[ntp:questions] Client doesn't drop failed source
david at ex.djwhome.demon.invalid
Sat Jan 9 09:31:34 UTC 2010
Richard B. Gilbert wrote:
> Michael Moroney wrote:
>> David Woolley <david at ex.djwhome.demon.invalid> writes:
>>> Michael Moroney wrote:
>>>> that synchronizes with the four clocks, and ntpq> peers shows one of
>>>> primaries with a "*" in the first column meaning it was synchronized
>>>> to as
>>>> time source, the other 3 show "+" as expected, meaning they are usable
>>>> sources. We disconnect the antenna of the selected clock. As expected
>>> * and + mean they are used, not just that they are usable. The time
>>> used to discipline the clock is a weighted average of all of them.
>> If it uses all of them, what is the difference between "*" and "+"?
>> It still doesn't explain why the disconnected clock doesn't get dropped.
> "*" designates the primary source of time. "+" designates an "advisory"
> source. It's available for use if something happens to the primary source.
You are making the same mistake that he was making. * means the source
of time used to determine the stratum, and downstream root distance and
dispersion. + and * both mean that the time is being used to discipline
the local clock. + is not a standby, as far as disciplining the clock
is concerned; + entries are actively used to discipline the clock.
On V3, the time used to discipline the local clock is a weighted average
based on a quality metric - I forget exactly which one. I'm not so sure
that V4 applies as much weighting.
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