MatchKAT: An Algebraic Foundation For Match-Action

Abstract: We present MatchKAT, an algebraic language for modeling match-action packet processing in network switches. Although the match-action paradigm has remained a popular low-level programming model for specifying packet forwarding behavior, little has been done towards giving it formal semantics. With MatchKAT, we hope to embark on the first steps in exploring how network programs compiled to match-action rules can be reasoned about formally in a reliable, algebraic way. In this paper, we give details of MatchKAT and its metatheory, as well as a formal treatment of match expressions on binary strings that form the basis of "match" in match-action. Through a correspondence with NetKAT, we show that MatchKAT's equational theory is sound and complete with regards to a similar packet filtering semantics. We also demonstrate the complexity of deciding equivalence in MatchKAT is PSPACE-complete.