We introduce Concurrent NetKAT (CNetKAT), an extension of the network programming language NetKAT with multiple packets and with operators to specify and reason about concurrency and state in a network. We provide a model of the language based on partially ordered multisets, well-established mathematical structures in the denotational semantics of concurrent languages. We prove that CNetKAT is a sound and complete axiomatization of this model, and we illustrate the use of CNetKAT through various examples. More generally, CNetKAT is an algebraic framework to reason about programs with both local and global state. In our model these are, respectively, the packets and the global variable store, but the scope of applications is much more general, including reasoning about hardware pipelines inside an SDN switch.

This is joint work with Jana Wagemaker, Nate Foster, Tobias Kappe, Dexter Kozen, and Jurriaan Rot.