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

David Woolley david at ex.djwhome.demon.invalid
Sun Jun 6 18:53:14 UTC 2010

David Mills wrote:
> goofyzig,
> This issue is widely misunderstood; yours is the second such message to 
> me today. So, please spread the word.
> When a server loses all sources it does not necessarily become 
> unsuitable for downstream clients. Ordinarily, it inherits error 
> statistics from upstream servers and provides them to downstream 
> clients. Servers and clients use these statistics to calculate the 

Whilst it may make sense to retain the system peer status, I don't see 
that it makes sense to retain the selected status.  As system peer 
currently also includes selected, maybe there is a need to split system 
peer from its selected implication.

> maximum error statistic which represents the maximum clock error 
> relative to the primary reference clock. See the error budget called out 
> in the specification. Once determined, the maximum error increases at a 
> rate (15 PPM) determined as the maximum disciplined clock frequency 
> error of the server clock. This increase continues indefinitely or until 
> the sources are again found.

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