An Empirical Study of Ageing in the Cloud

TL;DR

This paper empirically examines how different TCP congestion control algorithms age over long-distance paths, highlighting ACP+'s ability to deliver timely updates with minimal age despite lower throughput.

Contribution

It provides a comprehensive empirical comparison of TCP variants and introduces ACP+ as an adaptive protocol that minimizes age with significantly reduced throughput.

Findings

ACP+ achieves similar age as best TCP variants but with much lower throughput.

ACP+ effectively adapts update rates based on network conditions.

Significant age improvements are demonstrated over shared multiaccess channels.

Abstract

We quantify, over inter-continental paths, the ageing of TCP packets, throughput and delay for different TCP congestion control algorithms containing a mix of loss-based, delay-based and hybrid congestion control algorithms. In comparing these TCP variants to ACP+, an improvement over ACP, we shed better light on the ability of ACP+ to deliver timely updates over fat pipes and long paths. ACP+ estimates the network conditions on the end-to-end path and adapts the rate of status updates to minimize age. It achieves similar average age as the best (age wise) performing TCP algorithm but at end-to-end throughputs that are two orders of magnitude smaller. We also quantify the significant improvements that ACP+ brings to age control over a shared multiaccess channel.