DC.p4: programming the forwarding plane of a data-center switch.

ABSTRACTThe P4 programming language [29, 16] has been recently proposed as a high-level language to program the forwarding plane of programmable packet processors, spanning the spectrum from software switches through FPGAs, NPUs and reconfigurable hardware switches. This paper presents a case study of using P4 to express the forwarding plane behavior of a datacenter switch, comparable in functionality to single-chip shared-memory switches found in many datacenters today. This case study allows us to understand how specific P4 constructs were useful in modeling specific datacenter switch features. We also outline additional language constructs that needed to be added to P4 to support certain features of a datacenter switch. We discuss several lessons that we learned in the process and distill these into a proposal for how P4 could evolve in the future.