VLANs help to control traffic—With traditional networks, broadcast traffic that is directed to all network devices, regardless of whether they require it, causes congestion. VLANs increase the efficiency of your network because each VLAN can be set up to contain only those devices that must communicate with each other.
VLANs provide extra security—Devices within each VLAN can communicate only with member devices in the same VLAN. If a device in VLAN Marketing must communicate with devices in VLAN Sales, the traffic must cross a routing device.
VLANs ease the change and movement of devices—With traditional networks, network administrators spend much of their time dealing with moves and changes. If users move to a different subnetwork, the addresses of each endstation must be updated manually.