  Quantum Key Distribution has become a mature quantum technology that has
outgrown dedicated links and is ready to be incorporated into the classical
infrastructure. In this scenario with multiple potential nodes, it is crucial
having efficient ways to allocate the network resources between all the
potential users. We propose a simple method for routing and wavelength
assignment in wavelength multiplexed networks in which classical and quantum
channels coexist. The proposed heuristics take into account the specific
requirements of quantum key distribution and focus on keeping at bay the
contamination of the quantum channels by photons coming from the classical
signals by non-linear processes, among others. These heuristics reduce the
shared path between classical and quantum channels and improve the
signal-to-noise ratio in the quantum channels, improving their quantum key
rate. We compare the results to the usual classical RWA approach.
