All new networking architectures come with their own problems. Software Defined Networking (SDN) has its own challenges which are needed to be addressed by researchers as well. One of the crucial problems with SDN is the control plane scalability since it is a bottleneck for its evolution. As thenetwork grows, the number of messages a controller receives also increases. This increase puts the controller scalability in the heart of problems of SDN.
In this paper, we propose a hierarchy-basednetwork architecture along with an inter-AS routing approach with QoS. We exploit idea of levels in which networks with controllers reside and a main controller, which works like a broker, is on top of them to keep the global network state and view. Our experiment results indicate that a controller in a hierarchic setting handles 50% less number of traffic than a controller in a non-hierarchic environment.