Path: utzoo!attcan!uunet!cs.utexas.edu!sun-barr!newstop!sun!amdahl!netcom!jbreeden
From: jbreeden@netcom.UUCP (John Breeden)
Newsgroups: comp.sys.ibm.pc
Subject: Re: QEMM 5.0 Slo-o-o-o-ws system DMA
Message-ID: <11586@netcom.UUCP>
Date: 4 Jul 90 22:32:49 GMT
References: <3863@trantor.harris-atd.com> <11250143@hpldola.HP.COM>
Organization: NetCom- The Bay Area's Public Access Unix System {408 241-9760 guest}
Lines: 17

In article <11250143@hpldola.HP.COM> ppa@hpldola.HP.COM (Paul Austgen) writes:
>This has not been my experience.  This particular program is the
>public domain terminal emulator from NCSA.  It is controlling an
>"ethernet" card.  Programs like "Switch-It", that swap out tasks,
>will cause the connection to the cluster server (a Unix
>workstation in this case) to be lost.  I believe that there is
>either a keep-alive response that is required periodically, or
>else switching out the task drops some line on the interface
>card.

Acually, NCSA (and all IPs) use a protocol port that the transport layer
talks to. When DesQ switches it's time slice away from NCSA, the port
disappears and the sender (your workstation) times out. It's not a
problem with the ethernet card, there's just no method to tell the sender
that the port is really there (a number of solutions have been proposed).
The problem is how NCSA handles a multitasker (or multitasker handles
NCSA).