  Congestion control is an indispensable component of transport protocols to
prevent congestion collapse. As such, it distributes the available bandwidth
among all competing flows, ideally in a fair manner. However, there exists a
constantly evolving set of congestion control algorithms, each addressing
different performance needs and providing the potential for custom
parametrizations. In particular, content providers such as CDNs are known to
tune TCP stacks for performance gains. In this paper, we thus empirically
investigate if current Internet traffic generated by content providers still
adheres to the conventional understanding of fairness. Our study compares
fairness properties of testbed hosts to actual traffic of six major content
providers subject to different bandwidths, RTTs, queue sizes, and queueing
disciplines in a home-user setting. We find that some employed congestion
control algorithms lead to significantly asymmetric bandwidth shares, however,
AQMs such as FQ_CoDel are able to alleviate such unfairness.
