A virtual LAN (VLAN) allows for a single network to be partitioned to create multiple “virtual” networks. These VLAN’s are isolated so that network packets cannot traverse VLAN’s.
VLANs, allow for easy traffic pattern control and for quick reaction to relocations and also provide flexibility to adapt to network requirement changes and simplified administration.
VLAN trunks provide very high security levels with great flexibility against a comparatively low cost.
Quality of Service schemes can optimize traffic on trunk links for realtime data (VoIP) or low-latency requirements (SAN).
VLANs could also be used in a school or work environment to provide easier access to local networks, to allow for easy administration, and to prevent disruption on the network.
An example of how a network may be partitioned over VLAN, giving each group it’s unique set of rights and priveleges.