Decongestion and vector difference based wavelength routing and assignment schemes in DWDM networks

Wavelength switching networks are circuit switched networks with capabilities to route wavelengths across the ROADMs (Reconfigurable Optical Add-Drop Multiplexers). In this study we try to optimize network utilization. We present a new cost function to be used in routing to reduce congestion and a vector difference evaluation scheme for wavelength assignment to reduce blocking due to wavelength continuity. The new cost function, uses neighbor connectivity coefficients in route computation. Network blocking is then analyzed as a result of three factors: wavelength continuity, congestion, and partial connectivity within ROADM sites. Computational complexity for larger networks can be reduced using minimal spanning tree for wavelength assignment using vector difference wavelength assignment (VDWA) scheme. We further analyze varying network topologies like ring, 22 and 30 node mesh networks. These topologies are evaluated for random and uniform demand maps with varying traffic loads. Based on the results we demonstrate that the new cost function reduces blocking due to congestion and partial connectivity whereas VDWA reduces blocking due to wavelength continuity. A combination of the two reduces blocking due to wavelength continuity up to 40% in some cases.