Symptoms
Connected to the console port I was getting the following messages over and over again. In my case vlan 23 went to the WAN port on a IPS server and vlan 200 went to the LAN port on the same server. It is not a switch but I was told because it was crossing vlans cdp was reporting the issue even though it wasn't a problem.
Mar 9 23:15:26.022: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on GigabitEthernet1/0/3 (200), with 3750X-CS.kbsi-cs.com GigabitEthernet1/0/2 (23).
Mar 9 23:15:30.971: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on GigabitEthernet1/0/2 (23), with 3750X-CS.kbsi-cs.com GigabitEthernet1/0/3 (200).
Diagnosis
interface GigabitEthernet1/0/2
description Sentinel - WAN
switchport access vlan 23
switchport mode access
end
3750X-CS#sh run inter g1/0/3
Building configuration...
Current configuration : 133 bytes
!
interface GigabitEthernet1/0/3
description Sentinel - LAN
switchport access vlan 200
switchport mode access
end
Solution
In this case everything was working as designed. The notification was because the ports were connected to the same device crossing vlans. So we applied "no cdp enable" on both interfaces and the logs messages stopped.
