The Design And Implementation Of A Reliable Transport System Based On UDP For Large-scaledata Transmission

The network has become an integral part of everyday life.Communication network has been able to achieve the exchange of information transmission, it is mostly rely on the work of computer network protocols and routing algorithms and some computer hardware facilities and other elements.Wherein the communication protocols and routing algorithm is an important element of the design of computer communication network system. The central issue of the reliability of the design of efficient data transmission system is how to achieve efficient, reliable and fair transfer of data.In practice, the most widely used transport protocol is TCP/IP protocol. However,the TCP protocol transmission rate slow, taking up overhead, not easy to use in multimedia communications.Because of the real-time multimedia communication with efficiency and other characteristics, the system is also coincident with the characteristics of the UDP protocol, so most of the multimedia communications have adopted UDP protocol as the communication mechanism, while improving the working mechanism of the UDP, the communication system design based on improved UDP protocol. It is also an important communication network system design direction.UDP is not reliable transmission process performance, and often causes execution to transfer files quickly in the UDP, the file cannot reach the other side intact. If the communication process due to network conditions cause the packet to packet loss, UDP protocol often ignored it.Whether it is or after the end of the communication, UDP will not feedback to the communicating parties in the communication process. In addition, UDP protocol running in the transport layer, it is not reliable transport mechanisms, cannot complete a data packet to the application layer.This article is based on the above, we designed a computer transmission system is based on reliable UDP datagram protocol packet transmission, and improve the instability of UDP.The main work is as follows:Based on the UDP, we design and implement a serial number error correction and verification mechanisms,we recover datagram information with the forward error correction, we also design data packet acknowledgment and retransmission with the sliding window delivery mechanism.To achieve the above functions, we add datagram packet sequence number and set up the buffer zone in the sender and the receiver.Since the definition of a reliable transport protocol CUDP (Checked UDP-based Reliable Protocol), we make the realization and tested under Winsock.Comparative efficiency of our systems we designed with the same type of file transfer system used in the TCP and UDP protocols, we compare the packet loss rate of transmission system,the packet size and the transmission speed on the long-fat network environment make a subsequent optimization.The background of this paper is we need a PC to multiple PC and a number of other communication devices to transfer files under long-fat network environment, meanwhile we can post some large-scale software systems and networks instructional videos and information which are developed in the laboratory to the Internet for users to download. Users can take advantage of this file system to download files quickly complete the required information. Depending on the project and the needs of a relatively reliable design, hardware and software resources for a relatively small share of the transport protocol, and this protocol was designed based on a client PC file transfer system software, use this software to achieve large-scale data transmission, instant voice and video, but also can transmit massive video, etc., according to some of the background and the needs of the project, to be developed file transfer systems need to be able to have a strong robust, that meets the hardware and software transmission equipment smaller footprint, but the basic realization of reliable transport services. Although the TCP protocol enables reliable transmission of data, but the transmission rate is relatively slow, occupying more system resources, the structure is complicated, not easy transformation, does not meet the needs of the project. UDP protocol on the system overhead is relatively small, fast transfer rates, it is easy to transform it to do some transformation, has a certain reliability and meets the project needs.