Optimizing the Flexibility of SDN Control Plane

Facing fast changing network traffic, Software Defined Networking (SDN) endows the capability of efficient traffic forwarding and control plane resource management which results in flexibility, in comparison to networking with legacy rigid hardware. Meanwhile, flexibility has become an implicit target of many novel network algorithms and designs. This paper answers an interesting research question: "Can we optimize the flexibility as an objective" We study the impact of Data Centers (DCs) location on the flexibility of dynamic control plane. The flexibility is revealed when the control plane can adapt itself with controller migration and switch re-assignment in a timely manner for a new group of flows to satisfy the requirements of flow setup. We propose a model, named FLEXDC, for static DC placement and dynamic controller placement to optimize the control plane's flexibility. We also design heuristics to speed up the decision process. Our simulation over real network topology with synthetic flows shows the improved flexibility of the dynamic control plane. Furthermore, we can save up to 2 DCs while achieving the same flexibility, compared with a naive approach.