Software-Defined Networking (SDN) is a new architecture for computer networks, wherein control plane and data plane in network elements are separated, and control plane is implemented as an integrated and independent entity. This approach has advantages such as flexibility in service delivery to consumers, faster improvement in control plane and easier configuration of network elements. On the other hand, MPLS protocol has been widely used in IP Networks in prior years. Label switching mechanism which exists in this protocol, provides traffic management ability for network managers. However, MPLS standard needs lots of signaling to work. In this thesis, a design is proposed in which MPLS is used to simplify traffic management while taking care of quality of service guarantees for multimedia traffic in SDN networks. SDN with its integrated control plane sets up MPLS tunnels in network core. These tunnels connect edge switches together and each flow entering the network is mapped into a tunnel. In the mapping of new flows to tunnels, delays and costs of tunnels are considered. imulation results indicate that the purposes of current study are achieved. Keywords : Software-Defined Network, MPLS, Traffic Managament, Quality of service