Short-term fairness and long-term QoS in the Internet

We consider connection-level models of resource allocation in a simple symmetric three-link network, where files arrive into the network according to a Poisson process and the size of each file is exponentially distributed. For the simple network under consideration, we derive an optimal resource allocation policy which minimizes the steady-state expected number of files in the network. Using this result, we show that, in a heavy traffic regime, the mean file-transfer delay under the proportionally fair policy is at most 1.5 times the delay under the optimal policy. Simulation results indicate that the gap is even smaller. (C) 2009 Elsevier B.V. All rights reserved.