'biosdevname' is an external tool that works with the udev framework for naming devices. 'biosdevname' uses three methods to determine NIC names: 1. PCI firmware spec.3.1 2. smbios (matches # after "em" to OEM # printed on board or housing) 3. PCI IRQ Routing Table (uses # of NIC position in the device history). If the BIOS does not support biosdevname, no NICs' are re-named.