Gaussian traffic everywhere?

It is often assumed that Internet traffic exhibits Gaussian characteristics, and this assumption has been validated in various studies of real Internet traffic. Less is known, however, about possible boundaries: at what timescales is traffic Gaussian and how much user aggregation is required for traffic to be Gaussian? The goal of this paper is to investigate these questions by analyzing hundreds of traffic traces, collected at four representative locations. To assess whether traffic is Gaussian, the paper starts with introducing an easy and fast procedure, based on earlier work of Kilpi and Norros. This procedure is used to investigate Gaussianity at timescales ranging from 5 msec to 5 sec. Our study shows that, if traffic is Gaussian at one timescale, it usually preserves this property at other timescales. The paper also investigates Gaussianity as function of the number of users. We conclude that, although it is impossible to give a hard number saying `above N users traffic is Gaussian', it is fair to say that `only a few tens of users' usually makes the aggregated traffic fairly Gaussian.