NETWORK ABNORMALITY DETECTION DEVICE AND NETWORK ABNORMALITY DETECTION METHOD

PROBLEM TO BE SOLVED: To determine the presence of obstacles in the network to detect a transition of abnormal states while the network is in trouble.SOLUTION: A network abnormality detection device 100 comes with a reference vector R which is referenced to determine the presence of a transition of troubles and abnormal states and a temporary reference vector T, as shown in Fig. 1(c). When a second vector B is obtained at the current point of time, an angular difference RB between the reference vector R and the second vector B is made an abnormality score, so that when the abnormality score is larger than a threshold, it is determined that there exists abnormality (trouble). The temporary reference vector T is the same as a first vector A (in Fig. 1(b)) where it is already determined that there exists abnormality (trouble). Thus, an angular difference TB between the second vector B and the temporary reference vector T is made an abnormality score, so that when the abnormality score is larger than a threshold, it can be determined that an abnormal state different from the first vector A and the second vector B exists (i.e., there has been a transition of abnormal states).