Chapter 8 The Internet
计算机专业英语 8-1
Computer English
Chapter 8 The Internet,Technology
Background
Chapter 8 The Internet
计算机专业英语 8-2
了解 Internet的起源
掌握 Internet的关键技术概念
描述 Internet协议与应用程序的作用
解释当前 Internet的结构
理解当前 Internet的局限
描述 Internet II的潜在作用
掌握英语长句的翻译技巧
Requirements:
Chapter 8 The Internet
计算机专业英语 8-3
8.1 The Internet,Technology Background
New Words & Expressions
hyperlink n.[计 ]超链接 pundit n,空谈家,权威性的评论者
glibly adv.流利地,流畅地 conceptualize v.使有概念
legitimization n.合法化,认为正当 institutional adj.制度上的,机构上的
fledging n.刚会飞的幼鸟,无经验的人 follow-on 继续
slice vt.把,..切成薄片 ; 把,..分成部分 break down 破坏；拆散细分；分类
disabled n.禁止使用的 quad n,四元组
mainframe n.[计 ]主机,大型机 vulnerable adj.易受攻击的,
gigabyte n.十亿字节 (giga-为字首,―十亿” ) supercomputer n.[计 ] 超型计算机
reminiscent adj,怀旧的；回忆的 Domain Name 域名
host computer (host) 主机 instant messaging 即时信息服务
packet-switching 分组交换技术 client/server 客户机 /服务器
circuit switching 线路转接 bit n.[计 ]位,比特
Router [计 ] 路由器 routing algorithm 路径算法
Ethernet n.以太网 token ring networks 令牌环形网
Telnet 远程登录 Finger 查找因特网用户的程序
Ping 测试 IP地址的程序 Tracert 检查路由器程序
UNIX 美国 AT&T公司的操作系统,UNIX操作系统 let alone 更不用说 …
Chapter 8 The Internet
计算机专业英语 8-4
Abbreviations
TCP (Transfer Control Protocol) 传输控制协议
IP(Internet Protocol) 网际协议
FTP (File Transfer Protocol) 文件传输协议
POP (Post Office Protocol)邮局协议
HTTP(Hypertext Transfer Protocol)超文本传输协议
IP address IP地址
URL (Uniform Resource Locator) 统一资源定位
DNS (domain name system) 域名系统
SSL (Security Socket Layer) 加密套接字协议层
RAM (random access memory) 随机存储器
ARPANET (Advanced Research Projects Agency Network) 美国国防部高级研究计划局建立的计算机网
ICANN (Internet Corporation for Assigned Names and Numbers) 因特网域名与地址管理组织
SMTP (Simple Message Transfer Protocol)简单邮件传输协议,用于电子邮件的传输
IMAP (Internet Message Access Protocol) Internet消息访问协议
Chapter 8 The Internet
计算机专业英语 8-5
What is the Internet? Where did it come from,and how did it support
the growth of the World Wide Web? What are the Internet’s most
important operating principles? The Internet is an interconnected
network of thousands of networks and millions of computers
(sometimes called host computers or just hosts) linking businesses,
educational institutions,government agencies,and individuals
together,The Internet provides around 400 million people around the
world (and over 170 million people in the United States) with services
such as e-mail,newsgroups,shopping,research,instant messaging,
music,videos,and news,No one organization controls the Internet or
how it functions,nor is it owned by anybody,yet it has provided the
infrastructure for a transformation in commerce,scientific research,
and culture,
因特网是什么? 它来自何处，和它如何支持万维网的增长? 因特网最重要的运行原则是什么?因特网是成千上万的网络和数以百万计的计算机 (有时被称为主机计算机或主机 )将企业、教育机构、政府机关和个人联结起来的一个互联网络。因特网为全球大约
4亿人 (其中美国 1.7亿多人 )提供诸如电子邮件、新闻讨论组、购物、研究、即时信息、
音乐、视频和新闻等服务。没有任何组织控制因特网或它的运作,它也不被任何人所拥有,尽管它为商业交易、科学研究和文化提供基础设施。
Chapter 8 The Internet
计算机专业英语 8-6
The word Internet is derived from the word internetwork or
the connecting together of two or more computer
networks,The World Wide Web,or Web for short,is one of
the Internet’s most popular services,providing access to
over one billion Web pages,which are documents created
in a programming language called HTML and which can
contain text,graphics,audio,video,and other objects,as
well as,hyperlinks” that permit a user to jump easily
from one page to another,
因特网 (Internet)一词起源于互联网络 (internetwork)或两个或更多的计算机网络联接在一起。全球信息网,或简称万维网,是因特网上最流行的服务之一,提供对 10亿多网页的访问，这些网页是由一种叫做 HTML(超文本链接标示语言 )编程语言生成的文件，
它可以包含本文、图形、声频、视频和其他对象、以及允许用户容易地跳跃到其他网页的“超链接”。
Chapter 8 The Internet
计算机专业英语 8-7
8.1.1 THE EVOLUTION OF THE INTERNET 1961–2000
Internet I—today’s Internet—has evolved over the last
forty years,In this sense,the Internet is not ―new‖; it did
not happen yesterday,Although journalists and pundits
talk glibly about ―Internet‖ time—suggesting a fast-
paced,nearly instant,worldwide global change
mechanism,in fact,it has taken forty years of hard work
to arrive at today’s Internet.
