balance-rr or 0
Round-robin policy: Transmit packets in sequential
order from the first available slave through the
last. This mode provides load balancing and fault
active-backup or 1
Active-backup policy: Only one slave in the bond is
active. A different slave becomes active if, and only
if, the active slave fails. The bond's MAC address is
externally visible on only one port (network adapter)
to avoid confusing the switch.
In bonding version 2.6.2 or later, when a failover
occurs in active-backup mode, bonding will issue one
or more gratuitous ARPs on the newly active slave.
One gratutious ARP is issued for the bonding master
interface and each VLAN interfaces configured above
it, provided that the interface has at least one IP
address configured. Gratuitous ARPs issued for VLAN
interfaces are tagged with the appropriate VLAN id.
This mode provides fault tolerance. The primary
option, documented below, affects the behavior of this
balance-xor or 2
XOR policy: Transmit based on the selected transmit
hash policy. The default policy is a simple [(source
MAC address XOR'd with destination MAC address) modulo
slave count]. Alternate transmit policies may be
selected via the xmit_hash_policy option, described
This mode provides load balancing and fault tolerance.
broadcast or 3
Broadcast policy: transmits everything on all slave
interfaces. This mode provides fault tolerance.
802.3ad or 4
IEEE 802.3ad Dynamic link aggregation. Creates
aggregation groups that share the same speed and
duplex settings. Utilizes all slaves in the active
aggregator according to the 802.3ad specification.
Slave selection for outgoing traffic is done according
to the transmit hash policy, which may be changed from
the default simple XOR policy via the xmit_hash_policy
option, documented below. Note that not all transmit
policies may be 802.3ad compliant, particularly in
regards to the packet mis-ordering requirements of
section 43.2.4 of the 802.3ad standard. Differing
peer implementations will have varying tolerances for
1. Ethtool support in the base drivers for retrieving
the speed and duplex of each slave.
2. A switch that supports IEEE 802.3ad Dynamic link
Most switches will require some type of configuration
to enable 802.3ad mode.