Optical Switching for Variable Size Packets: Improved Void Filling through Selective Void Creation

Abstract

With ever-increasing demand for bandwidth, both optical packet switching and optical burst switching are proposed as alternatives to increase the capacity of optical networks in the future. In these packet-based switching techniques, Fiber Delay Lines are used to avoid contention between packets on a single wavelength. The involved scheduling algorithms decide on which Fiber Delay Line each packet is scheduled in order to maximize performance. By selectively delaying packets longer than strictly necessary, we proposed a schedule called void-creation that outperforms existing void-filling algorithms by up to 50 % for a specific setting with fixed packet size. This contribution extends the concept of void-creation to the case of variable size packets. By conditioning the theoretical value of the packet size on the scheduling parameters, we are able to extend the applicability of the void-creating algorithm to a plurality of settings. We therefore developed a numerical procedure that assigns a theoretical value (or, equivalently, negative cost) to each void based on how likely the void will eventually be filled and thus proven useful. Results obtained by Monte Carlo simulation show that our void-values provide a solid and consistent basis to decide upon void creation, and this for a variety of packet size distributions.