[ntp:questions] how will this effect stability
terje.mathisen at hda.hydro.com
Wed Feb 14 16:30:03 UTC 2007
marknmbox-88 at yahoo.com wrote:
> I am in an environment where the path to and from a
> time server can vary from milliseconds to a second and
> the return path may vary within the same range. The
> transit time for each direction will be independent of
> the time for the other. Thus the path to the server
> may take a few mills but the return path can take a
> second. The sum of both paths can range from a few
> mills to seconds.
> Will this cause ntpd problems with accuracy or
> stability or will the ntp calculations not be
Yes, it will, if the periods of severely one-sided delays last for many
minutes, i.e. long enough that ntpd can go through 5 or more sync cycles.
The only way you can make this work is by having a much longer history
buffer inside ntpd, allowing it to discover the actual "real round trip
time", i.e. when everything works OK.
There is a special option which you can use in your ntp.conf file, which
specifies this buffer, I'm trying to remember the name...google
What you want is something like 'tinker huffpuff 86400' to make a
24-hour buffer in which to look for the minimum round-trip time: All
packets which are delayed significantly more than this time will be
checked for consistency (i.e. the resulting time must be within the
possible interval), but will not directly modify the system clock.
- <Terje.Mathisen at hda.hydro.com>
"almost all programming can be viewed as an exercise in caching"
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