Date Added: Aug 2012
Software Defined Networks (SDN) gives network designers freedom to re-factor the network control plane. One core benefit of SDN is that it enables the network control logic to be designed and operated on a global network view, as though it were a centralized application, rather than a distributed system - logically centralized. Regardless of this abstraction, control plane state and logic must inevitably be physically distributed to achieve responsiveness, reliability, and scalability goals. Consequently, the authors ask: "How does distributed SDN state impact the performance of a logically centralized control application?" Motivated by this question, They characterize the state exchange points in a distributed SDN control plane and identify two key state distribution trade-offs.