In-situ Programmable Switching using rP4: Towards Runtime Data Plane Programmability

The existing chip architecture and programming language are incapable of supporting in-service updates by loading or offloading on-demand protocols and functions at runtime. We examine the fundamental reasons for the inflexibility and design a new In-situ Programmable Switch Architecture (IPSA) as a fix. We further design rP4, a P4 extension, for programming IPSA-based devices. To manifest the in-situ programming feasibility, we develop an rP4 compiler and demonstrate several use cases on both a software switch, ipbm, and an FPGA-based prototype. Our preliminary experiments and analysis show that, compared to PISA, IPSA provides higher flexibility in enabling runtime functional update with limited performance and gate-count penalty. The in-situ programming capability enabled by IPSA and rP4 opens a promising design space for programmable networks.