Using Debug Commands; Enabling Debugging On A Specific Feature - Cisco Catalyst 3750 Software Configuration Manual

Metro switch

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Troubleshooting

Using Debug Commands

This section explains how you use debug commands to diagnose and resolve internetworking problems.

It contains this information:

Because debugging output is assigned high priority in the CPU process, it can render the system

unusable. For this reason, use debug commands only to troubleshoot specific problems or during

troubleshooting sessions with Cisco technical support staff. It is best to use debug commands during

periods of lower network traffic and fewer users. Debugging during these periods decreases the

likelihood that increased debug command processing overhead will affect system use.

For complete syntax and usage information for specific debug commands, refer to the command

reference for this release.

All debug commands are entered in privileged EXEC mode, and most debug commands take no

arguments. For example, beginning in privileged EXEC mode, enter this command to enable the

debugging for Switched Port Analyzer (SPAN):

Switch# debug span-session

The switch continues to generate output until you enter the no form of the command.

If you enable a debug command and no output appears, consider these possibilities:

To disable debugging of SPAN, enter this command in privileged EXEC mode:

Switch# no debug span-session

Alternately, in privileged EXEC mode, you can enter the undebug form of the command:

Switch# undebug span-session

To display the state of each debugging option, enter this command in privileged EXEC mode:

Switch# show debugging

Enabling Debugging on a Specific Feature, page 34-13

Enabling All-System Diagnostics, page 34-14

Redirecting Debug and Error Message Output, page 34-14

The switch might not be properly configured to generate the type of traffic you want to monitor. Use

the show running-config command to check its configuration.

Even if the switch is properly configured, it might not generate the type of traffic you want to

monitor during the particular period that debugging is enabled. Depending on the feature you are

debugging, you can use commands such as the TCP/IP ping command to generate network traffic.

Catalyst 3750 Metro Switch Software Configuration Guide

Using Debug Commands