OpenCounter: Counting unknown flows in Software Defined Networks

The software defined paradigm is recently emerging as a very promising approach to simplify the way complex network applications are designed and integrated in large scale network scenarios. Typical examples of network-wide applications that may well benefit for such an approach are monitoring and security applications that collect information from multiple vantage points to provide higher lever analyses. In this context, this paper adopts the software defined approach to propose a novel distributed architecture that permits to effectively count the number of unknown flows in an SDN network, allowing the development of several monitoring security applications on top of it. The presented work relies on standard OpenFlow switches and on ad-hoc probabilistic variations of the sketch data structure. The proposed architecture is fully seamless for the underlying network behavior and the performance analysis carried out in laboratory test-bed proves its practical effectiveness.