CST: A new contention reduction scheme in all-optical packet switched star-based metro networks

We consider a metro network architecture that consists of a buffer-less all-optical core switch, where a number of edge switches are connected to the core switch. Slotted all-optical packet switching (OPS) is considered for this network in order to efficiently use network bandwidth. A major problem for slotted OPS is contention. However, basic contention resolution schemes such as optical buffers and wavelength converters are expensive. On the other hand, contention reduction techniques can provide a cheap but effective performance in a slotted OPS network. We propose a new slot transmission mechanism as a contention reduction scheme, called Coordinated Slot Transmission (CST), and provide loss rate performance analysis for CST under symmetric and asymmetric traffic arrivals. Under CST, ingress switches (transmitting edge switches) are loosely coordinated to send their traffic and the system is still lossy. We study and analyze the efficiency of the CST scheme when it is used in an OPS network based on star topology with multi-fiber architecture, with additional wavelength channels, and under the combined approach of multi-fiber architecture and additional wavelength channels.