Reliability and Scalability in SDN Networks

Software Defined Networking (SDN) is a software-based solution which setup a unified control plane, as an intelligent network manager, to control the whole network devices that only forward data, instead of controlling each device alone which wastes time and effort. The conversion from the traditional networks to the SDN network has significant challenges that need a deep consideration. We consider the reliability and the scalability as critical factors that affect the SDN network. Generally, the criteria of reliability and the scalability of network are the following: the desired data rate at the data delivery, the high availability of the controller by eliminating the single point of failure, and finally the multiple topologies that are ancillary for scalable network. These criteria must be achieved in the SDN network also. We examine in details multiple controller architectures (i.e., centralized, distributed and hierarchical). We propose a framework for controller failover that increases the availability of SDN network and makes its framework more reliable and scalable.