[ntp:questions] How should an NTP server fail?

David L. Mills mills at udel.edu
Fri Jun 11 14:29:29 UTC 2010


Miroslav,

Careful inspection of the code, experience with the debug trace and the 
evidence presented previously strongly suggests your conclusion has no 
relevance. See my previous messages on the number of samples in the 
clock filter. I have nothing further to offer you.

Dave

Miroslav Lichvar wrote:

>On Fri, Jun 11, 2010 at 03:08:53AM +0000, David L. Mills wrote:
>  
>
>>An hour later I disconnected the server. By second 4773 the server
>>became unreachable and was undeclared the system peer. ten minutes
>>later I reconnected the server which again became reachable and the
>>system peer.
>>    
>>
>
>You are missing the point. The bug doesn't show up if the clock
>filter is filled with 8 valid samples before the connection is
>blocked. There has to be at least one MAXDISPERSE sample (not the last
>one).
>
>Blocking the connection on ntpd start right after fourth reply was
>recevied seems to trigger the bug reliably.
>
>If you want to trigger it in a normal situation, you need to partially
>flush the filter, let few valid samples in and then block the
>connection pernamently. This doesn't work reliably and you might need
>to retry it several times.
>
>  
>
>>If you are using an old release version, that
>>might explain your results.
>>    
>>
>
>I can reproduce it with 4.2.6p1 and 4.2.7p32, I haven't tried
>anything else.
>
>  
>




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