System does not consider PREFIX value set in "ifcfg-ethX" file while booting in Red Hat Enterprise Linux 6.1

Issue

• After reboot system uses "source IP = alias IP" ie eth0:1 instead of eth0 while sending packets over network.
• Alias interface is configured as follows :-

eth0   > Physical IP
eth0:1 > Alias IP

• After reboot if "eth0:1" interface is brought DOWN and UP then system uses "source IP = eth0 IP" which is expected in first place after reboot.
• NETMASK is not applied properly on the interfaces as per given PREFIX in ifcfg files.