Using IPFW as a traffic limiting solution?

[Corey Frang]

I have looked into dummynet, and it seems to be what I want to do, 
however I am going a bit out of my league with this one.  Here is a 
description of the system I want to set up:

A) I want to be able to INSURE bandwidth without limiting it in dead 
times.  In other words, 10.1.0.0/16 should be able to always have 
250kbit/sec available, but if noone else is using bandwidth, allow it 
to go as high as possible.

B) I want to be able to mark some clients as always limited.

C) I want to be able to set up multiple "classes" (right now using 
10.1, 10.2, 10.3, 10.4, etc) with their own insurance on bandwidth.


Is dummynet the thing for this?  Anyone have any suggestions where to 
look?