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  2 minute read.

Last Modified 2021-07-30 11:07 EDT

A virtual LAN (VLAN) is a domain that is partitioned and isolated in a computer network at the data link layer (OSI layer 2). More information on VLANs can be found here. TrueNAS uses vlan(4) to manage VLANS.

To set up a VLAN interface, go to Network > Interface > Add.


Set the Type to VLAN and enter a Name for the interface. The name must use the format vlanX, where X is a number representing a non-parent interface. It is also recommended to add any notes or reminders about this particular VLAN in the Description.

Enabling DHCP or Autoconfigure IPv6 requires understanding how this new interface will function inside your particular network environment. By default, TrueNAS allows only one network interface to have DHCP enabled.

The remaining VLAN Settings must be configured for the interface to function properly:

  • Parent Interface : Select the VLAN Parent Interface. This is usually an Ethernet card connected to a switch port that has already been configured for the VLAN.
  • Vlan Tag : Enter a numeric tag for this interface. This is usually preconfigured in the switched network.
  • Priority Code Point : Define the VLAN Class of Service. The available 802.1p class of service ranges from Best effort (default) to Network control (highest).

With the VLAN-specific options set, there are a few additional interfaces options to review.

Other Settings

Every kind of network interface has common settings:


Disabling Hardware Offloading is discouraged as it can reduce network performance. However, disabling this option might be needed when the interface is managing Jails, Plugins, or Virtual Machines.

The Maximum Transmission Unit (MTU) is the largest protocol data unit that can be communicated. What the largest workable MTU size can be will change according to your available network interfaces and other physical hardware. 1500 and 9000 are standard Ethernet MTU sizes and the recommendation is to use the default 1500. The permissible range of MTU values is 1492-9216. Leaving this field blank sets the default value of 1500.

If additional tuning is needed, you can enter additional ifconfig settings in the Options

IP Addresses

Additional aliases for the interface can also be defined:


Either IPv4 or IPv6 addresses and subnets from 1-32 can be defined. Clicking Add will provide another field for defining an IP address.