How to config failover ip to my lxc on ubuntu 18.04

my lxc system operation is ubuntu 16.04.
I want to config 4 failover ip to my different 4 lxc container.
such as.
I want to failover IP(54.39.173.70) to my lxc container(ubuntu1604). there are some errors I face.
How to configure failover IP to my lxc container
below is my steps.
1, vim /etc/network/interfaces
auto lo
iface lo inet loopback
auto ens3:0
iface ens3:0 inet manual
auto br0
iface br0 inet dhcp
address 54.39.173.70
netmask 255.255.255.255
gateway 54.39.173.254
bridge_ports ens3:0

2, vim /var/lib/lxc/ubuntu1604/config
lxc.net.0.link = br0

3, vim /var/lib/lxc/ubuntu1604/rootfs/etc/network/interfaces
auto lo
iface lo inet loopback
auto eth0
iface eth0 inet static
address 54.39.173.70
netmask 255.255.255.255
gateway 54.39.173.254

then restart.
but no network in my ubuntu1604 container.
What should I do?