By default IPv6 is enabled on RHEL 6.4. When IPv6 is partially disabled, eDirectory installation fails. You can disable IPv6 by adding the below entries to /etc/sysctl.conf file:
net.ipv6.conf.all.disable_ipv6 = 1
net.ipv6.conf.default.disable_ipv6 = 1
Use the lsmod | grep ipv6 command to verify if some of the IPv6 modules are still running. If this command returns any output, proceed with the installation only after disabling it.