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LAGG(4) 		     Kernel Interfaces Manual			 LAGG(4)

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 de-
     fault), fec, lacp, loadbalance, roundrobin, and none.  The protocols deter-
     mine 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 re-
		  laxed 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 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  Aggre-
		  gated  Groups.   Each  LAG  is  composed  of ports of the same
		  speed, set to full-duplex operation.	The traffic will be bal-
		  anced 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 traf-
		  fic from any active port.  This is a static setup and does not
		  negotiate aggregation with the peer or exchange frames to mon-
		  itor the link.  The hash includes the Ethernet source and des-
		  tination 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 traf-
		  fic 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 distribu-
     tion if the hash is invalid or uses less of the  protocol	header	informa-
     tion.   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 inter-
     face  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 Ether-
     net 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 sys-
     tem and port priorities.  The current implementation  always  performs  ac-
     tive-mode LACP and uses 0x8000 as system and port priorities.

FreeBSD 8.4-stable		February 23, 2012			 LAGG(4)
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