Which NIC becomes eth0, and which eth1?

[Craig McPherson]

I've noticed that if I have two network cards in a machine, and both use different drivers, and both drivers are compiled as modules, then whichever one I modprobe first becomes eth0, and the second becomes eth1.

What if the drivers are compiled directly into the kernel, rather than as modules? Which becomes eth0, and which becomes eth1? Just curious.

[jscott]

That's set up I have, 3com support is built in. It seems that the kernel assigns eth0 to the nic in the first PCI slot (with a card) initialised.

For whatever reason, on all the machines here (work) this seems to be the PCI slot next to the AGP and decending from there. eg.

AGP --> video
PCI --> eth0
PCI --> eth1
PCI --> Sound
PCI --> eth2
ISA --> unused

this could be total crap, I know little on the internal but it's what I've been seeing.

[prince_kenshi]

I've heard that something gives priority to the NIC with the lowest MAC address. It wasn't this situation that I heard it about but it's a possibility I guess.