Default VLAN

The default VLAN ID of an interface is called the port default VLAN ID (PVID). Frames processed on a switch all carry VLAN tags. Whether the VLAN tags are added or removed depends on whether the frame is tagged or untagged, and whether the frame has the same VLAN ID as the interface's PVID. The details are as follows:

• When an interface receives an untagged frame, the switch adds a tag with the PVID to the frame and processes the frame. When an interface receives a tagged frame, the switch does not add a tag with the PVID to the frame.
• 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 following describes the effect of changing the default VLAN ID on different interface types:

• The default VLAN of an access interface is the VLAN allowed by the access interface. Changing the allowed VLAN of an access interface will change its 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.