;
• computing a correlation path which is correlated to the first degraded path;
• detecting a second degraded path from the correlation path;
• and
• localizing a node or a link connecting nodes as a failure node or a failure link, wherein the node or the link are traversed by both of the first degraded path and the second degraded path.

A storage medium for storing a communication program comprising:

• a first degraded path detecting process for detecting a wavelength path, as a first degraded path, whose quality is detected to be degraded, based on received parameters of wavelength paths in the network;
• a correlation path computation process for computing a correlation path which is correlated to the first degraded path;
• a second degraded path detecting process for detecting a second degraded path from the correlation path;
• and
• a failure localization process for localizing a node or a link connecting nodes as a failure node or a failure link, wherein the node or the link are traversed by both of the first degraded path and the second degraded path.