IP utillization software

[Tim Finkenstadt <timothy () erinet com>]

Greetings.

I am looking for IP address utilization software for the following purpose:
I work for a very large company with lots of facilities and offices.  Our
group needs to reclaim the space that was previously allocated before the
days of VLSM.

For example:
facility allocated 172.28.32/19 .  I want to be able to find out how much 
that facility is utilizing.  


thanks,

tim