Ubuntu 16.04 LTS uses configuration files found in /etc/network/interfaces.d/ or the file/etc/network/interfaces that describe how network interfaces should be configured.

Using a text editor, update the network interface file on each host as follows.

For controller01:

auto eth0
iface eth0 inet static
    address 10.10.0.100
    netmask 255.255.255.0
    gateway 10.10.0.1
    dns-nameserver 8.8.8.8
auto eth1
iface eth1 inet static
    address 10.20.0.100
    netmask 255.255.255.0
auto eth2
iface eth2 inet manual 

For compute01:

auto eth0
iface eth0 inet static
    address 10.10.0.101
    netmask 255.255.255.0
    gateway 10.10.0.1
    dns-nameserver 8.8.8.8
auto eth1
iface eth1 inet static
   address 10.20.0.101
   netmask 255.255.255.0
auto eth2
iface eth2 inet manual

For compute02:

auto eth0
iface eth0 inet static
    address 10.10.0.102
    netmask 255.255.255.0
    gateway 10.10.0.1
 dns-nameserver 8.8.8.8
auto eth1
iface eth1 inet static
    address 10.20.0.102
    netmask 255.255.255.0
auto eth2
iface eth2 inet manual

For compute03:

auto eth0
iface eth0 inet static
   address 10.10.0.103
   netmask 255.255.255.0
   gateway 10.10.0.1
   dns-nameserver 8.8.8.8
auto eth1
iface eth1 inet static
   address 10.20.0.103
   netmask 255.255.255.0
auto eth2
iface eth2 inet manual

For snat01:

auto eth0
iface eth0 inet static
   address 10.10.0.104
   netmask 255.255.255.0
   gateway 10.10.0.1
   dns-nameserver 8.8.8.8
auto eth1
iface eth1 inet static
   address 10.20.0.104
   netmask 255.255.255.0
auto eth2
iface eth2 inet manual

The eth2 interface will be used in a network bridge described in further detail in upcoming chapters. To activate the changes, cycle the interfaces using the ifdown and ifup commands on each node:

    # ifdown --all; ifup --all

For more information on configuring network interfaces, please refer to the Ubuntu man page at the following URL: http://manpages.ubuntu.com/manpages/xenial/man5/interfaces.5.html