I have rtl8139 integrated LAN (uses 8139too), but I usually connect via wireless pcmcia card which works with orinico_cs driver. The problem was that if the system was booted with the wireless card in the slot I used to have eth0 for it and eth1 for the integrated LAN. And oposite: if the system was booted with the wireless card NOT inserted I used to have eth0 for the wired LAN and my connection to the world was eth1 after inserting it. into the slot.
You imagine what happens with configs..
One solution I found was to disable the integrated LAN. So I will always have only one eth# and will be the wireless. It can be achieved with a line like this in /etc/modules.conf:
alias 8139too off
Another way I read in this forum is to blacklist the wired LAN module in /etc/hotplug/blacklist. And probably to modprobe it manually in rc.local after that. Didn't test it.
btw tricks like
alias eth0 8139too
alias eth1 orinoco_cs
just didn't work for me.
Finally I opened /etc/rc.d/rc.M for editing (I boot in runlevel 3) and swaped the pieces of script which run the hotplug system and the pcmcia system. In the original rc script PCMCIA was initialized first and after it - hotplug. Now I have rc.M script in which hotplug is started first and PCMCIA after it. As result, doesn't matter whether the wireless card is inserted or not during boot, my integrated wired LAN is eth0, so my wireless is always eth1.
Now, when I configurate eth1, I know what will happen on next boot