abstract network traffic anomaly refers to the status that traffic behaviors depart from the normal behaviors . many reasons, such as the misuse of network equipments, network operations anomaly, flash crowd, network intrusion and so on will cause network anomaly 网络流量异常指的是网络的流量行为偏离其正常行为的情形,引起网络流量异常的原因是多种多样的,例如网络设备的不良运行、网络操作异常、突发访问(flashcrowd)、网络入侵等。