Virtual LANs (VLANs)

With the introduction of Ethernet switches, and their subsequent replacement of Ethernet hubs in corporate LAN environments, came the power to manage traffic flow much more efficiently and in many different ways. One of those ways was to allow users on different switch ports to participate in their own network separate from, but still connected to, the other stations on the same or connected switch. This “network-within-a-network” concept became known as Virtual LAN (VLAN) technology.

Let’s say, for example, that you have a 48-port Ethernet switch. If you have a group of users that constantly use a particular server and produce very large amounts of broadcast traffic, you might want to separate them onto their own segment. But, with VLAN-capable switches, you are able to modify the segmentation within the switch itself, thus saving you the expense of additional network hardware. To do this, you would use the switch management software to assign the ports on which those users and their server were working to their own VLAN. The VLAN for this group could be VLAN #1, for example, and the VLAN everyone else is assigned to could be VLAN #2. Users would still be able to communicate with each other and their respective servers (assuming a router was installed), but broadcast traffic would be isolated.

With large, enterprise-capable switches, this benefit is realized even more so. With hundreds of ports, you can segment the network any way you’d like, even on the fly and into many different segments.