Applitec Systems Inc.

Ethernet Cable Technical Tip
RJ-45 Crossover Cable and Straight Through Pinouts

Overview
This article provides connectivity examples for hub-to-hub, hub-to-transceiver, transceiver-to-transceiver, pinouts and color coding for standarded ethernet cabling.

Discussion

Crossover Cable
RJ-45 PIN RJ-45 PIN
1 Rx+ 3 Tx+
2 Rc- 6 Tx-
3 Tx+ 1 Rc+
6 Tx- 2 Rc-

Straight Through Cable
RJ-45 PIN RJ-45 PIN
1 Tx+ 1 Rc+
2 Tx- 2 Rc-
3 Rc+ 3 Tx+
6 Rc- 6 Tx-

Please Note: The connector view shown is color-coded for a straight thru cable assembly, when connecting Hub to Xcvr or DNI Card.

Rule of Thumb: When connecting like devices you must use a crossover cable. For example when connecting hub to hub, Xcvr to Xcvr, or DNI to DNI, the wires must crossover at the opposite end of the cable assembly.

Interconnecting Your Hubs, Transceivers, and DNI Cards

As noted in the illustrations below, a crossover cable is required when connecting a Hub to a Hub, or a Transceiver to Transceiver, or DNI to DNI card, or Transceiver to DNI card. When connecting a Hub to a transceiver or DNI card, a straight through cable is always used.

Please Note: Some products are equipped with internal switches that can internallly cross the twisted pairs.

In these illustrations a Hub can refer to any standalone product.

Hub to Hub Connectivity

Hub to Tranceiver or DNI Card Connectivity

Transceiver to DNI Connectivity

Category 5 Wiring Standards

EIA/TIA 568A/568B and AT&T 258A define the wiring standards and allow for two different wiring color codes.

Pin # EIA/TIA 568A AT&T 258A, or EIA/TIA 568B Ethernet 10BASE-T Token Ring FDDI, ATM, and TP-PMD

1 White/Green White/Orange X X

2 Green/White Orange/White X X

3 White/Orange White/Green X X

4 Blue/White Blue/White X

5 White/Blue White/Blue X

6 Orange/White Green/White X X

7 White/Brown White/Brown X

8 Brown/White Brown/White X

Pairs may be solid colors and not have the stripe.

Category 5 cable must use Category 5 rated connectors.

Please see the origins of this page at Cabletron Systems.

Ethernet 10BaseT Crossover Cable

Here are instructions for building an Ethernet 10BaseT crossover cable.

The pinouts for an Ethernet 10BaseT crossover cable are as follows:

Connector 1
Pinout Connector 2
Pinout [Diagram of crossover pinout]

1 3

2 6

3 1

4 OPEN

5 OPEN

6 2

7 OPEN

8 OPEN

pin 1 to pin 3, pin 2 to pin 6, pin 3 to pin 1, and pin 6 to pin 2: All of the other pins are left open.

These instructions can also be used to purchase an Ethernet crossover cable to network your computer and printer together. Don't just buy any RJ-45 cable; the internal pinout for a crossover cable is different from the pinout of an RJ-45 cable normally used in Ethernet. Make sure the packaging is clearly labeled "crossover cable", or have someone create the cable for you.