Quick Definition
The VLAN whose frames pass untagged on a trunk link — VLAN 1 by default.
The native VLAN is the VLAN assigned to untagged frames on a trunk port. When a switch receives an untagged frame on a trunk port, it assigns the frame to the native VLAN. When the switch sends a frame from the native VLAN out a trunk port, it sends it without a tag. Both ends of a trunk link must agree on the native VLAN — a mismatch causes a VLAN ID mismatch error and traffic misdelivery.
A native VLAN mismatch causes Cisco switches to generate a CDP warning and can lead to traffic being delivered to the wrong VLAN. The exam often tests whether you can identify native VLAN mismatch from a show interfaces trunk output.
The native VLAN is the VLAN assigned to untagged frames on a trunk port. When a switch receives an untagged frame on a trunk port, it assigns the frame to the native VLAN. When the switch sends a frame from the native VLAN out a trunk port, it sends it without a tag. Both ends of a trunk link must agree on the native VLAN — a mismatch causes a VLAN ID mismatch error and traffic misdelivery.
A native VLAN mismatch causes Cisco switches to generate a CDP warning and can lead to traffic being delivered to the wrong VLAN. The exam often tests whether you can identify native VLAN mismatch from a show interfaces trunk output.
Native VLAN falls under the VLANs domain of the 200-301 exam. Understanding it in context with related terms like vlan and trunk-port is essential for answering scenario-based questions correctly.