Date Added: Feb 2011
Network delay is a crucial metric for evaluating the state of the network. The authors present in this paper a structural analysis of network delay, based on delay measurements of a backbone network. This delay analysis is performed using a subspace method called Principal Component Analysis (PCA). The analysis reveals that the delay time series can be decomposed into two constituents: a smooth periodic trend and a set of sparse bursts. They call the former the "Normal" component and the latter the "Abnormal" component. While this structural decomposition is appealing and may be used to further infer other delay information of interest, they find that using PCA in delay analysis has the same challenges as used in traffic analysis.