Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!iuvax!purdue!tut.cis.ohio-state.edu!unmvax!polyslo!rnicovic
From: rnicovic@polyslo.CalPoly.EDU (Ralph Nicovich)
Newsgroups: comp.protocols.tcp-ip
Subject: TELNET Buffering Woes
Message-ID: <10920@polyslo.CalPoly.EDU>
Date: 1 May 89 20:10:56 GMT
Reply-To: rnicovic@polyslo.CalPoly.EDU (Ralph Nicovich)
Organization: Cal Poly State University -- San Luis Obispo
Lines: 36



I have a buffering problem that I hope someone can help me with,
or perhaps point me in the right direction.

We have several systems running BSD 4.3 unix. A Pyramid is one
that I will use to illustrate the problem, however this occurs
on others. Also for purposes of example I will use the program
"cat" although this is not an exclusive problem of "cat", it is
just a simple example.

A user with a dumb terminal connected to a terminal server (in this
case a U.B. NIU-180) or with a PC connected directly to the Ethernet
TELNETs into the Pyramid which is connected to the Ethernet.
The user then "cat"s a large file to the screen, immediately tries to
abort with a control-c. The output keeps coming for a long time.

I have narrowed down the problem with a lan-analyser. The Pyramid
simply does not stop sending packets. It is my feeling that the "cat"
process has already sent all this data to "TELNET" and although
the control-c stops "cat" immediately, there is no way to flush the
buffers.

This is very disconcerting to the users who are use to a "rs-232"
connection. They don't wish to use "more" as it would not be applicable
in some other scenarios.

Does anyone out there have any Ideas or solutions, or perhaps this
is a "feature" of layered protocols ?
Perhaps a way of limiting the TCP segment size.

BTW- I do not administer the unix machine, only the network.

Ralph Nicovich
Network Engineering
Cal Poly State University, SLO