[ntp:questions] Re: offset of two acts servers

David L. Mills mills at udel.edu
Fri Feb 3 14:45:27 UTC 2006


Note the NIST servers are themselves wrangled by ACTS once per hour. The 
behavior is somewhat bumpy, as the machines do wiggle considerably over 
the hour. My data here with the Seattle server show wiggles in the order 
of 3 ms.


Garrett Wollman wrote:

> In article <11u59933rt89sae at corp.supernews.com>,
> rtxo  <gnu at wraith.sf.ca.us> wrote:
>>Oddly, one of the acts hosts is consistently 3-5 milliseconds behind,
>>and the other 3-5 milliseconds ahead:
> [...]
>>I wonder whats going on with these hosts. The refclock_acts driver code has
>>a comment that claims the acts adjusts for the round trip delay.
> Not sure how relevant it is, but have a look at
> <http://khavrinen.csail.mit.edu/ca-ntp-offsets.pdf>.  (It's more
> interesting on slower machines.)  That's offset on the Y axis and MJD
> on the X axis.  Note the odd behavior of time-b.nist.gov (another ACTS
> server).
> -GAWollman

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