Design and Implementation of RADIUS Client Based on Finite State Machine

RADIUS (remote authentication dial in user service) is a widely deployed protocol for network access authentication, authorization and accounting (AAA). Firstly the basic concept of RADIUS protocol is introduced, and then the signaling flow of RADIUS protocol is represented. In order to avoid poor implementation and meet the performance demand of network access server (NAS), a model of communication finite state machine (FSM) is established for RADIUS client module on NAS, and then its implementation is brought forward. Its implementation is proved to up to the telecom-level performance requirement both in testing and application.