Native Vlan Mismatch.

[Nooby69]

Hi,

Can someone help me understand why my native vlan was set to (inactive).

and I get an error on both switch device saying

CDP-W-NATIVE_VLAN_MISMATCH: interface gi6.Native VLAN mismatch detected on interface gi6.

If you have a fix please let me know that will be a big help 

[Filip Knezevic]

Hello,

Can you post configuration of both ports? You have a native vlan mismatch and it is usually a configuration issue.

[Filip Knezevic]

The problem is that on port Gi 6 you have have vlan 1 untagged and on port 50 you have it tagged. That's why you have a native vlan mismatch. Just paste the configuration of both ports and I'll tell you how to fix it.

[luis_cordova]

Hi @Nooby69 

Could you start the configurations of the connected devices?

Regards

[Deepak Kumar · Accepted solution]

Hi,

CDP-W-NATIVE_VLAN_MISMATCH: interface gi6.Native VLAN mismatch detected on interface gi6.

The Native VLAN mismatch is reported by the CDP protocol. Why is it happening? 

You had configured trunk port between two devices and there is VLAN misconfiguration on any of the device. For example:

SwitchA (Port1)----trunk port ------- SwitchB (Port2) are connected than where is a mistake:

Switch A port 1 configuration:

switchport mode trunk
switchport trunk native vlan 1
switchport trunk allowed vlan 10-16

Here you can notice that I had added Native VLAN as VLAN ID 1 (it is default native VLAN ID (1) and this command (switchport trunk native vlan 1) will not visible in the running configuration).

Switch B Port 2 Configuration:

switchport mode trunk

switchport trunk native vlan 16

switchport trunk allowed vlan 1, 10-15

Here you can notice that I had added Native VLAN as VLAN ID 16.

This is the reason for a native VLAN mismatch error. I have to make changes in the configuration of any one device as I am making changes on the Switch B

as

switchport mode trunk
switchport trunk native vlan 1
switchport trunk allowed vlan 10-16

Note: Trunk port VLAN allocations must be matched with another remote device trunk port otherwise you will face issues as no communication for mismatch VLAN, error messages on the device, etc.