Technical Summary
This memo presents the FQ-CoDel hybrid packet scheduler/AQM
algorithm, a powerful tool for fighting bufferbloat and reducing
latency.
FQ-CoDel mixes packets from multiple flows and reduces the impact of
head of line blocking from bursty traffic. It provides isolation for
low-rate traffic such as DNS, web, and videoconferencing traffic. It
improves utilisation across the networking fabric, especially for
bidirectional traffic, by keeping queue lengths short; and it can be
implemented in a memory- and CPU-efficient fashion across a wide
range of hardware.
Working Group Summary
An interesting aspect of this document is the combined use of CoDel with
FQ for improving flow-isolation properties. The working group had early
discussions about the differences between FQ and scheduling mechanisms
versus more pure AQM algorithms (like CoDel). This resulted in draft-
ietf-aqm-fq-implementation, which describes the terminology and
construction of hybrid systems. Any early disagreement in the WG about
this seems to have subsided after the subsequent discussions and work to
resolve terminology and scope.
Document Quality
Yes, there are existing implementations and deployments, including in
the Linux kernel. There have been other implementation efforts in
addition to the editors, and questions have been shared on the AQM
mailing list, with clarifications posted in draft updates. The Linux
implementation is from the editors of the document, and an independent
implementation in FreeBSD was done by Rasool As-Saadi at the Swinburne
University.
Personnel
Wes Eddy (wes@mti-systems.com) is the Document Shepherd. Martin
Stiemerling is the responsible AD.