VIRTUAL LAN (VLAN)
The working groups on a network, until now, have been created by the association of users on the same network segment, or a hub or hubs.
As a direct consequence, these working groups share the available bandwidth and domains of "broadcast", and the difficulty of management when there are changes to group members. Moreover, the geographical limitation which means that members of a group should be located adjacent to its connection to the same hub or network segment.
Schemes VLAN (Virtual LAN or virtual network), we provide the means to solve this problem through the group performed in a logical rather than physical.
However, virtual networks continue to share the characteristics of the physicists working in the sense that all users have connectivity between them and share their domains broadcast.
The main physical difference with the group, as mentioned, is that users of the virtual network can be distributed across a LAN, even standing at different concentrations of it.
Users can thus "move" through the network, while maintaining its membership of the working group logical.
Moreover, distributed to users of the same group through different logical segments, we achieved as a direct result, the increase in bandwidth in that group of users.
Moreover, the power distribution to users in different segments of the network, bridges and routers can be placed between them, separating segments with different topologies and protocols. For example, different users can maintain the same group, together with Ethernet and FDDI, both in terms of existing facilities and the bandwidth that each one requires, for its specific role within the group.
All this, of course, maintaining the desired security settings for each network administrator: You can allow or not the VLAN traffic in and out from / to other networks.
But you can still go further. Virtual networks that allow us to ubiquity is not limited to geographic hubs or different floors of a building, but to different offices interconnected via WAN or MAN, over countries and continents without any more than the limit imposed by the administrator of such networks.