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3.2 VLAN Function
The switch supports port-based VLAN, 802.1Q Tag Aware VLAN and eight VLAN groups. Some
VLAN related terminologies are described as follows:
VLAN Group
VLAN group specifies a VLAN information that can be referred by the switch in performing VLAN
mapping and packet forwarding for ingress port and the received packets. The information includes:
•Group Number : index number of the VLAN group ( 1 ~ 8 )
•VID (VLAN ID) : 12-bit value to indicate a VLAN to which the group is associated (1 ~ 4095)
•Member Ports : the ports belong to this VLAN group for egress
Ingress Port
Ingress port is the input port on which a packet is received.
Default VLAN Group Index (Port VLAN index)
Each port has this index, which points to a default VLAN group. It is used for mapping a VLAN group
for the ingress port under Port-based VLAN mode. It is also used for mapping to a VLAN group for
an untagged received packet under 802.1Q Tag Aware VLAN mode.
PVID (Port VID)
PVID is the default VID of an ingress port. It is obtained from the VID of the indexed default VLAN
group by the ingress port. It is often used in ingress packet filtering and egress tagging operation.
Egress Port
Egress port is the output port from which a packet is sent out after VLAN operation.
Null VID Packet
A tagged packet is called Null VID packet if the packet’s VID is equal to 0. Sometimes, it is also called
priority tag packet.
3.2.1 VLAN Operation
The following figure illustrates the basic VLAN operation flow beginning from a packet received on an
ingress port until it is transmitted from an egress port.