[Make-wifi-fast] I used to dream of a single wifi cpu, memory, and I/O

David Lang david at lang.hm
Mon Jul 10 23:02:38 EDT 2023


I'm providing the equipment (still 3800s running openwrt).

I did a presentation at LISA in 2012 and a paper in ;login going over a lot of 
this.

if you don't get the RF side right, you have no chance of having a good network 
under heavy load.

David Lang

On Mon, 10 Jul 2023, Bob McMahon wrote:

> That you can build these networks to operate well says more about you than
> the guys supplying parts & equipment. Impressive real world knowledge for
> sure.
>
> Bob
>
> On Mon, Jul 10, 2023, 4:34 PM David Lang <david at lang.hm> wrote:
>
>> First off, I am a Huge proponent of getting the RF layout clean before
>> anything
>> else. Directional signals sound like a fantastic idea, until you realize
>> that
>> the stations you are talking to are not using directional antennas, then
>> the
>> value drops significantly (under these conditions, directional antennas
>> create
>> more hidden transmitters)
>>
>> When I setup conference wifi, I take advantage of the fact that some walls
>> block
>> the wifi signals, so I can put the APs closer to the walls that block them
>> without worrying about what's on the other side. I also place them on the
>> ground
>> (under the chairs) as the bodies of the attendees absorb the signal and
>> let me
>> use more APs in a room than I could get away with otherwise. I also stick
>> to the
>> standard 10MHz channels, as that lets me re-use a channel with more
>> separation
>> between APs using the same channel
>>
>> And yes, I agree that it makes no sense to run an AP at a higher power
>> level
>> than the stations talking to it, so I turn the power way down.
>>
>> I haven't knowingly run into the problem you describe of clients
>> enumerating all
>> available APs, but I may not have setup a high enough density of APs to
>> run into
>> the problem, can you give more info on that?
>>
>>> There is no reason to send energy more than 29' as that's the distance
>> per
>>> fire code that a human has to be from a working smoke detector. and in
>> many
>>> cities, one can't sell a house without a hard-wired, battery backed up,
>> and
>>> inter connected smoke detectors.
>>
>> As someone who has been looking at building a house, it's not that simple.
>> Hard
>> wired smoke detectors are only needed in some rooms, not in all, and only
>> if the
>> house is above a minimum size. Then you need different amounts of power to
>> get
>> through walls depending on how they are built.
>>
>> When I setup wifi in a conference center exibit hall that's 25,000 sq ft,
>> I
>> don't believe that there are 80 smoke detectors in that one room (not to
>> mention
>> the fact that the cealing is more than 29' away, even if I'm standing
>> directly
>> under it)
>>
>> Then there's the fact that not everything is inside.
>>
>> David Lang
>>
>
>


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