Re: [Make-wifi-fast] REPOSTED: SmallNetBuilder Article: Does OFDMA really work? Part 2

[Bob McMahon <bob.mcmahon@broadcom.com>]

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Iperf 2.0.14 supports write to read trip times for both TCP and UDP

https://youtu.be/LOGpXiAk_cc

Bob

On Thu, May 28, 2020 at 7:22 AM Tim Higgins <tim@smallnetbuilder.com> wrote:

> Hi Bob,
>
> Thanks for the suggestions. The iper2 suggests are for UDP, correct?
>
> As I said in the article, I'm done hunting this snark for now. Maybe
> others will take up the challenge.
> ===========
> Tim
> On 5/27/2020 1:16 PM, Bob McMahon wrote:
>
> I would make a small packet run too. For iperf2 use -l 40 and -b 20000pps
> and vary the pps number. I would hope that OFDMA would increase this.
>
> Also, don't forget about jitter - the derivative of latency. Some
> protocols care more about jitter than they do latency.
>
> I'd look into measuring the actual latency and jitter of the traffic vs
> using a ping as a proxy. This will be supported in iperf 2.0.14 using the
> write (server) side clock and --write-ack.  Better though is to synchronize
> the clocks and use one way trip times. While I like to synchronize the
> realtime clocks to the GPS atomic clock as the reference, using PTP and
> synchronizing to a common reference of any PC oscillator may be good
> enough. PTP stats will give you errors and corrections and per the
> corrections one can get an idea of the error.
>
> Thanks for posting. I really don't think OFDMA is going to affect such
> large latencies in a noticeable manner. I think it will be the ultra low
> latencies or near zero queuing that will matter.  For data center switches
> this is driven mostly by high frequency traders. For WiFi it's going to be
> newer games with VR/AR. Those latencies are going to need to be very low
> compared to today's use cases.
>
> my $0.02,
>
> Bob
>
> On Wed, May 27, 2020 at 7:37 AM Tim Higgins <tim@smallnetbuilder.com>
> wrote:
>
>> Tests have been redone and article is back up.
>> ===========================
>> Hi All,
>>
>> This article uses the benchmark test described in Part 1 to test 6 Wi-Fi
>> consumer routers. Results are not impressive.
>>
>> https://www.smallnetbuilder.com/wireless/wireless-features/33223-does-ofdma-really-work-part-2
>>
>> ===========
>> Tim
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>
>
>

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