New Fiber Delay Line Usage Strategy in Optical Burst Switching Node

Optical Burst Switching (OBS) is a new paradigm for future all-optical networks. In an OBS node, a Fiber Delay Line may be used to delay a burst, effectively increasing its offset time. Traditionally, FDLs were used in contention resolution, i.e. a burst was only buffered if it would otherwise been dropped. We propose a different approach, where delay lines are used also to better arrange bursts in time. In our strategy both outgoing channels and FDL channels are assigned a price, according to their suitability for a particular burst. When a control packet arrives at a core node, all the possible ways of handling the corresponding burst are found (the outgoing channel, with or without a FDL), and the one with a lowest total price is chosen. This makes it possible to use most FDL channels for the majority of the time, reducing the probability of future contention. We present simulation results, showing how node performance depends on the size of a FDL bank, using either Last Available Unused Channel with Void Filling (LAUC-VF) and the traditional FDL usage strategy or our algorithm.