Computer English Unit 9 The Internet（计算机英语 第九单元 因(2)

variety of structures.

一个人如果“站”在一个域的网关处“向外看”云，就会发现各种结构。

Indeed, the Internet has grown in a somewhat haphazard way as various domains have found points at which to connect to the cloud.

的确，随着各种域找到与云建立连接的点，因特网也以有点随意的方式发展着。

One popular structure, however, is for the gateways of a number of domains to be connected to form a regional network of gateways. 然而，一种流行的结构是，将若干域的网关连接在一起，形成一个由网关组成的区域网络。

For instance, a group of universities could choose to pool their resources to construct such a network.

例如，一组大学可以选择将其资源集中起来，用于构建这样一个网络。

In turn, this regional network would be connected to a more global network to which other regional networks attach.

而这个区域网络接着又连接到一个更大的网络上，后者上面还连接有其他的区域网络。

In this manner, that portion of the cloud takes on a hierarchical structure.

这样，那部分云就呈现出了层次结构（图9A-1）。

Ⅱ. Connecting to the Internet 二、连接到因特网

To simplify the process of connecting to the Internet, numerous companies, called Internet service providers (ISPs), allow customers to connect their domains to the Internet via the ISP’s equipment or to become a part of a domain already established by the ISP.

为了简化连接到因特网上的过程，许多称为因特网服务提供商的公司允许客户通过公司的设备将他们的域连接到因特网上，或者成为公司已经建立的一个域的一部分。

Perhaps the least expensive connections to an ISP are obtained through temporary telephone links called dial-up connections.

与因特网服务提供商最经济的连接或许是通过临时电话链路建立的连接，这种连接称为拨号连接。 Using this approach, an individual connects his or her computer to the local telephone line and executes a software package that places a call to a computer at the ISP.

使用这种方法，一个人将其计算机连接到当地电话线上，然后运行一个软件包，向因特网服务提供商的一台计算机发出呼叫。

At this point the ISP provides Internet access for the duration of the telephone call.

这时，因特网服务提供商就为其提供因特网访问服务，持续时间为电话呼叫的时间长度。

This temporary connection model is popular (and, in fact, expanding) in the cell-phone/hand-held computer arena.

这种临时连接模型在手机/手持式计算机领域比较流行（实际上应用得越来越多）。

However, in fixed location applications it is rapidly giving way to permanent connections through higher bandwidth systems such as DSL,

cable television lines, and satellite links. 然而，在位置固定的应用中，临时连接快速让位于永久连接，这种连接通过数字用户线路、有线电视线路和卫星链路等带宽比较高的系统建立。

These technologies have greatly reduced the expense of broadband (high-capacity) Internet access (which used to be available only to large organizations that could afford the expense of dedicated Internet connections), making today’s multimedia applications accessible to home users. 这些技术大大降低了宽带（大容量）因特网访问（曾经只提供给负担得起专用因特网连接的大型机构）的费用，从而使家庭用户也可以访问今天的多媒体应用程序。

Another development taking place at the household level is that home computer systems are expanding from

single

computer

installations

to

multicomputer networks, usually implemented as Ethernet bus networks.

在家庭层面出现的另外一个发展是，家用计算机系统正在从单个计算机设备扩展为多个计算机的网络，这

种网络通常实现为以太网总线网络。

These networks gain access to the Internet by means of a router within the home that is permanently connected to an ISP via DSL, a cable television line, or a satellite link, making the home system a local network within a domain established by the ISP.

这些网络使用家里的路由器访问因特网，而该路由器通过数字用户线路、有线电视线路或卫星链路与因特网服务提供商永久连接，从而使家里的系统成为因特网服务提供商建立的一个域中的局部网。

The connection from the home’s router to the local computers is often wireless.

从家中路由器到家庭局部网中计算机的连接常常采用无线方式。

That is, each computer communicates with the router by means of a small transmitter/receiver with a range of approximately 100 feet. 也就是说，每台计算机使用一部作用距离大约为100英尺的小型发射机/接收机与路由器通信。

Such wireless local networks are popular outside