100 Mbps cabling specifications
                                                       v1.07

100 Mbps cabling specifications for Intel 82557-based PCI
adapters:
   
   EtherExpress(TM) PRO/100+ - TX

The EtherExpress PRO adapters have a small, snap-in RJ45
connector. RJ45 cabling is also known as Twisted-pair
Ethernet (TPE), Unshielded twisted pair (UTP), and 10BASE-T
cabling.

The type of cabling you must use depends on the adapter
you're using.

This document covers the following topics:

- EtherExpress PRO/100+ - TX adapters

- Link integrity

- Common problems
   
   NOTE: For 10 Mbps operation, refer to the 10 Mbps cabling
   specifications help file.


EtherExpress PRO/100+ TX adapters
=================================


Recommended cables
------------------

The cable must comply with the IEEE 802.3 10BASE-T standard
for 2-pair, Category 5, UTP cable. Select a high-quality
brand of Category 5 cable from your local supplier.

The cable between the computer and the hub must be less than
100 meters long.

EtherExpress PRO/100+ TX adapters do not support pre-10BASE-
T concentrators.


Cable and connector pinouts
---------------------------

If you need to repair a cable or provide connectors for UTP
cable, wire straight through as shown in the following
table.


Function    Pin#               Pin#
-----------------------------------
  TX+        1    <-------->    1
  TX-        2    <-------->    2
  RX+        3    <-------->    3
  RX-        6    <-------->    6

Use only four of the eight pins. Pins 1 and 2 must be a
pair, and pins 3 and 6 must be a pair.

To allow for a straight-through cable, the hub provides an
internal transmit/receive crossover function. This means the
transmit circuit of the network card is connected to the
receive circuit of the hub and vice versa.


Pinout for the RJ45 connector
-----------------------------
   ----------              -------------------------
1 |--        |          8 |------------             |
2 |--        |          7 |------------             |
3 |--         ---       6 |------------             |
4 |--            |      5 |------------             |
5 |--            |      4 |------------             |
6 |--         ---       3 |------------             |
7 |--        |          2 |------------             |
8 |--        |          1 |------------             |
   ----------              -------------------------
END                           TOP


Pin name and function:

1  Transmit Data Plus (TD+). The positive signal for the TD
differential pair. This signal contains the serial output
data stream transmitted onto the network.

2  Transmit Data Minus (TD-). The negative signal for the TD
differential pair. This contains the same output as pin 1.

3  Receive Data Plus (RD+). The positive signal for the RD
differential pair. This signal contains the serial input
data stream received from the network.

4  Not used.

5  Not used.

6  Receive Data Minus (RD-). The negative signal for the RD
differential pair. This signal contains the same input as
pin 3.

7  Not used.

8  Not used.


Connecting two workstations without a hub
-----------------------------------------

100BASE-T uses a star topology. This means a hub or
concentrator is in the center of a star, and each
workstation or server is connected to this hub.

For test purposes, you can directly connect two workstations
or a workstation and a server without using a hub. This
setup requires a special cable incorporating the crossover
function described earlier in this document. The table below
shows which wires need to be crossed over.


Function  Pin#              Pin#      Function
----------------------------------------------
TX+        1    <-------->   3        RX+
TX-        2    <-------->   6        RX-
RX+        3    <-------->   1        TX+
RX-        6    <-------->   2        TX-


   
   NOTE: This is not an IEEE supported configuration and
   should be used for test purposes only.


Link integrity
==============

There are three LEDs on the EtherExpress PRO/100+ TX
adapters:

1. A LNK light for link

2. An ACT light for activity

3. A 100 light which indicates a 100 Mbps connection

Refer to your adapter Installation Guide or the "Diagnostic
LEDs" Readme file for complete information.
   
   NOTE: The ACT LED indicates read/write activity on the
   network, not necessarily activity on the adapter.


Common problems
===============


A hub can't detect a workstation
--------------------------------

This is often the result of a crossed wire in the cable or
wiring closet.

Make sure the wiring is correct.


Workstations can't connect to the network
-----------------------------------------

Make sure hub port is configured to the correct speed. Also,
make sure last line in the NET.CFG file reads:
   
   lastdrive=F (for NETX systems)

or
   
   lastdrive=Z (for VLM systems)

Also try resetting the concentrator or hub or turn the power
off and on.


Polarity problems
-----------------

A common problem in 10BASE-T wiring is crossing the positive
and negative phases of the transmit or receive signals (for
example, crossing pins 1 (TX+) and 2 (TX-)).

EtherExpress PRO/100+ adapters automatically detect this
problem and adjust for it internally. However, it's best to
check your wiring and correct this problem if you find it.






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