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virtual LAN

Also called a "VLAN," it is a logical subgroup within a local area network that is created via software rather than manually moving cables in the wiring closet. It combines user stations and network devices into a single unit regardless of the physical LAN segment they are attached to and allows traffic to flow more efficiently within populations of mutual interest.

VLANs are implemented in port switching hubs and LAN switches and generally offer proprietary solutions. VLANs reduce the time it takes to implement moves, adds and changes.

VLANs function at layer 2. Since their purpose is to isolate traffic within the VLAN, in order to bridge from one VLAN to another, a router is required. The router works at the higher layer 3 network protocol, which requires that network layer segments are identified and coordinated with the VLANs. This is a complicated job, and VLANs tend to break down as networks expand and more routers are encountered. The industry is working towards "virtual routing" solutions, which allows the network manager to view the entire network as a single routed entity. See 802.1q.

Virtual LANs solve the problem of containing traffic within workgroups that are geographically dispersed. They allow moves, adds and changes to be performed via software at a console rather than manually changing cables in the wiring closet.
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References in periodicals archive ?
IEEE 802.1Q-based VLAN for network segmentation to improve performance and security
General Dynamics Mission Systems has introduced Agile virtual local area network (VLAN), adding capability to TACLANE encryptors by enabling users to send and receive layer two and high assurance Internet protocol encryptor (HAIPE) traffic, the company said.
VLAN access control lists (VACLs) can also be used as an enhanced security measure to specify and limit the types of traffic that can propagate over the VLAN.
The device has 4 LAN ports, 1 WAN port, Wi-Fi and supports multiple WAN with VLAN features.
Automatic Voice VLAN, Guest VLAN and Dynamic VLAN assignment
The need is to configure the EUB ingress port that goes to the desktop to have the appropriate L2 VLAN ID that will be mapped to the correct L3VPN.
This mechanism uses a VLAN tag for dividing a virtual network.
Today's mainstream VLAN technology, which accommodates customer systems using IPv4 addresses by logically dividing them to avoid interference, can only accommodate up to 4,000 IPv4 networks, or about 1,000 companies (assuming 4 VLANs per customer).
The technology, trademarked as VLAN Policy Mapping, enables network and security administrators to define and enforce how they want their authorised Wi-Fi traffic to map on the wired network segments.
A virtual local network (VLAN) is a logical grouping of local network components without regard to their physical grouping.