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Catalyst 2950 Desktop Switch Software Configuration Guide
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Chapter 28 Troubleshooting
Using Debug Commands

Using Debug Commands

This section explains how you use debug commands to diagnose and resolve internetworking problems.
It contains this information:
•Enab ling D e bugging o n a Spe cific Fea ture , page 28- 14
•Enab ling A ll -Syste m D iag nosti cs, pa ge 28 -15
•Redirect ing D ebug and Err or Me ssage Out put , page 28 -15
Caution Because debugging output is assigned high priority in the CPU process, it can render the system
unusab le. For th is re ason, use debug com mands only to trou bleshoot specific problems or du ring
troublesh ooti ng se ssions w ith Ci sco techn ica l sup por t sta ff. It is b est to u se debug commands during
period s of l ower ne twork t raffic and fewer use rs. D ebuggin g d urin g the se p erio ds de cr ease s the
likelihood tha t increas ed debug command processing overhead will affect system use.
Note For complete syntax and usage information for specific debug comman ds, refe r to the co mman d
refere nce fo r thi s r ele ase.

Enabling Debugging on a Specific Feature

All debug commands are entered in privileged EXEC mode, and most debug commands take no
arguments. For exa mple , beginni ng i n privileged E X EC mo de , en ter thi s c om mand t o enab l e th e
debugging f or Et h erCha nnel :
Switch# debug etherchannel
The sw itc h cont inue s to ge nera te ou tput un til yo u ent er t he no form of the command.
If you ena ble a debug command and no output is displayed, 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
monit or during th e partic ular per iod that debugging is enab led. De pending on the feat ure you are
debugging, you can use co mman ds such as the TC P/IP ping comm an d t o gene rat e ne twork t raffic.
To disab le de bugging of E the rChann el, e nte r th is com ma nd i n p rivileged EXE C mod e:
Switch# no debug etherchannel
Alternately, in privileged EXEC mode, you can enter the undebug form of the command:
Switch# undebug etherchannel
To display the state of e ach de bugging o pti on, e nte r th is c om mand in p rivileged E XEC mod e:
Switch# show debugging