  We refine a stimulating study by Sarvotham et al. [2005] which highlighted
the influence of peak transmission rate on network burstiness. From TCP packet
headers, we amalgamate packets into sessions where each session is
characterized by a 5-tuple (S, D, R, Peak R, Initiation T)=(total payload,
duration, average transmission rate, peak transmission rate, initiation time).
After careful consideration, a new definition of peak rate is required. Unlike
Sarvotham et al. [2005] who segmented sessions into two groups labelled alpha
and beta, we segment into 10 sessions according to the empirical quantiles of
the peak rate variable as a demonstration that the beta group is far from
homogeneous. Our more refined segmentation reveals additional structure that is
missed by segmentation into two groups. In each segment, we study the
dependence structure of (S, D, R) and find that it varies across the groups.
Furthermore, within each segment, session initiation times are well
approximated by a Poisson process whereas this property does not hold for the
data set taken as a whole. Therefore, we conclude that the peak rate level is
important for understanding structure and for constructing accurate simulations
of data in the wild. We outline a simple method of simulating network traffic
based on our findings.
