What Is a VLAN and How Does It Work?

A virtual LAN (VLAN) is a group of computers connected to the same network but are not physically near each other. Using a VLAN allows for more efficient use of network resources and can be helpful where there are too many devices for a single network.

So, what is a VLAN, how does it work, and when should you use one?

What Is a VLAN?

A VLAN is a Virtual Local Area Network. It’s a logical grouping of devices on a network, usually based on location or function. For example, all computers in a school’s library could be assigned to the “Library” VLAN, while all computers in the school’s computer lab could be assigned to the “Computer Lab” VLAN. In this way, VLANs can improve the efficiency and flexibility of a local area network.

A VLAN can improve security and performance by isolating traffic on your network. It can also make it easier to manage your network by grouping devices that need similar settings. Although VLANs are most commonly used in Ethernet networks, they can also be used in other network types, such as Asynchronous Transfer Mode (ATM) and Fiber Distributed Data Interface (FDDI).

How Does a VLAN Work?

A VLAN is created by adding a tag, or header, to each Ethernet frame. This tag tells the network which VLAN the frame should be sent to. Devices in different VLANs can’t see each other’s traffic unless connected to a router configured to allow it.

Why Use a VLAN?

There are many benefits to using VLANs.


1. Security

By isolating traffic on different VLANs, you can prevent unauthorized users from snooping on network traffic.

2. Performance

VLANs can improve performance by reducing broadcast traffic. Broadcast traffic is traffic sent to all devices on a network, regardless of whether they need it. By putting devices in different VLANs, you can reduce the amount of broadcast traffic your network has to deal with.

3. Flexibility

VLANs can make it easier to add or remove devices from your network. For example, if you want to add a new device to your network, you can simply assign it to the appropriate VLAN. You don’t need to reconfigure your whole network.

4. Management

VLANs can make it easier to manage your network by grouping devices that require similar settings. For example, you can put all the devices in your sales department on the same VLAN. This way, you can easily apply the same security and performance settings to all the devices in that group.

When Should You Use a VLAN?

There are a few circumstances when a VLAN can be beneficial. First, if you have a large network with many devices, you may want to use VLANs to segment it into smaller parts. This can make it easier to manage and troubleshoot your network. VLANs can also improve security by isolating traffic on your network.

Second, if you need to create a temporary network for events or projects, a VLAN can be a convenient way to do so. Finally, if you have devices that need to be on different network subnets for any reason, using a VLAN can allow you to keep them all on the same physical network.

Potential Security Risk of Using VLANs

Although VLANs offer many benefits, there is one potential security risk to be aware of. If a malicious user somehow gains access to a device connected to a router, they could conceivably send traffic to other VLANs that they should not have access to in a process known as VLAN hopping. To prevent this, ensure that you properly secure all devices on your network and only allow trusted users to access them.

It’s Time to Start Using a VLAN

VLANs can be a helpful tool in managing and securing large networks. However, as with any technology, there are potential risks to be aware of. Be sure to consider these when deciding whether to use VLANs on your network.

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