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Troubleshooting
This chapter provides these topics for troubleshooting problems:
Diagnosing Problems, page 33
Finding the Switch Serial Number, page 36
Diagnosing Problems
The switch LEDs provide troubleshooting information about the switch. They show boot fast failures, port-connectivity
problems, and overall switch performance. You can also get statistics from Device Manager.
Switch LEDs
Look at the port LEDs information when troubleshooting the switch. See
and their meanings.
Switch Connections
Bad or Damaged Cable
Always examine the cable for marginal damage or failure. A cable might be just good enough to connect at the physical
layer, but it could corrupt packets as a result of subtle damage to the wiring or connectors. You can identify this problem
because the port has many packet errors or it constantly flaps (loses and regains link).
Exchange the copper or fiber-optic cable with a known good cable.
Look for broken or missing pins on cable connectors.
Rule out any bad patch panel connections or media convertors between the source and the destination. If possible,
bypass the patch panel, or eliminate media convertors (fiber-optic-to-copper).
Try the cable in another port to see if the problem follows the cable.
Ethernet and Fiber-Optic Cables
Make sure that you have the correct cable:
For Ethernet, use Category 3 copper cable for 10 Mb/s UTP connections. Use either Category 5, Category 5e, or
Category 6 UTP for 10/100 Mb/s, and PoE connections.
Verify that you have the correct fiber-optic cable for the distance and port type. Make sure that the connected device
ports match and use the same type encoding, optical frequency, and fiber type.
Determine if a copper crossover cable was used when a straight-through was required or the reverse.
Cisco Systems, Inc.
www.cisco.com
33
LEDs, page 6
for a description of the LED colors
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