HHS-TCP: a novel high-speed TCP based on hybrid congestion control

This paper presents a new congestion control algorithm of TCP, called HHS-TCP (Hybrid High-Speed TCP), and provides its effective result through simulations and implementations. Recently, towards high-speed networks with large bandwidth delay product (BDP), a number of different approaches have been proposed to improve TCP performance. However, adopting more aggressive loss-based congestion control algorithm may severely decrease the throughput of other regular TCP flows sharing the same network path. On the other hand, pure delay-based approaches may not work well if they compete with loss-based flows. Some new approaches combing a loss-based protocol and a delay-based protocol have been proposed. Our HHS-TCP also belongs to this category. HHS-TCP exploits three useful characteristics of TCP-CUBIC, FAST-TCP, TCPReno in its congestion avoidance strategy. In short, congestion window is increased fast when the link is underutilized, and the increment becomes negative when the throughout comes to the network saturation point. Its friendliness to the TCP-Reno is sufficiently satisfied at the same time.