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):
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
lagg
N
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 802.1AX (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.
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 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.