VLAN Overview

The VLAN features include the following

  • VLAN is a function to divide a network by layer2 switch.
  • Improves network flexibility and scalability
  • Improves security by limiting the extent to which data is transferred.
  • Networks divided by VLANs are interconnected by routers/Layer 3 switches.

The VLAN is a feature of the Layer 2 switch that divides the network. How it is divided depends on the configuration. The network can be divided without changing the physical wiring or layout. This has the advantage of increasing the flexibility and scalability of the network configuration.

The following article explains how networks are divided by VLANs.

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VLAN behavior
https://www.n-study.com/en/vlan-detail/vlan-behavior/
The VLAN is very simple. It divides the network by "forwarding Ethernet frames only between ports of the same VLAN".

Note that VLAN only divides a network. The divided networks are not interconnected. Therefore, if the VLANs are different, no data will be transferred and no communication will be possible. This means that VLAN improves security.

The word “security” has so many different meanings, and each person who hears the word “security” will have a very different image of it.。

Security in VLAN is not about encrypting data or authenticating users. By limiting the range in which data is transmitted, VLAN improves security by limiting the impact of any unauthorized communication.

And it would be inconvenient to have no communication between different VLANs (networks). If the network is divided into VLANs for each department, communication between departments will be impossible. Therefore, the networks divided by VLANs are interconnected using routers/Layer 3 switches. In most cases, a layer 3 switch is used.

VLAN(Virtual LAN)