OVH VPS add the new IP:

1. cp /etc/sysconfig/network-scripts/ifcfg-eth0 /etc/sysconfig/network-scripts/ifcfg-eth0:0
2. nano /etc/sysconfig/network-scripts/ifcfg-eth0:0
DEVICE="eth0:0"
ONBOOT="yes"
BOOTPROTO="none" # For CentOS use "static"
IPADDR="IP_FAIL_OVER"
NETMASK="255.255.255.255"
BROADCAST="IP_FAIL_OVER"

3. ifup eth0:0