Virtual leaky bucket for congestion control in high-speed ATM networks

High speed ATM networks support a variety of communication services, that have different traffic characteristics, which causes the network to be congested quickly. An ATM network with different communication services, data, voice and video, is simulated to study the effect of congestion on network operation. A modified leaky bucket mechanism is used to shape the traffic entering the network, which improved the performance in terms of cell losses and cell delay. The original leaky bucket mechanism is so conservative, that it drops a large number of ATM cells. Another scheme called virtual leaky bucket is proposed in this thesis. In this scheme violating cells are marked and then allowed to enter the network. The scheme is simulated and its performance is compared to the leaky bucket mechanism. Shaped virtual leaky bucket with marking is shown to have much better performance as long as the minimum requirements of non-violating cells are guaranteed.