Optimal configuration of p-cycles in WDM optical networks with sparse wavelength conversion

In this paper, we study the optimal configuration of p-cycles in survivable WDM optical mesh networks with sparse wavelength conversion while 100% restorability is guaranteed against any single failures. We formulate the problem as an integer linear program. In our optimization model, working paths are known before protection configuration is done. p-cycles and wavelength converters are then optimally determined subject to the constraint that only a given number of nodes have wavelength conversion capability. The objective is to minimize the cost of link capacity used by all p-cycles to accommodate a set of traffic demands. In the proposed p-cycle configuration architecture, we take into account converter sharing: (a) when converters are used for accessing p-cycles and for wavelength conversion between two adjacent on-cycle spans; (b) when converters are used among disjoint straddling spans incident to the same node for accessing p-cycles. Converter sharing enables the network to require as few converters as possible to attain a satisfactory level of performance. Our simulation results indicate that the proposed approach significantly outperforms the approach for WP networks in terms of protection cost and can obtain the optimal performance as achieved by the approach for VWP networks, but requires fewer wavelength conversion sites and fewer wavelength converters.