Freeradius CoA - Need Help

[Nasser Heidari]

Hi, 

I'm going to setup Freeradius CoA Virtual Server, I have already gone
through originate-coa document, but need some help.
This is the way that I traditionally originate CoA or POD packets:
- I have wrote a Perl scripts that it listens on port 1810.
- when I want to disconnect a user , I use another script to get user
session info from DB , and then send it's information (User-Name,
Acct-Session-ID, NAS IP Address) to port 1810
- then simply my perl scripts generates radclient commend and sends it to
appropriate NAS.

For the CoA it's same , the only different is that  I send more AVP's to my
script.
Now what I couldn't understand is that, How should I trigger CoA server to
send appropriate AVP's to NAS? How should I tell that I need these AVP's to
be sent?
I have Googled it but I couldn't find any sample.

Thanks in advance.

Regards,
Nasser