[ntp:questions] Re: tinker step 0 (always slew) and kernel time discipline

Joe Harvell harvell at nortel.com
Wed Sep 27 17:40:02 UTC 2006



David Woolley wrote:
> In article <ef19v5$kqn$1 at zcars129.ca.nortel.com>,
> Joe Harvell <harvell at nortel.com> wrote:
> 
>> This actually happened in a testbed for our application. NTP stats show
> * that over the course of 22 days, the offsets of two configured NTP
> * servers (both ours) serving one of our NTP clients started diverging
> * up to a maximum distance of 800 seconds.  During this time, our NTP
> 
> This could only happen if either the implementation was broken, or
> they were mis-using the local clock pseudo reference clock. 

David:

I tracked down the configuration of the NTP servers 192.168.0.1 and 192.168.0.2. Their normal NTP configuration is shown below.  The problem occurred during a system upgrade on 16 Aug when the ntp.conf file of 192.168.0.1 was accidentally truncated (empty).  This was fixed on 8 Sep to the normal configuration shown below.

I don't understand why sysmgr0 or sysmgr1 would ever look at the time from 192.168.0.1 since it should have shown it was unsynced.  I suspect it has to do with the "prefer" keyword.  Should I file a bug report?

==============================================================================
192.168.0.1
==============================================================================

   # BEGIN NTP SERVERS
   server ntp-3
   server ntp-2
   server ntp
   # END NTP SERVERS

   # BEGIN NTP PEERS
   # END NTP PEERS

   # BEGIN NTP OPTIONS
   driftfile /var/opt/NTP/ntp.drift
   statsdir /var/opt/NTP/ntpstats
   filegen peerstats file peerstatistics_log type week enable
   # END NTP OPTIONS


==============================================================================
192.168.0.2
==============================================================================

   # BEGIN NTP SERVERS
   server ntp-3
   server ntp-2
   server ntp
   # END NTP SERVERS

   # BEGIN NTP PEERS
   # END NTP PEERS

   # BEGIN NTP OPTIONS
   driftfile /var/opt/NTP/ntp.drift
   statsdir /var/opt/NTP/ntpstats
   filegen peerstats file peerstatistics_log type week enable
   # END NTP OPTIONS
   # 

> If the
> servers were using a proper reference clock as their primary source,
> root dispersion would have exceeded it's maximum value when the
> error was probably a lot less than a second and the servers would have
> been rejected completely.
> 




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