The RADIUS protocol, defined in (RFC2865), does not support unsolicited messages sent from the RADIUS server to the Network Access Server (NAS). However, it may be desirable for changes to be made to session characteristics, without requiring the NAS to initiate the exchange. For example, it may be desirable for administrators to be able to terminate user session(s) in progress. Alternatively, if the user changes authorization level, this may require that authorization attributes be added/deleted from user session(s). To overcome these limitations, several vendors have implemented additional RADIUS commands to enable unsolicited messages to be sent to the NAS. These extended commands provide support for Disconnect and Change-of-Authorization (CoA) packets.