In this paper, we propose an Application-aware Routing Scheme (App-RS) to meet network requirements of all classes of applications in SDN-based cloud datacenters. The proposed App-RS takes into account end-to-end delay and link load for real time applications (class 1), delay variation and link load for streaming applications (class 2), and link load for miscellaneous applications (class 3) to improve the performance of all classes of applications. Using Estinet, simulation results have shown that the average bandwidth ratio of class 1, class 2, and class 3 applications of the proposed App-RS are 9.86%, 4.53%, and 4.07% better than that of CORouting, respectively. The average end-to-end delay of class 1 applications of App-RS is 25.47% lower than that of CORouting. The average delay variation of class 2 applications of App-RS is 49.65% lower than that of CORouting. Therefore, the proposed App-RS can better meet the network requirements of all classes of applications in SDN-based cloud datacenters than CORouting.