Today network security, uptime and performance of network are important and serious issue in computer network. Anomaly is deviation from normal behavior affecting network security. Anomaly extraction is identification of unusual flow from network, which is need of network operator. Anomaly extraction aims to automatically find the inconsistencies in large set of data observed during an anomalous time interval. Extracted anomalies will be important for root cause analysis, network forensics, attack mitigation and anomaly modeling.