Abstract and subjects
The modeling and analysis of computer communications networks give rise to a variety of interesting statistical problems. This chapter focuses on network tomography, a term used to characterize two classes of large-scale inverse problems. The first deals with passive tomography where aggregate data are collected at the individual router/node level and the goal is to recover path-level information. The main problem of interest here is the estimation of the origin-destination traffic matrix. The second, referred to as active tomography, deals with reconstructing link-level information from end-to-end path-level measurements obtained by actively probing the network. The primary application is estimation of quality-of-service parameters such as loss rates and delay distributions. The chapter provides a review of the statistical issues and developments in network tomography with an emphasis on active tomography. An application to internet telephony is used to illustrate the results.