Analysis of an output queued batcher-Banyan switch (oqbbs) for atm networks

This paper proposes an ATM switch architecture called the output queued Batcher banyan switch (OQBBS). It consists of a Batcher sorting network, banyan routing network, and output queueing modules. The principles of channel grouping and output queueing are used to increase the maximum throughput beyond that of the Batcher-banyan throughput limit of a 0.58. Since the N inputs and K x N outputs of banyan routing network routes cells based on their destined output groups, it requires less than 1092N switching stages. One distinctive feature of the OQBBS is that the upper limit of number of cells simultaneously delivered to their desired output is not limited by the value K, but it is limited by the number of cells destined to the same output group. The switch architecture is shown to be modular and easily expandable to large size. The performance of the OQBBS in terms of throughput, cell delays, and cell loss rate under uniform random traffic condition is evaluated by computer simulation. For a switch load of 0.95, simulation results indicate that the throughput of a 1024 x 1024 OQBBS is close to I and the average cell delay is about 12 cell-times. This is close to the performance- of an ideal N x N output queued non-blocking switch with throughput I and average cell delays of 11.4 cell-times. It is also shown that the OQBBS meet the cell loss probability -requirement of 10-6.