Router Commands

There are several commands available in the Cisco IOS that can help in the trouble-shooting of physical layer problems. All these commands reside in the show family of commands. Debug commands for the upper layer protocols can be used in conjunction with other techniques to help diagnose physical layer problems. For instance, if you are watching debug information for IP errors, and you jiggle a cable that you believe to be bad and at the same time the IOS outputs that frame errors have been encountered, it is fairly safe to correlate the two events. Jiggling a network cable while watching for errors is a technique that you just seem to pick up over time. It is a hands-on technique that is passed from experienced network professionals ...

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