Design considerations for managing wide area software defined networks

SDN has the potential to simplify network configuration and reduce management complexity. In today¿s networks control and forwarding functions are tightly coupled and embedded within each switch/router. SDN, in contrast, accumulates the control functionality in one or more dedicated network entities called controllers, which provide a unified interface to configure and control the network. Packet forwarding, on the other hand, remains the responsibility of the switches/routers. Many datacenter networks have benefited from the abstraction provided by SDN. However, in a Wide Area Network (WAN) a single controller becomes a performance bottleneck. Multiple controller solutions are proposed as a natural consequence. In this article we present the requirements, design alternatives, and a possible management architecture for a single administrative domain WA-SDN. We also discuss the functional components that should be present in a multi-controller architecture for managing WA-SDN deployments.