In next generation networks (NGNs), the broadband networks consist of various layer 2 and layer 3 devices, e.g., ethernet switches and routers. To deploy broadband networks, how the devices are appropriately located is an important issue. The device location problem could be treated as a hierarchical facility location problem (FLP). In this work, we present detailed mathematical models for the hierarchical FLP encountered in broadband network planning. Through experiments based on real networks, we demonstrate that the linearity of model could significantly improve both the computational complexity and the optimality.