Command Section
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), lacp, loadbalance, roundrobin, broadcast, 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 traffic only through the active 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.

                  By default, received traffic is only accepted when they are
                  received through the active port.  This constraint can be
                  relaxed by setting the
                  sysctl(8) variable to a nonzero value, which is useful for
                  certain bridged network setups.  loadbalance mode.

     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
                  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.  Using roundrobin mode can cause unordered
                  packet arrival at the client.  Throughput might be limited
                  as the client performs CPU-intensive packet reordering.

     broadcast    Sends frames to all ports of the LAG and receives frames on
                  any port of the LAG.

     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.

     The loadbalance and lacp modes will use the RSS hash from the network
     card if available to avoid computing one, this may give poor traffic
     distribution if the hash is invalid or uses less of the protocol header
     information.  Local hash computation can be forced per interface by
     setting the use_flowid ifconfig(8) flag.  The default for new interfaces
     is set via the sysctl(8).

     Create a link aggregation using LACP with two bge(4) Gigabit Ethernet

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

     Create a link aggregation using ROUNDROBIN with two bge(4) Gigabit
     Ethernet interfaces and set the limit of 500 packets per interface:

           # ifconfig bge0 up
           # ifconfig bge1 up
           # ifconfig lagg0 create
           # ifconfig lagg0 laggproto roundrobin laggport bge0 laggport bge1 \
           # ifconfig lagg0 rr_limit 500

     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 ether 00:11:22:33:44:55
           # ifconfig create wlan0 wlandev ath0 ssid my_net up
           # ifconfig lagg0 create
           # ifconfig lagg0 laggproto failover laggport em0 laggport wlan0 \

     (Note the mac address of the wireless device is forced to match the wired
     device as a workaround.)

     ng_one2many(4), ifconfig(8), sysctl(8)

     The lagg device first appeared in FreeBSD 6.3.

     The lagg driver was written under the name trunk by Reyk Floeter
     <[email protected]>.  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.

FreeBSD 11.1-RELEASE-p4        January 23, 2016        FreeBSD 11.1-RELEASE-p4
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