Evolution of the Generalized Parallel Delta Networks towards a photonic switching environment

This paper deals with the non-blocking properties of the Generalized Parallel Delta Networks and their application to the photonic switching environment. The peculiar characteristics of GPDNs well suit the constraints arising from this new application area In particular, these characteristics consist in a low number of stages and a high fault tolerance due to the stacking of identical Delta networks. Moreover, it is here demonstrated that the crosstalk due to the switch crossover can be completely avoided by means of a proper dimensioning of the network parameters. A new classification of the non-blocking properties is proposed. In particular, a new non-blocking condition, named as strong, has been defined. It establishes that two paths are not in conflict if they do not share any switching element. The strong non-blocking condition has been considered together with the traditional one. This second condition is normally applied in the electronic environment; as it is based on the unshareability of the interstage links, here, it is named as weak. The conditions which have to be satisfied so that a Generalized Parallel Delta Network can be weakly and/or strongly non-blocking have been found and demonstrated.