Simple definition
The native VLAN is the VLAN to which a device assigns untagged Ethernet frames received on certain links carrying multiple VLANs, especially 802.1Q trunks.
Technical definition
On a trunk, most VLANs are transported with an 802.1Q tag. Depending on the vendor and configuration, one VLAN can be designated as native or associated with the port PVID to handle untagged frames. The transmit and receive behavior for untagged traffic must be consistent on both ends of the link.
How it works / role
Its role is to define how a trunk handles traffic that has no VLAN tag. It can be used for device management or compatibility requirements, but it must be designed carefully to avoid unintended traffic mixing.
What is it used for?
Carry multiple VLANs over one link while explicitly defining how untagged traffic is handled.
Practical example
A wireless access point uses a native VLAN for management and tagged VLANs for different SSIDs. The switch and access point must agree on which VLAN is used for untagged frames.
Common issues
- Native VLAN mismatch between the two ends of the trunk
- Management traffic placed in the wrong VLAN
- Unexpected untagged traffic accepted on the trunk
- Confusion between native VLAN, access VLAN, and PVID terminology across vendors
Key takeaway: On a trunk, always document how untagged frames are handled and verify that both ends use a consistent configuration.