Two-layer parallel switching: a practical and survivable design for performance guaranteed optical packet switches

An optical packet switch (OPS) is called performance guaranteed if it can achieve 100% throughput with bounded packet delay. Presently, high speedup requirement and large packet delay are two main disadvantages in designing performance guaranteed OPS. Survivability is another important issue that must be considered for real OPS implementations. In this paper, we propose a two-layer parallel OPS architecture together with an efficient scheduling scheme to address all the above issues. The tradeoff between speedup and packet delay under this new parallel architecture is also formulated to provide more design flexibility. Compared to the single-layer OPS, our proposed solution can simultaneously reduce both speedup and packet delay. For example, a delay of 4/spl delta/N slots can be achieved with a speedup of 2 in our solution (where N is the switch size and /spl delta/ is the switch reconfiguration overhead), whereas the single-layer OPS needs a speedup of 6 for a delay of 7/spl delta/N slots. We show that this significant improvement benefits from a careful overall design rather than simply adding an extra switching layer.