Configuring Device Information 295Figure 7-39. MSTP Interface TableConfiguring VLANsVLANs are logical subgroups of a Local Area Network (LAN) created via software rather than defining ahardware solution. VLANs combine user stations and network devices into a single domain regardless of thephysical LAN segment to which they are attached. VLANs allow network traffic to flow more efficientlywithin subgroups. VLANs managed through software reduces the amount of time in which network changesare implemented.VLANs have no minimum number of ports, and can be created per device or any other logical connectioncombination, as VLANs are software based and not defined by physical attributes.VLANs function at Layer 2. Since VLANs isolate traffic within the VLAN, a Layer 3 router functioningrouter is needed to allows traffic flow between VLANs. Layer 3 routers identify segments and coordinatewith VLANs. VLANs are broadcast and Multicast domains. Broadcast and Multicast traffic is transmittedonly in the VLAN in which the traffic is generated.VLAN tagging provides a method of transferring VLAN information between VLAN groups. VLANtagging attaches a tag to packet headers. The VLAN tag indicates to which VLAN the packet belongs.VLAN tags are attached to the packet by either the end station or by the network device. VLAN tags alsocontains VLAN network priority information. Combining VLANs and GVRP enables the automaticdispersal of VLAN information. To open the VLAN page, click Switch→ VLAN in the tree view.QinQ tagging allows network managers to add an additional tag to previously tagged packets. CustomerVLANs are configured using QinQ. Adding additional tags to the packets helps create more VLAN space.The added tag provides VLAN ID to each customer, this ensures private and segregated network traffic. TheVLAN ID tag is assigned to a customer port in the service providers network. The designated port thenprovides additional services to the packets with the double-tags. This allows administrators to expandservice to VLAN users.
