Routing, wavelength assignment and spectrum allocation for reconfigurable optical mesh networks having a combination of fixed and Flexible Spectrum ROADM nodes

Next Generation of Optical Networks will witness the advent of Flexible Spectrum/Grid ROADMs. The Pass Band of these Next Generation ROADMs can be varied depending on the spectral width of the incoming signal. With the Pass Band becoming a variable, Spectrum Allocation becomes an added constraint to the currently employed RWA (Routing and Wavelength Assignment) algorithm and hence turns it into a RWSA (Routing, Wavelength and Spectrum Allocation) problem. In reality, the future networks will be a mix of “Fixed Spectrum” and “Flexible Spectrum” ROADM nodes. Considering this fact, the paper presents a novel Routing, Wavelength Assignment and Spectrum Allocation (RWSA) algorithm. The proposed algorithm is applied on NSFNET and the results are presented.