Problems on replying attributes

[Marco Miglietta]

Dears.
In the authentication process on my freeradius v3 server, I reply to 
user its IP address to access VPN (Framed-IP-Address vsa).
Now, I have to assign different IP address depending on which NAS the 
user wants access to.
Is there a simple solution that I'm not finding ?
Can anyone tell me in what direction should I direct my studies ?
Thank you.
Marco.

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