What is an Ethernet crossover cable and why would I use one?

Ethernet crossover cables allow two Ethernet devices (two computers or a computer and printer, etc.) to connect directly without the use of an Ethernet hub. In the past, these cables have been not supported by Apple. However, iMac can often benefit from using a crossover cable. Here are a few points to remember with these cables:

Use cables that are manufactured, not hand made.
Always LABEL the crossover cable so it can be differentiated from a standard Ethernet cable at
a later date.

If your Macintosh has an AAUI Ethernet port, you'll need to use 10Base-T transceiver, as well as a crossover cable. You can purchase an Ethernet crossover cable and transceiver at an Apple-authorized retailer. Although the Ethernet crossover cable is the easiest method to make an Ethernet connection between two devices, a small Ethernet hub can also be used with standard Ethernet cabling.

Once you have the cable (and the transceiver, if necessary), follow these steps to set up file sharing between the two computers:

1. If you need to use a 10Base-T transceiver, connect it to your other Macintosh computer.
2. Connect one end of the crossover cable to the Ethernet port on your iMac.
3. Connect the other end of the cable to the Ethernet port on your other Macintosh computer. If you're using a 10Base-T transceiver, connect the cable to the transceiver.
4. On both computers, open the Apple menu and choose Control Panels.
5. Double-click the AppleTalk or Network control panel to open it.
6. Select Ethernet, then click the close box to close the window.
7. On both computers, double-click the File Sharing control panel to open it.
8. Make sure your name is listed in the Owner Name box.
9. If you don't remember your password, type a new one in the Owner Password box. For security purposes, you'll see bullets instead of letters as you type.
10. In the File sharing section, click Start, then click the close box to close the window.
11. Make sure a folder or volume is shared by highlighting it and selecting "Sharing..." from the file menu.
12. On either computer, open the Chooser.
13. Click AppleShare in the upper-left corner, then select the computer you want to connect with in the list on the right.

Crossover cables do not work with Ethernet hubs. For this reason, users must make sure that any crossover cable is prominently labeled.

The most likely symptom of a crossover cable being mixed in with regular Ethernet cables is that one device will not be recognized on the network. Simply disconnect the problematic device's Ethernet cable and switch it with another working Ethernet cable. That is quickest test to identify the crossover cable.