A VLAN, such as the LAN it lies atop, works at the Ethernet-level Layer 2 of the network. VLANs divide a single switching network into a collection of virtualization that can fulfill various functional and security criteria. 

A virtual LAN (VLAN) is a virtual layer network that organizes and isolates the traffic for a subset of machines that use a physical LAN. It has become recently popular as a source of networking in contrast with other modes.

This article will explain what is a VLAN. Furthermore, the advantages and effects of using VLAN will be discussed in detail. Lastly, the consequences of using VLAN in comparison with other modes will be highlighted. 

What Is A LAN?

A LAN is a collection of devices or computers that use the same network infrastructure in the same location, such as the same campus or building.  

A LAN is typically connected with just an Ethernet (Layer 2) broadcasting domain, which refers to the set of network devices that may receive an Ethernet broadcast packet. This segmentation eliminates the requirement for several, unique physical networks for various use cases.

Machines on the LAN communicate either directly or via access points (AP’s) linked to the same switch port. Computers also can link to one of a group of linked switches, such as a group of access switches connected to a core switch. 

Once traffic traverses a router and performs Layer 3 (IP-related) operations, it is no longer regarded as being on the same LAN, even though all devices remain on the same floor. Consequently, a site may include several linked LAN’s.

What Is The Purpose Of Using A VLAN?

Without VLAN’s, a host’s broadcast can reach all devices without difficulty. Every gadget will process received broadcast frames. It might raise the CPU burden on each gadget and decrease network security overall however.

If interfaces on both switches are placed in distinct VLAN’s, broadcasting from each host can only reach devices within the same VLAN. Clients of separate VLAN’s will be completely unaware of the communication.

VLAN’s are utilized by network engineers and security professionals for numerous purposes, including the following:

1. Enhance Performance

By decreasing the quantity of traffic an endpoint sees and processes, VLAN’s can enhance the performance of devices on them. 

VLAN’s fragment broadcast domains, hence decreasing the number of hosts from which a particular device receives broadcasts to enhance performance to bolster security in order to simplify administration.

Additionally, engineers can create distinct traffic regulations per VLAN. For instance, they can configure rules to prioritize video traffic on the VLAN that connects the equipment in a conference room in order to ensure the functioning of video conference devices.

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2. Enhance Security

VLAN’s can also enhance security by allowing more control over which devices can communicate with one another. For instance, network teams may limit administrative access to network equipment or internet of things (IoT) devices to particular VLAN’s.

Separating your IoT devices from your other computing devices will help enhance the security of those devices. IoT devices are built with bad security so you need to everything in your power to secure them and any network traffic going to and from them.

This process of separating categories or different devices from one another is called network segmentation. This means that the VLAN cannot communicate with or (screenshot below). This is good because if a machine were to be compromised on any of those three VLAN’s, then an attacker cannot pivot to the other networks or attack other machines, aside from what’s in the current VLAN they breached.

3. Simplify Administration

Using VLANs to combine endpoints also allows administrators to organize devices for non-technical administrative objectives. For instance, they may place all accounting machines on one VLAN, the human resource management computers on another, etc. Again, this is an example of network segmentation and a very common use of it in a corporate environment.

What Are The Types of Virtual LANs?

VLAN’s can be port-based (occasionally referred to as static) or used logically (sometimes called dynamic). These are explained as:

1. VLAN Port-Based Or Static

Port-based VLAN’s are created by designating ports on a switch port to a VLAN. These ports only communicate via the specified VLAN’s, and each port belongs to a single VLAN. 

Although port-based VLAN’s are commonly referred to as static VLAN’s, it is crucial to note that they are not actually static, as the VLAN’s allocated to the port can be modified on the fly, either manually or through network automation.

2. VLAN Based On Use Or Dynamic

Network engineers build use-based VLAN’s by dynamically allocating information to a VLAN depending on the kind of traffic or the device generating it. 

A port may be allocated to a VLAN depending on the linked device’s identification — as evidenced by an authentication server — or the internet protocol in use. Multiple dynamic VLAN’s might be associated with the same port. 

Switching the device that’s attached to a port or even how the current device is utilized, may alter the VLAN allocated to that port.

3.. VLAN Usage Cases

Some VLAN’s have straightforward and functional purposes, such as separating printer access from other network devices. Administrators can configure them to allow computers on a certain VLAN to view printers on that VLAN, but not those on other VLAN’s.

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Other VLAN’s perform more intricate functions. For instance, machines in a consumer banking department cannot interface directly with trading department computers. 

