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Setting up a Virtual IP address (VIP)

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These instructions are for CentOS/Redhat Linux distributions.

1. Identify your current NIC’s and IP addresses in use.

$ /sbin/ifconfig
eth0      Link encap:Ethernet  HWaddr 00:30:48:98:9C:A6
          inet addr:192.168.53.201  Bcast:192.168.53.255  Mask:255.255.255.0
          inet6 addr: 0080::230:48ff:fe98:9ca6/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:6159779 errors:0 dropped:0 overruns:0 frame:0
          TX packets:6137085 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:100
          RX bytes:1158210510 (1.0 GiB)  TX bytes:541617489 (516.5 MiB)
          Memory:e8000000-e8020000

lo        Link encap:Local Loopback
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          RX packets:3791468208 errors:0 dropped:0 overruns:0 frame:0
          TX packets:3791468208 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:740660664181 (689.7 GiB)  TX bytes:740660664181 (689.7 GiB)

Determine which NIC you want the VIP on, in this case eth0 (the private address). We want to add the address 192.168.53.220

$  echo "DEVICE=eth0
BOOTPROTO=static
BROADCAST=192.168.53.255
IPADDR=192.168.53.220
NETMASK=255.255.255.0
NETWORK=192.168.53.0
ONBOOT=yes" > /etc/sysconfig/network-scripts/ifcfg-eth0:0

$ /etc/sysconfig/network-scripts/ifup-aliases eth0

Check your /sbin/ifconfig and now you should have a virtual IP address.

$ /sbin/ifconfig
eth0      Link encap:Ethernet  HWaddr 99:30:48:98:9C:A6
          inet addr:192.168.53.201  Bcast:192.168.53.255  Mask:255.255.255.0
          inet6 addr: 0080::230:48ff:fe98:9ca6/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:6159779 errors:0 dropped:0 overruns:0 frame:0
          TX packets:6137085 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:100
          RX bytes:1158210510 (1.0 GiB)  TX bytes:541617489 (516.5 MiB)
          Memory:e8000000-e8020000

eth0:0    Link encap:Ethernet  HWaddr 99:30:48:98:9C:A7
          inet addr:192.168.53.220  Bcast:192.168.53.255  Mask:255.255.255.0
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          Memory:e8100000-e8120000

lo        Link encap:Local Loopback
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          RX packets:3791468208 errors:0 dropped:0 overruns:0 frame:0
          TX packets:3791468208 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:740660664181 (689.7 GiB)  TX bytes:740660664181 (689.7 GiB)