Architectural Perspectives in Switching: From Electronics to Photonics

This talk is an introductory exposition of digital switch fabric architectures, focussing at an understanding of fundamental principles. We explain in broad perspectives the evolution from traditional circuit switching to state-of-the- art packet (or ATM, Aynchronous Transfer Mode) switching techniques. The emphasis is not on a detailed coverage of various interconnect fabrics, but rather on a simple fationalization of some key concepts such as blocking, call set-up, scheduling, time-multiplex switching, conflict resolution and buffering. We highlight a few examples from the classic TST (circuit) switch to the recent (packet) fabrics of the Buffered Banyan, the Batcher Banyan and the Knockout Switch, demonstrating in each case the underlying principle. We then revisit various concepts and issues in the context of photonics and discuss briefly future research challenges and opportunities.