Or at least, don’t blame the hardware first.
Cisco’s Technical Assistance Center (better known as TAC) put together a list of common issues that seem to be caused by the hardware, but can often be fixed without replacing anything. Save some time by checking for these common causes first.
- Memory related error messages: Most of these are software issues, or just informational. Use the system error message decoder to find out what it really means.
- It seems to be working, but there’s no response: Most of time this is due to an incorrect cable or incompatible terminal settings.
- System crashes: Some crashes are due to hardware, but the majority are software issues. Try “show tech” in the Output Interpreter first.
- Unrecognized module or interface card: Usually caused by a mis-match between the installed software and hardware.
- Lost configuration after a power cycle: This can happen if the config-register is not reset or saved after a password recovery or other change. More details are explained here.
- “Show interface” output errors: Rule out unusual conditions (drops, e.g.) or external causes (incorrect clocking, noise, or bad cables) first.
- Failure to completely boot: Check the config-register and boot system commands, and beware of relying on the system to boot the first image in flash.