Normal forms for match-action programs

Abstract

Packet processing programs may have multiple semantically equivalent representations in terms of the match-action abstraction exposed by the underlying data plane. Some representations may encode the entire packet processing program into one large table allowing packets to be matched in a single lookup, while others may encode the same functionality decomposed into a pipeline of smaller match-action tables, maximizing modularity at the cost of increased lookup latency. In this paper, we provide the first systematic study of match-action program representations in order to assist network programmers in navigating this vast design space. Borrowing from relational database and formal language theory, we define a framework for the equivalent transformation of match-action programs to obtain certain irredundant representations that we call "normal forms". We find that normalization generally improves the capacity of the control plane to program the data-plane and to observe its state, at the same time having negligible, or positive, performance impact.