Analyzing and validating global fairness of TCP rate allocation

Network flow control is formulated as a global optimization problem of user profit in this paper. A general global optimization flow control model is used to study the global rate allocation characteristic of TCP congestion control mechanism. It is proved that with active queue management TCP rates tend to be allocated to maximize the aggregate of a user utility function U_s (called Unfairness) when the network reaches equilibrium. Compared with other fairness criteria, Us fairness is a more general conclusion because it considers the arbitrary topology and heterogeneous RTT case. A typical multi-bottleneck topology is used to validate Us fairness. Simulation results show the global rate allocation of TCP tends to accord with Unfairness in most scenarios