Installation guide

CHAPTER
4-1
Catalyst 3550 Multilayer Switch Hardware Installation Guide
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4
Troubleshooting
This chapter describes these troubleshooting topics:
• Understanding POST Results, page 4-1
• Clearing the Switch IP Address and Configuration, page 4-2
• Diagnosing Problems, page 4-3
Understanding POST Results
When the switch powers on, it automatically begins POST, a series of tests that
verifies that the switch functions properly. When the switch begins POST, the
port LEDs turn green, the system LED blinks green, the RPS LED turns off, and
then the first two port LEDs turn off. When POST completes, the port LEDs
return to the status mode display, and the system LED is green. If POST fails, the
system LED is amber, and the port LED associated with the test is amber.
Note POST failures are usually fatal. Call Cisco Systems if your switch does not pass
POST. See the “Obtaining Technical Assistance” section on page xxiii for contact
information.
A POST failure usually means that there is physical damage to a port. A common
cause for failure is ESD. If an Ethernet controller fails it results in port failure.
During the switch power-up sequence, you can monitor the POST tests through a
console port connection. When the switch is running, you can also use the show
post privileged EXEC command to see if any port has failed a POST test.