Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Posting-Version: version B 2.10.3 4.3bsd-beta 6/6/85; site ucbvax.BERKELEY.EDU
Path: utzoo!watmath!clyde!cbosgd!ucbvax!red.rutgers.edu!HEDRICK
From: HEDRICK@RED.RUTGERS.EDU (Charles Hedrick)
Newsgroups: mod.protocols.tcp-ip
Subject: Re: Zero window probes
Message-ID: <12158537451.44.HEDRICK@RED.RUTGERS.EDU>
Date: Mon, 11-Nov-85 22:20:59 EST
Article-I.D.: RED.12158537451.44.HEDRICK
Posted: Mon Nov 11 22:20:59 1985
Date-Received: Wed, 13-Nov-85 06:57:47 EST
References: <851108205728.000456@CISL-SERVICE-MULTICS.ARPA>
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The ARPA Internet
Lines: 22
Approved: tcp-ip@ucbvax.berkeley.edu

If this is what I think it is, I think it depends upon the
application.  If you are a TCP user process, and the other
end doesn't accept any data in 5 minutes, there is probably
something wrong.  But suppose you are a print spooler talking
to a remote printer.  We have a situation just like that.
When the printer runs out of paper, or is otherwise in need
of attention, it XOFF's the connection.  Eventually, the result
is that TCP refuses to accept any data.  The operator may take
a long time to get to this.  We'd like to keep the connection
open as long as necessary.  Similarly, consider the connection
between a host and one of our terminal servers.  The terminal
server allows a user to have several connections open at once.
However the terminal is connected to only one session at a time.
There are commands to let you go back and forth between connections.
Obviously the server has only a finite buffer.  When you are
not connected to a session, and its buffer fills, TCP will
stop accepting data.  Again, we would like the host to keep the
connection open indefinitely.  Currently TOPS-20 will time out
after a certain time.  Our users all consider this to be a bug.
They are annoyed when they reconnect to a TOPS-20 session and
find that TOPS-20 has given up.
-------