The Emerging Control Hierarchy for Service Provider SDN-Enabled Networks

The control hierarchy for SDN networks is converging toward a three-tier structure. This paper describes this three-tier control hierarchy, which includes a service orchestrator, a network controller, and multiple domain controllers. It also describes the benefits of using a three-tier structure, which include faster innovation, a stable ecosystem of collaborating parties, and flexibility to replace building blocks with minimal effort and without vendor lock-in.