Queue delay estimation and its application to TCP Vegas

This paper proposes a modified Vegas algorithm, which can be adjusted to take a fair share of the bandwidth compared to other TCP’s. In order to do this, we investigate the maximum round-trip time achievable in steady state flows fully utilizing available link capacities without marking packets. With this, the marking queue delay is defined. We also propose an estimation algorithm for the marking queue delay in TCP data traffic by using the Kalman filter. The modified Vegas algorithm supplements the shortcomings of Vegas such as unfairness due to overor under-estimations of the round-trip propagation delay. This study analyzes the model of the marking probability in active queue management like RED in terms of round trip time. This algorithm gives a robust estimate of the marking queue delay, and the Vegas algorithm in the congestion avoidance phase is modified using this estimation. The simulation results validate the advantages of the proposed algorithm in terms of performance and fairness.