jpbion@cisco.com (Joel P. Bion) (11/03/90)
No -- it is only with the MCI cards -- MECs are not affected. Joel
daly@cisco.com (Tom Daly) (11/04/90)
Last week, while debugging a problem at a customer site, we
discovered that the MCI card had been optioned for Ethernet version 1
instead of IEEE 802.3 (Ethernet version 2). Further investigation
uncovered that an error had crept into the documentation because a
figure of the MCI had been re-drawn with a different orientation.
The net effect is that many of the MCI boards in the field may be
optioned for Ethernet version 1. (Yes, the factory reads
the documentation.) While this configuration generally
works, it may cause an increase in the number of collisions (e.g. 3%
rather than .3%) and/or interoperability problems with some transceivers
and repeaters.
The correct orientation of the jumpers is described in the documentation
revision below:
--------------------------------------
MCI Card Version 3, Erratum to:
1. Hardware Products Installation Guide, October 1990, pp. 6-54, 6-55
2. Hardware Products Installation Guide, January 1990, pp. 6-33, 6-34
3. Field Service Manual, September 1989, pp. 42, 43
The revision to the text is noted by asterisks (*):
Jumpers W94 and W93* are 3-pin jumpers that select between Ethernet
and IEEE 802.3 electrical levels. Using the orientation shown in
the figure below (card edge connector down),
place a jumper on the lower** pair of pins to
select IEEE 802.3 or Ethernet Version 2, or on the upper*** pair
of pins to select Ethernet Version 1.
Jumper W94 controls the first Ethernet and jumper W93 controls the
second Ethernet. The factory default is to select IEEE 802.3/Ethernet
Version 2. This setting must be changed to operate with an Ethernet
Version 1 transceiver.
* From W193 to W93
** From upper to lower
*** From lower to upper
-------------------------
|
|
o W93 |
_ |
|o| |
|o| |
|_| |
o |
_ |
|o| |
|o| |
W94 |_| |
<backplane edge connector>
------------------------------------------
For MCI/2 the jumper correspondence is as follows:
interface MCI/3 MCI/2
Ether 0 W94 L10
Ether 1 W93 L30
As with the MCI/3, jumpers in the down position select IEEE802.3 mode.
Please accept cisco's apology for any inconvenience this may have caused.
Tom Daly
Director, Hardware Engineering
cisco Systems, Inc.
daly@cisco.com