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From: ggl@mhuxi.UUCP (LASKARIS)
Newsgroups: net.micro.att
Subject: Unix PC communications trouble
Message-ID: <423@mhuxi.UUCP>
Date: Tue, 1-Apr-86 16:27:06 EST
Article-I.D.: mhuxi.423
Posted: Tue Apr  1 16:27:06 1986
Date-Received: Sat, 5-Apr-86 01:45:10 EST
Organization: AT&T Bell Laboratories, Murray Hill
Lines: 55

- f - o - o - d - - - f - o - r - - - t - h - o - u - g - h - t -
Trouble with Unix PC Release 3.0, communications, and remote terminals:

We have a couple of Unix 7300's here, linked together via rs232 expansion
ports.  In addition, just to add a bit of spice, each has a telephone
line for cu and telephone manager, and one has a terminal (an AT&T 510a).

We have observed the following strange and wonderful behaviour.  The
hotline has so far not been able to help, although I have not allowed
all that long before trying alternate routes.

When someone is logged into the terminal (9600 baud direct connect)
and the computer is involved in a 'cu' or 'uucico' via either the
rs232 to the other computer or the phone line to another remote machine,
OFTEN but not ALWAYS:
	1) the terminal will hang up
	2) if uucico is being used, it will fail, usually with a
	   timeout.
This leaves the terminal hung up until a reboot, and leaves the communications
port in an extremely strange place.  I can get into 'cu' (whether I was 
already there or in uucico) and dial a remote machine.  I then carry on a
strange dialogue:  I type, and the correct number of characters echo.  The
remote machine responds, and again the correct number of characters are shown
on my screen.  If I am a good typist, I can log in, give a password, and
issue commands to the remote system.  Always, the correct number of characters
result.

HOWEVER, although the characters are correct in number, they are not
what either I or the remote machine are typing.  In fact, they are what
has already happened, perhaps 200 characters back.  In other words, if
the machine hung this way during a uucico, the characters that echo at
me will be those from the uucico file, along with the handshaking protocol.
If I keep working this way, eventually my remote terminal session will be
displayed, including my typing entries (and including any spelling errors
I made because I couldn't see what I was typing at the time).  In other
words, it seems that there is a buffer somewhere associated with the
remote line, and that a pointer into that buffer is screwed up.  I keep
adding to the end of the buffer, and the beginning of the buffer keeps
getting displayed.  We just don't agree as to where input and output are.

The only solution I have come up with is to reboot the system.  Crude,
but it works.

By the way, without the remote user logged in this problem has NEVER 
occurred.  With the remote user logged in, it has probably occurred 25
times now.  I guess we can't use remote logins.

Help!


Adthanksvance,

David Laurance
ihnp4!mhuxi!ggl
(201) 953-7633