What is a VLAN and why is it needed in modern organizations?

A VLAN, or Virtual Local Area Network, is a technology that allows you to logically divide a single physical network of switches into several isolated virtual segments. As a result, devices connected to different physical switches can be grouped together as if they were in the same room and connected to the same device, and vice versa.

The primary goal of implementing a VLAN is to improve the security, manageability, and performance of a corporate network. Without division into virtual networks, all broadcast traffic from every device spreads across the entire physical network, creating unnecessary load and reducing overall speed. Using VLANs allows you to solve the following tasks:

To exchange data between different VLANs, a layer 3 device of the OSI model is required, such as a router or a managed switch with routing capabilities. To transmit tagged traffic of multiple VLANs over a single physical cable between switches, special trunk ports are used that add a virtual network identifier to each frame.