Hi,
thanks for the reply. It seems to only confirm my fears - Fedora just doesn't (knowingly) support a PXE setup that isn't an ugly hack.
If I understand it correctly, the whole .iso is stuffed into the initrd image and transferred to the machine as part of the "
append" command in
pxelinux.cfg. pxelinux only works with TFTP AFAIK, so for a 700MB file, this alone would take ~
3 minutes 
Couple that with the huge memory requirement, and this a "yeah, kinda works but no one would
want to use this".
It would be a huge boost for Fedora to support at least Clonezlla-style PXE booting, where the initrd contains a wget binary and the .iso (actually, Clonezilla downloads just the
filesystem.squashfs) file is downloaded using either FTP or HTTP. Those are orders of magnitude faster than TFTP, even on only FastEthernet.
Since you've brought up CentOS, they do mention fetching some files over http here:
http://wiki.centos.org/HowTos/PXE/PXE_Setup/Menus Maybe there is something like wget in the initrd image already?