TRUNK(4) FreeBSD Kernel Interfaces Manual TRUNK(4)
NAME
trunk - link aggregation and link failover interface
SYNOPSIS
pseudo-device trunk
DESCRIPTION
The trunk interface allows aggregation of multiple network interfaces as
one virtual trunk interface.
A trunk interface can be created using the ifconfig trunkN create
command.
The driver currently supports the trunk protocols broadcast, failover,
lacp, loadbalance, none, and roundrobin (the default). 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.
broadcast Sends frames to all ports of the trunk and receives frames
on any port of the trunk.
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.
lacp Uses the IEEE 802.3ad (renamed to 802.1AX in 2014) Link
Aggregation Control Protocol (LACP) and the Marker Protocol
to increase link speed and provide redundancy. LACP trunk
groups are composed of ports of the same speed, set to full-
duplex operation. This protocol requires a switch which
supports LACP. By default, the LACP implementation uses
active-mode LACP, slow timeout, and 0x8000 (medium) priority
as system and port priorities.
loadbalance Distributes outgoing traffic through all active ports and
accepts incoming traffic from any active port. A hash of
the protocol header is used to maintain packet ordering.
The hash includes the Ethernet source and destination
address and, if available, the VLAN tag, and the IP source
and destination address.
none This protocol is intended to do nothing: it disables any
traffic without disabling the trunk interface itself.
roundrobin Distributes outgoing traffic through all active ports and
accepts incoming traffic from any active port. A round-
robin scheduler is used to aggregate the traffic.
The configuration can be done at runtime or by setting up a
hostname.if(5) configuration file for netstart(8).
EXAMPLES
Create a simple round robin trunk with two bge(4) Gigabit Ethernet
interfaces:
# ifconfig bge0 up
# ifconfig bge1 up
# ifconfig trunk0 trunkport bge0 trunkport bge1 \
192.168.1.1 netmask 255.255.255.0
The following example uses an active failover trunk 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 trunk0 trunkproto failover trunkport em0 trunkport ath0 \
192.168.1.1 netmask 255.255.255.0
SEE ALSO
inet(4), hostname.if(5), ifconfig(8), netstart(8)
HISTORY
The trunk device first appeared in OpenBSD 3.8.
AUTHORS
The trunk driver was written by Reyk Floeter <
[email protected]>.
CAVEATS
The trunk protocols loadbalance and roundrobin require a switch which
supports IEEE 802.3ad static link aggregation; otherwise protocols such
as inet6(4) duplicate address detection (DAD) cannot properly deal with
duplicate packets.
The trunk interface takes its MTU from the first trunkport. To avoid
mismatches, adding a child interface with a different MTU is not
permitted.
FreeBSD 14.1-RELEASE-p8 August 24, 2020 FreeBSD 14.1-RELEASE-p8