What is VLAN network?

VLAN stands for Virtual Local Area Network or virtual LAN. A VLAN is defined as a logical group of network devices and is set up based on factors such as functions, parts, applications . of the company.

Currently, VLAN plays a very important role in LAN technology. To see the benefits of VLAN, let's consider the following case:

Suppose a company has 3 divisions: Engineering, Marketing, Accounting, each of which is spread out over 3 floors. To connect computers in one part together, we can install each switch on each floor. That means that each floor has to use 3 switches for 3 parts, so to connect 3 floors in the company need to use 9 switches. Obviously, this method is very expensive and cannot take full advantage of the inherent port numbers of a switch. Therefore, VLAN solution was born to solve the problem in a simple way but still save resources.

As shown in the figure above, each layer of the company needs only one switch, and this switch is divided into VLANs. The computers in the engineering department will be assigned to VLAN Engineering, the PCs in other parts will also be assigned to the corresponding VLANs, Marketing and Accounting. This way of making it possible to save the maximum number of switches must be used and make the most of the available ports.

VLAN classification

1. Port - based VLAN: is a simple and popular VLAN configuration. Each switch port is attached to a specific VLAN (default is VLAN 1), so any host device attached to that port belongs to a certain VLAN.
2. MAC address based VLAN: This configuration is rarely used because of the inconvenience in management. Each MAC address is marked with a specific VLAN.
3. Protocol - based VLAN: This configuration is similar to MAC Address based, but uses a logical address or IP address to replace the MAC address. The configuration is no longer common using the DHCP protocol.

Benefits of VLANs

1. Save bandwidth of network system:
   VLAN divides the LAN into several small segments, each of which is a broadcast domain. When there is a broadcast, it is transmitted only in the corresponding VLAN. Therefore, dividing VLANs saves network bandwidth.
2. Increase security:
   Because devices in different VLANs cannot access each other (unless you use a router connected between VLANs). As in the above example, computers in VLAN accounting can only communicate with each other. The machine in VLAN accounting cannot connect to the computer at VLAN engineer (Engineering).
3. Easily add or remove computers to VLANs:
   Adding a computer to the VLAN is very simple, just configure the port for that machine to the desired VLAN.
4. Help the network with high flexibility:
   VLANs can easily move devices. Suppose in the above example, after a period of use the company decided to leave each part on a separate floor. With VLANs, you only need to reconfigure switch ports and place them on the required VLANs.
   VLANs can be configured static or dynamic. In a static configuration, the network administrator must configure each port of each switch. Then, assign it to a VLAN. In the dynamic configuration, each switch port can configure its VLAN based on the MAC address of the connected device.