Multiple input single output optical buffers for asynchronous optical packet switched networks

Optical buffering is one major challenge in realizing all-optical packet switching. In this paper we focus on a delay-line buffer architecture, called a Multiple-Input Single-Output FIFO (MISO-FIFO) optical buffer. This architecture reduces the physical size of a buffer by up to an order of magnitude or more by allowing reuse of its basic optical delay line elements. We consider the MISO-FIFO optical buffers in a network scenario where the incoming packets are asynchronous and of variable length. A simple Markov model is developed to analyze the performance of our buffering scheme, in terms of packet loss ratio, average packet delay and the output link utilization. Both simulation and analytical results show that increasing the buffer size will significantly improve the performance of this optical buffer under low system load. However, under high system load, its performance will deteriorate when increasing the buffer size. In addition, this paper gives clear guidelines for designing the optimal basic delay line lengths under different system loads, in order to get the minimal packet loss. It is noticeable that this optimal basic length value is independent of the buffer sizes.