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LAGG(4) BSD 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), 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 and receives traffic only through the master 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.

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 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.

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 nwid my_net up
# ifconfig lagg0 laggproto failover laggport em0 laggport ath0 \

192.168.1.1 netmask 255.255.255.0

SEE ALSO

ng_fec(4), ng_one2many(4), 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 AT openbsd DOT 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.

WPA security does not currently work correctly with a wireless interface added to the lagg port.

BSD April 17, 2007 BSD

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