Control-Theoretic Approach for a QoS Router

Network QoS control is gaining importance in the computer network area. In this paper, we present a practical design for the control-theoretic approach for Quality of Service (QoS) control in network routers. To achieve both robustness and efficiency, we adopted a discrete time domain form of PID control algorithm as a primary control scheme for the Control-Theoretic QoS Router (CTQR) system. The proposed system can operate independent of internal states of routing. This approach simplifies the design of the control system and guarantees the intended output performance. We have implemented a protorype system using Linux, and measured the performance under various network QoS constraints. As expected, the prototype CTQR system was able to provide QoS control without too much overhead.