What is a VLAN?

The idea

Without VLANs, every device plugged into the office network can usually see every other device. Staff computers, the guest Wi-Fi, security cameras, printers and phones all share one space.

A VLAN, short for virtual local area network, divides the network into separate groups. Devices in one VLAN cannot reach devices in another unless the network is set up to allow it. It all runs over the same cables and switches.

Common ways businesses use them

• Guest Wi-Fi in its own VLAN, with internet access only.
• Phones in their own VLAN, so calls get priority and stay clear.
• Cameras, door controllers and smart devices kept apart from computers.
• Payment systems separated from everything else.
• Servers on their own segment, with only the access each group needs.

Why it helps

• Security. If a camera or a guest’s laptop is compromised, the attacker cannot simply reach your file server.
• Performance. Traffic from one group does not crowd out another.
• Control. Rules between VLANs, set on the firewall, decide exactly what can talk to what.

VLANs need switches and access points that support them, and someone to set them up and keep the rules current.