What is a VLAN?- How VLAN Works

What Is VLAN?

Virtual Local Area Network (VLAN) refers to a logical grouping of different hosts in a similar broadcast domain. VLAN simplifies the task for the IT network administrators to divide and make groups in a network, based on their functional and security requirements without having to plug and unplug physical LAN cables or modify the existing IT network infrastructure.

Switch & Broadcast Domains

A switch is a physical networking device that connects multiple hosts on a Local Area Network (LAN) like our computers, laptops, tablets, and more. The switch helps to route the data back and forth in between hosts. A switch has many ports based on its models and manufacturers, and each port serves one host device on a LAN.

An interface is the logical connection and configuration on a switch port that helps in communication. For example, when a host system operated using one switch port through an ethernet cable, this communication channel can be called as an interface.

VLANs get configured on a switch by placing few interfaces (like tagging) into a single broadcast domain. A single VLAN can spread across various switches but remain in the same subnet or the broadcast domain. VLANs are similar to physical LANs. The difference is that it allows grouping of the host devices, even if they are on different switches.

broadcast domain in a switch refers to the domain that receives the broadcast messages. Broadcasting a message means to send it to all the connected host devices that are a part of that domain. By default, all the ports are grouped in a common broadcast domain in a switch or a hub. This is why the switch floods (sends) the message received from one port to all the other connected ports. So all the hosts that are attached to these ports receive the same message. This process is called flooding.

Let’s now look at an example of a broadcast domain in a switch:

Imagine that a switch has eight ports and eight different hosts are connected to these ports. If a broadcast message reaches the switch from one of these hosts, the switch forwards them to all other seven hosts as they are a part of the common broadcast domain, which comes configured from the factory.

In contrast, the ports on a router aren’t in a common broadcast domain. It treats each port separately.

In the diagram that’s just appeared on your screen, there are two switches and two broadcast domains. Switch 1 has three hosts connected to it, and all the three hosts share the same broadcast domain. Similarly, all the three host systems of switch 2 belong to a common broadcast domain.

How VLAN Works

Virtual local area networks, or VLANs, have become important as network complexity has exceeded the capacity of typical local area networks (LANs). Originally, a LAN connected a group of computers and associated devices to a server via cables in a shared physical location (hence the term “local”). Many LANs now connect devices via wireless internet, rather than Ethernet, although most LANs use a combination of both connectivity types. Over time, organizations have grown in their networking needs, requiring solutions that enable networks to grow in size, flexibility, and complexity.

VLANs circumvent the physical limitations of a LAN through their virtual nature, allowing organizations to scale their networks, segment them to increase security measures, and decrease network latency.

Why would you use a VLAN?

Organizations benefit greatly from the advantages of VLAN usage, including increased performance, more flexibility in network configuration and workgroup formation, and reduced administrative efforts.

VLANs are cost-effective, because workstations on VLANs communicate with one another through VLAN switches and don’t require routers unless they are sending data outside the VLAN. This empowers the VLAN to manage an increased data load because, while switches have fewer capabilities than a router, routers cause bottlenecks. VLANs do not need to forward information through a router to communicate with devices within the network, decreasing overall network latency.

VLANs offer more flexibility than nonvirtual networking solutions. VLANs can be configured and assigned based on port, protocol, or subnet criteria, making it possible to alter VLANs and change network design when necessary. Furthermore, because VLANs are configured on a basis outside their physical connection to hardware or proximity to other devices, they allow for groups who collaborate—and presumably transfer a great deal of data to one another’s devices—to share a VLAN even if they work on separate floors or in different buildings.

VLANs decrease the amount of administrative oversight required by network overseers like managed services providers (MSPs). VLANs allow network administrators to automatically limit access to a specified group of users by dividing workstations into different isolated LAN segments. When users move their workstations, administrators don’t need to reconfigure the network or change VLAN groups. These factors decrease the amount of time and energy administrators must devote to configuration and security measures.

It will reduce to buy enough switches

Segment our networks into multiple subnets

Control traffic in the data flow

Restrict the access for the users to use the system within the network

It will reduce latency and network traffic.

It can be easy to manage even it is located in a different geographical location

Relocation of the network is much easier

Types of VLAN

There are five main types of VLANs depending on their purpose:

  1. Management VLAN
  2. Data VLAN
  3. Voice VLAN
  4. Default VLAN
  5. Native VLAN

Management VLAN

It is a separate VLAN set up for management traffic like system/application logging, monitoring, and other management-related sensitive tasks. When we see the benefits apart from security, the bandwidth is high when the number of the user makes the traffic at the same time.

Data VLAN

The data VLAN is also called as user VLAN because it is designed only for user-generated data. The network can be designed based on a group of users or workgroups. Take an example of an institute, the network workgroup would be configured based on departments. Likewise, it can occur in all business units and when we set up this network, we need to spend some time understanding the landscape how best to group the users.

Voice VLAN

The organization using the voice over IP (VoIP) with the help of a separate voice VLAN. It will preserve the bandwidth of other applications and need to ensure voice quality.

Default VLAN

The default VLAN can be referred to as two types. The first one is referred to all the ports on the device is belong to one when the switch is on. On the second one refers; some network manager is configured with the VLAN based on all the ports are assigned even when the switch is not in used.

Native VLAN

The native VLAN is one the untagged traffic accepts when it is received on the trunk port. This is most commonly used for the legacy or unsupported devices which didn’t tag. It is most likely a wireless access point to the network.

Benefits & Uses of VLANs

Uses:

Segmentation of a network helps to increase security, reliability, and efficiency of a network. There are a variety of ways a VLAN can be utilized to fit an organization’s needs. One popular use of a VLAN is to separate guest traffic from staff traffic through segmentation of the network. This allows guest users to access the internet without being on the same network as staff. VLANs can also be used to limit user access to a certain network segment, which then allows only authorized users to have access to networks with highly sensitive information. The guest/staff example fits this scenario, but another example would be to separate financial employees from HR employees. This segmentation not only separates user traffic, but it increases both safety and usability.

Costs:

Most businesses operate with the purpose of making a profit, and because of this, most business-related decisions revolve to some degree around cost. Every successful organization operates with the help of budgets, which usually include an IT budget. Use of a VLAN configurations can help save organizations money by reducing the need for network upgrades. Instead, VLANs utilize existing bandwidth and uplinks in a more efficient manner.

Security:

A major positive aspect of using a VLAN are the security benefits it provides. The separation of traffic on a network prevents unwanted and unauthorized users and devices from traveling on a specific network, reducing threats and risks and protecting sensitive data. Different security software and firewalls can be installed for each VLAN in a network, which helps prevent compromission of the entire system if one VLAN faces a breach.

Simple IT Management:

VLANs allow for easier and simplified IT management of the network system. If VLANs are segmented based on users with similar network requirements and/or functions, this allows IT to manage each VLAN and groups of devices in a simpler fashion. For example, management can establish specific security controls based off of the users in each VLAN, and if there is an issue with one VLAN, troubleshooting problems can be solved much faster due to different users operating on different VLANs. Each VLAN can also easily be named to fit the characteristics of the VLAN (examples include: “guest,” “staff,” “finance,” etc.).

Flexibility:

Along with easier network management, VLANs also provide flexibility for both the administration and users. VLANs allow geographically-dispersed users and devices to easily connect with other users. Even if a user moves desks in an office, for instance, the user can stay on their same network. Utilizing VLANs also set organizations up to be prepared for future business growth; a reliable, expandable network is essential for growth.

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