It is known that to pursuit end-to-end QoS of a class-based traffic flow is inefficient in Differentiated Service Networks. Therefore in this thesis, we propose an effective throughput-recovery mechanism to allow high-priority traffic flow to receive suitable resource allocation, and hence the end-to-end QoS is guaranteed. The proposed throughput-recovery mechanism assures a predefined minimum departure rate of low-latency EF dataflow. It consists of two parts. The first part is referred to as the feedback self-adaptive mechanism, where the egress node measures and monitors throughput of EF dataflow to decide whether to send the control messages to ingress node. When ingress node receives the control messages, it will reallocate the resources to improve EF throughput. The second part is referred to as the dynamic weight adjustment mechanism, which can prevent EF packets from dropping when congestion occurs in the core routers. For the purpose of demonstration, we build a mathematical model and use NS-2 simulator. We have proved our throughput-recovery mechanism is effective in improving the throughput of EF traffic flow. Finally, we modify the traditional WRR such that it can adjust weight based on the delay requirements.