Crossover Ethernet Wiring: One Cable, Two Standards
A crossover cable is not a special cable type. It is a standard cable terminated to two different colour codes.
Quick Answer
| Pin | T568A end | T568B end |
|---|---|---|
| 1 | White green | White orange |
| 2 | Green | Orange |
| 3 | White orange | White green |
| 4 | Blue | Blue |
| 5 | White blue | White blue |
| 6 | Orange | Green |
| 7 | White brown | White brown |
| 8 | Brown | Brown |
Terminating one end to A and the other to B crosses the transmit and receive pairs, producing a crossover cable.
Terminating Correctly
Prepare the end
Strip about 25 millimetres, untwist minimally, and fan the pairs.
Follow one standard per end
Decide which end is A and which is B before placing conductors.
Check the order twice
Colour mistakes are the most common fault and are invisible from outside.
Test the result
A cable tester that reports pair swaps confirms the termination.
Verifying an Unknown Cable
- Look at both ends side by side.
- If the colour order is identical, it is straight through.
- If orange and green pairs swap positions, it is crossover.
- Confirm pins 4, 5, 7, 8 are the same at both ends.
- Test with a wiremap tester before relying on it.
Real-World Applications
- Building a crossover cable for legacy equipment.
- Verifying an unlabelled cable in an old installation.
- Training in termination skills.
- Repairing a damaged end on an existing crossover run.
Related Guides
For the cable itself, read crossover Ethernet cable. For the LAN form, see crossover LAN cable wiring. For straight through colour codes, start with Cat5e colour code.
FAQ
Which standard should I use?
T568B is the common default for straight through. A crossover is A at one end and B at the other.
Does mixing standards damage anything?
No. It simply makes the cable a crossover.
Can I buy a premade crossover?
Yes, though demand has fallen and availability varies.
How do I test a terminated cable?
A wiremap tester that shows pair order will confirm it.