Optimized design of delay-line buffers with an input-feedback mechanism for asynchronous optical packet switching...

The delay-line buffer is widely used to solve contention by exploiting the time domain for optical packet switching (OPS) networks. How to optimize the length of the delay-line element to minimize the packet loss is a major challenge in designing delay-line buffers efficiently. In this paper we consider the buffers in asynchronous OPS networks with different incoming traffic patterns. For a specific mean packet length, we first demonstrate that the optimum length value of the delay-line element mainly depends on the incoming traffic load. The dependence of packet loss ratio on the delay-line granularity under different traffic loads and buffer sizes is given by both analytical model and simulation results. An optimum delay granularity is found under each traffic load, and this optimum granularity is independent of the buffer sizes. According to this finding, we designed an adaptive delay-line buffer structure with an input-feedback mechanism, namely an improved multiple-input single-output optical buffer, which could automatically configure the switch fabric and adjust the delay-line granularity according to the incoming traffic load. It is shown that the proposed buffer structure can achieve optimum performance for packet loss rate under different network scenarios.