Q: Someone told me that I need to use an ethernet crossover cable to hook my two computers together if I don’t use a router, switch, or hub. What’s the difference between a crossover cable and a regular ethernet cable?
A: An ethernet crossover cable (a.k.a. crosslink cable) reverses the connections for transmit/receive at one end compared to a regular ethernet cable. This is done to allow two devices of the same type to communicate.
Based on your question, let’s take the example of two computers that are connected directly to one another:
With a regular ethernet cable, the transmit pair of connections on one computer would be connected to the transmit pair of connections on the other computer, the receive pair of connections to the receive pair of connections, and so on, and the cable would not work. A crossover cable should be used.
If an ethernet hub, switch, or router is used between the two computers, the connections are reversed properly within the hub/switch/router, so regular ethernet cables should be used.