You can see that FastEthernet0/1 is up/up, so that is all good. A common issue would be if you’ve got different VLAN settings on both sides of the link.īelow is an example output of ‘show ip interface brief’.
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In this case, check if the interface configuration is the same on both sides of the link. The last setting you can have there for the status in a ‘show ip interface brief’ is “up/down.” That typically indicates a Layer 2 issue or a speed mismatch. If a device on the other side is powered off, or if you don’t have a cable securely connected on both sides, the interface will show as “down/down.” So, check that it is cabled in at both ends and that the device on the other side is powered on. If it shows “down/down,” that means that the administrator has done a ‘no shutdown’ on the interface, but there’s a Layer 1 issue. So, enter that command to bring the interface up. If it shows “administratively down,” that means you haven’t entered the ‘ no shutdown’ command. When you enter the command, it will show you the status of the interface. CAT7 has got much better shielding than CAT3 cable does.Ī useful command for troubleshooting at Layer 1 is: That is not such a big problem if you’ve got a newer cable. Lastly, Electro-Magnetic Interference (EMI) sources such as motors or microwaves can cause errors in transmission. Also, bent or stretched cables can break the internal wires or fibers. Therefore, there isn’t anything to retain it in the interface it’s plugged into, and it’s easy for it to get a loose connection that way. On an Ethernet cable, the RJ45 connector with the clip on the end, it’s quite easy for that to get broken off. Also, if a device on the other end of the cable is powered off, then you’re not going to have any traffic going through there either.īroken connectors can cause loose connections and this happens quite commonly as well. If the cable is disconnected on one or on both ends, then obviously, you’re not going to have any traffic going through there. If you configure an interface on a router, remember to do the no-shutdown command.
![hider 2 troubleshoot hider 2 troubleshoot](https://walter.trakt.tv/images/episodes/005/583/468/screenshots/original/28a612a434.jpg)
On routers, interfaces are shut down by default. It’s actually best practice to shut down unused interfaces to stop users from plugging devices in there. On switches, interfaces are up by default, but administrators can manually shut them down. Some common Layer 1 problems include the interface is administratively shut down. You’ll see it happening quite a lot in the real world. Don’t bundle them up and wrap them up together because you’re liable to break them if you do that. First thing, our copper and fibre cables are liable to break if not handled correctly.