Detecting Network-wide Traffic Anomalies based on Spatial HMM

In contrast to many techniques exploiting temporal patterns of traffic from a single network element, network-wide traffic analysis mainly focuses on the spatial behavior across the whole network. This paper proposes a spatial hidden Markov model (SHMM) to learn the normal patterns of network-wide traffic. Combined with topology information, SHMM models traffic volumes on links as probabilistic outputs of underlying interactions between routers. Based on a trained SHMM, a nonparametric CUSUM algorithm is used to track the change of entropy of observation sequences in different sliding windows for anomaly detection. Background traffic collected from real network and synthetic anomalies are used for validation of the detection method. The results prove our method effective for network-wide traffic anomaly detection.