An explicit rate switch scheme monitors the load at each link and gives feedback to the sources. We define the overload factor as the ratio of the input rate to the available capacity. In this paper, we present three overload based switch schemes which provide MCR guarantees for the ATM (asynchronous transfer mode) ABR (available bit rate) service. The switch schemes proposed use the overload factor and other terms including current source rate and target utilization to calculate feedback rates. A dynamic queue control mechanism is used to achieve efficient usage of the link, control queues and, achieve constant queuing delay at steady state. The proposed algorithms are studied and compared using several configurations. The configurations were chosen to test the performance of the algorithms in presence of link bottlenecks, source bottlenecks and transient sources. Finally, a comparison of the proposed algorithms based on the simulation results is given.

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