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单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,2015/1/12,#,Lesson,Internet Infrastructure,19,Lesson Internet Infrastructure,1,Where,does the name Internet comes from,?,2.Who owns the Internet?,Warm-up Exercises,Where does the name Internet,2,interconnected,互相,连接,的,host,computer,主机,oversee,监督,，,审,Internet Service Provider(ISP,),因特网服务提供者,local area network(LAN),局域网,Point of Presence(POP),电话,接入网点,Network Access Points,（,NAPs,）,网络,接入点,Word,Preparation,interconnected 互相连接的Word Prep,3,rack,机架,dial,into,拨号,到,corporate,公司,fiber,optic,光纤,intercommunicate,相互,通信,trillion,万亿,Word,Preparation,rack 机架Word Preparation,4,One of the greatest things about the Internet is that nobody really owns it.It is a global collection of networks,both big and small.These networks connect together in many different ways to form the single entity that we know as the Internet.,In fact,the very name comes from this idea of interconnected networks,.,Since its beginning in 1969,the Internet has grown from four host computer systems to tens of millions.,However,just because nobody owns the Internet,it doesnt mean it is not monitored and maintained in different ways.The Internet Society,a non-profit group established in 1992,oversees the formation of the policies and protocols that define how we use and interact with the Internet.,Text,但是，虽然,Internet,不真正属于任何人，但仍然以不同方式得到监管和维护。,Internet,学会是,1992,年成立的非营利性组织，负责监督相关政策与协议的建立，确定,Internet,如何使用和交互。,One of the greatest things abo,5,Every computer that is connected to the Internet is part of a network,even the one in your home,.For example,you may use a modem and dial a local number to connect to an Internet Service Provider (ISP).At work,you may be part of a local area network(LAN),but you most likely still connect to the Internet using an ISP that your company has contracted with.When you connect to your ISP,you become part of their network.The ISP may then connect to a larger network and become part of their network.,The Internet is simply a network of network,s.,Text,每个连接,Internet,的计算机都是网络的一部分，即使你的家用计算机也是,Internet,就是网络的网络,Every computer that is connect,6,Most large communications companies have their own dedicated backbones connecting various regions.In each region,the company has a Point of Presence(POP).The POP is a place for local users to access the companys network,often through a local phone number or dedicated line.,The amazing thing here is that there is no overall controlling networ,k.Instead,there are several high-level networks connecting to each other through Network Access Points or NAPs.,Text,这里的奇怪之处是没有总体控制的网络,Most large communications comp,7,Heres an example.Imagine that Company A is a large ISP.In each major city,Company A has a POP.The POP in each city is a rack full of modems that the ISPs customers dial into,.Company A leases fiber optic lines from the phone company to connect the POPs together.,Imagine that Company B is a corporate ISP.Company B builds large buildings in major cities and corporations locate their Internet server machines in these buildings.,Company B is such a large company that it runs its own fiber optic lines between its buildings so that they are all interconnec,ted.,Text,公司,A,从电话公司租用光缆，将,POP,连接起来。,公司,B,很大，大楼之间有自己的光缆，因此它们都是互连的。,Heres an example.Imagine th,8,In this arrangement,all of Company As customers can talk to each other,and all of Company Bs customers can talk to each other,but there is no way for Company As customers and Company Bs customers to intercommunicate.,Therefore,Company A and Company B both agree to connect to NAPs in various cities,and traffic between the two companies flow,s between the networks at the NAPs.,In the real Internet,dozens of large Internet providers interconnect at NAPs in various cities,and trillions of bytes of data flow between the individual networks at these points.,The Internet is a collection of huge corporate networks that agree to all i,ntercommunicate with each other at the NAPs.In this way,every computer on the Internet connects to every other.,Text,因此，公司,A,和,B,同意连接不同城市的,NAP,，两个公司间的通信流在,NAP,处的网络间流动,Internet,是大公司网络的集合，协定在,NAP,处进行所有相互通信。,In this arrangement,all of Co,9,POP,ISP,（,Internet service provider)is a company which provides other companies or individuals with access to,or presence on,the Internet.Most ISPs are also Internet Access Providers;extra services include help with design,creation and administration of World-Wide Web sites,training,and administration of intranets.,POP(point of presence)is a site where there exists a collection of telecommunications equipment,usually modems,digital leased lines and multi-protocol routers.An Internet access provider may operate several PoPs distributed throughout their area of operation to increase the chance that their subscribers will be able to reach one with a local telephone call.The alternative is for them to use virtual PoPs(virtual points of presence)via some third Party.,Key Terms,ISP,POPISP（Internet service provid,10,Fiber optic,A system of two or more computers,term
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