[ntp:questions] Re: HOWTO prepare ntpd to the leap of a second

David L. Mills mills at udel.edu
Thu Dec 29 14:16:09 UTC 2005


Serge,

I don't understand your concern. The existing code inspects the 
leapsecond file and considers the latest entry. If that entry is in the 
future the leap bits are set. Otherwise not. This assumes the file is 
updated following the most recent insertion opportunity. As the current 
file is dated in July and specifies a leap insertion at the end of this 
year, this condition is satisfied. The rationale for that is included as 
comments in the file itself.

Dave

Serge Bets wrote:
> Hello David,
> 
>  On Sunday, December 25, 2005 at 1:36:26 +0000, David L. Mills wrote:
> 
> 
>>If Autokey is running with a number of servers, only the latest data
>>are used. Since old leap epoches don't change, the only thing that can
>>happen is the addition of a new epoch at the next opportunity.
> 
> 
> Another thing could happen: IERS decision of *no* leap second insertion
> at the next opportunity. Result for leap-seconds file is then:
> 
>  - Unchanged events table.
>  - Unchanged lastmod timestamp.
>  - Unchanged filename extension.
>  - Expiration timestamp pushed by 6 monthes.
> 
> | $ awk '/^#@/{print $2}' leap-seconds.3331497600
> | 3360441600
> 
> This is currently the NTP timestamp of 28 June 2006. Sometime early
> January 2006, IERS would decide to not brake the Earth, and thus no leap
> second insertion will be necessary on 30 June. They would announce it in
> their bulletin C29. Sometime later in January 2006 NIST would update the
> leap-seconds.3331497600 file, with one change only: Expiration date
> advanced to 29 December 2006.
> 
> The NIST file is absolutely true until expiration. This fact is not
> exploited by the NTP daemon, but could perhaps be.
> 
> 
> 
>>With Autokey each association is restarted once per day, so the latest
>>leapsecond data will be retained from each server. If those servers do
>>the same thing, it may take a few days for the data to flow from an
>>authoritative source.
> 
> 
> OK: Thanks for the confirmation. I had misunderstood your previous
> explanation.
> 
> 
> Thankfully, Serge.




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