Literature study on the macroscopic fundamental diagram (MFD) based traffic control im3 posed an impractical assumption on the homogeneity of large urban networks during dynamic control processes. This motivates the work of this paper on the optimal control of a two-region traffic network to evaluate the effect of traffic modeling on the control. A cost function with adjustable weighting factors is proposed to specify the protection priority of the two regions. Two modeling approaches are employed to describe the traffic network. They include a cell transmission model (CTM) approach, which can properly describe traffic dynamics, and a bin model approach under the assumption on traffic homogeneity in the control process. Simulation results have revealed that the designed control and the resulted system performance highly depend on the system modeling.