Overview
Configuring virtual LANs (VLANs) helps control the size of broadcast domains and keeps local traffic local. VLANs are associated with individual networks or subnetworks; therefore, network devices in different VLANs cannot communicate with one another without a layer 3 router.

When an end station in one VLAN needs to communicate with an end station in another VLAN, inter-VLAN communication is required. Routing is required to support communication between VLANs. You configure one or more Route Processors or routers to route traffic between VLANs.