NAME

       lagg — link aggregation and link failover interface

SYNOPSIS

       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):

             if_lagg_load="YES"

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.

       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  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 net.link.lagg.failover_rx_all sysctl(8)
                    variable to a nonzero value, which is useful for certain bridged network setups.

       fec          Supports Cisco EtherChannel.  This is an alias for loadbalance mode.

       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.

       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
       net.link.lagg.X.use_flowid sysctl(8) variable to zero where X is the interface number.  The  default  for
       new interfaces is set via the net.link.lagg.default_use_flowid sysctl(8).

EXAMPLES

       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 \
                     192.168.1.1 netmask 255.255.255.0

       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 laggproto failover laggport em0 laggport wlan0 \
                     192.168.1.1 netmask 255.255.255.0

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

SEE ALSO

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

HISTORY

       The lagg device first appeared in FreeBSD 6.3.

AUTHORS

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

BUGS

       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.

Debian                                          February 23, 2012                                        LAGG(4)