Q Vlan Standard - D-Link DFL-1600 User Manual

9.2. Virtual LAN (VLAN) 57
to the same VLAN, and Client B can only communicate with Server C
through the firewall.
Figure 9.1: A VLAN Infrastructure.
9.2.2

802.1Q VLAN Standard

The IEEE 802.1Q standard defines the operation of VLAN devices that
permit the definition, operation and administration of Virtual LAN
topologies within a LAN infrastructure.
802.1Q specification establishes a standard method for tagging Ethernet
frames with VLAN membership information. As defined in the standard, a
4-byte tag is appended to the Ethernet frame containing one part for
VLAN frame type indicator (0x8100), one VLAN identifier(VID), and some
control information (shown in Table 9.1).
There are 12 bits for VID within each 4-byte tag. With these 12 bits of
identifier, there could be up to 4096 VLANs on a physical network.
However, all ones are reserved and all zeros indicate no VLAN association.
All other identifiers can be used to indicate a particular VLAN.
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