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Date:      Sat, 21 Dec 1996 11:40:28 -0700 (MST)
From:      Nate Williams <nate@mt.sri.com>
To:        Richard Wackerbarth <rkw@dataplex.net>
Cc:        dicen@hooked.net, freebsd-questions@freebsd.org, Nate Williams <nate@mt.sri.com>
Subject:   Re: User ppp not hanging up modem.
Message-ID:  <199612211840.LAA27342@rocky.mt.sri.com>
In-Reply-To: <l03010d01aee1dc47c650@[208.2.87.3]>
References:  <Pine.OSF.3.95.961221100409.6960B-100000@professor.eng.umd.edu> <32BBA85F.41C67EA6@hooked.net> <199612211751.KAA27123@rocky.mt.sri.com> <32BBB4C1.794BDF32@hooked.net> <l03010d01aee1dc47c650@[208.2.87.3]>

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> >> That's *NOT* the correct thing.  What happens when for some reason
> >> PPP happens to send the sequence '+++' to the modem?  All of a sudden
> >> it'll drop into command mode and you're screwed.  User-PPP (as well as
> >> all other PPP/SLIP implementations I've worked with) assumes that you've
> >> disabled the escape sequence at least temporarily.
> >>
> >Interesting. But, what exactly is the prabobalitity of that? I will have
> >think about this one.
> 
> Actually, NOTHING happens. The escape sequence must be followed by a period
> of idle (output only) time. If you transmit any character before the
> timeout period expires, the modem ignores the sequence.

There is still a *very* small chance that the last three characters in a
packet could be in fact three escape characters.  Small as it is, I
still contend that depending on the escape character/hangup behavior is
prone to errors and failure.


Nate



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