Path: utzoo!attcan!uunet!husc6!bloom-beacon!tut.cis.ohio-state.edu!mandrill!neoucom!wtm
From: wtm@neoucom.UUCP (Bill Mayhew)
Newsgroups: comp.dcom.modems
Subject: Re: Trailblazer Bugs (was Trailblazer, Misc)
Summary: xon/xoff was the bug!
Message-ID: <1197@neoucom.UUCP>
Date: 24 May 88 17:46:02 GMT
References: <10273@ulysses.homer.nj.att.com> <10277@ulysses.homer.nj.att.com> <1084@teemc.UUCP>
Organization: Northeastern Ohio Universities College of Medicine
Lines: 41


Thanks to Michael Wayne for the suggestions on running the
trailblazer with the interface speed locked and running uucp at
other than 9600 baud.

It turned out that the vax end was running the trailblazer locked
at 9600 baud and using xon/xoff protocol.  This caused problems for
us when uucico on the vax started dumping data intot the modem at
9600 baud, but the connection was only running at 2400.  Quite
obviously, after a few seconds, the modem sent back what it felt
was an obligatory xoff as the buffer filled up.  The xoff character
apparently cuased the g-protocol to barf.  I'm not sure why the
effect always manifested itseft was just a single file getting
though.

I never saw the problem on my end of the line with impulse (a 3b1)
because it always originated calls, and when it places calls, I
also have it switch baud rates going to the serial port.  Since the
data rate was always within the thoughput bounds of the modem on my
end, I never saw the real cause of the problem.

The people at Telebit might want to consider a little footnote for
their manual in the next release.  This is an easy trap to fall
into, and pretty easy to overlook.  I sure left dumb that I didn't
notice it myself.

Unfortunately, the tty driver on the vax end doens't support
harware handshaking, so it looks like the solution is to use the
circular baudrate selection in gettydefs.  Yuck.  There are quite a
few inexperienced users that call on that line between 8:00 and
5:00 pm, and it's hard enough to get them to connect, let alone
handle mulitple baudrates and hitting the break key.  I suppose one
way around it would be to set up two gettydefs and have crontab
switch them back and forth.  Also could rewrite the tty driver, but
our computer gurus don't like that idea.

Any ideas out there?  Thanks to all on the net who've assisted.
Your help is definitely appreciated.

--Bill
  wtm@neoucom.UUCP