Abstract:
The design of optical buffers for packet contention resolution has been recognized as a key issue in all-optical packet switching. One of the most general buffering schem...Show MoreMetadata
Abstract:
The design of optical buffers for packet contention resolution has been recognized as a key issue in all-optical packet switching. One of the most general buffering schemes is priority queues, which includes first-in first-out (FIFO) queues and last-in first-out (LIFO) queues as special cases. In a priority queue, each packet is associated with a unique priority upon its arrival, the packet with the highest priority is sent out from the queue whenever there is a departure request and there are packets in the queue, and the packet with the lowest priority is dumped from the queue whenever there is a buffer overflow. In this paper, we consider the constructions of optical priority queues by using a feedback system consisting of an optical (bufferless) crossbar switch and multiple optical FIFO multiplexers with delay one (FM1’s) in the feedback path for buffering packets and feeding packets back to the switch. Such a feedback system is a generalization of that used in one of the authors’ earlier attempt for the constructions of optical priority queues in Tang et al. (2020). We fix the no-buffering problem in Tang et al. (2020) by using optical FM1’s to replace the optical FIFO multiplexers (FM’s) in Tang et al. (2020), which enables us to successfully achieve an exact emulation of a priority queue. We improve the utilization of buffering capacity over that in Tang et al. (2020) by routing packets to the optical FM1’s according to their buffering tags instead of their tags as used in Tang et al. (2020). We also extend and generalize the construction in Tang et al. (2020) and obtain a much larger class of constructions of optical priority queues. Our constructions are made possible by showing that the highest-priority (resp., lowest-priority) packet is always available at the input links of the switch whenever it needs to be routed to the departure (resp., loss) link, and by showing that there is no collision and there is no buffer overflow at any FM1 at any time so that...
Published in: IEEE Transactions on Communications ( Volume: 70, Issue: 3, March 2022)