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From: Eivind Eklund <perhaps@yes.no>
To: joerg_wunsch@uriah.heep.sax.de (Joerg Wunsch)
CC: hackers@FreeBSD.ORG
In-reply-to: j@uriah.heep.sax.de's message of Thu, 11 Sep 1997 06:42:31 +0200
Subject: Re: Kernel clock runs inaccurately
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> 
> As Eivind Eklund wrote:
> 
> > >   (They are probably living in somewhat of an ivory tower with
> > > good NTP refclocks readily available on a cheap Internet, something
> > > that is not my situation, sitting behind dialup lines everywhere.)
> > 
> > Shouldn't it be still be possible to set up xntpd with
> > drift-correction and synchronization often, and just suppress
> > xntpd-messages from starting the ppp-link?
> 
> Too expensive still.  The dialup itself is ISDN, so the setup time is
> ~ 2 seconds or less, but having an xntpd calling each 5 or 15 minutes
> would greatly increase our phone and Internet costs.

I was suggesting _suppressing_ dial-out when xntpd tried to send a
packet.  Ie, something similar to the dial filter in IIJ-PPP, ignoring
NTP-packets.  No call every 15 minutes, just a synchronization when
you're online for another reason.  With a continuous connection,
though, xntpd is supposed to lower the check-interval as it get more
info on your clock-drift, ending up at once every 6 hours or so.  The
timing on an ISDN-link might not be stable enough for this to happen,
though.

BTW: What kind of setup are you running to get <2s setup time?  I'm
consistently ending up at 4-5s, having tried with different external
TAs, ISDN-adapters, PPP-implementations and portmasters.

Eivind.