Dynamic Controller Placement in Edge-Core Software Defined Networks

Software Defined Networking (SDN) is fast gaining acceptance as a networking architecture, which simplifies network management, by separating the control plane from the data plane. Edge-Core SDN is an extended SDN architecture which divides the underlying network into edge and core components. This decouples the edge switch requirements from the network core switch behaviour. When the number of networking elements and traffic flows increase, a single centralized controller can not efficiently manage, the large network nor the diverse requirements of the core and edge switches. We therefore need multiple controllers for wide area SDN deployments. Distributed controller architectures are already recommended to resolve scalability issues. The drawback of these approaches is that they use static mapping of switches to controllers. When the traffic conditions changes this static allotment may lead to unbalanced partitioning of load among the controllers. In this paper, we present controller placement algorithms for SDN, where the edge and core of the network are separated. The algorithm uses a different set of metrics for the edge and core algorithms. Also, in order to establish the Edge-Core model, we use source routing, which embeds the path information into the packet header itself. We also discusses the switch migration procedure for transfer of switch from one controller to another, such that, on going connections are not disrupted. We build a prototype of the above architecture, evaluate it and present our results here.