The existing network infrastructure becomes inadequate to handle the requirements of new networking concepts such as cloud computing, network function virtualization, and next generation mobile services. Software Defined Networking (SDN) is a new paradigm specifically created to address these challenges by decoupling control and data planes and using a logically centralized controller to manage the network resources. In this paper, a dynamic traffic engineering mechanism, which can alleviate the network congestions by rerouting the Dows over the alternative paths, is proposed for SDN networks. The proof of concept demonstration has been done using Mininet to emulate OpenFIow enabled switches and Opendayligbt as an SDN controller. The proposed system automatically re-routes TCP traffic over the alternative path when the network congestion is detected.