[ntp:questions] Ntp looses sync

Maarten Wiltink maarten at kittensandcats.net
Wed Apr 1 12:03:38 UTC 2009

"Towli" <towli at oldboyz.dk> wrote in message
news:49d3328d$0$90265$14726298 at news.sunsite.dk...

> We're testing a DCF77 appliance box (EMC professional from
> www.gude.info), which every now and the looses its connection to the
> DCF77 signal and switches over to quartz mode. Upon doing this, our
> test switch looses its sync to it, and considers it a stratum 11 server
> instead of a stratum 1. The switch also has configured an "ordinary"
> stratum 5 windows-server, and it seems to me that it uses this one,
> when the appliance box is seen as being stratum 11 (and syslog says
> the switch lost ntp-sync to the stratum 11 appliance box, but syncs
> back when the DCF77 signal is restored).
> Will a switch allways use the lower stratum server?

Simple version: yes.

>                                                     Can i stop the
> switch from synching with other servers (when the dcf box looses its
> signal and runs in the otherwise reliable quarts-mode), while still
> having a backup ntp server configured in case the appliance bos goes
> down?

You might be able to mark the DCF box as a 'preferred' server. For the
exact syntax, see the manual.

>       Is a constant sync important or is it ok for the switch to
> synch with different servers 'along the way'?

Constant sync is nice but redundancy is better. Note that for
redundancy to be useful, some flexibility is required.

As an aside, the DCF box takes pains to play nice and warn about reduced
accuracy but it may well be better than a Windows host even then.

Maarten Wiltink

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