[ntp:questions] NTP architecture recommendation

George N. White III aa056 at chebucto.ns.ca
Fri Aug 17 23:18:54 UTC 2007

On Fri, 17 Aug 2007, Harlan Stenn wrote:

> Depending on your budget you might want some sort of atomic clock in there
> for the times when you are not getting a signal.  You might also want to
> look at a modem driver as a 2nd source.
> To my knowledge Meinberg has never been bitten by a software bug where their
> clocks would report incorrect time.
> Regardless, I tend to suggest to folks that they peer all their top-tier
> servers and use different vendors *and* different modalities.

This is an important point that seems to encounter resistence from 
purchasing depts, etc. who prize uniformity, so be prepared to state
the case.

> Finally, I believe President Bush said that in the time of certain
> emergencies he would order the GPS satellites to broadcast incorrect time
> (which would make GPS unreliable for ... navigation); this possibility is at
> least something to be aware of.

During the first Gulf War the US had to increase the accuracy of GPS time 
because they ran short of military spec GPS's.  Soldiers were relying on 
consumer grade GPS's, so the first "emergency" was not a problem for GPS 
users.  Still, the capability is there and might be used accidently if not
on purpose.

George N. White III  <aa056 at chebucto.ns.ca>

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