因特网 I——今天的因特网 ——已经发展了四十多年。在这个意义上，因特网不是
“新的”,它不是昨天才发生的事。虽然新闻记者和博学家口若悬河地谈论“因特网”时代 ——指一种快步调的、几乎即时的、全球性的变化机制，事实上，因特网达到今天的水平花费了四十年的艰苦努力。
Chapter 8 The Internet
计算机专业英语 8-8
The history of the Internet can be segmented into three phases,In
the first phase,the Innovation Phase,from 1961 to 1974,the
fundamental building blocks of the Internet were conceptualized and
then realized in actual hardware and software,The basic building
blocks are,packet-switching hardware,client/server computing,and
a communications protocol called TCP/IP (all described more fully
below),The original purpose of the Internet,when it was conceived
in the late 1960s,was to link together large mainframe computers on
college campuses,This kind of one-to-one communication between
campuses was previously only possible through the telephone
system or postal mail.
因特网的历史可以划分为三个阶段。在第一阶段即发明阶段，从 1961年到
1974年，因特网的基本构建模块被概念化并随之用真正的硬件和软件实现。
其基本的构建模块是,分组交换硬件、客户机 /服务器计算技术和一个被称为传输控制协议的通信协议 (它们都将在后文进行全面描述 )。 当在 20世纪
60年代末期构思的时候，因特网最初的目的是将大学校园内的大型计算机联结起来。在校园之间这种一对一的通信先前只有经过电话系统或邮政邮件才可能进行。
8.1.1 THE EVOLUTION OF THE INTERNET 1961–2000
Chapter 8 The Internet
计算机专业英语 8-9
In the second phase,the Institutional Phase,from 1975 to 1995,large
institutions such as the Department of Defense and the National Science
Foundation provided funding and legitimization for the fledging invention
called the Internet,Once the concept of the Internet had been proven in
several government-supported demonstration projects,the Department of
Defense contributed a million dollars to develop the concepts and
demonstration projects into a robust military communications system that
could withstand nuclear war,This effort created what was then called
ARPANET (Advanced Research Projects Agency Network),In 1986,the
National Science Foundation assumed responsibility for the development of
a civilian Internet (then called NSFNet) and began a ten-year-long $200
million expansion program.
在第二阶段即机构化阶段,从 1975年到 1995年，像国防部和国家科学基金委等一些大机构为这项被称为因特网的刚刚起步的发明提供资金并使其合法化。当因特网的概念在一些政府支持的示范性项目中被证实后，国防部提供了一百万美元资金将这个概念和示范性项目发展成为一个可以承受核战的军事通信系统。这个努力产生了以后被称作 ARPANET的东西 (高级研究计划局建立的计算机网 )。在 1986年，国家科学基金委承担了建立民用因特网的任务 (那时叫做 NSFNet)，并且开始了为期十年、耗资 2亿美元的扩展计划。
8.1.1 THE EVOLUTION OF THE INTERNET 1961–2000
Chapter 8 The Internet
计算机专业英语 8-10
In the third phase,the Commercialization Phase,from
1995– 2001,government agencies encouraged private
corporations to take over and expand both the Internet
backbone and local service to ordinary citizens—families
and individuals across America and the world who were
not students on campuses,By 2000,the Internet’s use
had expanded well beyond military installations and
research universities.
