Freeradius and WiMAX Access Point

[Ming-Ching Tiew]

I shall not name the vendor name here. I just got some info from the 
vendor that the WiMAX Access Point does not do 'interim accounting',
'acctupdate' and so on. Only thing possible right now is authenticate
and start/stop accounting.

That being the case, I wonder how one implement stuff like fair-use 
policy on a WiMAX user ? If the radius server does not get interim
accounting, the way the users is going to "cheat" is just to power
off the device at the end of his usage !!!

Am I missing something here ?

The way I see it is that if one have to implement a more intelligent
authentication and accounting, for WiMAX, one has to put a box, 
either as a bridge or as a router in front of the APs, where all the 
data path goes through the box. And that box will create 
session information and accounting on behalf of the APs. 

If one has to introduce this box, using Linux solutions,
what would be the right way to do this, so that the
traffic accounting can be done on each APs ? 

( iptables or Coova chilli comes to my mind ).

How does the commercial solutions work ? Anyone care to 
share his knowledge on this ?

Once again thanks for reading and best regards.
Ming-Ching