FOCUS: Function Offloading from a Controller to Utilize Switch power
Software Defined Networking (SDN) uses a logically centralized controller to replace the distributed control plane in a traditional network. One of the central challenges faced by the SDN paradigm is the scalability of the logical controller. As a network grows in size, the computational and communication demand faced by a controller may soon exceed the capabilities of a commodity server. In this work, we revisit the task division of labour between the controller and switches, and propose FOCUS, an architecture that offloads a specific subset of control functions, i.e., stable local functions, to the switches' software stack. We implemented a prototype of FOCUS and analyzed the benefits of converting several SDN applications. Due to space restrictions, we only present results for ARP, LLDP and elephant flow detection. Our initial results are promising and they show that FOCUS can reduce a controller's communication overhead by 50% to nearly 100%, and the computational overhead from 80% to 98%. Furthermore, we observe that FOCUS offloading to the switches saves switch CPU because FOCUS reduces the overheads for communication with the controller.
