proxied server and right flamed IP to ppp clients

Is there any way to ensure (or check) that the proxied server assigned a right framed IP within a specific range of IPs? unlang perhaps? Main Server proxy to +-> freeradius Server 1 | (must be use ip pool 10.0.0.0/24) +------+ | | | +-> freeradius Server 2 | (must be use ip pool 10.0.1.0/24) | Main server check if the framed IP is within the correct pool, if not reject. Thank you.