tagged VLAN
You can identify
packets as belonging to the same tagged VLAN (Virtual LAN) by putting a value
into the 12-bit (4 octet) VLAN ID field that is part of the IEEE 802.1Q field of the header.
Using this 12-bit field, you can configure up to 4096 individual VLAN addresses (usually
some are reserved for system VLANs such as management and default VLANs); these tagged VLANs
can exist across multiple devices. The tagged VLAN can be associated with both tagged and
untagged ports.