Adaptive token bucket algorithm for fair bandwidth allocation in DiffServ networks

We propose an adaptive token bucket algorithm for achieving proportional sharing of bandwidth among aggregate flows in differentiated service (DiffServ) networks. By observing the simulation results obtained in a study of the throughput of TCP flows in a DiffServ network, we note that the aggregate flow with a lower target rate occupies more bandwidth than its fair share, while the aggregate flow with a higher target rate gets less than its fair share. The proposed algorithm solves this unfairness problem by adjusting the target rate according to the edge-to-edge feedback information. This algorithm does not require any additional signaling protocol or measurement of per-flow states, since it can be implemented in a distributed manner using only two-bit feedback information carried in the TCP acknowledgement. Using ns-2 simulations, we show that the proposed algorithm provides fair bandwidth sharing under various network conditions.