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RJ45 and crossover cable

I got a cross over CAT6 cable and somehow the computers on which I used it do not like it... So I thought maybe it was not a valid crossover cable. Searching on the net I found a page with the following images which gave me the answer. You have to look for the colors of the wires in the RJ45. It's not very easy to see, but it is different enough (assuming you see colors...) that you should be able to tell exactly.

The easiest is simply to look for the "red" (orange) cable. If it is close to the edge in one RJ45 and far from the edge on the other, then you have a crossover cable.

First a picture that shows the pin numbers. That can be important.

The next picture show the colors of the cables wired on those pins.

This figure shows the cabling of a crossover RJ45 cable or jack (they now sell jacks that do the crossover for you!)

So, just like with a serial cable, you swap the transmit and receive cables. That way the TX (transmit) on one ends, ends up on the RX (receive) at the other end and vice versa.

In a switch or a hub, that cross over is in the device itself.

This last picture shows you the difference between a straight through cable and a cross over cable. As you can see the orange wire (often referenced as the red wire) has a quite different position in both RJ45 jacks if you have a crossover. You should be able to see that wire in the Jack.

I found those images on What is the defference between Cross Cable and Straight Cable.

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