[LibreQoS] Fwd: [Make-wifi-fast] An "Accurate" Platform for Investigating TCP Performance in Wi-Fi Networks

Dave Taht dave.taht at gmail.com
Wed Jul 19 21:51:13 EDT 2023

---------- Forwarded message ---------
From: Bob McMahon <bob.mcmahon at broadcom.com>
Date: Wed, Jul 19, 2023 at 6:48 PM
Subject: Re: [Make-wifi-fast] An "Accurate" Platform for Investigating
TCP Performance in Wi-Fi Networks
To: Dave Taht <dave.taht at gmail.com>
Cc: Make-Wifi-fast <make-wifi-fast at lists.bufferbloat.net>,
<hiendtt at uit.edu.vn>, <s.aoyagi at chiba-u.jp>,
<sekiya at faculty.chiba-u.jp>, <yuuki-ho at chiba-u.jp>, Kien NGUYEN
<nguyen at chiba-u.jp>, <duyld at uit.edu.vn>, <thanhnd at uit.edu.vn>

I think making WiFi tech accessible to students is a very good thing.
That students make mistakes is also a good thing. I understand the
frustration though.

I've recently rolled out a raspberry pi 4 crib sheet on how to build
an L4S capable device. It's a fun project and comes in at around $100
U.S.  Throw in some switches, USB WiFi cards, ethernet for control, a
GPS hat for pulse per second, use iperf 2 and pyflows. All for less
than $500.

The expensive part is placing the RF under control but that's doable
too - though likely in the few thousands of dollars and maybe just a
bit more. The math is already done thanks to those studying molecular


On Wed, Jul 19, 2023 at 5:30 PM Dave Taht via Make-wifi-fast
<make-wifi-fast at lists.bufferbloat.net> wrote:
> It is hard to contain my disappointment that a modern work on wifi,
> that even mentions bufferbloat, could have missed our work on fixing
> wifi (such as "ending the anomaly", now the default APIs in the linux
> kernel), and make claims for the emulator that are so completely
> wrong, and further claim that the behaviors matched a real world AP.
> re: https://mdpi-res.com/d_attachment/futureinternet/futureinternet-15-00246/article_deploy/futureinternet-15-00246.pdf?version=1689771540
> Can I suggest strongly to the authors that they try to understand rate
> vs range vs buffering, the intersection of the half duplex txop
> infrastructure with multiple stations, the side effects of
> aggregation, and other scheduling difficulties mininet does not come
> even close to handling?
> 20 packet buffers?? A more typical number is much greater.
> Test through walls or at distance?
> Here are 4 resources that might help deepen your understanding.
> https://www.youtube.com/watch?v=Rb-UnHDw02o&t=1532s (10 minutes here,
> but do the whole thing)
> https://bufferbloat-and-beyond.net/
> https://www.cs.kau.se/tohojo/airtime-fairness/
> https://blog.cerowrt.org/post/minstrel/
> --
> Podcast: https://www.linkedin.com/feed/update/urn:li:activity:7058793910227111937/
> Dave Täht CSO, LibreQos
> _______________________________________________
> Make-wifi-fast mailing list
> Make-wifi-fast at lists.bufferbloat.net
> https://lists.bufferbloat.net/listinfo/make-wifi-fast

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Podcast: https://www.linkedin.com/feed/update/urn:li:activity:7058793910227111937/
Dave Täht CSO, LibreQos

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