The new AQM kids on the block: An experimental evaluation of CoDel and PIE

Abstract

Active Queue Management (AQM) design has again come into the spotlight of network operators, vendors and OS developers. This reflects the growing concern and sensitivity about the end-to-end latency perceived by today's Internet users. CoDel and PIE are two AQM mechanisms that have recently been presented and discussed in the IRTF and the IETF as solutions for keeping latency low. To the best of our knowledge, they have so far only been evaluated or compared against each other using default parameter settings, which naturally presents a rather limited view of their operational range. We set thus to perform a broader experimental evaluation using real-world implementations in a wired testbed. We have in addition compared them with a decade-old variant of RED called Adaptive RED, which shares with CoDel and PIE the goal of “knob-free” operation. Surprisingly, in several instances results were favorable towards Adaptive RED.