How to configure virtual network interfaces in Solaris 8/9/10?

Creating virtual network interfaces in Solaris 8 onwards is very easy. Here is the three steps to do this:

1) Create the hostname.INTERFACE_NAME:NUMBER files for interface and inside, name the interface.
2) Edit /etc/hosts file to include the IP addresses for these virtual interfaces.
3) Reboot the system. It will come up with three IP addresses on one physical card (as shown in the following example).

(Note: If you are an advanced user/admin, step #3 can be replaced with ifconfig command with necessary arguments. Whenever you reboot next time, these settings will be retained.)

# ls -l /etc/hostname*
-rw-r--r--   1 root     root           8 Mar 28  2008 /etc/hostname.eri0
-rw-r--r--   1 root     other         16 Oct 23  2008 /etc/hostname.eri0:1
-rw-r--r--   1 root     other         17 Oct 23  2008 /etc/hostname.eri0:2

# cat /etc/hostname.eri0
unixgeekws


# cat /etc/hostname.eri0:1
unixgeekws-virtual


# cat /etc/hostname.eri0:2
unixgeekws-virtual1


# cat /etc/hosts
# Internet host table
127.0.0.1       localhost
10.20.30.145    unixgeekws        loghost
10.20.30.146    unixgeekws-virtual
10.20.30.147    unixgeekws-virtual1

NOW Reboot the system. Check my special note if you are advanced user.
Upon reboot, it will show as below:

# ifconfig -a
lo0: flags=1000849 mtu 8232 index 1
        inet 127.0.0.1 netmask ff000000
eri0: flags=1000843 mtu 1500 index 2
        inet 10.20.30.145 netmask ffffff00 broadcast 10.20.30.255
        ether 0:3:ba:44:f4:17
eri0:1: flags=1000843 mtu 1500 index 2
        inet 10.20.30.146 netmask ffffff00 broadcast 10.20.30.255
eri0:2: flags=1000843 mtu 1500 index 2
        inet 10.20.30.147 netmask ffffff00 broadcast 10.20.30.255