Overview
A VLAN is a logical group of network devices that appear to be on the same LAN, regardless of their physical location. They are configured so that they can communicate as if they were attached to the same physical connection, when in fact they are located on a number of different LAN segments. VLANs can be configured with management software, such as the NMC-RX application, and are extremely flexible because they are based on logical, rather than physical, connections.
With the NMC-RX application, you create VLANs and then associate them with Ethernet interfaces.
A VLAN permits multiplexing multiple IP and/or Point to Point Protocol over Ethernet (PPPoE) interfaces over a single physical Ethernet port. This multiplexing is accomplished through VLAN subinterfaces.
When you create a VLAN, you create a network-wide object with a logical name and a VLAN ID. You can then associate this VLAN with Ethernet interfaces. When you make this association, a major interface (if one does not already exist) and a subinterface with this VLAN's ID are created automatically.
Figure 1 shows a basic VLAN protocol stack.
