RETURN LANs and Novell


Ethernet Pinouts

10/100BaseT Ethernet wiring is based upon 8-pin modular jacks.  Two wiring guidelines are offered in Electronic Industry Association (EIA)/Telecommunications Industry Association (TIA) standards:

  • EIA/TIA 568A
  • EIA/TIA 568B

A standard Ethernet NIC card (DTE) has the following RJ-45 modular pinout:

 Pin  Function
 1  Tx+
 2  Tx-
 3  Rc+
 6  Rc-

The RJ-45 modular jack has 8 conductors/pins.  Viewed from the front:


TIA-568B is the most common wiring scheme used in 10/100BaseT configurations.  The standard Ethernet “Patch” cable that connects a hub port to a NIC card uses TIA-568 wiring at both ends of a “straight-through” cable:



In TIA-568A wiring schemes, the White/Orange and White/Green pairs are transposed.  An Ethernet “Crossover” cable can be made by using TIA-568B at one end of the cable and wiring to TIA-568A at the other end of the cable.  These “Crossover” cables can be used to interconnect NIC cards directly, without the need for a hub.  “Crossover” cables are usually “RED” in color: