S-shaped TCP: A new transport protocol for fast long-distance networks

It is well known that TCP does not fully utilize the available bandwidth in fast long-distance networks. Several high speed transport protocols have been proposed in an effort to solve this scalability problem. This paper proposes S-shaped TCP (SS-TCP). The window growth function of SS-TCP is, in the steady state, S-shaped, and it can be divided into three regions. In region I, the window growth rate of SS-TCP is the same as that of standard TCP. In region II, the window of SS-TCP grows faster than that of standard TCP. In region III, SSTCP decreases its window growth rate as the network is becoming congested. Simulations show that SS-TCP has good performance in terms of buffer requirement, TCP friendliness, and responsiveness.