Patent ID: 7623465

Claim:
A network system including a plurality of monitoring target computers, a network monitoring device and a plurality of network devices for relaying TCP communications, said plurality of monitoring target computers each comprising: a communication function for performing TCP communications with at least another one of the plurality of monitoring target computers; and an abnormal phenomenon occurrence notifying message sending function of monitoring an occurrence frequency of an abnormal phenomenon in each session of TCP communication performed by said communication function and, when the occurrence frequency of the abnormal phenomenon in each session of TCP communication performed by said communication function becomes larger than a specified value, sending an abnormal phenomenon occurrence notifying message showing a report that the abnormal phenomenon has occurred to said network monitoring device, said network monitoring device comprising: an operation status detecting function of detecting whether each of said plurality of network devices operates normally or not; a detection result display function of displaying a result of the detection by said operation status detecting function on a display; an abnormal phenomenon occurrence notifying message management function of managing the abnormal phenomenon occurrence notifying message sent by each monitoring target computer and of generating and managing, when receiving two abnormal phenomenon occurrence notifying messages within a predetermined period of time and the two abnormal phenomenon occurrence notifying messages are messages from two monitoring target computers among said plurality of monitoring target computers that transfer and receive information through the TCP communications with one another, an abnormal phenomenon occurrence notifying message into which these two abnormal phenomenon occurrence notifying messages are aggregated; and an occurred abnormal phenomenon presenting information display function of displaying, on the display, occurred abnormal phenomenon presenting information containing at least a piece of information indicating which monitoring target computer is a sender of the abnormal phenomenon occurrence notifying message with respect to every abnormal phenomenon occurrence notifying message managed by said abnormal phenomenon occurrence notifying message management function.