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4–Diagnostics/Troubleshooting
Power-On Self Test
4-2 59229-05 A
Power-On Self Test
The switch performs a Power-On Self Test (POST) as part of its power-up
procedure. The POST diagnostic program performs the following tests:
Checksum tests on the boot firmware in PROM and the switch firmware in
flash memory
Internal data loopback test on all ports
Access and integrity test on the ASIC
During the POST, the switch logs any errors encountered. If there are no errors,
the CPU Heartbeat LED blinks at a steady rate of once per second. If a fatal error
occurs, the Chassis Fault LED illuminates and the CPU Heartbeat LED may show
an error code blink pattern.
Error Code Blink Patterns
The CPU Heartbeat LED indicates the operational status of the switch. When the
POST completes with no errors, the CPU Heartbeat LED blinks at steady rate of
once per second. When the switch is in maintenance mode, the Heartbeat LED
illuminates continuously. Refer to “Recovering a Switch Using Maintenance Mode”
on page 4-15 for more information about maintenance mode. All other blink
patterns indicate critical errors.
The CPU Heartbeat LED shows an error blink pattern for the following conditions:
2 blinks - Internal Firmware Failure Blink Pattern
3 blinks - Fatal POST Error Blink Pattern
4 blinks - Configuration File System Error Blink Pattern