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LAGG(4)                FreeBSD Kernel Interfaces Manual                LAGG(4)

     lagg - link aggregation and link failover interface

     To compile this driver into the kernel, place the following line in your
     kernel configuration file:

           device lagg

     Alternatively, to load the driver as a module at boot time, place the
     following line in loader.conf(5):


     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.

     The driver currently supports the aggregation protocols failover (the
     default), fec, lacp, loadbalance, roundrobin, and none.  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 and receives traffic only through the master port.  If
                  the master port becomes unavailable, the next active port is
                  used.  The first interface added is the master port; any
                  interfaces added after that are used as failover devices.

     fec          Supports Cisco EtherChannel.  This is a static setup and
                  does not negotiate aggregation with the peer or exchange
                  frames to monitor the link.

     lacp         Supports the IEEE 802.3ad Link Aggregation Control Protocol
                  (LACP) and the Marker Protocol.  LACP will negotiate a set
                  of aggregable links with the peer in to one or more Link
                  Aggregated Groups.  Each LAG is composed of ports of the
                  same speed, set to full-duplex operation.  The traffic will
                  be balanced across the ports in the LAG with the greatest
                  total speed, in most cases there will only be one LAG which
                  contains all ports.  In the event of changes in physical
                  connectivity, Link Aggregation will quickly converge to a
                  new configuration.

     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.

     roundrobin   Distributes outgoing traffic using a round-robin scheduler
                  through all active ports and accepts incoming traffic from
                  any active port.

     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 or using the
     cloned_interfaces variable in rc.conf(5).

     The MTU of the first interface to be added is used as the lagg MTU.  All
     additional interfaces are required to have exactly the same value.

     Create a 802.3ad link aggregation using LACP with two bge(4) Gigabit
     Ethernet interfaces:

           # ifconfig bge0 up
           # ifconfig bge1 up
           # ifconfig lagg0 laggproto lacp laggport bge0 laggport bge1 \

     The following example uses an active failover interface to set up roaming
     between wired and wireless networks using two network devices.  Whenever
     the wired master interface is unplugged, the wireless failover device
     will be used:

           # ifconfig em0 up
           # ifconfig ath0 nwid my_net up
           # ifconfig lagg0 laggproto failover laggport em0 laggport ath0 \

     ng_fec(4), ng_one2many(4), ifconfig(8)

     The lagg device first appeared in FreeBSD 6.3.

     The lagg driver was written under the name trunk by Reyk Floeter
     <>.  The LACP implementation was written by YAMAMOTO
     Takashi for NetBSD.

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

     WPA security does not currently work correctly with a wireless interface
     added to the lagg port.

FreeBSD 11.0-PRERELEASE         April 17, 2007         FreeBSD 11.0-PRERELEASE


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