A Study of Fast Flexible Bandwidth Assignment Methods and their Blocking Probabilities for Metro Agile All-optical Ring Networks

In emerging agile all-optical networks, the time division multiplexing technique in the optical domain is implemented on top of wavelength-division multiplexing to increase channel utilization and to support dynamic bandwidth demands. However, the corresponding dynamic routing, wavelength and timeslot assignment (RWTA) problem has not yet been well addressed with respect to appropriately handling the bandwidth availability. In this paper, we consider a ring topology and apply local-information-based distributed schemes to accommodate fast dynamic bandwidth requests in order to enhance network survivability and to decrease the degree of coordination among nodes. We propose an analytical model to iteratively compute blocking performance of single-fibre networks and present RWTA algorithms for multi-fibre networks based on an indexed fibre designation scheme in order to enhance network blocking performance in all-optical metro networks. A systematic study of the possible combinations of algorithms has been performed, which showed not only that packed algorithms reduce blocking probability, but also that our indexed fibre designation scheme enhances performance.