checking authorization in the duration of connection

Hi, My radius server use ldap server for authorize and authentication.I set an attribute in ldap server that is the check-name in sqlcounter to limit users Input traffic. I want when user traffic reaches to this amount the user become stop but radius checks ldap attributes only at the first of connection not in the middle. How can I set radius server check users traffic with the amount of this attribute in ldap server in the duration of connection?