I just remembered:

I vaguely recall that a system swapped eth0 and eth1 when replacing a 2.0.x kernel with a 2.2.x kernel (or 2.4 to 2.6, or something like that). Which didn't surprise me much, and is why God made rc files editable.

And ifrename is cool.

I've encountered _zero_ instances of network interfaces changing their device nodes on RHEL/CentOS, under any circumstances, for the simple reason of DEVICE and HWADDR directives being used in the default /etc/sysconfig/networking/devices/ifcfg-* files. DEVICE=eth0 HWADDR=11:22:33:44:55:66 Which can optionally be used to assign devices names of your choosing such as 'lan' and 'wan'. I guess the 'network interfaces have come up in a different order' scenario seems to be primarily a Debian/*buntu, etc. one (that has never arisen in my use-cases), and mostly involves USB (and other equally flaky hotplug hardware schemes). Did I mention that ifrename is cool? ;->