[ntp:questions] Clock time synchronization of four computers

David J Taylor david-taylor at blueyonder.co.uk.invalid
Mon Jul 9 06:51:40 UTC 2012


"Nazmul Islam"  wrote in message 
news:CAFtrfEZN5mhQ_bOdEG5KZ7L2kGA5s6NgsmFBHYkSmxxm9GF5rQ at mail.gmail.com...

>
> Hello,
>
> I have not used ntp processing before. I apologize in advance if my
> questions seem too novice.
>
> I am trying to synchronize the clocks of four computers. The timing does
> not have to be accurate but they have to be sync'd with each other.  An
> error tolerance of 10-20 ms is acceptable. The computers are connected to
> the servers.
=============================================


In addition to Paul Kennedy's suggestion, you can make one or two computers 
stratum 1 servers by adding a low-cost GPS device.  These have serial RS-232 
output which can be parallel connected to two PCs (on the PC's data input 
and DCD lines), making two of the 4 PCs stratum-1 servers.  You can peer the 
two PCs with each other, and make these two PCs servers for the remaining 
two.  With a simple line driver you could likely connect all four PCs to the 
GPS source.  All PCs should also retain several Internet servers for backup. 
I have descriptions of a couple of low-cost GPS devices on my Web site:

  http://www.satsignal.eu/ntp/FreeBSD-GPS-PPS.htm
  http://www.satsignal.eu/ntp/Sure-GPS.htm

The performance I get (using Windows) is shown here:

  http://www.satsignal.eu/mrtg/performance_ntp.php

Cheers,
David 



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