Packet Transactions: High-level Programming for Line-Rate Switches

TL;DR

This paper introduces Domino, a high-level language for programming stateful data-plane algorithms in switches, enabling line-rate execution and post-deployment programmability on emerging hardware.

Contribution

It presents a novel approach using packet transactions and a C-like language to compile complex algorithms into microcode for programmable switches.

Findings

Algorithms can be expressed naturally in Domino.

Line-rate performance is achievable with modest hardware overhead.

Demonstrated multiple data-plane algorithms in Domino.

Abstract

Many algorithms for congestion control, scheduling, network measurement, active queue management, security, and load balancing require custom processing of packets as they traverse the data plane of a network switch. To run at line rate, these data-plane algorithms must be in hardware. With today's switch hardware, algorithms cannot be changed, nor new algorithms installed, after a switch has been built. This paper shows how to program data-plane algorithms in a high-level language and compile those programs into low-level microcode that can run on emerging programmable line-rate switching chipsets. The key challenge is that these algorithms create and modify algorithmic state. The key idea to achieve line-rate programmability for stateful algorithms is the notion of a packet transaction : a sequential code block that is atomic and isolated from other such code blocks. We have developed this idea in Domino, a C-like imperative language to express data-plane algorithms. We show with many examples that Domino provides a convenient and natural way to express sophisticated data-plane algorithms, and show that these algorithms can be run at line rate with modest estimated die-area overhead.