Designing and implementing a new type of transport-layer socket: The UDTCP socket case

On most operating systems, the UDP and TCP sockets are the two main types of sockets used to provide transport-layer networking services. However, for several reasons, UDP and TCP sockets are unsuitable for transporting delay-sensitive but error-tolerant streaming data such as the data generated by multimedia streaming applications. In this paper, we create a new type of socket that is suitable for transporting such data and propose a novel and simple implementation for it. We have implemented this new type of socket in Free BSD 4.8 and call it the ' UDTCP socket.' It has both the UDP and TCP socket properties suitable for delay-sensitive but error-tolerant streaming data but not those UDP and TCP socket properties unsuitable for such data. When transporting a stream of such data whose sending rate needs to be regulated by TCP congestion control, our simulation results show that the UDTCP socket can provide a much better delay and delay-jitter performance than the TCP socket.