Optical networks have been proposed as the main infrastructure for interconnecting networks with large data flows. For those networks, two switching paradigms have been discussed: the optical burst switching (OBS) and optical circuit switching (OCS). A direct comparison between the performance of OBS and OCS is important for the design of more efficient networks. In this paper, various settings of routing and wavelength selection algorithms, for both OCS and OBS networks are implemented and compared. The blocking probability and the average transmission duration for a Poissonian traffic are the evaluation parameters.