Flow-level state transition as a new switch primitive for SDN

In software-defined networking, the controller installs flow-based rules at switches either proactively or reactively. The reactive approach allows controller applications to make dynamic decisions about incoming traffic, but performs worse than the proactive one due to the controller involvement. To support dynamic applications with better performance, we propose FAST (Flow-level State Transitions) as a new switch primitive for software-defined networks. With FAST, the controller simply preinstalls a state machine and switches can automatically record flow state transitions by matching incoming packets to installed filters. FAST can support a variety of dynamic applications, and can be readily implemented with today's commodity switch components and software switches.