Cisco Systems 2960 Verify Switch POST Results, Monitor Switch LEDs, Verify Switch Connections

Chapter 4 Troubleshooting

Diagnosing Problems

Verify Switch POST Results

As the switch powers on, it begins the POST, a series of tests that runs automatically to ensure that the switch functions properly. It might take several minutes for the switch to complete POST.

When the switch begins POST, the system LED slowly blinks green. When POST completes, the system LED blinks amber. If POST fails, the system LED remains amber. If POST completes successfully, the system LED rapidly blinks green.

Note POST failures are usually fatal. Contact your Cisco technical support representative if your switch does not pass POST.

Monitor Switch LEDs

You must have physical access to the switch to do this. Look at the port LEDs for troubleshooting information about the switch. See the “LEDs” section on page 1-12for a description of the LED colors and their meanings.

Verify Switch Connections

Review these sections when troubleshooting switch connectivity problems:

•Bad or Damaged Cable, page 4-2

•Ethernet and Fiber Cables, page 4-3

•Link Status, page 4-3

•Transceiver Module Port Issues, page 4-3

•Port and Interface Settings, page 4-3

•Ping the End Device, page 4-4

•Spanning Tree Loops, page 4-4

Bad or Damaged Cable

Always look at the cable for marginal damage or failure. A cable might connect at the physical layer but then cause packet corruption because of subtle damage to its wiring or connectors. You can identify this situation because the port will have many packet errors, or the port constantly loses and regains link. In these situations:

•Change the copper or fiber-optic cable with a known, good cable if necessary.

•Look for broken or missing pins on cable connectors.

•Rule out any insufficient patch panel connections or media convertors between the source and the destination. If possible, bypass the patch panel or eliminate faulty media convertors, such as fiber-optic-to-copper convertors.

•Try using the cable in another port or interface to see if the problem also exists there.

Catalyst 2960 Switch Hardware Installation Guide

4-2 OL-7075-05