Recent measurements of local-area and wide-area traf®c [14, 22, 28] have shown that network traf®c exhibits variability at a wide range of scales. Such scale-invariant variability is in strong contrast to traditional models of network traf®c, which show variability at short scales but are essentially smooth at large time scales; that is, they lack long-range dependence. Since self-similarity is believed to have a signi®cant impact on network performance [2, 15, 16], understanding the