LAGG(4)

NAME
lagg - link aggregation and link failover interface

SYNOPSIS
pseudo-device lagg

DESCRIPTION
The lagg interface allows aggregation of multiple network interfaces as one virtual lagg interface for the purpose of providing fault-tolerance and high-speed links.

A lagg interface can be created using the ifconfig laggN create command. It can use different link aggregation protocols specified using the laggproto proto option. Child interfaces can be added using the laggport child-iface option and removed using the -laggport child-iface option. A priority of each child interface can be configured using the laggport child-iface pri N or laggportpri child-iface N option. The interface preferentially uses the child interface that is the smallest numeric in the priority.

The driver currently supports the aggregation protocols failover, loadbalance, lacp, and none (the default). The protocols determine which ports are used for outgoing traffic and whether a specific port accepts incoming traffic. The interface link state is used to validate if the port is active or not.

failover
    Sends traffic only through the active port that is the highest priority. When the same priority is configured, The first interface added is used for sending traffic. If the link-state of the sending port becomes down, The next priority port is used.

    Received traffic is accepted through all active port if laggfailover rx-all option is enabled. The option is enabled by default, and it can be disabled by laggfailover -rx-all option. If the option is disabled, received traffic is only accepted through the sending port.

loadbalance
    Balances outgoing traffic across the active ports based on hashed protocol header information and accepts incoming traffic from any active port. This is a static setup and does not negotiate aggregation with the peer or exchange frames to monitor the link. The hash includes the Ethernet source and destination address, and, if available, the VLAN tag, and the IP source and destination address.

lacp
    Supports the IEEE 802.1AX (formerly 802.3ad) Link Aggregation Control Protocol (LACP) and the Marker Protocol. LACP will negotiate a set of aggregable links with the peer into a Link Aggregated Group. The LAG is composed of ports of the different speed, set to full-duplex operation, if lagglacp multi-speed option is configured. The function can be disabled by lagglacp -multi-speed option. Outgoing traffic across the distributing ports based on hashed protocol header information and accepts incoming traffic from any collecting port. The maximum number of active ports in a LAG can be configured by lagglacp maxports N option.

none
    This protocol is intended to do nothing: it disables any traffic without disabling the lagg interface itself.

Each lagg interface is created at runtime using interface cloning. This is most easily done with the ifconfig(8) create command.

The MTU of the lagg(4) is applied to each physical interfaces. And the physical interfaces can not change its MTU directly.

EXAMPLES
Create a link aggregation using LACP with two wm(4) Gigabit Ethernet interfaces:

    # ifconfig wm0 up
    # ifconfig wm1 up
    # ifconfig lagg0 create
    # ifconfig lagg0 laggproto lacp laggport wm0 laggport wm1 \
    	192.168.1.1 netmask 255.255.255.0

Create a link aggregation using FAILOVER with two wm(4) Gigabit Ethernet interfaces and set each priority:

    # ifconfig wm0 up
    # ifconfig wm1 up
    # ifconfig lagg0 create
    # ifconfig lagg0 laggproto failover
    # ifconfig lagg0 laggport wm0 pri 1000
    # ifconfig lagg0 laggport wm1 pri 2000
    # ifconfig lagg0 inet 192.168.1.1 netmask 255.255.255.0

SEE ALSO
ifconfig(8)

HISTORY
The lagg device first appeared in NetBSD 10.0.

AUTHORS
-nosplit The lagg driver was written under the name trunk by Reyk Floeter <reyk@openbsd.org>.

BUGS
There is no way to configure LACP administrative variables, including system priority. The current implementation always performs active-mode LACP and uses 0x8000 as system priority.