计算机网络英文版课件1.pptVIP

江西师大软件学院 Computer networkChapter 1Introduction 郭 斌 E_mail: jxnuit@163.com Topics What is Computer Networks Uses of Computer Networks Components of Computer Networks Reference Model of Computer Networks Basic Concepts of Data Transmission What is Computer Network Collection of autonomous computers interconnected by a single technology. The old model of a single computer serving all of the organizations computational needs has been replaced by one in which a large number of separate but interconnected computers do the job. computer network vs. distributed system The key distinction is that in a distributed system, a collection of independent computers appears to its users as a single coherent system. A distributed system is a software system built on top of a network. The software gives it a high degree of cohesiveness and transparency. Thus, the distinction between a network and a distributed system lies with the software (especially the operating system), rather than with the hardware. Uses of Computer Networks Business Applications Resource Sharing E-mail Videoconferencing E-commerce Home Applications Access to remote information Person-to-person communication Interactive entertainment Electronic commerce Access to remote information surfing the World Wide Web for information or just for fun. Many newspapers have gone on-line and can be personalized. on-line digital library. Interactive entertainment video on demand game playing client-server model peer-to-peer Model In peer-to-peer system there are no fixed clients and servers. Mobile Users Mobile computers, such as notebook computers and personal digital assistants (PDAs), are one of the fastest-growing segments of the computer industry Why would anyone want Wireless networks ? Although wireless networking and mobile computing are often related, they are not identical . Components of Computer Networks Hardware: how you can configure a bunch of computers into a network: Local Area Networks (LAN