The practical applications of a VLAN include the following:
You can create VLANs, or workgroups, for common interest groups.
You can create VLANs, or workgroups, for specific types of network traffic.
You can add, move, or delete members from these workgroups without making physical changes to the network.
By dividing the network into separate VLANs, you can create separate broadcast domains. This arrangement conserves bandwidth, especially in networks supporting broadcast and multicast applications that flood the network with traffic. A VLAN workgroup can include members from a number of dispersed physical segments on the network, improving traffic flow between them.
The switch performs the Layer 2 switching functions necessary to transmit information within VLANs, as well as the Layer 3 routing functions necessary for VLANs to communicate with one another. You can define a VLAN for a single switch or spanning multiple switches. A port can be a member of multiple VLANs. A VLAN is associated with a spanning tree group.
A VLAN packet is classified before it is forwarded. If the packet matches a classification rule, the port membership is checked. If the port is not an allowed member (potential, static, or active), the system drops the packet.