An Optical WDM ATM Switch Based on the Parallel Reservation Scheme

Abstract

A scaleable optical asynchronous transfer mode (ATM) switch using a combination of wavelength-division multiplexed (WDM) and space-division multiplexed (SDM) interconnection network has been shown by other researchers to be able to achieve near 100 % throughput but the delay is worse than that of an input-queued switch for low loads, and is significantly inferior to that of an output-queued switch for high loads. Another drawback is the difficult hardware implementation if it to support non-uniform traffic. In this paper, we propose a modified ATM switch also based on the combination of WDM/ SDM but it can largely overcome the disadvantages suffered by the existing switch. Our scheme requires simple hardware implementation and offers two different modified switching architectures, one based on fixed tuned optical filters and the other on tunable optical filters. The performances of these architectures are studied by simulation. Under a non-uniform and highly bursty input traffic, both attain near 100 % throughput and average delays similar to that of an output-queued switch. The former architecture is simpler to implement but the latter yields a slightly lower delay and supports more nodes given the same number of wavelengths in the switch.