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1、Lesson,Internet Infrastructure,Where does the name “Internet“ comes from? 2. Who owns the Internet?,Warm-up Exercises,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
2、入点,Word Preparation,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,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 dif
3、ferent 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 does
4、nt 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.,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
5、督相关政策与协议的建立，确定Internet如何使用和交互。,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
6、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 networks.,每个连接Internet的计算机都
7、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,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 d
8、edicated line. The amazing thing here is that there is no overall controlling network. Instead, there are several high-level networks connecting to each other through Network Access Points or NAPs.,这里的奇怪之处是没有总体控制的网络,Heres an example. Imagine that Company A is a large ISP. In each major city, Company
9、 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 t
10、heir 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 interconnected.,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。,In this arrangement, all of Company As customers can talk to each o
11、ther, 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 flows between the network
12、s 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 intercommunicate with each ot
13、her at the NAPs. In this way, every computer on the Internet connects to every other.,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。,POP,ISP（Internet service provider) is a company which provides other companies or individuals with access to, or presence on, the Interne
14、t. 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,
15、 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 (
16、virtual points of presence) via some third Party.,ISP,Fiber optic,A system of two or more computers, terminals, and communications devices linked by wires, cables, or a telecommunications system in order to exchange information. The network may be limited to a group of users in a local area (local area network), or be global in scope, as the Internet is. vt. To link a group of computers or their users so that information can be mutually accessed or exchanged.,Use of light transmitte
