TrueNAS CORETrueNAS CORE Nightly Development Documentation
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Setting Up Link Aggregations

A Link Aggregation (LAGG) is a general method of combining (aggregating) many network connections. The connections are either parallel or in series. This provides extra bandwidth or redundancy for critical networking situations. TrueNAS uses lagg(4) to manage LAGGs.

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


Set the Type to Link Aggregation.

Enter a name for the interface. The name must use the format laggX, where X is a number representing a non-parent interface. Enter any notes or reminders about this particular LAGG in the Description field.

Go to LAGG Settings and then Lagg Protocol to configure the interface ports to match your networking needs:

Lagg Protocols


The most commonly used LAGG protocol. It is one part of IEEE specification802.3ad. LACP mode performs negotiation with the network switch to form a group of ports. These are all active at the same time. The network switch must support LACP for this option to function.


Failover sends traffic through the primary interface of the group. Traffic diverts to the next available interface in the LAGG if the primary is not accessible.

Load Balance

Load Balance accepts inbound traffic on any port of the LAGG group. It then balances the outgoing traffic on the active ports in the LAGG group. It is a static setup that does not watch the link state nor does it negotiate with the switch.

Round Robin

Round robin accepts inbound traffic on any port of the LAGG group. It sends outbound traffic using a round robin scheduling algorithm. The outbound traffic sends in sequence, using each LAGG interface in turn.


This mode disables traffic on the LAGG interface without disabling the LAGG interface.

Lagg Interfaces

Now define the Lagg Interfaces and review the remaining interface options.

See Interfaces Screen for more information on settings.

Other Settings

Every kind of network interface has common settings:


Disabling Hardware Offloading can reduce network performance. It is not recommended.

Disabling this option is sometimes necessary. For example, when the interface is managing jails, plugins, or virtual machines.

MTU stands for maximum transmission unit. It is the largest protocol unit for transferring data. MTU size varies. Physical hardware and available network interfaces determine the largest workable MTU size. 1500 and 9000 are standard Ethernet MTU sizes. 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.

You can enter more tuning ifconfig settings in the Options.

IP Addresses

Additional aliases for the interface can also be defined:


It is possible to define either IPv4 or IPv6 addresses and subnets from 1-32. Clicking Add provides another field for defining an IP address.