Design of an admission controller for a distributed network server system

Inmodern times, communication network systems such as the Internet and the GSM (Global System for Mobile Communication) consist of two types of nodes: service control nodes (server systems) and switching nodes (switches and routers). The switching nodes are utilized for transmission of data across the network while the service controls nodes save and distribute vital information. The recent sharp global increase in communication network activities has led to high network traffics in switching nodes and equally high rates of incoming requests in service control nodes. As a result, long queues of client requests now cause the overloading of the service control nodes. Server systems are very sensitive to overload. Consequently, there are now recurring cases of client request rejection, service timeouts and longer server response time experienced on most communication networks. This research presents the use of admission control system based on queuing theory to optimize the performance server systems. A PI-controller (Admission Controller) has been designed and integrated into a typical G/G/1-system (Single Server Queue) based on the nonlinear (probability) model. The controller has been evaluated and verified by simulating the overall system to determine its stabilizing and optimizing effects on web/application server systems.