I'm an inordinate amount of trouble getting F15 to run without NetworkManager. If I boot with the NetworkManager service enabled, my NIC presents as expected at /dev/eth0 (I'm using biosdevname=0). However, when I stop the NetworkManager service, /dev/eth0 disappears from the filesystem
If I boot without NetworkManager enabled, /dev/eth0 is never created. Reviewing dmesg, udev is loading an ethernet driver. There's just no device file to go with it.