Port VLAN ID

A Port VLAN ID (PVID) is a default VLAN ID that is assigned to an access port to designate the virtual LAN segment to which this port is connected. The PVID places the port into the set of ports that are connected under the designated VLAN ID. Also, if a trunk port has not been configured with any VLAN memberships, the virtual switch's Port VLAN ID (PVID) becomes the default VLAN ID for the ports connection.

In Short, Setting a Port VLAN ID will cause the selected port to participate on the VLAN network and become isolated from the rest of the network, this is often used in networks which require a certain VLAN (Such as Management or CCTV) to not be accessible by other on the network.