Nonparametric internet tomography

The substantial overhead of performing global Internet monitoring motivates techniques for inferring spatially localized information about performance using only host-based, end-to-end measurements. In this paper, we present a novel methodology for inferring queuing delay distributions across internal links in the network based solely on unicast, end-to-end measurements. A key feature of our new approach is that it is nonparametric, meaning that no a priori limit is placed on the number of unknown parameters used to model the delay distributions. The nonparametric approach is required in order to accurately estimate the wide variety of internal delay distributions. The methodology is formulated according to a recently proposed nonparametric, wavelet-based density estimation method in combination with an expectation-maximization optimization algorithm that employs a novel fast Fourier transform implementation. We perform network level ns simulations to verify the accuracy of the estimation procedure.