By defining VLANs on a LAN we aim to achieve the following objectives:
- Data traffic from certain logical units should be concealed from the other network users.
- Broadcast traffic should also be restricted to these logical units, to avoid placing unnecessary load on the entire LAN.
- Data traffic from certain logical units should be handled with a higher priority for certain network users.
An example by way of illustration: In a LAN, a switch is connected to a hub, which connects 4 PCs in the Marketing department to the network. A server and two PCs in the Accounting department are connected directly to the switch. The final segment is a wireless-network base station that connects four WLAN clients from the Sales department to the network.
The PCs from Marketing and Sales should be able to communicate with one another. The Accounting department also needs access to the server, but their communications should remain concealed from the other PCs.
