Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uunet!mcsun!ukc!acorn!unipalm!leo
From: leo@unipalm.uucp (E.J. Leoni-Smith)
Newsgroups: sco.opendesktop,comp.dcom.lans
Subject: Re: SCO Unix breaking Telnet connections.
Message-ID: <1991Feb6.222826.6205@unipalm.uucp>
Date: 6 Feb 91 22:28:26 GMT
References: <1991Jan31.040311.3283@shl.com>
Organization: Unipalm Ltd., Cambridge, England
Lines: 32

phil@shl.com (Phil Trubey) writes:

>I have this annoying problem with my SCO Unix machine.  Every once in
>a while when I'm logged in via a Telnet session, the Unix machine just
>drops my connection.  In fact it drops all telnet connections from 
>my machine if I have multiple connections outstanding (I use PC/TCP from
>a PC to telnet in).  When it drops the connections, my session just
>freezes until PC/TCP realizes that the other end is not talking anymore
>and then lets the connection go.  After dropping my connections, I can't
>initiate new connections - it just times out.  A few minutes later I can
>initiate new connection and continue as if nothing happened.

>Any ideas on what might be causing this?

I have seen similar behaviour on another TCP/IP : My guess - and it 
is only a guess - is that you might be seeing two packets hitting
the ethernet adapter in quick succesion, the second whilst the first
is still being processed under interrupt. Then the driver exits the ISR
clears down the interrupt - and maybe doesn't reset the hardware correctly.
I have written bad hardware interface code like this om several occasions.

You don't say what hardware you are using: I have heard rumours of this 
behaviour with certain intelligent cards...but no more than that.

In my case it happened on a development release on a WD8003 - but so 
infrequently that it was not a problem. Sometimes Heavy NFS would
cause it, and it would sometimes clear if i sent an outbound packet -
sometimes not - needed reboot.

I am intereseted in further detail. I run the support dept of a company
that has to support connections TO SCO (we don't sell that) so if I can
get info - it saves ME time!