Technical Summary
Bufferbloat is a phenomenon where excess buffers in the network cause
high latency and jitter. As more and more interactive applications
(e.g. voice over IP, real time video streaming and financial
transactions) run in the Internet, high latency and jitter degrade
application performance. There is a pressing need to design
intelligent queue management schemes that can control latency and
jitter; and hence provide desirable quality of service to users.
This document presents a lightweight active queue management design,
called PIE (Proportional Integral controller Enhanced), that can
effectively control the average queueing latency to a target value.
Simulation results, theoretical analysis and Linux testbed results
have shown that PIE can ensure low latency and achieve high link
utilization under various congestion situations. The design does not
require per-packet timestamp, so it incurs very small overhead and is
simple enough to implement in both hardware and software.
Working Group Summary
There were no matters of large controversy, though there have been some criticisms of PIE.
The IPR did not seem to be a blocking point for anyone, but some participants prefered
algorithms free of IPR. There are multiple algorithms that were proposed to the AQM
working group, and there are still some developing. Some aspects of the PIE design were
critiqued, and there are some identified matters for future research, but there did not seem
to be any disagreement that this is useful to publish at this time. It is understood that this
does not block other algorithms or improvements from happening. The critical reviews are
useful in understanding the differences with other algorithms, and making improvements
to PIE while in experimental stage.
Document Quality
Yes, there are multiple existing implementations, including in simulations, Linux, FreeBSD,
and some may be based on description in the DOCSIS specification. All of the
implementation experience was helpful in improving the document quality and clarity when
describing the algorithm. A very thorough technical review was done by Bob Briscoe, and
posted as a complete document itself.
Personnel
Wesley Eddy (wes@mti-systems.com) is the document shepherd, and Mirja Kühlewind (ietf@kuehlewind.net) is the AD.