Don’t Blame the Hardware

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.

  1. 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.
  2. It seems to be working, but there’s no response: Most of time this is due to an incorrect cable or incompatible terminal settings.
  3. System crashes: Some crashes are due to hardware, but the majority are software issues. Try “show tech” in the Output Interpreter first.
  4. Unrecognized module or interface card: Usually caused by a mis-match between the installed software and hardware.
  5. 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.
  6. “Show interface” output errors: Rule out unusual conditions (drops, e.g.) or external causes (incorrect clocking, noise, or bad cables) first.
  7. 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.
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