Multifractality in TCP/IP traffic: the case against

The discovery of long-range dependence (a kind of asymptotic fractal scaling) in packet data from LANs and WANs, was followed by further work detailing evidence for multifractal behaviour in TCP/IP traffic in WANs. In terms of networking however, physical mechanisms for such behaviour have never been convincingly demonstrated, leaving open the question of whether multifractal traffic models are of black box type, or alternatively if there is anything 'real' behind them. In this paper we review the evidence for multifractal behaviour of aggregate TCP traffic, and show that in many ways it is weak. Our study includes classic traces and very recent ones. We point out misunderstandings in the literature concerning the scales over which multifractality has been claimed. We explain other pitfalls which have led to the multifractal case being overstated, in particular the possibility of 'pseudo scaling' being confused with true scaling, due to shortcomings in the statistical tools. We argue for an alternative point process model with strong physical meaning. It reproduces the higher order statistics of the data well, despite not being calibrated for them, yet is not multifractal. From its standpoint, the empirical multifractal behaviour is seen as a misinterpretation due to a lack of power in the statistical methodology.