what network driver routines are invoked via "ifup" and "ifdown"?

[rpjday at crashcourse.ca]

   first time poking around network drivers, and i'm wondering what
platform driver routines are called when invoking ifup/ifdown from
user space (if any). i'm *assuming* (possibly incorrectly) that the
probe() and remove() routines are invoked only on loading and
unloading the driver, not simple ifup and ifdown.

   guidance, anyone?

rday