In the globalization of mobile communication, the importance of AAA(authentication, authorization, and accounting) service is rapidly increasing. The Mobile IP and EAP application of AAA (Diameter protocol) provide authentication, authorization, and accounting (AAA) services to a wireless network. For a robust and load-sharing accounting network for a Diameter-based AAA system, the current paper proposes an accounting network management function within the base protocol framework to interact between the AAA session and accounting back-end session instead of the original (draft) integrated stand-alone AAA server framework. An authentication server is also proposed to perform a load-balancing function in the accounting server network, which includes distributed accounting servers for transporting bulky accounting records. The proposed protocol has advantages as regards network reliability and load management. Furthermore, the proposed protocol can be applied to wireless LAN AP as an AAA client network.