# apt-get install ifenslave

alterar o ficheiro /etc/network/interfaces:

auto bond0

iface bond0 inet static
address 10.31.1.5
netmask 255.255.255.0
network 10.31.1.0
gateway 10.31.1.254
slaves eth0 eth1
bond_mode active-backup
bond_miimon 100
bond_downdelay 200
bond_updelay 200

# reboot

https://wiki.debian.org/Bonding