Default VLAN
The default VLAN ID of an interface is called the port default VLAN ID (PVID). Frames processed in a switch all carry VLAN tags. When the switch receives an untagged frame, it adds a VLAN tag to the frame according to the default VLAN of the interface that received the frame. The PVID is used in the following scenarios:
- When an interface receives an untagged frame, the interface adds a tag with the PVID to the frame and sends the frame to the switch for processing. When an interface receives a tagged frame, the tag is not added.
- When an interface sends a frame in which the VLAN ID is the same as the PVID, the switch removes the tag from the frame before sending it out from the interface.
Each interface has a default VLAN. By default, the default VLAN ID of all interfaces is VLAN 1.
- The default VLAN of an access interface is the VLAN allowed by the access interface. Changing the allowed VLANs will also change the default VLAN.
- Trunk and hybrid interfaces allow multiple VLANs but have only one default VLAN. Changing the allowed VLANs will not change the default VLAN.
