Disclaimer:   this brief post doesn't even contain the word P*rl.

I've done something similar, but placed snippet in Debian's /etc/ppp/ip-up.d/ so address-updating script is run only when connection is established.   Saves you the grief of waiting up to 1/2 hour after line drop.

Dunno if Win32 RAS/DUN has anything similar, or if (Win or Linux) can do same for Ethernet-attached cablemodem/DSL router.
    cheers,
    Don
    striving for Perl Adept