Abstractions for model checking SDN controllers

Software defined networks (SDNs) are receiving significant attention in the computer networking community, with increasing adoption by the industry. The key feature of SDNs is a centralized controller which programs the packet forwarding behavior of a distributed underlying network. This centralized view of control-which is absent in traditional networks-opens up opportunities for full formal verification. While there is recent research in formal verification of these networks, model checking the controller behavior as it updates the underlying network has only seen limited application. Existing approaches are limited to verifying the controller for a small number of exchanged packets in the network. In this case study, we extend the state of the art by presenting abstractions for model checking controllers for an arbitrarily large number of packets exchanged in the network. We validate the utility of these abstractions through two applications: a learning switch and a stateful firewall.