In order to improve the wavelength utilization as well as the fairness of the light trail networks, we modified the FP MAC from the view point of weight balance by introducing a weight mode. The weight mode is composed of two factors, real-time factor and node activity ratio. Moreover, the weight mode is used as a bid by each LT node to compute the priority. Hence, the priority of the LT node is adjusted dynamically in every round and the MAC protocol with dynamic priority adjustment is entitled as DPA MAC. Simulation results show that the performances of DPA MAC protocol are much better than that of FP MAC protocol in terms of packet loss rate and activity percentile.© (2010) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.