VLAN (Virtual Local Area Network)

VLAN (Virtual Local Area Network)

Virtual local networks (VLANs) in switch devices are used to reduce broadcast domains and divide them into different networks. This network configuration is a logical setup created by the network administrator on the switch device. Switch ports are assigned to these virtual networks, allowing devices to be grouped logically rather than physically.

Although switch devices physically operate as if they provide a single network to all connected devices, they can be logically divided into different networks to serve multiple groups. These logical networks are known as VLANs. Switches come preconfigured with a default VLAN (VLAN 1). If no additional VLANs are configured, all switch ports operate within this default VLAN. When new VLANs are established, broadcast traffic is confined within each VLAN, preventing it from affecting other VLANs on the same switch.

VLAN Illustration

VLAN Types

VLANs can be categorized according to the type of traffic they carry or their intended purpose. A Data VLAN is created for users and is used to carry user data traffic. The Default VLAN is the initial configuration of the switch; when first powered on, all ports are included in this VLAN, and it serves as the default network until further configuration. The Native VLAN is used for untagged traffic on trunk ports; by default, VLAN 1 is the native VLAN, but it is recommended to use a different VLAN to prevent untagged data traffic issues. A Management VLAN is assigned an IP address to allow remote management of the switch via applications like telnet and SSH; the virtual interface for this VLAN is called an SVI (Switched Virtual Interface). Voice VLANs are dedicated to voice traffic, ensuring high-priority and clear communication by separating voice data from other types of traffic. Reserved VLANs are preconfigured on the switch for specific network protocols and cannot be removed or reconfigured, ensuring essential network functionality.