[ntp:questions] Win7: ntpd adjusting time backwards

David Taylor david-taylor at blueyonder.co.uk.invalid
Tue Dec 11 19:58:38 UTC 2012


On 11/12/2012 19:35, Rick Jones wrote:
> David Taylor <david-taylor at blueyonder.co.uk.invalid> wrote:
>
>> What happens if the link to the Internet is rather asymmetrical?  For
>> example, here I am stuck with 30 Mb/s down, but only 3 Mb/s up.
>
> Handwaving a bit... The query and the response seem to be something
> like 90 bytes (including an Ethernet header). That then is 720 bits.
> At 3 Mbits/s that would be 0.24 milliseconds of transmit time.  It
> would then be 0.024 milliseconds on the downlink.  I suspect that
> asymmetry is dwarfed by either queueing delays (bufferbloat) when
> either/both are active and/or the rest of the delays from your system
> to the server(s).
>
> rick jones

Yes, I see what you mean, but I was thinking of the whole network, and 
not simply the up and down speeds.  That we have a 10:1 ratio may 
suggest how the rest of that ISP's network is configured.  The delays in 
the cable modem, Samknows box, router and 1 Gb/s switch are likely to be 
far in excess of the 0.024 ms and even the 0.24 ms!
-- 
Cheers,
David
Web: http://www.satsignal.eu



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