Ethernet Troubleshooting

Troubleshooting of an Ethernet interface is fairly straightforward. If you know that the cabling to the Ethernet interface is good, then there are only a couple of things that could cause the interface to not come up. One of these is incorrect pin wiring on the Ethernet cable. The interface would show a status of up, but the line protocol would show a status of down. For instance, use of a normal straight through cable when a crossover cable is required. This would be the case if you were connecting two routers back to back rather than through a hub or a switch. Refer back to Chapter 14, "Troubleshooting the Physical Layer," for physical layer troubleshooting.

Another problem that can be the result of human error ...

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