Research And Implementation Of Acceleration In High Loss Rate WAN Environment

With the development of computer networks, the bandwidth which is used to access to Internet is growing. However, affected by two inherent characteristics of Internet, transmission latency and packet loss, it can not bring about the same proportion to enhance the throughput while improving bandwidth proportionally. Thus how to improve the transmission performance of WAN is widespread concern. In recent years, the research has extended from optimization of transport protocol to application protocol behavior analysis, and has formed a set of optimization systems for acceleration gradually.Based on the analysis and study of the existing WAN acceleration technology, three deployment solutions for WAN acceleration are summarized in this thesis.Aimed at centralized data server for enterprise environments, the single gateway acceleration platform SGAP has been developed and designed. SGAP can provide download acceleration through adding related acceleration strategies and being deployed on the exit of server side.In this thesis we have analyzed the SGAP platform architecture and some critical technologies, at the same time have described corresponding realization and design in detail of all SGAP parts.Traditional congestion control has the issues of inefficient transmission performance in cross-regional,inter-network, or even transnational network which of high packet loss rate.Aiming at this, an improved congestion control version named Rapid TCP has been proposed in this thesis.Once the network packet loss occurs, it doesn’t traditionally reduce the congestion window quickly. Instead, it is on the basis of whether the loss rate increasing to decide whether reducing the congestion window. And in fast recovery phase, Rapid TCP chooses different window adjustment strategy based on in which section the congestion window is.There has description of Rapid TCP’s design methodology, Congestion control mechanism and the implementation of Linux kernel in this thesis. Finally, Rapid TCP is implanted into SGAP. It becomes an acceleration solution for download. We use it to do a series of tests in our Linux network testbed. Then a contrast result of download rate is obtained between the acceleration solution and traditional way. Experiments show that Rapid TCP can effectively adapt to the network environment of high packet loss rate, and access to higher bandwidth utilization. The SGAP can provide a convenient acceleration platform for centralized data server application. Also it shows the superiority of the combination between SGAP and Rapid TCP.