Layered Software Defined Networking

Over last few decades, computer network has grown exceedingly complex due to advent of newer network protocols and exponential expansion of its size. A new network architecture named software defined networking (SDN) simplifies network by decoupling data plane and control plane. As per SDN, data plane is solely concerned with data forwarding while control plane takes care of logic, processing and management-related functions. But this concept is still evolving; on the other hand, we have witnessed the success of OSI reference architecture and TCP/IP suite. One of the prominent reasons of their success is the layered architecture, where each layer serves its upper layer and uses services of the layer below. On top of that, entire architecture can be viewed as a layered framework allowing proper abstraction and division of responsibilities. Thus, we are proposing seven-layer architectures for software defined networking, viz. physical layer, device link layer, service abstraction layer, worker layer, management layer, presentation layer and application layer. SDN controller consists of three layers, namely service abstraction layer, worker layer and management layer. Device link layer and presentation layer serves as south bound and north bound interfaces, respectively, of the controller. Application layer comprises of applications which are running on the controller, and physical layer consists of physical and/or virtual switches. The key idea of this architecture is to increase cohesion and reduce coupling between the immediate layers.