The time and frequency reference in the three laboratories of Besançon is based on Cesium clocks for absolute accuracy and long-term stability at the LAOB, on a H-maser for medium and long term stability at the LCEP, and on a liquid-He whispering gallery sapphire oscillator for best spectral purity and short-term stability at LPMO. These standards are located at three different sites, at a few hundreds meter from one another. In order to obtain the full accuracy and stability at least at one site, we combine these references using a frequency locked loop. The 100 MHz frequency reference is transferred via a two-way optical link. This article reports on measurement of the the phase noise and of the stability of the link.