Feature Issue on Transmission in Optically Transparent Core Networks We investigate a new routing algorithm able to finely consider signal quality during propagation in an optical WDM meshed network. To evaluate the quality of transmission, we propose an analytical estimator based on experimental measurements, along with an assessment of its accuracy. The proposed algorithm 'places' optoelectronic (OEO) regenerators, taking into account the wavelength occupation and the quality of transmission of the selected optical path, so it can optimize the number of required OEO operations for a connection. To validate the interest of the proposed algorithm and the quality of transmission estimator, we present dimensioning results for two different routing strategies and two different estimators of transmission quality. The performance of the proposed methods is particularly relevant compared to works in present literature where system characteristics are not ideal.