Efficient Video Streaming using TCP

While most of the traffic on the Internet today consists of TCP flows, conventional wisdom holds that TCP is unsuitable for video streaming applications due to its insistence on reliability and lack of throughput guarantees. However, most streaming protocols need to implement many features of TCP including congestion control and recovery from packet loss. Additionally, using TCP for streaming is often unavoidable when the target clients are located behind firewalls. This work seeks to dispel the notion that TCP is inherently unsuitable for streaming. We focus on the common case of streaming video to receivers whose last mile connections to the Internet are bandwith-limited and act as network bottlenecks. Users generally run multiple concurrent networking applications that compete for the scarce bandwidth resource. Standard TCP shares bottleneck link capacity according to connection round-trip time (RTT), and therefore may not provide streaming applications with the necessary bit-rate. In our prior work, we outlined a receiver-based bandwidth sharing system (BWSS) for allocating the capacity of last mile bottlenecks among TCP flows according to a user’s preferences. This system does not require modifications to the TCP protocol, network infrastructure or sending hosts, making it easy to deploy. By breaking TCP fairness between flows on the access link, the BWSS can limit the throughput fluctuations of high-priority applications. In the present paper we utilize the BWSS to perform video streaming over TCP. We establish the benefits of our proposed approach over standard TCP through Internet experiments involving a prototype for the Linux operating system. Furthermore, we demonstrate scenarios in which a client using our bandwidth control system may actually obtain better performance than TCP-friendly UDP streaming protocols.