A VLAN (Virtual Local Area Network) is a method of segmenting a physical network into multiple logical networks. It allows administrators to group devices together even if they’re not physically connected to the same switch, improving security, performance, and management.

Why use VLANs?

• Security: Isolates traffic between departments (e.g., HR, Finance).
• Efficiency: Reduces broadcast traffic and improves performance.
• Flexibility: Devices can be grouped by function rather than location.

How VLANs work: Each VLAN is assigned a unique ID. Switch ports are configured to belong to a specific VLAN. When a device sends traffic, it’s tagged with that VLAN ID (in 802.1Q tagging) and routed accordingly.

Example use case:

• VLAN 10: HR computers
• VLAN 20: Sales team
• VLAN 30: Guest Wi-Fi

A router or Layer 3 switch is required to allow communication between VLANs—a process known as inter-VLAN routing.

VLAN Types:

• Static VLAN: Ports are manually assigned to a VLAN.
• Dynamic VLAN: Devices are assigned to VLANs based on MAC address or other attributes.

Using VLANs simplifies network management and enhances security, especially in enterprise or campus environments. Understanding VLANs is a key skill for network administrators and cybersecurity professionals.