Nine years of observing traffic anomalies: Trending analysis in backbone networks

We present the longitudinal trending analysis of traffic anomalies on a trans-Pacific backbone network over nine years. Throughout our analysis, we try to answer several questions: how frequent do such anomalies appear and how long do they last? Does a set of anomalous hosts occur correspondingly? We answer these by applying the state-of-the-art anomaly detectors to (un)anonymized packet traces and look into interesting insights from the long-term analysis. The key observations are as follow. The sources of anomalies are decreasing over the recent years, but take a significant portion of traffic volume during the measurement period (i.e., 0.03% of all IP addresses take up to 30% of traffic volume). The frequency analysis reveals that there is a clear periodicity of anomalies and anomalous host occurrences in various durations. Finally, we find the influences of anomaly detectors to the overall trending and how they differ from each other.