In this paper, we study a meshed ring communications network that employs cross-connect switches. For an all-optical network using WDM, these switches are implemented as wavelength routers. For a certain class of meshed rings, under a uniform traffic matrix, we derive the optimal topology that achieves maximum throughput efficiency. Using such a topology, we obtain upper and lower bounds on the number of wavelengths required to achieve that efficiency level. For routing purpose, wavelength subnetworks are embedded in the topology.
Nodes communicate with each other across one of the subnetworks to which both belong.
Wavelength graphs are constructed to demonstrate the implementation of the routing scheme using the number of wavelengths that is equal to the derived upper bound. For practical implementation reasons, we investigate the performance of networks that employ a reduced number of wavelengths. We demonstrate that by increasing the bandwidth allocated to wavelength subnetworks, the required number of wavelengths is reduced. Furthermore, we show that by modifying the topological layout of the meshed ring network, we can reduce substantially the number of required wavelengths, while incurring just a modest reduction in throughput efficiency. For each type of such a subnetwork, different protection methods are proposed to identify an alternate route under a single failure.