This note describes a problem that is seen on older MicroVax systems that
use the now-obsolete DEQNA ethernet interface card.

The DEQNA is no longer supported by Digital for use under VMS. The current
solution is to upgrade to a DELQA controller.

The following excerpt was posted many years ago by Dale Moore, one of the
CMU/Tek-IP developers. Note that at the time this posting was written (1987)
the DEQNA was the only available interface...

Thanks to Richard Gilbert for dredging up this article from his archives...

Date: 15 Oct 1987 17:01:59 EST
From: Dale.Moore@PS1.CS.CMU.EDU
Subject: Problems with uVax and DEQNA

This note explains
  - a possible problem with the CMUTEK software on micro-Vaxes,
  - when the problem arises,
  - what the possible solutions are, and
  - how to work around the problem.

Inside the Micro-VAX there is a device called a DEQNA.
The DEQNA is the device that connects the micro-VAX to the network.

It occasionally causes problems for the CMU-TEK IP/TCP software.
This is a problem with DEC hardware and DEC software.  It is not
a problem with the CMU-TEK IP/TCP software.
The way the problem will manifest itself is this.

OPCOM (thats the operator console) will issue messages like
	IPACP: XE $QIO read error, EC=00000A00
	IPACP: Network Offline - ACP exiting

This device error directly translates to
	%SYSTEM-W-NOMORENODE, NO MORE NODES
which is nonsense and bears no relationship to the actual problem.
But, that is what DEC's device driver declares to be the problem.

This device has problems under heavy and sometimes moderate load.
This usually arises when there are "Broadcast Storms" on the local
network.  These storms are sometimes caused by misconfigured SUN
workstations.  Other times it is just ordinary heavy traffic.
Our local network protocol police go into action every time we
detect such "Broadcast Storms".  As quickly as possible they try
to isolate the perpetrators.

Early versions of the DEQNA had this problem to the extreme.
Almost all of our DEQNA's here have received an FCO from DEC
that is suppose to alleviate the problem.  This FCO (Number DEQNA-R-001)
is available from DEC for free.  A quick check to see whether
your DEQNA has received this FCO is the presence of chip
#23-087K4-OO in location E11.  This FCO changes the DEQNA from
being completely brain dead to just severe brain damage.
If your DEQNA has not yet received this FCO, please contact your
local service rep.

Occasionally, but not very often, it is possible to have a privileged
user merely restart the network software with the command
	$ @SYS$MANAGER:IP_STARTUP.COM

But unfortunately, the most effective, and sometimes only solution,
that I've found is to reboot the machine.

I know of no suitable workaround hardware or software solutions.
Unfortunately, the DEQNA appears to be the only reasonable choice
for an Ethernet interface for the Micro-Vax.
I've been assured several times that DEC is aware of the problem.