Cisco Systems OL-6157-01 Troubleshooting, Understanding POST Results, Diagnosing Common Problems

C H A P T E R 3

Troubleshooting

The front-panel LEDs provide troubleshooting information about the switch. They show power-on self-test (POST) failures, port-connectivity problems, and overall switch performance. For a full description of the LEDs, see the “LEDs” section on page 1-6.

You can also get statistics from the device manager, the Network Assistant application, the command-line interface (CLI), or a Simple Network Management Protocol (SNMP) workstation. See the switch software configuration guide, the switch command reference, or the documentation that came with your SNMP application for details.

This chapter provides these topics for troubleshooting problems:

•Understanding POST Results, page 3-1

•Diagnosing Common Problems, page 3-1

Understanding POST Results

While the switch powers on, it automatically begins POST, a series of tests that verifies that the switch functions properly. POST lasts approximately 1 minute.

If POST passes successfully, only the SYST and STAT LEDs, as shown in Figure 1-3 on page 1-6, remain on.

If POST fails, the SYST LED turns amber. Table 3-3 on page 3-5lists two causes and resolutions for a POST failure. POST failures are usually fatal. Contact your Cisco representative if your switch does not pass POST.

Diagnosing Common Problems

Common switch problems fall into these categories:

•Connectivity problems (Table 3-1)

•Poor performance (Table 3-2)

•Corrupted software (Table 3-3)

Catalyst 2940 Switch Hardware Installation Guide

OL-6157-01 3-1