[Make-wifi-fast] Re: [Bloat] Re: [Codel] [Rpm] Re: Re: [Cake] "Fi-Wi is a new forwarding plane for wireless" - Bob McMahon

[dan <dandenson@gmail.com>]

I have to argue these points on wifi saturation.  It's like an argument
from 2015, it's true for devices speaking in 2015's language but it's
simply false for modern APs and devices.

First, I'll acknowledge that CSMA based wifi does suck in the ways
described and there's no way to fix that but to replace it.  Also, any AP
that routinely handles CSMA clients even in mixed modes will struggle with
CSMA mostly from hidden node.

Also, I don't operate in a niche space, my space is where every
non-ethernet connected device operates.  I do home, small business, large
event centers, hotels, campgrounds, whole building solutions with hundreds
of concurrent users.  My wISP operation is the smallest part of the
business, it just happens to have the cheapest clients so needs the
cheapest solutions.  I'm the anti-niche.

The issues described above are non-OFDMA experiences.  OFDMA, at it's very
core, is a bi-directional scheduler that is TDMA which erases the CSMA
problems that cause retransmit 'storms'.  A single OFDMA AP and virtually
any number of OFDMA clients before you run out of CPU, will not collapse
under saturation on OFDMA because they have strict timeslots.

Worth noting, most decent WiFi7 access points with 6Ghz can strongly
encourage OFDMA in clients if you setup a 6Ghz WPA3 only SSID.  It's not a
hard rule, but that combination generally strips out all non-OFDMA speaking
devices.

This comes down to quality drivers/software on the AP.  WiFi8 is still a
paper tiger practically speaking, but WiFi7 is out in full deployment and
showing it's power.  Noise at a client is reported to the AP, the AP won't
schedule noisy RUs to that client, and vice versa.  Multiple AP deployments
see the other APs and channels and schedule RUs based on the amount of data
to deliver.  It'll use noisy RUs at lower modulations and clean ones at
higher modulations and it does it bi-directionally so noise at the AP can
be used to transmit to clients that don't see that noise and vice versa.

We have been deploying a hybrid approach with APs operating with WPA3 and
>=80Mhz channels to encourage OFDMA and then separate APs on separate
channels for older devices on WPA2.

So when you guys give these anecdotal answers describing <=wifi5/CSMA, I'd
really like to know where and if I can get in contact with the facility
management and offer them a real, modern wifi network, because we put a LOT
of pressure on wifi and your issues are a thing of the past.  They just do
not happen on a well designed wifi system encouraging OFDMA use and
accommodating older devices.

This might be the space FiWi wants to be, but FiWi will show up to solve a
problem that is years in the past.

Further, I don't think Dave really cared where the bottleneck was, only
that there were full buffers and that was a solvable problem.  Putting
fq_codel or cake on the AP's interface was the ideal place to handle lots
of things, including device-to-device communications, but note that he's a
founding member of libreqos that puts the shapers on the internet edge as
well, and we had multiple conversations about fq_codel on every
intermediate port you could find, each one improving the links.