电子与通信工程专业英语 教学课件 ppt 作者 徐存善 Unit 23

1、Unit 23,Introduction to Internet,Introduction to Internet,电子与通信工程专业英语,The Internet is a collection of individual networks, connected by intermediate networking devices, that functions as a single large network. 1 it is made up of millions of computers linked together around the world in such a way that information can be sent from any computer to any other 24 hours a day.,电子与通信工程专业英语,Internet是各个独立的网络通过中间网络设备连接到一起，形成一个功能上独立的大的网络集合。它是由世界上数百万的计算机连接在一起，并能一天24小时提供信息服务的网络系统。,These computers can be in

2、homes, schools, universities, government departments, or businesses small and large. They can be any type of computer and be single personal computers or workstations on a school or a company network. The Internet is often described asa network of networks because all the smaller networks of organizations are linked together into the one giant network called the Internet.2 All computers are pretty much equal once connected to the Internet, the only difference will be the speed of the connection

3、which is dependent on your Internet Service Provider and your own modem.,电子与通信工程专业英语,这些计算机可以放在家里、学校的、大学的、政府部门或大小企业里。它们可以是任何类型的，例如私人计算机或者是一个学校或公司网络的工作站。互联网经常被描述为“网络的网络”，因为它是由一些小组织的网络结合到一起，构成一个巨大的称为因特网的网络。所有联络到因特网上的计算机都是平等的，惟一不同的地方就是连接速度，这取决于网络供应商提供和自身的速率。,Figure 14 illustrates some different kinds of network technologies that can be interconnected by routers and other networking devices to create one part of Internet.,Fig. 23-1 Network diagram,电子与通信工程专业英语,图23-1就显示了不同网络的技术通过路由器和其他网络设备连接在一起构成了互联网的一

4、部分。,History of network The first networks were time-sharing networks that used mainframes and attached terminals. Such environments were implemented by both IBMs Systems Network Architecture (SNA) and Digitals network architecture. Local-Area Networks (LANs) evolved around the PC revolution. LANs enabled multiple users in a relatively small geographical area to exchange files and messages, as well as access shared resources such as file servers and printers.,电子与通信工程专业英语,网络发展历史 最早的网络是使用主机和连接终端的时分

5、复用网络，主要应用在IBM的系统网络体系结构和数字网络结构中。 局域网随着个人电脑的发展得到了发展，局域网可以使相对小的区域内的多个用户交换文件和信息，也能够共享文件服务器的资源和打印机。,Wide-Area Networks (WANs) interconnect LANs with geographically dispersed users to create connectivity. Some of the technologies used for connecting LANs include T1, T3, ATM, ISDN, ADSL, Frame Relay, radio links, and others. New methods of connecting dispersed LANs are appearing everyday. Today, high-speed LANs and Internet are becoming widely used, largely because they operate at very high speeds and

6、support such high-bandwidth applications as multimedia and videoconferencing.,电子与通信工程专业英语,广域网是将分散区域的局域网互连在一起形成互通的网络，使用的一些连接技术包括T1，T3，ATM，ISDN，ADSL，桢中继，无线链路和其他技术。每天都会有连接分散局域网的新技术出现。 当今，高速率的局域网和互联网被广泛的使用，因为它们运行速度快，支持高速率的带宽应用，如多媒体和视频会议业务。,TCP/IP All computers on the Internet communicate with one another using the Transmission Control ProtocolInternet Protocol suite, abbreviated to TCP/IP. TCP/IP is a communications protocol used to transfer digital data around the Internet. TCP and IP were develope

7、d by Department Of Defense (DOD) research project to connect different networks designed by different vendors into a network of networks (the“Internet”).3 Computers on the Internet use a client/server architecture. This means that the remote server machine provides files and services to the users local client machine. Software can be installed on a client computer to take advantage of the latest access technology.,电子与通信工程专业英语,TCP/IP 互联网上所有的计算机都使用传输控制协议/互联网协议簇进行通信，简称TCP/IP。 TCP/IP是在因特网中传输数据的通信协议。

8、它是由美国国防部开发的研究项目，用来将不同网络供应商设计的网络连接一个因特网。互联网上的计算机采用客户机/服务器结构，这意味着远端的服务器为使用者的客户机提供文件和服务。软件可以安装到客户机上就可以使客户机利用最新的接入技术连接入网。,Internet services An Internet user has access to a wide variety of services: electronic mail，file transfer, vast information resources, interest group membership, interactive collaboration, multimedia displays, real-time broadcasting, breaking news, shopping opportunities, and much more.,电子与通信工程专业英语,网络服务 互联网的用户可以获取广泛的服务，如电子邮件、文件传输、大的信息资源、会员服务、交互式协作、多媒体、实时广播、新闻、网络购物等。,The Internet

9、 represents a global resource in the form of information and knowledge and provides a platform for cooperative ventures. This has resulted in the establishment of a wide variety of information service providers. Unfortunately, the Internet has also seen the establishment of a number of unwholesome service providers, such as those dealing in child pornography and extremist propaganda. Perhaps we are oversimplifying, but there is good and bad information. Information can also be categorised in another way: as open or internal information, with security measures required to protect the latter category.,电子与通信工程专业英语,互联网代表的是全球的信息和知识资源，也提供了一个全面合作的商务平台，这就导致了各种信息服务供应商的出现，不幸的是，在互联网上也可以看到一些不健康的网络服务商，例如那些毒害儿童的色情和极端言论信息，也许我们有些过虑，但确实在网上有好的信息也会有坏的信息。信息也可以用另外一种方式分类，即开放的信息和内部的信息，而后者也是需要安全保护的信息。,Computers on the Internet may use one or all of the following Internet services: (1) Electronic mail (e-mail). Permits you to send and receive mail. (2) Telnet or remote login.4 Permits your computer to

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