Ref: 02880025
Title: Incompatibility Between Ethertalk Driver 1.2 and Etherlink/NB
Date: 2/21/90

Copyright 3Com Corporation, 1991.  All rights reserved.

According to Apple Corporation, there is a known incompatibility between
the Ethertalk driver 1.2 and the Etherlink/NB Rev A & B adapter boards
(Assy 4042-03 Rev A or B).

Some Macintosh IIx or IIcx computers equipped with the 3Com Etherlink/NB
board and running Ethertalk 1.2 may intermittently experience system bombs.
Usually, the system bomb will show up as a blank rectangular box in the
middle of the screen with no error code or message.  However, some users
have noticed "System Error=12" appear then disappear.  (System Error=12
means that an unimplemented trap was executed.)

Recently it was observed that, of two identical workstations on the same
Ethernet segment, only one may experience system bombs.  The only
difference between them is that the workstation that does not bomb has an
older Etherlink/NB board (Assy 4042-02 Rev 09).  The Macintosh that bombs
has the newer Etherlink/NB (Assy 4042-03 Rev B) board.  When the older
adapter board was replaced with the newer Rev B board, the Macintosh began
showing system bombs.


Aggravating Factors

The problem seems to be correlated to the amount of Ethernet traffic on
the LAN.  When an Ethernet bridge was placed between an entire floor that
was experiencing the problem, it reduced traffic and effectively eliminated
the system bombs.

Also, during extremely high traffic peaks, it was observed that the
Macintosh computers were experiencing the bombs more frequently.  High
traffic peaks were about 900-1000 packets per second.

A Macintosh connected to a network via Appletalk to a Kinetics
Fastpath will not experience the system bombs.  But as soon as it is
connected to the Ethernet and the Ethertalk driver is activated in
the control panel, the Macintosh will begin to experience the system
bombs.


Typical Workstation:              Network Information:
-------------------               -------------------
System 6.0.4                      Approx 800+ nodes, 30 servers
Finder 6.1.4                      200 repeater segments
Ethertalk 1.2                     20 T1 1.544 bridges
Standard Memory Config 4MB        (Media Access Level/Auto Learn)
3+SHARE 1.3.1                     Traffic - 1 second peak 900 pps
                                  Traffic - average 300 pps
                                  Cable utilization: 1 second
                                  Peak 47%, Avg 16%


