Peer-to-Peer System Structures And Data Transmission Strategies: Design And Implementation

Since the opening of the networks to public interests in the 1990s,the Internet is booming,with thousands of applications and services throughout the globe.According to the evolution of the application requirements,the structure of the Internet changed from peer-to-peer(P2P) mode to client/server mode,and then back to P2P mode.Through the rapid development of end host equipments and network facilities, the data processing and transmission capability of the Internet is also growing,making the prosperous P2P applications even more prosperous.New applications include file sharing systems,video on demand systems and video over IP systems.However,the development of P2P applications overwhelms the increment of the Internet transmission abilities in recent years,causing serious network congestions. IPv4 does not provide Quality of Service(QoS) assured transmission mechanism;while IPv6 does provide the QoS mechanism,the massive deployment of IPv6 has been postponed for years.Without the QoS mechanism,P2P traffic occupies most of the bandwidth, severely downgrades the performance of other network services.Internet service providers(ISP) spent vast sums of money on enhancing the network facilities,but failed to fulfil the enormous requirement.Therefore,ISPs have no choice but to limit,or even block the traffic caused by P2P applications.The spread of P2P systems to wireless networks deteriorates the situation,because the wireless networks have less data processing capabilities than wireline networks.In this dissertation,we propose methods to balance the network traffic,in order to relieve the tensions caused by P2P applications. We also make effort to build P2P file sharing applications and a VVoIP application on AnyServer,a cross network platform for seamless data interoperability.The main contributions of this dissertation are:Firstly,we propose a scoring mechanism to protect wireless peers in hybrid P2P file sharing structure.In a P2P file sharing system with vast wireless peers,if we do not seriously consider the capability of wireless peers,they may be out of service soon, which in turn severely downgrades the efficiency of the system.In a hybrid P2P system where 80%of the peers are wireless peers,The source peer selection algorithm we put forth can reduce the out-of-service rate of wireless peers by 50%,and save the total file transmission time by 50%,effectively improving the overall performance of the hybrid P2P system.Secondly,we provide an optimized model of P2P file sharing system based on WiMAX and Wi-Fi.WiMAX and Wi-Fi are highly complementary.Hence,it is very profitable to build up P2P systems over WiMAX and Wi-Fi networks simultaneously.In this dissertation,we propose a layered distributed P2P structure for the application layer overlay network,in order to save the air interface of the wireless networks,and shorten the lookup time.By simulations,we claimed that the requested file can be found in the local subscribe station mesh network in 90%of the time,if that file's popularity rate is over 2.5%.Thirdly,we propose an adaptive SIP-based VVolP system.Because of the shortness of IP addresses in IPv4,NAT are massively deployed in the network.SIP/SDP protocol stack does not define the behavior of SIP client with NAT.ICE is a good solution for NAT,but quite complicating for VVoIP applications.The SIP-based adaptive VVoIP system we implemented can guarantee P2P connection between two clients. Through a series of experiments,we proved that the system can relieve the pressure of multimedia server,and reduce the delay time of the session.Fourthly,We present a series of cooperative transmission strategies for SIP-based VVoIP system over AnyServer.The emergence of VVoIP really reduces the size of the world.However,in a VVoIP system,the data size of the video stream overwhelms the data size of the voice data.If video data are transmitted without consideration of the voice data,serious jitters may occur.In this dissertation,we provide a series of transmission strategies called VVTS,which can effectively reduce the fluctuation of data transmission,and improve the voice quality of the system.Finally,we describe the whole structure of AnyServer in detail,and discuss the development trends of P2P VVoIP systems in the near future.