LAGG(4) FreeBSD 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
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 net.link.lagg.failover_rx_all
sysctl(8) variable to a nonzero value, which is useful for
certain bridged network setups.
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 net.link.lagg.default_use_flowid sysctl(8).
EXAMPLES
Create a link aggregation using LACP with two bge(4) Gigabit Ethernet
interfaces:
# ifconfig bge0 up
# ifconfig bge1 up
# ifconfig lagg0 create
# ifconfig lagg0 laggproto lacp laggport bge0 laggport bge1 \
192.168.1.1 netmask 255.255.255.0
Create a link aggregation using ROUNDROBIN with two bge(4) Gigabit
Ethernet interfaces and set a stride of 500 packets per interface:
# ifconfig bge0 up
# ifconfig bge1 up
# ifconfig lagg0 create
# ifconfig lagg0 laggproto roundrobin laggport bge0 laggport bge1 \
192.168.1.1 netmask 255.255.255.0
# 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 \
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.)
The following example shows how to create an infiniband failover
interface.
# ifconfig ib0 up
# ifconfig ib1 up
# ifconfig lagg0 create laggtype infiniband
# ifconfig lagg0 laggproto failover laggport ib0 laggport ib1 \
1.1.1.1 netmask 255.255.255.0
SEE ALSO
ng_one2many(4), ifconfig(8), sysctl(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.
FreeBSD 13.1-RELEASE-p6 October 21, 2020 FreeBSD 13.1-RELEASE-p6
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