在第三阶段即商业化阶段,从 1995年至 2001年，政府机构鼓励私营公司接管并扩展因特网主干和接管为普通市民提供的地方性服务，普通市民包括在全美国和全世界的家庭以及非在校学生等个体。到 2000年，因特网的应用已大大超出了军事设备和大学研究的范围。
8.1.1 THE EVOLUTION OF THE INTERNET 1961–2000
Chapter 8 The Internet
计算机专业英语 8-11
8.1.2 THE INTERNET,KEY TECHNOLOGY CONCEPTS
In 1995,the Federal Networking Council (FNC) took the
step of passing a resolution formally defining the
term Internet,
“Internet” refers to the global information system that—
I,is logically linked together by a globally unique
address space based on the Internet Protocol (IP)
or its subsequent extensions/follow-ons;
在 1995 年，联邦的网络委员会 (FNC)通过了一个关于因特网术语正式定义的决议。
“因特网”是这样的全球信息系统 ——
I,通过以因特网协议或其扩展或继续为基础的、独特的地址空间被逻辑性地联结起来；
Chapter 8 The Internet
计算机专业英语 8-12
8.1.2 THE INTERNET,KEY TECHNOLOGY CONCEPTS
II,is able to support communications using the
Transmission Control Protocol/Internet Protocol
(TCP/IP) suite or its subsequent extensions/follow-
ons,and/or other IP-compatible protocols; and
III,provides,uses or makes accessible,either
publicly or privately,high level services layered on
the communications and related infrastructure
described herein.
II.能够支持使用 TCP/IP(传输控制协议 /因特网协议 )组或其扩展
/继续、和 /或其他与 IP协议 (因特网协议 )兼容的协议进行的通信；并且
III.提供、使用或使可访问此处描述的通信及其相关基础设施
(不论公用的还是专用的 )上分层次的高水平服务。
Chapter 8 The Internet
计算机专业英语 8-13
Based on the definition,the Internet means a network
that uses the IP addressing scheme,supports the
Transmission Control Protocol (TCP),and makes
services available to users much like a telephone system
makes voice and data services available to the public2.
基于这个定义，因特网表示这样一个网络 ——使用 IP地址分配方案、支持传输控制协议，并使用户可以使用多种服务 ——与电话系统使公众能够使用声音和数据服务非常类似。
8.1.2 THE INTERNET,KEY TECHNOLOGY CONCEPTS
Chapter 8 The Internet
计算机专业英语 8-14
Behind this formal definition are three extremely important
concepts that are the basis for understanding the Internet,
packet switching,the TCP/IP communications protocol,and
client/server computing3,Although the Internet has evolved
and changed dramatically in the last 30 years,these three
concepts are at the core of how the Internet functions today and
are the foundation for Internet II.
在这个正式的定义背后，隐含着三个极其重要的概念,分组交换,TCP/IP(传输控制协议 /网际协议 )通信协议和客户机 /服务器计算技术，它们乃是理解因特网的基础。尽管因特网在过去
30年发生了引人注目的进化和变化，但这三个概念仍是今天因特网运转的核心，也是因特网 II的基础。
8.1.2 THE INTERNET,KEY TECHNOLOGY CONCEPTS
Chapter 8 The Internet
计算机专业英语 8-15
Packet Switching,Packet switching is a method of slicing digital
messages into parcels called ―packets,‖ sending the packets
along different communication paths as they become available,
and then reassembling the packets once they arrive at their
destination,Prior to the development of packet switching,early
computer networks used leased,dedicated telephone circuits to
communicate with terminals and other computers,In circuit-
switched networks such as the telephone system,a complete
point-to-point circuit is put together,and then communication
can proceed.
分组交换。分组交换是传输数据的一种方法，它先将数据信息分割成许多称为“分组”的数据信息包；当路径可用时，经过不同的通信路径发送；
当到达目的地后，再将它们组装起来。在分组交换发展之前，早期计算机网络使用租用的专用电话线路和终端与其他计算机进行通信。在线路交换网络如电话系统中，一个完全点对点的线路被连结在一起，然后才能进行通信。
8.1.2 THE INTERNET,KEY TECHNOLOGY CONCEPTS
Chapter 8 The Internet
计算机专业英语 8-16
However,these ―dedicated‖ circuit-switching techniques
were expensive and wasted available communications
capacity—the circuit would be maintained regardless of
whether any data was being sent,For nearly 70% of the
time,a dedicated voice circuit is not being fully used
because of pauses between words and delays in
assembling the circuit segments,both of which
increased the length of time required to find and connect
circuits,A better technology was needed.
