[ntp:questions] handling falseticker

catia.lavalle at bechtle.com catia.lavalle at bechtle.com
Tue Feb 17 07:51:43 UTC 2009


I have the following configuration Stratum 0 configuration: 

1 x Stratum 0 (DCF "Clock") --> 1 x Stratum 1 (let's give it the IP
1 x Stratum 0 (GPS "Clock") --> 1 x Stratum 1 (let's give it the IP
I do not have (for security policy) the possibility to give any other 
alternative (extern) time source to the Stratum 2 Servers.

This means that my Stratum 2 Servers have only 2 servers. Obviously this 
configuration is not "falseticker save". 
I have a monitoring active which warns me if the time offset between the 2 
Stratum 1 server gets bigger than a fixed limit.

In such a situation anyway the NTP daemon on the Stratum 2 servers would 
mark one of the 2 Stratum 1 servers as a falseticker and "ignore" the time 
coming from it.
Since there are only 2 Stratum 1 server to choose from the "voting" 
decision do not really apply, in such a way that the decision that the NTP 
on the Stratum 2 servers take upon "ops! there is a falseticker. Which one 
is falseticker?" is rather casual (I guess). 

Say they mark the server as falseticker. 

     remote           refid
*          .GPS. 
x10.1.1.2           .DCF.    .LOCL. 

At this point I will get a warning from my monitoring, I will check 
manually with an external source which time really is and have a look to 
the decision that NTP on the Stratum 2 Server took. Say I realize that the 
decision taken is wrong: the is not the false ticker, the true 
false ticker is

What should I do? I mean is there a way to force NTP "on the fly" to 
change it's mind? I have in mind something like a command line saying 
"force to trust server" (which simultaneously automatically will 
imply "then ignore since this means it is the true 
falseticker")? ==> to force the following "switch"

     remote           refid
x10.1.1.1          .GPS. 
*           .DCF.    .LOCL. 

Sure I could reconfigure ntp.conf with a prefer on the server, 
and restart the daemon (would it work? I guess so), but I do not really 
like it, I find it to "permanent".


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