You will need to run /usr/pluto/bin/Diskless_CreateTBZ.sh on the core before you will be able to boot MDs. You should really be using 2 NICs to boot MDs as well... I couldn't comment on your methods so far as I have no experience with single NIC setups.
The post your replying to is quite old and related to outdated installs. You should open a new topic if you continue to have problems after running the above script.