What Is VLAN (Virtual LAN)?


VLAN is network topology and methodology which is used to create separate and isolated single or multiple LANs’s over the physical LAN. VLANs are created logically over the LANs and creating VLAN is easy with the help of different network protocols. VLAN is the short form for the Virtual LAN or in a long-form Virtual Local Area Network. VLANs make is very easy to isolate and run multiple different networks inside a single physical network without any extra hardware router, switch, cable, wireless router.

VLANs can work with different types of network devices and environments like Wi-Fi, wireless router, home router, an enterprise switch, etc.

VLAN Types

VLANs can be created for different purposes with different methodologies. We can categorize VLANs into 3 different types.

  • Protocol VLAN is created to handle packages according to their protocols and process VLAN switching according to this package protocols.
  • Static VLAN or Port-Based VLAN is the most used and simplest type of VLAN where the switch, router or related device ports are assigned into a specific VLAN and only these VLAN packages are transmitted over this port.
  • Dynamic VLAN is created to create and manage VLANs in a dynamic way where the VLANs are created dynamically according to the device characteristics or provided rules dynamically.

Why Use VLAN?

VLANs provide a lot of advantages to the network administrators and most of the enterprise networks use VLAN technology. Here are some reasons to use VLANs.

  • Isolating unwanted devices from the network
  • Isolating unwanted network traffic
  • Preventing broadcast-related network
  • Creating different level secured networks
  • Making logical separation for different departments in the same physical location
  • Detailed and granular network traffic management
  • Decreasing host count in a single network
  • Creating a flexible network topology
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How VLAN Works?

VLANs work with physical ports. In the default configuration, all ports in the same switch will work on the same network by default. But VLAN is used to put these ports into different logical switches even they are on the same physical switch.

VLANs rely on IEEE 802.1Q protocol which will add some Ethernet header to the Ethernet Frames. So VLAN works as a Layer 2 protocol which is mainly handled by the Layer Devices like a switch. Adding 802.1Q protocol into the ethernet header is also called as tagging because the given ethernet frame is tagged as a specific VLAN. If it is not tagged with a 802.1Q information it is called as untagged.

On a switch, if there is no explicit VLAN configuration it is numbered with the VLAN 1. According to 802.1Q protocol, the maximum count of the VLANs is 4,096. But in practice, this number is around 2000 where other VLANs are used for specific purposes and private VLAN range which are different types of VLAN.

Standard VLANs

As on a single physical LAN can be used to create multiple VLANs there are some standard VLANs defined for specific reasons.

  • Native VLAN is used for all untagged traffic coming from the ports. This is like a default VLAN and numbered as VLAN 1 by default.
  • Management VLAN is a special VLAN where only network administrators can access. This management VLAN includes virtual interfaces to access network devices like router, firewall, switch, etc. A special VLAN number is assigned to this management VLAN which is different from VLAN 1 as a best practice. For example, VLAN 100 can be used for the management VLAN.
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VLAN Advantages

VLAN is very popular because it provides a lot of advantages over regular LANs. Here are some of the advantages of implementing and using VLANs.

  • Dividing networks into smaller segments
  • Reducing the broadcast traffic
  • Implementing specific network policy for specific hosts
  • Securing and Isolating hosts
  • Easy security management for a different group of hosts
  • Ease of network administration and management
  • Cost-effective network administration and management
  • Flexible network administration and management

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