P4-CoDel: Experiences on Programmable Data Plane Hardware

TL;DR

This paper explores implementing the CoDel Active Queue Management algorithm on programmable P4 data plane hardware, addressing challenges, demonstrating feasibility, and providing open-source code and measurements.

Contribution

It presents techniques for deploying AQM algorithms like CoDel on high-speed P4-programmable hardware, which was previously challenging.

Findings

Feasibility of implementing CoDel on P4 hardware

Latency performance measurements across different hardware targets

Open source implementation and reproducibility instructions

Abstract

Fixed buffer sizing in computer networks, especially the Internet, is a compromise between latency and bandwidth. A decision in favor of high bandwidth, implying larger buffers, subordinates the latency as a consequence of constantly filled buffers. This phenomenon is called Bufferbloat. Active Queue Management (AQM) algorithms such as CoDel or PIE, designed for the use on software based hosts, offer a flow agnostic remedy to Bufferbloat by controlling the queue filling and hence the latency through subtle packet drops. In previous work, we have shown that the data plane programming language P4 is powerful enough to implement the CoDel algorithm. While legacy software algorithms can be easily compiled onto almost any processing architecture, this is not generally true for AQM on programmable data plane hardware, i.e., programmable packet processors. In this work, we highlight corresponding challenges, demonstrate how to tackle them, and provide techniques enabling the implementation of such AQM algorithms on different high speed P4-programmable data plane hardware targets. In addition, we provide measurement results created on different P4-programmable data plane targets. The resulting latency measurements reveal the feasibility and the constraints to be considered to perform Active Queue Management within these devices. Finally, we release the source code and instructions to reproduce the results in this paper as open source to the research community.