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Date:      Sun, 11 Apr 1999 08:28:16 +0200
From:      "Martin Husemann" <>
To:        "Julien Oster" <>, <freebsd-isdn@FreeBSD.ORG>
Subject:   RE: Setting time from ISDN and using AOCD
Message-ID:  <000001be83e4$7b93f9b0$>
In-Reply-To: <>

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> 1.) I'd like to set my system time from the ISDN timestamps.

This is on my todo list. I'll have to check for an easy place to pick up the
timestamps inside the I4B kernel part yet [*], then deliver them to a
special /dev/i4brefclock and pick them up by xntpd (or ntpd). I've already
set up a DCF77 clock, just to check how good the timestamps are on my local
switch. There have been reports of the ISDN timestamps drifting a few
seconds, which makes them useless from an NTP point of view.

> ratetype                = 0
> unitlength              = 90
> unitlengthsrc           = aocd

This is fine, just a default until the first aocd unitlength can be
calculated (which is after the first unit is charged!). This means: default
unitlength is 90 secondes (but ignore this for now), take the current
expected unitlength from the ratesfile, entry type 0 (which means "local
call" in the distributed ratesfile).

You now only need to tell isdnd when to hangup:

earlyhangup             = 5


P.S.: * = This is hardware driver dependend, so what we realy need is a API
inside I4B to tell drivers "please deliver timestamps" and a way to deliver
a timestamps to the i4brefclock device. I tried it once with my active Diehl
card, but I never got a timestamp from the card, and there is no way to
influence the on-card stack to filter or not filter this events. Maybe Dirk
Meyer is right and most switches don't deliver timestamps nowadays. It's an
optional service and you can't even subscribe to it at Telekom.

P.P.S.: I payed 40 DM for a DCF77 clock (Conrad), and of course had to write
the driver myself. Just a hint that there are viable alternatives...

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