Phase transition and 1/f noise in a computer network model

Using a simple cellular automaton model of data packets transport in the Internet, the travel times of data packets and transport rates of routers along a fixed path are studied. In this model the additive increasing of transport rates, extraneous random interferences and finite capacity of router are considered. Changing the mean injecting rate of data packets, numerical simulation results show that there exists free flow and congested phase characterized by the different power spectrum of the travel times and the transport rates. While the power spectrum of both the travel times and the transport rates show 1/f noise (power law) in the free flow, the power spectrum of the travel times is approximately characterized by 1/f noise at low frequencies and white noise at high frequencies, and that of transport rates of routers only by white noise in the congested phase. These results are in agreement with previous experimental data.