When the ISW receives an untagged VLAN packet, it will add a VLAN tag to the frame according to the PVID setting on a port. As shown in the following figure, the untagged packet is marked (tagged) as it leaves the ISW through Port 2, which is configured as a tagged member of VLAN100. The untagged packet remains unchanged as it leaves the ISW through Port 7, which is configured as an untagged member of VLAN100.