然而，这些“专用的”线路交换技术既价格昂贵又浪费有效的通信能力 —
—不论是否有数据输送都需要维持线路。由于字间的停顿和组装时的延迟，
一条专用的声音线路在几乎 70%的时间内没有得到充分利用，而这两种因素都增加寻找和连接线路所需的时间长度。因此需要一种比较好的技术。
8.1.2 THE INTERNET,KEY TECHNOLOGY CONCEPTS
Chapter 8 The Internet
计算机专业英语 8-17
The first book on packet switching was written by Leonard
Kleinrock in 1964,and the technique was further developed by
others in the defense research labs of both the United States and
England,With packet switching,the communications capacity
of a network can be increased by a factor of 100 or more,The
communications capacity of a digital network is measured in
terms of bits per second,Imagine if the gas mileage of your car
went from 15 miles per gallon to 1,500 miles per gallon—all
without changing too much of the car!
第一本关于分组交换的著作是由 Leonard Kleinrock于 1964年所著，美国和英国防卫研究实验室的其他研究人员使这项技术得到进一步发展。由于使用分组交换技术，网络的通信能力提高了 100倍甚至更多。数字网络的通信能力用每秒位来衡量。想象一下汽车行驶的里程，从每加仑汽油行驶
15里提高到每加仑汽油行驶 1500 里 ——而汽车没有太大的改变 !
8.1.2 THE INTERNET,KEY TECHNOLOGY CONCEPTS
Chapter 8 The Internet
计算机专业英语 8-18
In packet-switched networks,messages are first broken down into packets.
Appended to each packet are digital codes that indicate a source address
(the origination point) and a destination address,as well as sequencing
information and error control information for the packet,Rather than being
sent directly to the destination address,in a packet network,the packets
travel from computer to computer until they reach their destination,These
computers are called routers,Routers are special purpose computers that
interconnect the thousands of different computer networks that make up the
Internet and route packets along to their ultimate destination as they travel4.
To ensure that packets take the best available path toward their destination,
the routers use computer programs called routing algorithms.
在分组交换的网络中，信息首先被分解为许多信息包。每个信息包附加数字代码用于指示其源地址 (开始点 )和目的地地址、以及顺序信息和错误控制信息。在分组网络中，信息包不是直接被送到目的地地址,而是在计算机与计算机之间旅行直到它们到达目的地。这些计算机叫做路由器。路由器是一种特殊用途的计算机，它将组成因特网的成千上万个不同计算机网络互相联接起来，并在信息包旅行时将它们的向终极目的地发送。路由器使用一种叫做路由算法的计算机程序，以确保信息包取通向它们目的地的最佳可用路径。
8.1.2 THE INTERNET,KEY TECHNOLOGY CONCEPTS
Chapter 8 The Internet
计算机专业英语 8-19
Packet switching does not require a dedicated circuit but
can make use of any spare capacity that is available on
any of several hundred circuits,Packet switching makes
nearly full use of almost all available communication
lines and capacity,Moreover,if some lines are disabled
or too busy,the packets can be sent on any available line
that eventually leads to the destination point.
分组交换不需要一个专用线路，但是可以利用几百条线路中任何可用的空闲能力。分组交换几乎充分利用了所有可用的通信线路和能力。而且，如果一些线路不通或太忙的话,信息包能在任何可用的、最终通向目的地的线路上传送。
8.1.2 THE INTERNET,KEY TECHNOLOGY CONCEPTS
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计算机专业英语 8-20
TCP/IP,While packet switching was an enormous
advance in communications capacity,there was no
universally agreed upon method for breaking up digital
messages into packets,routing them to the proper
address,and then reassembling them into a coherent
message,This was like having a system for producing
stamps,but no postal system (a series of post offices
and a set of addresses).
TCP/IP。尽管分组交换是通信能力的一个巨大进步,但对于将数字信息分解为信息包、将它们传输到适当的地址,然后重新组装为原来的信息，还没有一种公认的方法。这就像有了一个生产邮票的系统,而没有邮政系统 (一系列的邮局和一套住址 )一样。
8.1.2 THE INTERNET,KEY TECHNOLOGY CONCEPTS
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TCP/IP answered the problem of what to do with packets on the Internet and
how to handle them,TCP refers to the Transmission Control Protocol (TCP).
IP refers to the Internet Protocol (IP),A protocol is a set of rules for
formatting,ordering,compressing,and error-checking messages,It may
also specify the speed of transmission and means by which devices on the
network will indicate they have stopped sending and/or receiving messages.
