[ntp:questions] Have Pi, have GPS = low powered NTP server?

DaveB g8kbv at uko2.co.uk
Mon Jun 11 11:33:03 UTC 2012


In article 
<CAMbSiYAFdPaprWsLha07cCui0qBdXULdQjN76VtYY37SQsppdA at mail.gmail.com>, 
hart at ntp.org says...
> 
> On Thu, Jun 7, 2012 at 10:30 AM, DaveB <g8kbv at uko2.co.uk> wrote:
> > pi at raspberrypi:~$ ntpq -p
> > remote          refid       st t when poll  reach  delay  offset  jitter
> > ========================================================================
> > *192.168.42.24  .GPS.        1 u  362  1024 377    0.563   0.669  0.284
> >  time.xilo.net  82.219.4.30  3 -   5h  1024   0   21.571  13.885  0.000
> >  dns0.rmplc.co 195.66.241.3  2 -   5h  1024   0 2019.75  -1000.8  0.000
> >
> > If those delay/offset and jitter figures are in milli seconds (?) could
> > that be down to the USB hosted LAN port on the Pi?  The same figures for
> > the BSD box at 192.168.42.24 are 0.000 0.004 and 0.002 respectively, I
> > just remoted into that and checked.
> 
> Yes, having your network behind a USB adapter is going to degrade
> performance compared to a PCI-connected NIC.  A half-millisecond delay
> is quite high for 100Mbit LAN.  Offset and jitter in the same range
> are to be expected.
> 
> The output of:
> 
> ntpq -c "rv 0 version precision"
> 
> would shed a bit more light on which ntpd version and the time to read
> the clock on that system.
> 
> Cheers,
> Dave Hart

As requested..

pi at raspberrypi:~$ ntpq -c "rv 0 version precision"
version="ntpd 4.2.6p2 at 1.2194-o Sun Oct 17 13:24:55 UTC 2010 (1)"

That's all the output it gave.

And the latest stat's  (The other listed servers are still ignored or 
are unreachable) after several days left to do it's thing.

pi at raspberrypi:~$ ntpq -p
remote           refid     st t when poll reach   delay   offset  jitter
========================================================================
*192.168.42.24   .GPS.     1 u  491  512  377     0.559   -0.148   0.102

So by my understanding so far, that would agree with the expected 
behaviour of a USB based LAN adapter for this sort of use.

Regards.

Dave B.



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