What is a VLAN? Understanding Virtual Local Area Networks

What is a VLAN? How does it work? When one or more LANs are combined, they create a custom network known as VLAN. This network aims to connect devices in different networks in one logical group. While administered like a physical LAN, but it’s in fact a virtual LAN.

What is the Importance of VLAN?

When the VLAN is not in place, the broadcast shared by a host can easily reach all devices present in the network. So, each device in the network will process broadcast, and as a result, the CPU overhead will be increased. Moreover, it reduces the overall security of the network.

When the VLAN is in place, the broadcast from one host will reach the available devices within the same VLAN. More importantly, the hosts will not even be aware of the communication. In simple words, VLAN is the virtual extension of LAN.

How Does VLAN Work?

The step-by-step working details of VLANs are given below:

• A number identifies VLAN in networking, and the valid number range is 1-4094
• You can assign a proper VLAN number to ports on a VLAN switch
• It’s the switch’s responsibility to allow data to be sent between different ports with the same VLAN number
• All networks are larger than a switch, so ensure that there is a proper way for sending traffic between two switches
• The most simple and easy way is to assign a port to each network switch and ensure a proper VLAN number. You can also attach a cable between the switches.

Characteristics of VLAN

If you’re still unsure about what is a VLAN, then read the following characteristics:

• It can help structure the different groups of devices regardless of their networks
• As it decreases the number of hosts connected to the broadcast domain, so it reduces the security threats
• If the host contains sensitive information, it can help configure the separate VLAN
• It groups the users according to their department instead of their location
• In VLAN, changing port-level configuration can help you change hosts or users
• Each VLAN acts as an individual virtual LAN, so it shares traffic and reduces congestion
• It allows each workstation to be used at full bandwidth
• Single VLAN can span various switches
• Terminal relocation is easy in VLAN
• VLAN increases the broadcast domains

Applications of VLAN

VLAN has many uses, such as:

• You can use it when there are over 200 devices on your LAN
• It’s helpful, especially when you have lots of traffic on LAN
• It’s used when users/hosts need more security
• VLAN helps when the broadcasts slow down the network
• It converts a single switch into multiple ones
• When all the users are not on a broadcast domain, you can use VLAN

What are the Types of Virtual Local Area Networks?

Predominately, there are three types of VLAN:

Port-Based

This type of network is grouped by a port. A port is manually configured to a VLAN member in this VLAN type. In this type, ports are configured with the same VLAN number, so the devices connected to this port will associate with the same broadcast domain.

Setting this type of network is a challenge because it’s not easy to identify which ports are appropriate to each virtual local area network. The physical port of a switch doesn’t give you the idea of VLAN membership. If you want to know this detail, you can find it by checking the configuration details.

Protocol Based

This VLAN type is used to process traffic using a protocol. This protocol can help define criteria for tags. Moreover, it also filters the criteria for untagged packets. In this type, it’s easy to determine the membership of VLAN, and it can be done by carrying layer-3 protocol through the frame. This type is mainly used in multi-protocol environments. Remember, it’s not a good idea to use it in a predominantly IP-based network.

MAC Based

This VLAN type assigns VLAN numbers to untagged packets. As a result, they identify traffic by using the packet source address.

In VLAN mapping, you’ll have to define the MAC address and specify the entry using the proper VLAN ID. It’s easy to classify traffic because all the device ports contain the configuration of tables.

Why use VLANs?

VLANs can be used in a business environment for several reasons:

Performance

In networks, traffic consists of broadcasts, and by using VLAN, you can reduce the traffic to unnecessary destinations. Let’s clear it with an example. If there are ten users in a broadcast domain, and the traffic is intended for only five users, you can place those five users on a separate VLAN, reducing the traffic.

Routers have to do more work to process the incoming traffic. So, when the traffic through routers increases, the latency in the routers also increases. As a result, the performance is compromised. In contrast, VLAN uses switches and reduces the number of routers by creating broadcast domains.

Formation of Virtual Workgroups

Nowadays, you’ll see many cross-functional teams containing members from different departments. Organizations create these workgroups for a short period, during which there will be lots of communication between departments during this period. So, setting up a VLAN can be the best approach.

VLAN helps place members together. If you don’t want to use VLAN, then you’ll have to move all the workgroup members physically close to each other. It looks like a practical solution, but it also comes with some problems. All the users might not be on the same floor. Moreover, there is a need for centralized server farms.

Reduced Cost

As mentioned earlier, it reduces the need for expensive routers by creating broadcast domains. So, it’s a cost-effective solution.

Security

There is a possibility that the sensitive data is broadcasted on a network, so placing only those users with access to VLAN can prevent outsiders from gaining access to sensitive data. Moreover, people use VLANs to restrict access, set up firewalls, and control broadcast domains.

Easy and Simple Administration

The high costs of the network are due to changes and the addition of users in the network. For example, adding new cables and providing new routers becomes essential when a new user comes in LAN. But you can simplify tasks and reduce costs by using a VLAN. For example, there is no need to configure routers when a user is moved within VLAN.  

Moreover, the other administrative tasks are also eliminated by using VLAN. It has been observed that VLAN adds a layer of administrative complexity. However, it’s still essential to use it to manage virtual workgroups.

Advantages and Disadvantages of VLAN

Like LAN, MAN, and WAN, VLAN also has advantages and disadvantages.

Pros

So, let’s discuss the most important pros of VLAN:

• VLAN fixes the broadcast problems
• It allows you to add extra security to networks
• VLAN makes device management accessible and simple
• It helps make the logical grouping of connected devices according to their functionality instead of location
• It reduces the size of broadcast domains
• It allows you to segment departments logically based on project teams, departments, and tasks
• VLAN reduce the latency
• It improves the network security
• VLAN helps to keep hosts separated
• It protects information so the users can work on the data without being viewed by others
• It removes the physical boundaries
• VLAN makes the network segmenting easy
• You can save costs because it doesn’t need additional cabling
• It can change the user’s IP subnet in the software
• It’s excellent for reducing the number of devices for a particular network
• VLAN makes the management of physical devices easy
• It improves the network performance

Drawbacks

It has some cons as well, so let’s have a look at them as well:

• If the injected packet gets leaked, it can result in a cyber-attack
• If there is a threat in a single system, it can cause havoc through the whole network
• In the case of large networks, you need additional routers to control the workload
• Forwarding network traffic from one VLAN to another isn’t possible
• Interoperability problems are expected in VLANs

Is there a difference between a LAN and VLAN?

Yes, there are lots of differences between both networks. Let’s look at some of the differences between a LAN (Local Area Network) and vLAN (Virtual Local Area Network):

• LANs connect devices in the same geographic area.
• vLANs are a network created by one or more LANs
• The latency of VLAN is low as compared to LAN
• LAN is expensive than VLAN
• In a LAN, the packet is advertised and viewed by each device, while in VLAN, the packet is shared with a specific broadcast domain
• LAN uses FDDI and ring as a protocol while the VLAN uses VTP and ISP protocols

Also Read: LAN vs WAN: What is the difference between a LAN and a WAN?

Final Words

VLAN is different from LAN in many ways but keeping the advantages of VLAN in mind. VLANs are ideal for improving the network’s security by controlling the latency and cost.