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VLAN and its Applications

In this article, we will review the topic of VLANs and its application in computer networking. We start by looking at what a VLAN is, and then the types of VLAN, the deployment examples and the benefits of VLAN.

What is a VLAN?


A Virtual Local Area Network (VLAN) is a logical group of workstations, servers, and network devices that appear to be on the same LAN despite their geographical dispersion.  In businesses or organisations, the members of a workgroup are often located in different locations within a building or even in different buildings. VLAN allows the computers or devices of these members to have unified networking settings such as NAT rules, Firewall rules, QoS, etc. In the diagram below, a landlord of an office building sets up VLAN groups, one for each floor. Each VLAN group has its own set of network rules and is isolated from other VLANs.


Types of VLAN

DrayTek routers support two types of VLAN: Port-based and 802.1q tag-based VLAN.

Port-Based VLANS (Untagged)

Port-based VLAN allows a number of physical LAN ports on a DrayTek router to be grouped into a logical group. In the example below, LAN ports 1 to 3 forms VLAN0 which is connected to staff in the Sales Department. Similarly, LAN ports 4 to 6 forms VLAN1 which is connected to staff in the Admin Department. Network traffic in VLAN 1 will be isolated from VLAN0 and this provides an additional level of security.



802.1Q Tag-based VLANS

Most DrayTek router and switch products allow VLANs to be assigned a VLAN ID (VID). The VID identifies which VLAN a data packet belongs to.  This allows multiple VLANs to be associated with a single router LAN port and multiple switch ports to create 802.1Q VLAN trunks. The diagram below shows that with a single LAN cable to the network switch, 3 VLAN groups can be set up to cater for 3 different work groups or departments.


With tag-based VLAN, switches in multi-floor buildings or locations can be cascaded to form VLAN groups as required.

Multi-Workgroup Deployment Example

The diagram below shows a typical business with multi-workgroups located on various floors or physical space.


In this example, with the router and the network switch are located on the first floor, the Administration and Sales Departments on the 2nd floor and the Warehouse Departments on the ground floor, are connected by network cables and supported by tag-based VLANs.

Benefits of VLANs

  • Provides additional security to network communication among workgroups within an organisation.
  • Easy and flexible expansion and relocation of network devices as well as workgroups.
  • Allows network administrators to configure the network in a centralized environment.
  • Reduces latency and traffic load on the network and the network devices, thus improving network performance.
  • Real-time services, such as VoIP or video streaming, can be set up in separate VLANs and be isolated from network congestion due to  traffic from other data types.

For more information on VLAN and its applications you can view our recorded webinar at

Click here for VLAN configuration examples available on our support webpage.

Additional application notes are also available here.

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