In this paper, the impact of dependent failures of optical links on the availability of the optical network is analyzed using Monte Carlo simulation. Simulation is used because analytical approach to availability calculation is too complex when there are dependencies between failures. Availability model is described and used in two case studies: ring topology and several functional structures of two wavelength paths. Results of the simulation for the case studies are analyzed and compared. The results of the simulation are verified using analytical availability calculations for a simple structure without dependent failures.