In recent years, performance of the Mobile Ad-Hoc Network (MANET) has become an important research area in the wireless networks community. MANET consists of clusters of Mobile Nodes (MNs) on the access network that could be connected to other clusters through a fixed backbone of routers. The access link contention can severely constrain the end-to-end throughput of the path between a pair of source and destination MNs connected through the backbone. In this paper, we propose an integrated routing system for MANET that includes the backbone paths and the ad-hoc paths formed as a result of direct communication among MNs without going through the backbone. In our proposed routing system, an alternative ad-hoc path can be used only when the primary backbone path is severely constrained due to access links contention. We also propose a scheme for making the MN aware of link quality measures, and incorporate throughput metric in the core of AODV. We implemented the proposed routing system in the OPNET simulator, and evaluated the performance of our scheme under a variety of conditions. Simulation results show that the alternative ad-hoc path is effective in delivering higher throughput when the backbone path is severely constrained.