I have two workstations A and B connected to the same L3 switch at 1Gbps. Workstation A generates an MPEG2-TS UDP video stream at 10Mbps data rate. Workstation B receives this stream correctly. The switch is connected to an edge router via 100Mbps port.
Workstation C, which is on the other end of a private WAN, receives poor quality video stream: the first N lines of the image are good quality (N randomly changes) and the other lines suffers severe pixel blocks. WAN link capacity is 20Mbps.
The fact the first N lines are always good quality made me think it is not random packet loss. However I didn't understand at all why a 10Mbps stream could saturate a 20Mbps link.
To my surprise, after limiting NIC on workstation A to 100Mbps, workstation C could correctly receive and display the video stream. Why?