Virtual LAN (VLAN) is created on Layer 2 switch to reduce the size of broadcast domain. It is one of the technologies used to improve network performance by the separation of large broadcast domains into smaller ones.
There are 5 main types of VLANs depending on the type of the network they carry:
- Default VLAN –
When the switch initially starts up, all switch ports become a member of the default VLAN (generally all switches have default VLAN named as VLAN 1), which makes them all part of the same broadcast domain. Using default VLAN allows any network device connected to any of the switch port to connect with other devices on other switch ports. One unique feature of Default VLAN is that it can’t be rename or delete.
- Data VLAN –
Data VLAN is used to divide the whole network into 2 groups. One group of users and other group of devices. This VLAN also known as a user VLAN, the data VLAN is used only for user-generated data. This VLAN carrying data only. It is not used for carrying management traffic or voice.
- Voice VLAN –
Voice VLAN is configured to carry voice traffic. Voice VLANs are mostly given high transmission priority over other types of network traffic. To ensure voice over IP (VoIP) quality (delay of less than 150 milliseconds (ms) across the network), we must have separate voice VLAN as this will preserve bandwidth for other applications.
- Management VLAN –
A management VLAN is configured to access the management capabilities of a switch (traffic like system logging, monitoring). VLAN 1 is the management VLAN by default (VLAN 1 would be a bad choice for the management VLAN). Any of a switch VLAN could be define as the management VLAN if admin as not configured a unique VLAN to serve as the management VLAN. This VLAN ensures that bandwidth for management will be available even when user traffic is high.
- Native VLAN –
This VLAN identifies traffic coming from each end of a trunk link. A native VLAN is allocated only to an 802.1Q trunk port. The 802.1Q trunk port places untagged traffic (traffic that does not come from any VLAN) on the native VLAN. It is a best to configure the native VLAN as an unused VLAN.