Networking Connectivity
Intel® PRO/100B Adapter
100-Mbps Cabling Specifications for Intel® 82557-based PCI Adapters

The PRO/100 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:

Note: For 10 Mbps operation, refer to the 10 Mbps cabling specifications help file.

EtherExpress PRO/100B TX Adapters

Recommendations

  • The cable must comply with the IEEE 802.3 10BASE-T standard for 2-pair, Category 5, UTP cable.
  • The cable between the computer and the hub must be less than 100 meters long.

     This UTP cable works well:

Manufacturer
Belden
Model number
1588A
No. of pairs
2

EtherExpress PRO/100B 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.

EtherExpress PRO/100B T4 adapters

When operating at 100 Mbps, the cable must comply with the IEEE 802.3u 100BASE-T4 specification. The cable between the computer and the hub must be less than 100 meters long.

The EtherExpress PRO/100B T4 adapters do not support pre-10BASE-T concentrators.

Cable and connector pinouts

Unlike TX cabling, T4 cabling does not use separate, dedicated pairs to transmit or receive data. T4 cabling uses all four pairs of wires. Three pairs are used to transmit data, while the fourth pair is used to detect collisions.

Pin pairings are as follows:

  • Pins 1 and 2 must be a pair.
  • Pins 3 and 6 must be a pair.
  • Pins 4 and 5 must be a pair.
  • Pins 7 and 8 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.

Link integrity

There are three LEDs on the EtherExpress PRO/100B T4 and TX adapters:

  • A LNK light for link
  • An ACT light for activity
  • 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

Problem
A hub can't detect a workstation

Solution
This is often the result of a crossed wire in the cable or wiring closet. Make sure the wiring is correct.

Problem
Workstations can't connect to the network

Solution
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/100B 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.

This applies to:

Intel® PRO/100B Adapter



Solution ID: CS-015975
Last Modified: 17-Oct-2014
Date Created: 29-Sep-2004
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