/viː.læn/
noun — "the invisible walls that organize a network."
VLAN, short for Virtual Local Area Network, is a network configuration that segments a physical LAN into multiple logical networks, allowing devices to be grouped together based on function, department, or security requirements rather than physical location. VLANs improve traffic management, enhance security, and reduce broadcast domains within enterprise networks.
Technically, VLANs use tagging protocols like IEEE 802.1Q to mark Ethernet frames, enabling switches to identify and segregate traffic. Switches and routers enforce VLAN boundaries, apply QoS (QoS), and support inter-VLAN routing to allow controlled communication between segments.
Key characteristics of VLANs include:
- Segmentation: separates network traffic into logical groups.
- Traffic control: improves performance and reduces congestion.
- Security: limits access to sensitive resources.
- Scalability: easy to reconfigure without changing physical cabling.
- Inter-VLAN communication: controlled via routers or Layer 3 switches.
In practical workflows, network engineers configure VLANs on switches to isolate departments, separate guest Wi-Fi traffic, or prioritize critical applications, ensuring efficient and secure network operation.
Conceptually, a VLAN is like having separate rooms in an open office: everyone shares the same building but works in isolated, well-defined spaces.
Intuition anchor: VLAN organizes networks logically, giving control and security without extra hardware.