trusty (4) lagg.4freebsd.gz

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.