What Is a Crossover Cable?

What Is a Crossover Cable?
An ordinary patch cable connects different types of devices, for example, a computer and a network switch. A crossover cable connects two devices of the same type.
You can wire the ends of a patch cable in any way as long as both ends are identical. Compared to straight-through Ethernet cables, the internal wiring of a crossover cable reverses the transmit and receive signals.

You can see the reversed color-coded wires through the RJ-45 connectors at each end of the cable:

– Standard cables have an identical sequence of colored wires on each end.
– Crossover cables have the first and third wires (counting from left to right) crossed and the second and sixth.

Do You Need a Crossover Cable?
In the 1990s and 2000s, IT professionals used crossover cables to connect Ethernet devices directly, as older Ethernet standards required transmit and receive signals on specific wires and needed an intermediate device. The introduction of MDI-X enabled devices to auto-detect and adjust signal directions, preventing conflicts. Most routers and Gigabit Ethernet devices now support MDI-X, making crossover cables largely unnecessary except for older, non-Gigabit client-to-client connections.

How to Use Ethernet Crossover Cables
Use crossover cables only for direct device-to-device connections; using them with old routers or switches may cause connection issues. While available in stores, many hobbyists and IT pros prefer making their own by rewiring a straight-through cable.

Credit : https://www.lifewire.com/crossover-cable-ethernet-817870