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NETWORKING · SWITCHING

What Is a VLAN?

A VLAN (Virtual LAN) is a logical segment of a network created in a managed switch. Using IEEE 802.1Q tags, it separates traffic into independent broadcast domains over the same physical wiring, so devices behave as if they are on separate networks.

01

The Short Answer

A VLAN groups devices into a logical network that behaves as if it were separate, even though they share the same physical switch and cabling. A managed switch tags each frame with an IEEE 802.1Q VLAN ID and only forwards it to ports in the same VLAN, so traffic in one VLAN never reaches another without passing through a router.

02

How It Works

Each VLAN has a numeric ID (up to 4094). An access port belongs to one VLAN; a trunk port carries several tagged VLANs between switches. Because each VLAN is its own broadcast domain, traffic that needs to cross from one to another has to be routed at Layer 3.

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    Segmentation Keep control, video and corporate traffic on separate logical networks over one set of cables.
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    Security Contain a compromised device or a broadcast storm within its own VLAN.
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    Performance Smaller broadcast domains mean less flooded traffic on each segment.
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    Flexibility Group devices logically, by function, rather than by where they are wired.
03

What You Need

VLANs are a managed-switch feature; an unmanaged switch cannot create them.

VLANs are configured on a managed switch — see our guide to managed vs unmanaged switches, or browse our industrial Ethernet switches.