24.4.3 Configuring native VLAN for trunk ports
- Points to note
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Set a native VLAN for handling untagged frames on a trunk port. Only port VLANs can be set for a native VLAN.
When the VLAN ID of a native VLAN is specified for the switchport trunk allowed vlan command, the VLAN handles untagged frames on the trunk port. The native VLAN is VLAN 1 (the default VLAN) unless explicitly specified otherwise in the configuration.
To handle tagged frames (where the VLAN tag has a VLAN ID of 1) for the default VLAN on a trunk port, change the native VLAN to another VLAN.
Command examples
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(config)# vlan 10,20
(config-vlan)# exit
Creates VLAN ID 10 and VLAN ID 20 as port VLANs.
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(config)# interface gigabitethernet 1/0/1
(config-if)# switchport mode trunk
Switches to the Ethernet interface configuration mode for port 1/0/1. Then, sets the port as a trunk port. At this point, the native VLAN for trunk port 1/0/1 is the default VLAN.
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(config-if)# switchport trunk native vlan 10
(config-if)# switchport trunk allowed vlan 1,10,20
Sets the native VLAN for trunk port 1/0/1 to VLAN 10. Also, set VLAN 1,10,20. VLAN 10 (the native VLAN) handles untagged frames, and VLAN 1 (the default VLAN) and VLAN 20 handle tagged frames.