What Is The Function of VLAN?

A VLAN ID identifies a VLAN on network switches. Each port on a switch may be allocated to one or even more VLAN ID’s; if none are set, the port will join the default VLAN. Each VLAN gives data-link access to any computers linked to switch ports with its VLAN ID defined.

A VLAN ID is converted to a VLAN tagged, which is a 12-bit column in the Ethernet frame header data for every frame delivered to that VLAN. Since a tag is 12 bits in length, a switching domain may specify up to 4,096 VLAN’s. 

IEEE defines VLAN tagging in the 802.1Q specification. When an Ethernet transmission is obtained from a connected host, no VLAN tag is present. IEEE stands for Institute of Electrical and Electronics Engineers. This organization educates and trains professionals in the technical career fields and creates literature and standards computing.

The VLAN tag is added by the switch. Inside a static VLAN, a switching inserts the tag corresponding to the VLAN ID of the ingress port. It adds the tag linked with such a device’s ID or even the kind of traffic it produces in a dynamic VLAN. Switches transmit tagged frames to their target access control address, but only to ports that are affiliated with the VLAN. 

Multicast, broadcast, and unknown unicast data are sent to all VLAN ports. Trunk links connecting switches are aware of which VLAN’s span them and accept and forward all information for any VLAN that is used on either end of the trunk. 

When a frame arrives at its target virtual switch, the VLAN identifier is conducted due to transmission to the target device. Spanning Tree Protocol (STP) is employed to build a loop-free topology among Layer 2 switches. 

Utilizing a per-VLAN spanning tree protocol (STP) implementation supports diverse Layer 2 topologies. Many STP instances can be utilized to decrease STP costs for the same topology. Per-VLAN spanning tree protocol (PVST), is a Cisco proprietary protocol that which separate spanning tree for every VLAN. The spanning tree helps with issues occurring when computers fight to use shared network paths at the same time on the LAN. It also helps with redundancy and prevents data looping.

What Are The Disadvantages of VLANs?

VLAN’s aid in controlling broadcast traffic, enhancing security, simplifying management, and enhancing performance. However, they also have certain downsides:

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1. VLAN’s Maximum Per Switching Domain

In a contemporary data center or cloud infrastructure, the limitation of 4,096 VLAN’s per changing domain is a downside of VLAN’s. 

A specific network segment may support a large number of systems with a large number of tenant organizations, each of whom may require dozens or dozens of VLAN’s.

Other protocols, such as Virtual Extensible LAN, Network Virtualization utilizing Generic Routing Encapsulation, and Generic Network Virtualization Encapsulation, have been developed to overcome this problem. 

They feature bigger tags, which permit the definition of additional VLAN’s, as well as the capability to tunnel Layer 2 packets inside Layer 3 packets.

2. Administration Of Spanning Tree Structures

When there are numerous and big VLAN’s, it might be challenging for the network to manage the spanning tree topologies required to avoid traffic loops. The simplest solution is to eliminate redundant network lines. 

Unfortunately, this then exposes the network to a singular point of failure wherever a redundant connection was eliminated.

3. VLAN Identification Using Wall Jacks And Access Points

It might be difficult to easily identify the VLAN’s with which a particular wall socket or AP has access. This can make it more challenging for end users or field service support personnel to connect new devices to the network.

Another problem that is not specific to VLANs but nevertheless impacts them, is inadequate planning, that makes the entire VLAN design too complex, fragile, and hard to maintain when requirements and underlying network gear change.

What Is An Illustration Of A VLAN?

Due to their offices and numerous staff, a WAN (wide area network) is utilized by a number of firms. Multiple VLAN’s would considerably accelerate network operations in these situations. 

Large organizations frequently engage in cross-functional projects. The simplicity of setting VLAN’s and reassigning users to VLAN’s allows interdepartmental teams to be placed on the same VLAN to support a large amount of data exchange. 

When network segmentation promotes flexible teaming, marketing, sales, IT, and industry experts may collaborate most effectively to achieve high-stakes objectives.


Although VLAN’s face their own challenges, such as VLAN incompatibilities, manged service providers (MSP’s) who understand how to establish a VLAN correctly may utilize the significant network segmentation features of VLAN’s to make their customers’ networks more secure and physically flexible. 

Therefore, it can be conclusively said that MSP’s that are able to perform VLAN maintenance and verify device distribution can boost and maintain network performance as networks grow over time. VLAN’s is a viable option in this regard.