Performance evaluation of hierarchical control systems in switching exchanges

Optimal placement of software functionality in distributed control systems of switching exchanges can be used to achieve a cost effective design in the ISDN and IN environments. New telecommunications services have emerged which will place quite disparate processing demands on control systems, and the optimal system configuration will depend on the call mix to be supported by the exchange. Optimal function allocation can also be used to facilitate the evolution of existing control systems to broadband network applications without the need for high-cost system re-design. A simple control system model based on queueing networks, and able to capture the main features of the system, is proposed and used to investigate the effect of various system and call parameters on the optimal function allocation. The resultant algorithms can be used as evaluation tools allowing designers to compare the performance of candidate systems to satisfy particular specifications in a cost effective manner. Applying the model to a hierarchical control system shows the potential benefits of optimal function allocation.