Cisco 2800, 3800, 1560 APs: when connected to a Cisco Switch CDP-4-DUPLEX_MISMATCH log is seen
CSCvi02106
Symptom:
You might see "CDP-4-DUPLEX_MISMATCH" messages on a Cisco switch that refer to a port where a Wave 2 AP is connected. By default, these messages are logged every 60 seconds per port. This could cause the syslog buffers to fill up and lose more important messages.
Conditions:
Cisco 2800/3800 & 1560 Series access points connected to Cisco switchports with CDP enabled.
Running 8.3 AP-COS - not 8.4 or above.
Workaround:
In order to prevent these duplex mismatch warning messages from being captured in your syslogs, complete one of these workarounds:
Disable CDP and enable Link Layer Discovery Protocol (LLDP) (if the switch supports it) on the switch port connected to the AP.
Note: For the AP to power on its radios without CDP, enable LLDP for power management.
config terminal
lldp run
interface
no cdp enable
end
Raise the threshold of syslogging to be higher than severity 4, that is, severity 3 (errors) or higher.
config terminal
logging {buffered/trap/console} 3
end
If you do this, the switch will no longer log messages of severity 4 (warnings) or lower.
Further Problem Description:
This doesn't have any operational impact; both AP and Switch are actually operating in full duplex.
For more information, see the field notice https://www.cisco.com/c/en/us/support/docs/field-notices/702/fn70252.html .
This bug affects only 8.3 AP-COS - not 8.2 nor 8.4 or above.
Note: even with this CSCvi02106 fix, you can still see spurious CDP duplex mismatch errors, if using LAG with 2802/3802 APs. Track CSCvi84511 for the fix for that scenario.
You might see "CDP-4-DUPLEX_MISMATCH" messages on a Cisco switch that refer to a port where a Wave 2 AP is connected. By default, these messages are logged every 60 seconds per port. This could cause the syslog buffers to fill up and lose more important messages.
Conditions:
Cisco 2800/3800 & 1560 Series access points connected to Cisco switchports with CDP enabled.
Running 8.3 AP-COS - not 8.4 or above.
Workaround:
In order to prevent these duplex mismatch warning messages from being captured in your syslogs, complete one of these workarounds:
Disable CDP and enable Link Layer Discovery Protocol (LLDP) (if the switch supports it) on the switch port connected to the AP.
Note: For the AP to power on its radios without CDP, enable LLDP for power management.
config terminal
lldp run
interface
no cdp enable
end
Raise the threshold of syslogging to be higher than severity 4, that is, severity 3 (errors) or higher.
config terminal
logging {buffered/trap/console} 3
end
If you do this, the switch will no longer log messages of severity 4 (warnings) or lower.
Further Problem Description:
This doesn't have any operational impact; both AP and Switch are actually operating in full duplex.
For more information, see the field notice https://www.cisco.com/c/en/us/support/docs/field-notices/702/fn70252.html .
This bug affects only 8.3 AP-COS - not 8.2 nor 8.4 or above.
Note: even with this CSCvi02106 fix, you can still see spurious CDP duplex mismatch errors, if using LAG with 2802/3802 APs. Track CSCvi84511 for the fix for that scenario.