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

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

[Tim Higgins]

[-- Attachment #1: Type: text/html, Size: 970 bytes --]

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

[Bob McMahon]

[-- Attachment #1: Type: text/plain, Size: 1818 bytes --]

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
> _______________________________________________
> Make-wifi-fast mailing list
> Make-wifi-fast@lists.bufferbloat.net
> https://lists.bufferbloat.net/listinfo/make-wifi-fast

[-- Attachment #2: Type: text/html, Size: 2774 bytes --]

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

[Tim Higgins]

[-- Attachment #1: Type: text/html, Size: 4422 bytes --]

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

[Bob McMahon]

[-- Attachment #1: Type: text/plain, Size: 2330 bytes --]

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
>> _______________________________________________
>> Make-wifi-fast mailing list
>> Make-wifi-fast@lists.bufferbloat.net
>> https://lists.bufferbloat.net/listinfo/make-wifi-fast
>
>
>

[-- Attachment #2: Type: text/html, Size: 4455 bytes --]