In this article, we will take a bird’s eye view on multiple controller scenarios for software-defined networks (SDNs). In this article, when we discuss the multi-controller scenarios, we will not restrict to those controllers that use standard protocols such as OpenFlow. Instead, we’ll use the broader meaning of the term “controllers.â€
I would like to highlight that, with the growth of NFV, the multiple-SDN-controllers’ use-cases/scenarios are taking a lot of importance, mainly due to the inherent nature of the NFV-based services. NFV-based service realization may require orchestration of management of heterogeneous resources and at multiple geographical locations and involve multiple administrative domains.
The SDN Controller cluster can be seen as a system that manages a large-scale network, handling control plane communications, consisting of a large number of network elements. Typically, such systems consist of multiple controllers and expose themselves as a single logical entity.
