Practical solutions for optical packet switches with shared wavelength converters: performance and complexity evaluations

Multi-stage optical packet switching fabric based on the broadcast-and-select principle is considered to implement the shared-per-node wavelength conversion scheme. This approach fairly allows to combine contention resolution in the wavelength and space domains. A scheduling algorithm is proposed to control optical packet forwarding in synchronous context. The results aim at showing how the sharing of wavelength converters impacts on node performance, the degree of sharing achieved with respect to the reference shared-per-node architecture, and at providing a meaningful support for cost-performance benchmarking studies. An important aspect dealt with in the paper is the complexity evaluation in terms of expensive optical components, tunable wavelength converters (TWCs) and semiconductor optical amplifiers (SOAs) used as optical gates. The multi-stage switching fabric is compared with the reference shared-per-node scheme in terms of complexity, thus showing the better scalability property of the proposed architecture, given the reduced number of optical gates employed.