$ sudo cat /etc/network/interfaces
auto lo
iface lo inet loopback
dns-search maas
dns-nameservers 172.16.0.2
auto eth0
iface eth0 inet static
address 172.16.0.129/24
mtu 1500
auto eth1
iface eth1 inet manual
bond-xmit_hash_policy layer2
bond-master bond0
bond-lacp_rate slow
mtu 1500
bond-mode active-backup
bond-miimon 100
auto eth2
iface eth2 inet manual
bond-xmit_hash_policy layer2
bond-master bond0
bond-lacp_rate slow
mtu 1500
bond-mode active-backup
bond-miimon 100
auto eth3
iface eth3 inet static
address 172.16.1.129/24
mtu 1500
auto bond0
iface bond0 inet manual
bond-slaves none
mtu 1500
hwaddress 52:54:00:35:a2:72
bond-xmit_hash_policy layer2
bond-mode active-backup
bond-miimon 100
bond-lacp_rate slow
auto juju-br0
iface juju-br0 inet static
gateway 172.16.0.1
address 172.16.0.130/24
hwaddress 52:54:00:35:a2:72
bridge_ports bond0
source /etc/network/interfaces.d/*.cfg