I have prepared the topology: 2 physical hosts and one computer with ODL Hydrogen and OVS 2.0.2 installed. I stream the audio-visual stream from one host to another and transfer the file via the FTP server run on one of the hosts at the same time. The result is packets drop and quality of video is not good. I have created 3 flows in ODL to control the traffic. My target is to make QoS to prioritize stream packets and avoid the influence of downloading file (no changes in video quality during stream and downloading file at the same time). I tried to modify ToS field via Hydrogen and even in Wireshark the classification is shown (DSCP field is filled), there is no effects. Can you please tell me is there another way to prioritize the traffic? I learned something about the queues in OVS but I am curios about ODL Hydrogen solutions. I will be grateful for any kind of answer.