[ntp:questions] Re: isolated network + accuracy

Richard B. Gilbert rgilbert88 at comcast.net
Tue Dec 14 02:12:03 UTC 2004


Bjorn Gabrielsson wrote:

>"Richard B. Gilbert" <rgilbert88 at comcast.net> writes:
>
>  
>
>>Using an internet server as a time source will almost certainly not
>>allow you to achieve 1ms accuracy!  10ms accuracy is possible over the
>>internet but cannot be guaranteed.
>>    
>>
>
>I get sub 1ms time from internet servers. 
>  
>

The internet servers I use tend to wander within plus/minus 5-10ms of my 
GPS receiver!!  I'm using the best servers I can find and I've seen far 
worse than the ones I finnally settled on.   Their clocks my be far 
better than what I'm seeing but by the time the packets get here the 
quality looks really poor.  Your milage may vary.

>  
>
>>1ms accuracy is a very high standard and quite difficult to meet.  I
>>don't believe that  Windows is capable of it.  Linux may not be
>>either.   Some flavors of Unix are capable, at least in principle.  I
>>believe that Solaris is.  I lack sufficient recent experience with
>>other flavors of Unix to offer an informed opinion.
>>    
>>
>
>My Linux computers shows no problem reaching below 1ms. 
>  
>
My RedHat Enterprise Linux 3.0  workstation rarely runs an offset less 
than 5ms.  Once again your milage may vary!!



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