[Bloat] DualPI2 qdisc implementation available for Linux

Stephen Hemminger stephen at networkplumber.org
Tue Oct 25 01:12:00 EDT 2016


Why not submit it upstream where it can get more review and will get picked
up by more users?


On Fri, Jul 29, 2016 at 2:08 AM, De Schepper, Koen (Nokia - BE) <
koen.de_schepper at nokia-bell-labs.com> wrote:

> Hi all,
>
> For those who missed the L4S BoF, the PI2 AQM with DualQ option is
> available on the following git: https://github.com/olgabo/dualpi2
>
> PI2 (PI Improved with a Square) is a simplification of PIE (PI Enhanced)
> with the advantage of also supporting L4S congestion controls (like DCTCP).
> PI2 controls by default a single queue, with a common target (default
> 20ms). To get the most out of the L4S traffic you need a second L4S queue
> and a coupled AQM. PI2 supports this by specifying the "dualq" option. The
> L4S queue is having an immediate step ECN marker at 1ms, while the classic
> queue still has the 20ms target (with mark/drop coupled back to both L4S
> and Classic).
>
> Note that PI2 supports DCTCP, but DCTCP is not the target to be used on
> the internet. The TCP-Prague requirements (https://tools.ietf.org/html/
> draft-briscoe-tsvwg-aqm-tcpm-rmcat-l4s-problem-02#appendix-A) defines
> what is needed to have an end-system CC implementation which behaves
> similar to what FQ-X achieves in the network. FQ-X is a way the network can
> correct the behavior of classic TCP CCs, TCP-Prague is the end-system
> alternative that keeps the network simple and transport layer independent.
>
> Feel free to try it out, and join in developing a TCP CC that meets the
> TCP-Prague requirements.
>
> Regards,
> Koen.
>
>
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