Performance study of a nonblocking space-division packet switch with window policy

In a nonblocking space-division packet switch (such as ATM) with input queueing, head-of-line (HOL) blocking affects significantly the maximum throughput of the switch. We study the performance of a window policy which allows each input queue to scan up to a fixed number of packets, called the window size, to select for transmission on the outputs. The performance of the window policy is characterized by a closed queueing network model, and explicit closed-form formulae are obtained for the maximum throughput of the packet switch as a function of the window size and the size of the switch. The formulae easily determine the effectiveness of the window policy.