[ntp:questions] Re: NTP adjustment mechanism

Ulrich Windl Ulrich.Windl at RZ.Uni-Regensburg.DE
Mon Sep 1 12:45:06 UTC 2003

Depending on the scale you are looking at it, I guess every clock does
a bit of fine wobble; so does the NTP clock model. However it's not as
cruse as you do describe (you may read the clock during that 0.25
seconds to verify). You also should be more specific with your questions...


ryandrk at hotmail.com (Drk Ryan) writes:

> If clock adjustment is limited by tickadj/ticksize eg 4/10000 = +-400
> ppm , will this essentially mean that for a +100 ppm clock drift, NTP
> will run at -400 ppm for the first 0.25 of each second making
> adjustments each tick => accumulate an error (relative to actual
> clock) of -100 usec and then over that second the actual clock will
> gain +100 => balance out ..=> this means that worst case scenario NTP
> error will be at 0.25 sec in each sec interval and will be -100 (due
> to adj mechanism) +25 (accumulated error at thsi stage due to inherent
> error) = -75 msec...is this correct?

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