Ethernet & Wireless Media

Unshielded Twisted Pair (UTP) Cable

UTP cabling, terminated with RJ-45 connectors, is a common copper-based medium for interconnecting network devices, such as computers, with intermediate devices, such as routers and network switches.

Different situations may require UTP cables to be wired according to different wiring conventions. This means that the individual wires in the cable have to be connected in different orders to different sets of pins in the RJ-45 connectors. The following are main cable types that are obtained by using specific wiring conventions:

• Ethernet Straight-through
• Ethernet Crossover
• Rollover

The figure shows the typical application of these cables as well as a comparison of these three cable types.

Using a crossover or straight-through cable incorrectly between devices may not damage the devices, but connectivity and communication between the devices will not take place. This is a common error in the lab and checking that the device connections are correct should be the first troubleshooting action if connectivity is not achieved.

T568A:

Pin 1,2        white-green; green

Pin 3           white-orange

Pin 4,5        blue; white-blue

Pin 6           orange

Pin 7,8        white-brown; brown

T568B:

Pin 1,2        white-orange; orange

Pin 3           white-green

Pin 4,5        blue; white-blue

Pin 6           green

Pin 7,8        white-brown; brown