On generality of the data plane and scalability of the control plane in software-defined networking

The control and data planes are decoupled in software-defined networking (SDN), which enables both planes to evolve independently, and brings about many advantages such as high flexibility, programmability, and rapid implementation of new network protocols. However, in order to improve the scalability of the control plane at present, some control functionalities are added to the data plane, which is probably to impact on the generality of the data plane. The key challenge of adding control functionalities to the data plane is to strike a careful balance between the generality of the data plane and the scalability of the control plane. We propose some basic principles that both control and data planes should comply with, based on the evolutionary trend of SDN. Moreover, we take two approaches for reference according to the principles, viewed from the control messages in OpenFlow-based SDN. Our evaluations demonstrate that the approaches can maintain the generality of the data plane and improve the scalability of the control plane.