Assessment of blocking performance in unidirectional and bi-directional wavelength routed ring networks

In this paper, we present a comparison of the blocking performance in unidirectional and bi-directional wavelength routed ring networks. This performance comparison reveals that, for the same load per node and equal number of wavelengths per link, the performance of a unidirectional ring with N nodes is very close to the performance of a bi-directional ring with 4N nodes. This comparison also suggests that, for the same number of nodes and equal number of wavelengths per link, the performance of a unidirectional ring network with a load per node of ρ is similar to the performance of a bi-directional ring network with a load per node of 4ρ. An explanation is presented for this four-fold capacity increase of bi-directional rings over unidirectional rings, regarding number of nodes or loads per node.