Path: utzoo!mnetor!uunet!husc6!uwvax!dogie!uwmcsd1!ig!agate!ucbvax!QUABBIN.SCRC.Symbolics.COM!DCP
From: DCP@QUABBIN.SCRC.Symbolics.COM (David C. Plummer)
Newsgroups: comp.protocols.tcp-ip
Subject: Re: TCP Keep-alives, also push bit
Message-ID: <19880321204001.0.DCP@SWAN.SCRC.Symbolics.COM>
Date: 21 Mar 88 20:40:00 GMT
References: <984@thumper.bellcore.com>
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The Internet
Lines: 12

This seems to come up once a year.  When I was implementing the
Symbolics TCP implementation some 3 or 4 years ago, I asked about active
connection sensing.  The UNANIMOUS answer I got were that such things
were 100% against the spec.  Therefore, BSD is in error.
[Philosophically, sending a garbage byte is disgusting.]  What IS
allowed, as far as I know, is to send a zero length IN ORDER TO ELICIT A
RESET if the connection absolutely doesn't exist.  This is what we do.
Yes, it will cause packet traffic.  If the link or remote host is down,
the connection will not go away until active data is sent or the host
comes up and IT declares that the connection doesn't exist.

This will surely come up again in 10 to 14 months...