A Scalable Architecture for Openflow Controllers

The architectural principles of Software-Defined Networking (SDN) and its most prominent supporting protocol OpenFlow keep gaining momentum. SDN relies essentially on the decoupling of the control plane from the data plane, placing the former in a logically centralized component to be executed on commodity hardware the SDN controller. OpenFlow’s reactive programming enables the programming of the network based on real-time decisions taken as new traffic hits the data plane, but it requires the first packet of every new flow traversing any SDN controlled device to be sent to the controller and evaluated, which when considered in large network environments becomes too large to be handled by a single SDN controller instance. In this work we propose a new architecture for an elastic SDN controller cluster as a solution to overcome the aforementioned limitations by allowing for the existence of multiple SDN controller instances acting as a single controller but handling each a subset of the OpenFlow switches that comprise the network. A proof of concept of the said architecture has been implemented by extending the Floodlight controller and integrating it with the Linux Virtual Server project.