[ntp:questions] Proposed NTP solution for a network

Terje Mathisen "terje.mathisen at tmsw.no" at ntp.org
Wed Mar 4 12:49:16 UTC 2009

Jason wrote:
> Terje Mathisen wrote:
>> First you buy 3 or 6 Garmin 18 LVCs (or better: Synergy/Oncore timing 
>> receivers set in Zero-D mode) and connect them directly to your 
>> primary servers (using the appliance NTP servers as backup), then run 
>> both clockstats and loopstats logging files.
> I'm pretty sure the appliance might be more capable than the LVC18, same 

It is probably better than the Garmin, but almost certainly much less 
good than a dedicated FreeBSD box with an Oncore timing receiver.

The most important point though is the fact that no such appliance box, 
(afaik, and I own/operate 3-4 different brands), supports proper logging 
of its own performance, so you have no way to check/verify after the 
fact if a given timestamp actually was good or not.

My nearly free (< $100 total cost) FreeBSD+Garmin based box otoh has a 
much more powerful processor (Pentium III from 5-8 years ago) than any 
appliance, so it responds to NTP requests much more quickly, and it 
supports far more clients.

Yes, the PPS signal is only good to +/- 1 or 2 us, but this is still 
dead stable as seen from any network client of the box.


- <Terje.Mathisen at tmsw.no>
"almost all programming can be viewed as an exercise in caching"

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