This document compares reactive and proactive approaches for OpenFlow controllers and discusses their scalability. It summarizes the results of benchmarking different OpenFlow controllers. Reactive controllers like Floodlight and NOX see round-trip times increase rapidly with more switches due to weak hardware. Maestro has more steady performance. Reactive approaches have efficient flow table usage but slow setup times, while proactive approaches have zero setup time but hard management. A hybrid approach may improve efficiency and scalability.