[ntp:questions] How to determine if the local clock can be used?

Tim Tanguy.ropitault at gmail.com
Tue Apr 4 16:01:54 UTC 2006

so here is my problem...
My company is making switch router embedded card, and want to implement
the NTP protocol on it in order to keep the LAN managed by the card
One typical configuration should be:
My switch routeur use its local clock as reference clock (I know it's
not a good thing but, it's like that) and sometimes, when Internet
connexion is available, it uses public NTP server for synchronisation
instead of local clock... the problem is I dont know the availability
of Internet connexion, so I will have problem is the case that my local
clock has an offset greater than 128ms compared to the public server
NTP. If my clock is stable and if I have estimated the frequency drift,
it wont happen I think but can you confirm that? and I wont to know
what measurement will I have to make for estimating my clock stability?
I think that measuring the drift frequency would be a good thing (it
must be <50PPM) but is there other thing that i Can measure for
estimating the stability of my clock??

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