Performance Analysis of WDM Optical Packet Switches with a Hybrid Buffering Architecture

For lack of optical random access memory, optical fiber delay line (FDL) is currently the only technology to implement optical buffering. Feed-forward and feedback are two types of FDL structures in optical buffering, both have advantages and disadvantages. In this paper, we present a novel architecture for WDM optical packet switches with an effective hybrid FDL buffering that combines the merits of both feed-forward and feedback schemes. The core of the switch architecture is the arrayed waveguide grating (AWG) and the tunable wavelength converter (TWC). It requires smaller optical device sizes and fewer wavelengths and has less noise than feedback architecture. At the same time, feed-forward architecture can only do non-preemptive priority routing while ours supports preemptive priority routing. Our empirical results show that the new switch architecture significantly reduces packet loss probability.