In this paper, we propose the use of Optimal Least Weight Routing (OLWR) Algorithm for routing QoS flows in high-speed networks. The main principle of our algorithm is that the choice of the most appropriate route, is based on a set of parameters that estimate the impact that, the acceptance and routing decision of a call request belonging to a specific class, would have on the network and other classes of service. The performance evaluation results demonstrated that OLWR outperforms both the Multi-hop Least-Loaded Routing algorithms and the Multi-hop Most-Loaded Routing algorithms in terms of both revenue and carried load.