Method and system for detecting exception flow of network

A detection method of network abnormal flow rate includes carrying out statistics and analysis on network flow rate data and generating abnormal flow rate event and its packet according to language definition of abnormal flow rate rule ; judging whether abnormal is occurred or not according to whether ratio occupied by packet in total flow rate is consistence to range of certain threshold or not or according to whether ratio , sum and D?Cvalue between two packets is satisfied to a threshold or not as well as according to whether variation slope of packet flow rate is satisfied to a threshold or not .