Compared to standard Ethernet cables, the internal wiring of Ethernet crossover cables reverses the transmit and receive signals. The reversed color-coded wires can be seen through the RJ-45 connectors at each end of the cable:
- Standard cables have an idential sequence of colored wires on each end
- Crossover cables have the 1st and 3rd wires (counting from left to right) crossed, and the 2nd and 6th wires crossed
Ethernet crossover cables should only be used for direct network connections. In particular, attempting to connect a computer to a hub with a crossover cable will prevent that network link from functioning. Home broadband routers have become an exception to this rule: modern consumer routers contain logic to automatically detect crossover cables and allow them to function with other types of Ethernet devices.