[ntp:questions] Synchronization and Non-Synchronization status
jaiprabhu at somewhere.in.this.world
Sat Feb 20 20:01:24 UTC 2010
David Woolley wrote:
> Jaiprabhu wrote:
>> I have observed that the server reaches the reject state, while the
>> stratum stays the same (it was at 1), a long time after it moved into
>> the reject state. The server was moved to the reject state by making
>> it unreachable by adding it's IP in an iptables drop rule. The reject
>> state already means that the server is not a synchronization source.
>> What's the rule of thumb on the duration it would take for the stratum
>> shifting to 16?
> It should shift when the last available sample is too old to really
> correlate well with the true time. There is a definite drop dead when
> the root dispersion reaches about a second. I thought that the stratum
> collapses when somewhere between about 4 and 6 polls have been lost, but
> it might not be until the estimated error (root dispersion) becomes too
On my x86, running Ubuntu 9.04 and ntpd 4.2.4p4, it did not collapse
even after losing the 6th poll. I did not track the root dispersion but
I was tracking the time elapsed after all the configured hosts were made
unreachable for a while, and, it did not drop to stratum 16 till at
least 30 minutes after. I stopped keeping track after that.
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