Do not use this on system where you will have BONDS as it turns off bonds completely see RH bug 531873

To prevent the IPv6 kernel module (ipv6) from being automatically loaded, add the following line to /etc/ modprobe.conf

install ipv6 /bin/true

and edit /etc/sysconfig/network add the the lines

NETWORKING_IPV6=no
IPV6INIT=no