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<font face="Times New Roman, Times, serif">I take your point, Bob,
and agree single-ended latency measurements like you produce with
iperf would be more technically correct.<br>
<br>
I write and review for a consumer audience, where ping is the
standard for latency aka lag measurement. So that's why I'm using
ping.<br>
That, and the fact that iperf isn't integrated into octoScope's
toolset yet. But they're working on it and all their STA
instruments are properly time-synced, so the measurements will be
accurate.<br>
<br>
Thank your for all your work in iperf, BTW. The features you've
added are a welcome improvement.<br>
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<div><font size="-1" face="Times New Roman, Times, serif">===========<br>
Tim <br>
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<div class="moz-cite-prefix">On 4/29/2020 8:32 PM, Bob McMahon
wrote:<br>
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<div dir="ltr">I'm thinking ping may not be ideal for
benchmarking OFDMA effects on latency. Also, the end/end
latency preferred seems to me the socket write() to final socket
read() per that write(). Also, for TCP, there are the connect
times. I realize network stack guys focus on stack related
measurements, e.g. RTT, but the latencies users experience
include the application level and system level os interactions.<br>
<br>
Just some food or thought.<br>
<br>
Bob<br>
<br>
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<div dir="ltr" class="gmail_attr">On Wed, Apr 29, 2020 at 5:07
PM Dave Taht <<a href="mailto:dave.taht@gmail.com"
moz-do-not-send="true">dave.taht@gmail.com</a>> wrote:<br>
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<blockquote class="gmail_quote" style="margin:0px 0px 0px
0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">throughput
and latency are interrelated, whats the throughput?<br>
<br>
On Wed, Apr 29, 2020 at 2:40 PM Tim Higgins <<a
href="mailto:tim@smallnetbuilder.com" target="_blank"
moz-do-not-send="true">tim@smallnetbuilder.com</a>>
wrote:<br>
><br>
> Hi all,<br>
><br>
> I finally have my testbed working the way I want and am
starting to run tests to see if OFDMA does anything useful.<br>
><br>
> This will all be covered in detail in an upcoming
SmallNetBuilder article. But I wanted to sanity check
something with this esteemed group.<br>
><br>
> The tests are basically the flent rtt_fair_var up and
down tests ported to the octoScope platform I use for WiFi
testing.<br>
> The initial work was done on flent, with a lot of
hand-holding from Toke. (Thank you, Toke!)<br>
><br>
> Using 4 Intel AX200 STAs on Win10. iperf3 is running
traffic using TCP/IP with unthrottled bandwidth. I've taken
Bjørn's idea and have each STA using a different DSCP priority
level, but with TCP/IP traffic, not UDP. I'm sticking to using
CS0-7 equivalents and confirmed that the iperf3 --dscp values
properly translate to the intended WiFi priority levels. Each
STA has a different priority, either CS0,3,5 or 6 (best
effort, excellent effort, video and voice).<br>
><br>
> Ping is used to measure latency and always runs from AP
to STA. Only TCP/IP traffic direction is reversed between the
down and uplink tests.<br>
><br>
> One thing that jumps out immediately is that uplink
latencies are *much* lower than downlink, with either OFDMA on
or off. Attached are three examples. The CDFs are average
latency of the 4 STAs.<br>
><br>
> The NETGEAR R7800 is a 4x4 AC Qualcomm-based. I'm using
this as a baseline product.<br>
><br>
> The NETGEAR RAX15 is 2x2 AX Broadcom-based. You can see
what I mean when I say OFDMA doesn't help.<br>
><br>
> Does this much difference between up and downlink latency
pass the sniff test?<br>
><br>
> ===<br>
> Tim<br>
> _______________________________________________<br>
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<br>
<br>
<br>
-- <br>
Make Music, Not War<br>
<br>
Dave Täht<br>
CTO, TekLibre, LLC<br>
<a href="http://www.teklibre.com" rel="noreferrer"
target="_blank" moz-do-not-send="true">http://www.teklibre.com</a><br>
Tel: 1-831-435-0729<br>
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