Cisco Systems 3560 Manual De Usuario

To run TDR, enter the test cable-diagnostics tdr interface interface-id privileged EXEC command:

To display the results, enter the show cable-diagnostics tdr interface interface-id privileged EXEC 
command. For a description of the fields in the display, see the command reference for this release.

These sections explains how you use debug commands to diagnose and resolve internetworking 
problems:

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, see 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:

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.

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