Global IP traffic is forecast to triple by 2020 to reach 2.3 ZB per year. Such an explosion will inevitably be the catalyst of Operator infrastructure transformation. In this context, SDN is the technology that is shaping the future of carriers' networks. It offers the opportunity to implement more powerful control algorithms. In this perspective, we put forward a SD-WAN architecture to enhance the network resources allocation and hence improve the QoS of distributed applications. The main idea is to take profit from the accurate network view provided by the controller to optimize the flows routing in WAN environments. To do so, we formulate the path computation problem as an Integer Linear Program by taking into consideration both network application requirements and the network occupation status. The problem is then resolved in a polynomial time leveraging the branch-and-cut algorithm. Results obtained based an experimental platform show that our ONOS SDN framework outperforms the most prominent related work solutions in terms of network consumption and applications satisfaction level.