@article {24987,
	title = {Operating ranges, tunability and performance of CoDel and PIE},
	journal = {Computer Communications},
	volume = {103},
	year = {2017},
	month = {05/2017},
	pages = {74-82},
	publisher = {Elsevier},
	abstract = {Bufferbloat is excessive delay due to the accumulation of packets in a router\&rsquo;s oversized queues. CoDel and PIE are two recent Active Queue Management (AQM) algorithms that have been proposed to address bufferbloat by reducing the queuing delay while trying to maintain a high bottleneck utilization. This paper fills a gap by outlining what are the operating ranges, that is the network characteristics (in terms of round-trip times and bottleneck capacity), for which these algorithms achieve their design goals. This new approach to the problem lets us identify deployment scenarios where both AQM schemes result in poor performance when used with default parameters. Because PIE and CoDel have been proposed with RED\&rsquo;s deployment issues in mind, it was essential to evaluate to what extent we can tune them to achieve various trade-offs and let them control the queuing delay outside their default operating range. We find that, by appropriate tuning (1) the amount of buffering can easily be controlled with PIE, (2) the Round Trip Time (RTT) sensitivity of CoDel can be reduced. Also, we observe there is more correlation between the congestion level, the achieved queuing delay and the targeted delay with CoDel than with PIE. This paper therefore concludes there is no single overall best AQM scheme, as each scheme proposes a specific trade-off.},
	keywords = {AQM, Bufferbloat, CoDel, congestion control, PIE},
	doi = {http://dx.doi.org/10.1016/j.comcom.2016.07.013},
	author = {Kuhn, Nicolas and Ros, David and Amadou Baba {Bagayoko} and Kulatunga, Chamil and Fairhurst, Gorry and Khademi, Naeem}
}
@techreport {abe-caia-2015,
	title = {Alternative Backoff: Achieving Low Latency and High Throughput with ECN and AQM},
	year = {2015},
	month = {07/2015},
	publisher = {Centre for Advanced Internet Architectures (CAIA), Swinburne University of Technology},
	address = {Melbourne, Australia},
	abstract = {CoDel and PIE are recently proposed Active Queue Management (AQM) mechanisms that minimize the time packets spend enqueued at a bottleneck, instantiating shallow, 5 ms to 20 ms buffers with short-term packet burst tolerance. However, shallow buffering causes noticeable TCP performance degradation when a path{\textquoteright}s underlying round trip time (RTT) heads above 60ms to 80ms (not uncommon with cross-continental and inter-continental traffic). Using less-aggressive multiplicative backoffs is known to compensate for shallow bottleneck buffering. We propose ABE: {\textquotedblleft}Alternative Backoff with ECN{\textquotedblright}, which consists of enabling Explicit Congestion Notification (ECN) and letting individual TCP senders use a larger multiplica- tive decrease factor in reaction to ECN-marks from AQM- enabled bottlenecks. Using a mix of experiments, theory and simulations with standard NewReno and CUBIC flows, we show significant performance gains in lightly- multiplexed scenarios, without losing the delay-reduction benefits of deploying CoDel or PIE. ABE is a sender- side-only modification that can be deployed incrementally (requiring no flag-day) and offers a compelling reason to deploy and enable ECN across the Internet.},
	url = {http://caia.swin.edu.au/reports/150710A/CAIA-TR-150710A.pdf},
	author = {Khademi, Naeem and Welzl, Michael and Armitage, Grenville and Kulatunga, Chamil and Ros, David and Fairhurst, Gorry and Gjessing, Stein and Zander, Sebastian}
}
@inproceedings {bufferbloat-eucnc,
	title = {Tackling Bufferbloat in Capacity-limited Networks},
	journal = {Proceedings of EuCNC 2015},
	year = {2015},
	address = {Paris},
	abstract = {Over-provisioned network buffers, often at the Internet edge, induce large queuing delay and high latency; this issue is known as Bufferbloat. In response to this, a set of recently proposed Active Queue Management (AQM) algorithms attempt to reduce standing queues, while maintaining the bottleneck utilisation at an acceptable level. This paper assesses the performance of two AQM schemes (CoDel and FQ-CoDel) over capacity-limited networks with large Round-Trip Time (RTT). In such settings, these AQM schemes have difficulty controlling the buffering level, resulting in both momentarily high queuing delay and low bottleneck utilisation, even if the methods are claimed to be insensitive to link rates and round-trip delays. We explore this issue and show that it is possible to adapt the parameterisation of CoDel and FQ-CoDel to offer a higher bottleneck utilisation while maintaining a low queuing delay. We present experiments over an emulated test bed and a satellite network to confirm that our new parameterisation improves the download time of moderate-size files and reduces the latency for capacity-limited and large-RTT networks.},
	keywords = {AQM, Bufferbloat, CoDel, Rural Broadband},
	author = {Kulatunga, Chamil and Kuhn, Nicolas and Fairhurst, Gorry and Ros, David}
}
