I got this from here. Hope this helps.
RED-HAT 9.0 and later
(Cut'n'pasted from Dax Kelson web page)
A little known fact is that newer versions of RHL support
multiple network profiles. This is useful for machines that commonly
plug into different networks (think laptops). The easy way to create
network profiles is to use the redhat-config-network command. The
question then becomes, what happens when you type "ifup eth0"? The
behavior wasn't defined in previous versions, however, now in RHL 9
the following behavior is defined;
search path for:
# ifup $DEV
A cool trick is to boot your RHL box directly into a profile
from the GRUB boot screen. To do this, create a separate
/etc/boot/grub.conf entry for each network profile, and in each entry
add the kernel argument netprofile=profilename.