[ntp:questions] frequency adjusting only

maxime louvel m.louvel at gmail.com
Wed Apr 23 06:30:22 UTC 2008


HI again,

I am thinking that NTP should behave correctly if the activity on the nodes
(small temperature, hence frequency variation) and on the network (small
latency of the switch) are roughly constant.
But if not it will have some trouble, either to compensate the frequency
change or to deal with the network delay latency.

what do you think ?

thanks,

Maxime

On Wed, Apr 23, 2008 at 7:12 AM, maxime louvel <m.louvel at gmail.com> wrote:

> Hi,
>
> - my network contains only one switch, and all the node are in the same
> room.
> Thus I don't think cabling is a problem. I still have to check the latency
> of the switch.
>
> - I can't use a GPS or other material. I though I wouldn't need any
> because I don't won't a great accuracy with the real time, just between my
> nodes. I also think it would have been easier and better to have a common
> high precision time source (GPS)... But I can't afford that ;)
>
> Do you have an explanation of the so different performances observed in
> your NTP synchronisations ?
>
> - I'm going to look at chrony, which at first glance seems usable in my
> case.
>
> - I am already using the -x option, to be certain to avoid any step.
>
> Maxime
>
>
> On Wed, Apr 23, 2008 at 2:10 AM, Unruh <unruh-spam at physics.ubc.ca> wrote:
>
> > Steve Kostecke <kostecke at ntp.org> writes:
> >
> > >On 2008-04-22, Unruh <unruh-spam at physics.ubc.ca> wrote:
> >
> > >> Steve Kostecke <kostecke at ntp.org> writes:
> > >>
> > >> ??? In my experience, on a Lan ntpd shows an internode offset of
> > about
> > >> 5-15 usec, and on the internet (ADSL) an offset of about 200usec.
> >
> > >Here's an aggregated plot of the node offsets on my LAN over the last
> > 24
> > >hours. I see +3/-5 milliseconds, not anything near 5-15 microseconds.
> >
> > >
> > http://support.ntp.org/bin/viewfile/Users/SteveKostecke?rev=1;filename=typical_aggregate_lan_offsets.png
> >
> > I agree those are pretty bad. HOw are they hooked up? It looks like one
> > of
> > the hops is via a telephone modem!
> >
> > See www.theory.physics/chrony/chrony.html
> > Mind you those are running with maxpoll 7 not maxpoll 10 (Its my lan and
> > ntp server, and I'll do what I want to.)
> >
> >
> > >--
> > >Steve Kostecke <kostecke at ntp.org>
> > >NTP Public Services Project - http://support.ntp.org/
> >
> > _______________________________________________
> > questions mailing list
> > questions at lists.ntp.org
> > https://lists.ntp.org/mailman/listinfo/questions
> >
>
>
>
> --
> Maxime Louvel
> 0044 7964 5555 80
> 43 Allen road
> Whitemore reans
> WV60AW Wolverhampton
> United Kingdom
>



-- 
Maxime Louvel
0044 7964 5555 80
43 Allen road
Whitemore reans
WV60AW Wolverhampton
United Kingdom



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