Everything You Need to Know About a VLAN

A VLAN is a collection of devices on one or more LANs wired to communicate as though they were connected to the same cable, despite the fact that they are spread over many LAN segments. VLANs are extremely flexible because they are based on logical rather than physical connections. In a Layer 2 network, VLANs define broadcast domains. A broadcast domain is a collection of all devices that will broadcast. In a Layer 2 network, VLANs describe broadcast domains. A broadcast domain is a collection of all instruments that can accept broadcast frames from any system. Since routers do not forward broadcast frames, broadcast domains are usually bounded by routers. Layer 2 switches build broadcast domains depending on the switch’s setup. Switches are multi-port bridges that connect several devices.

Switches are multi-port bridges that allow the development of multiple broadcast domains. Each broadcast domain is analogous to a separate virtual bridge within a switch. Within a switch, you can define one or more virtual bridges. Each virtual bridge you add to the switch creates a new broadcast domain (VLAN). Traffic cannot be diverted or transferred directly to another VLAN (or between transmitted domains) inside the switch or within switches.  Routers or Layer 3 switches must be used to link two separate VLANs.

How VLAN works

  • In networking, VLANs are marked by a number.
  • 1-4094 is a legitimate range. On a VLAN swap, you allocate the required VLAN number to each port.
  • The transfer then allows data to be transmitted between ports that are part of the same VLAN.
  • Since nearly all networks have more than one switch, there should be a way to send traffic between them.
  • One convenient and fast way to do this is to add a VLAN port to each network switch and connect them with a cable.

Basic VLAN Characteristics 

  • Virtual LANs have framework for grouping machines, even though their networks are not the same.
  • It extends the number of transmitted domains that can be used in a LAN.
  • Implementing VLANs eliminates security risks by reducing the number of hosts linked to the broadcast domain.
  • This is achieved by configuring a separate virtual LAN with only the hosts that hold confidential data.
  • It has a modular networking model that groups users based on departments rather than network location.
  • Changing hosts/users on a VLAN is a simple method. It just needs a new port-level setup.
  • It will minimize congestion by exchanging traffic since each VLAN operates as a single LAN.
  • Each port on a workstation can be used for maximum bandwidth.
  • Terminal reallocations become simple.
  • A VLAN can span several switches.
  • The trunk connection can carry traffic from several LANs.

Types of VLANs

There are three types:

  • Protocol based VLAN
  • Port based VLAN
  • MAC based VLAN

Protocol Based VLAN

This VLAN handles traffic using a protocol that can be used to determine filtering parameters for tags, which are untagged packets. The Layer 3 protocol is borne by the frame in this Virtual Local Area Network to determine VLAN membership. It is applicable in multi-protocol settings. This approach is impractical in a network that is mostly IP-based.

Port Based VLAN

Port-based virtual local area networks arrange virtual local area networks by port. In this type of virtual LAN, a transfer port may be manually allocated to a VLAN member. Since all other ports are configured with a similar VLAN number, devices connected to this port will belong to the same broadcast domain. The problem with this type of network is deciding which ports are suitable for each VLAN. The VLAN membership cannot be decided simply by testing a switch’s physical port. You will find out by looking at the configuration data.


MAC Based VLAN assigns virtual LANs to incoming untagged packets, allowing traffic to be classified based on the packet source address. A MAC address to VLAN mapping is described by mapping the entry in the MAC table to the VLAN table.

Pros and Cons of VLAN

Although VLAN provides a number of usage benefits, it also has some cons. Let’s have a look at both.


  • It resolves a broadcast problem.
  • The size of transmitted domains is reduced by VLAN.
  • VLAN enables you to add an extra layer of encryption.
  • It has the potential to simplify system management.
  • Instead of grouping devices by position, you can group them logically by purpose.
  • It enables the creation of groups of logically linked devices that behave as though they are on their own network.
  • Users can operate on confidential details that other users must not see.
  • It makes it easy to segment the network.
  • It assists in the improvement of network security.
  • VLAN may be used to hold hosts apart.
  • You don’t need any extra hardware or cabling, which lets you save money.
  • It has technical benefits because modifying the user’s IP subnet is achieved in software.
  • It decreases the number of devices needed for a given network topology.
  • VLAN simplifies the management of devices.


  • A packet may be transferred from one VLAN to another.
  • An injected packet may result in a cyber-attack.
  • A threat in a particular device has the potential to distribute a virus through an entire logical network.
  • In wide networks, an external router is needed to monitor the workload.
  • Inter-operability issues can arise.
  • A VLAN cannot send network traffic to another VLAN.

Although VLANs provide their own collection of problems, such as VLAN mismatches, MSPs that understand how to configure a VLAN correctly may use their powerful network segmentation advantages to render their clients’ networks quicker and more stable, while still having physical versatility. MSPs that understand how to do VLAN maintenance and verify system delivery can improve and maintain network capacity as all networks change over time. Since they allow for improved data protection and logical partitioning, VLANs provide more flexibility than even a LAN segment. Remember that, even though it is just a segment, a VLAN functions as a single LAN. This ensures that a VLAN’s broadcast domain is the VLAN itself, not each network section.