A Comparison between Tnime-slot Scheduling Approaches for All-Photonic Networks

The internal switches in all-photonic networks do not perform data conversion into the electronic domain. Although this removal of O-E-O conversion eliminates a potential capacity bottleneck, it also introduces scheduling challenges; photonic switches cannot perform queuing operations, so traffic arrivals at these switches must be carefully scheduled. The (overlaid) star topology is an excellent match for an all-photonic network because it simplifies the scheduling problem. In such a network architecture, optical time division multiplexing (OTDM) approaches for scheduling the state of the central switch in the star are attractive. In this paper, we describe two OTDM algorithms that we have recently developed, one that performs scheduling on a slot-by-slot basis and another that schedules frames of multiple slots. We report and analyze the results of OPNET simulations that compare the performance of these scheduling algorithms