Native VLAN Tagging Configuration on Cisco Switches
Native VLAN Tagging behavior can vary depending on the platform and IOS version of a Cisco device. On some platforms, such as those using the CML vIOS_L2 image, tagging must be configured globally for all trunk interfaces on the device. Advanced platforms like the Cisco 6500/6800 series allow per-interface tagging but require an IOS version that supports it.
To enable native VLAN tagging on a per-interface basis on platforms that support it, the following command is used:
Switch(config-if)#switchport trunk native vlan tag
According to the "Cisco IOS Interface and Hardware Component Command Reference," this interface configuration mode command does not activate native VLAN tagging unless the switch is first configured to globally to tag native VLAN traffic. To enable native VLAN tagging globally, use the following command in global configuration mode.
vlan dot1q tag native
For more information, take a look at VLAN - Native VLAN best practices.