
Chapter 3 Troubleshooting
Diagnosing Common Problems
Table 
| Symptom | Possible Cause | Resolution | |
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 | |
| No connectivity to SFP | • The SFP module was | • Remove and reinstall the | |
| module. | installed after the switch | SFP module, and reboot the | |
| 
 | was powered on. | switch. | |
| 
 | Note By default, the | Note See the “Connecting to | |
| 
 | an SFP Module” section | ||
| 
 | enabled and the SFP | on page  | |
| 
 | module slot is disabled if | Cisco Small | |
| 
 | an SFP module is not | ||
| 
 | already installed when | Modules Installation | |
| 
 | the switch is powered on. | Notes (order number | |
| 
 | 
 | ||
| 
 | 
 | procedures on removing | |
| 
 | 
 | an SFP module. | |
| 
 | • A  | • Remove the connection to | |
| 
 | connected to the switch. | the  | |
| 
 | 
 | reinstall the SFP module, | |
| 
 | 
 | and reboot the switch. | |
| 
 | 
 | 
 | |
| Switch placed in | Bad or  | Remove SFP module from the | |
| module. | switch, and replace it with a | ||
| module is inserted. | 
 | ||
| 
 | 
 | errdisable recovery cause | |
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 | 
 | |
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 | configuration command to verify | |
| 
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 | port status, and enter a time | |
| 
 | 
 | interval to recover from the | |
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 | 
 | ||
| 
 | 
 | See the command reference for | |
| 
 | 
 | information about the errdisable | |
| 
 | 
 | recovery command. | |
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Catalyst 2940 Switch Hardware Installation Guide
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