What is a vlan?

Hey folks, I want to touch on some of the functionalties and in this specific post I want to discuss the term vlan and hopefully make you guys understand what it is all about.

A vlan is basically a virtual lan so if you think of a single lan , just think of vlans as a feature that creates many lans in one switch that can be subdivided.

Source Image

This type of setup is typically for a larger business that has many users and the need for different lans with different subnets as depicted above. Vlans can improve the performance of networks that are extremely busy and the traffic is generally handled by a core or firewall. In my experience I would rather use a core switch for this type of routing instead of a firewall, my opinion is that a firewall should be used purely for internet activities.

Another term that is commonly used is vlan tagging, so no matter where a user is plugged into on a switch, as a Network Engineer you will be able to tag/untag the user for the vlan you require him to be on as per the above diagram.

This is only a basic overview of vlans and puts into perspective a lot of confusion when you try to understand how you may have multiple subnets in your environment and don't really understand how they communicate.

Thanks for reading.

Regards,
@trev03