Research On Key Technology Of TCP Acceleration In High Speed Networks

With the rapid development of network technology, the speed of networks becomes faster and faster. How to make transfer be more efficient becomes the focus of network research. The transmission control mechanism of conventional TCP is designed for previous networks, and faces big challenge in high speed networks. TCP must be accelerated.In the research of TCP acceleration, the issues followed must be considered carefully. First, how to utilize the indication of routers to serve for traffic control in end-systems efficiently, and set up the mechanism for cooperation and control between end-systems and routers. Second, how to obtain better fairness among end-systems for bandwidth allocation. Third, how to avoid the impact of reverse traffic to acknowledgments of forward traffic. Fourth, how to utilize hardware to improve TCP performance in end-systems. We study these critical issues from view of software and hardware, and propose some efficient approaches.Now ECN is used between end-systems and routers. End-systems adjust sending rate according to ECN. Due to the absence of clear network status, end-systems can not adjust sending rate efficiently. We analyze the importance of network resources to TCP performance carefully, and discuss the impact of buffer oscillation. We suggest that some indications of router resources should appear in packet. We also propose an approach of explicit proportional bandwidth allocation with router assistance, called Explicit Proportional Bandwidth Allocation, EPBA, and design an algorithm for it. The novel approach sets up a mechanism for feedback and cooperation between end-systems and routers efficiently, this lets end-systems obtain more indications from routers and adjust sending rate quickly and efficiently with clear objective. What's more, EPBA can be implemented and deployed easily. Results of our experiments show that EPBA can let end-systems obtain stable transfer, and utilize network resources adequately, and improve TCP performance significantly.TCP Vegas utilizes delay-based congestion control mechanism and uses fixed rate control factor. We find that this lets TCP performance be proportional to link propagation delay and leads unfair bandwidth allocation. We analyze the impact of buffer in delay-based congestion control mechanism carefully, and propose an approach of rate control factor for all-around optimization, called Rate Control Factor Adaptive Adjusting, RCFAA, and design an algorithm for it. RCFAA can not only keep the advantages of delay-based congestion control mechanism, but also adjust rate control factor quickly based on link propagation delay. Results of our experiments show that RCFAA improves fairness in delay-based congestion control significantly and enhances the performance. Reverse traffic can lead degradation of TCP performance. To resolve this problem, we analyze the impact of reverse traffic carefully, and obtain the relation between reverse traffic and TCP performance. We propose an approach of rate control optimized for unidirectional trip time, and design an algorithm for rate control, called Unidirectional Trip Aware Rate Control, UTARC. UTARC splits original congestion window into two parts, update control window and rate control window. The update control window obtains delay from below unit, and adjusts congestion window based on delay. The rate control window is responsible for real sending rate. Results of our experiments show that UTARC can avoid the impact of reverse traffic efficiently in delay-based congestion control, and utilize network resources adequately.With the development of network technology, protocol processing becomes heavy burden of end-system. To alleviate the burden of end-system, we analyze the technology of TCP implementation based on hardware carefully, and study the process of TCP protocol deeply. We optimize the dominating operation of TCP protocol and propose an approach optimized for hardware. This approach is used to reorder disordered packets. At last, we design and implement a system based on FPGA, called TCP Hardware Acceleration Engine, THAE, and study some key issues in THAE deeply. Results of our tests show that our system can improve TCP performance in end-system significantly.To improve TCP performance, we study the technology of TCP acceleration and optimization carefully from view of software and hardware. We hope that our research can help people study TCP acceleration deeply later.