I. Introduction
Software-defined networking (SDN)
[Online]. Available: https://www.opennetworking.org/
is a revolutionary network architecture that separates out network control functions from the underlying equipment and deploys them centrally on the controller, where OpenFlow is the standard interface. With SDN, applications can treat the network as a logical entity which makes enterprises and carriers gain unprecedented programmability, automation, and network control. In addition, SDN also provides a set of application programming interfaces (APIs) to simplify the implementation of common network services such as routing, multicast, security, access control, bandwidth management, quality-of-service (QoS), and storage optimization [3].