Non-blocking conditions in scalable ATM switches using path-switching scheme

The three-stage Clos network has been studied extensively as a framework for the implementation of large-scale ATM switches. Previously, a quasi-static routing scheme for three-stage Clos networks, called the path-switching scheme, has been proposed by Lee and Lam to achieve low switch complexity and high throughput. We derive in this paper the nonblocking conditions when the bandwidth requirements of traffic are rounded up to simplify switch operation. We discuss the implications of these results for switch implementation. In particular, we show how use the results to build a semi-optical network to reduce switch complexity.