Simple tricks for RHEL that are common to me.
RHEL 5.4 has an easy way to disable ipv6. The other methods don't work when the iscsi driver is loaded. To disable:
echo "options ipv6 disable=1" > /etc/modprobe.d/disable-ipv6
http://planet.admon.org/2009/09/how-to-disable-the-ipv6-protocol/ - How to disable the IPv6 protocol?