Protocols can be implemented in either hardware or software,TCP/IP is
implemented in Web software called server software (described below),TCP
is the agreed upon protocol for transmitting data packets over the Web,TCP
establishes the connections among sending and receiving Web computers,
handles the assembly of packets at the point of transmission,and their
reassembly at the receiving end.
TCP/IP回答了在因特网上用信息包做什么和如何处理信息包的问题。 TCP指传输控制协议,IP表示网际协议。协议是一组用于信息的格式化、次序化、压缩和检查错误的规则。它也可以限定传输速度和网上设备显示它们已停止发送及 (或 )接收信息的方法。协议既可以通过硬件也可通过软件来实现。 TCP/IP(传输控制协议 /网际协议 )通过被称为服务器软件的网络软件来实现 (在下文描述 )。 TCP(传输控制协议 )
是用来在网上传输数据的公认协议。 TCP(传输控制协议 )在发送和接收网络计算机之间建立连接,处理信息包在传输点的组装和在接收端的重新组装。
8.1.2 THE INTERNET,KEY TECHNOLOGY CONCEPTS
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TCP/IP is divided into four separate layers,with each
layer handling a different aspect of the communication
problem,The Network Interface Layer is responsible for
placing packets on and receiving them from the network
medium,which could be a Local Area Network (Ethernet)
or Token Ring Network,or other network technology.
TCP/IP(传输控制协议 /网际协议 )被分为四个独立的层,由每层处理通信问题的一个不同方面。网络接口层负责信息包在网络媒体上的排列和接收,网络媒体可能是局域网 (以太网 )、令牌环形网或其他网络技术。
8.1.2 THE INTERNET,KEY TECHNOLOGY CONCEPTS
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TCP/IP is independent from any local network technology and can
adapt to changes in the local level,The Internet Layer is responsible
for addressing,packaging,and routing messages on the Internet.
The Transport Layer is responsible for providing communication
with the application by acknowledging and sequencing the packets
to and from the application,The Application Layer provides a wide
variety of applications with the ability to access the services of the
lower layers,Some of the best known applications are Hyper Text
Transfer Protocol (HTTP),File Transfer Protocol (FTP),and Simple
Mail Transfer Protocol (SMTP),all of which we will discuss later in
this chapter.
TCP/IP(传输控制协议 /网际协议 )独立于任何局部网络技术，并能适应在局部水平上的改变。因特网层负责信息的寻址、封装及其在因特网上的路线排定。通过对信息包去与来应用层的确认和排序，传送层负责为应用层提供通信。应用层为许多应用提供访问较低层服务的能力。一些众所周知的应用是超文本传输协议 (HTTP)、文件传输协议 (FTP)和简单邮件传输协议
(SMTP),稍后我们将本章中讨论
8.1.2 THE INTERNET,KEY TECHNOLOGY CONCEPTS
Chapter 8 The Internet
计算机专业英语 8-24
IP Addresses,TCP handles the packetizing and routing
of Internet messages,IP provides the Internet’s
addressing scheme,Every computer connected to the
Internet must be assigned an address — otherwise it
cannot send or receive TCP packets,For instance,when
you sign onto the Internet using a dial-up telephone
modem,your computer is assigned a temporary address
by your Internet Service Provider.
IP地址。 TCP(传输控制协议 )处理因特网信息的分组化和传输路线排定。
IP(网际协议 )提供因特网的地址分配方案。每部连接到因特网的计算机必须分配一个地址，否则它不能够发送或接受 TCP(传输控制协议 )信息包。
举例来说，当你在使用调制解调器拨号上网时，你的计算机由因特网服务提供商分配一个临时地址。
8.1.2 THE INTERNET,KEY TECHNOLOGY CONCEPTS
Chapter 8 The Internet
计算机专业英语 8-25
Internet addresses,known as IP addresses,are 32-bit numbers
that appear as a series of four separate numbers marked off by
periods,such as 201.61.186.227,Each of the four numbers can
range from 0–255,This,dotted quad” addressing scheme
contains up to 4 billion addresses (232),The leftmost number
typically indicates the network address of the computer,while
remaining numbers help to identify the specific computer
within the group that is sending (or receiving ) a message.
因特网地址,即众所周知的 IP地址，是一个 32位的数字，它以一串由园点隔开的四个数字出现,例如 201.61.186.227。四个数字中的每一个都在 0-255
范围内。这个“点分四元组”地址分配方案包含多达到 40亿个地址 (232)。
最左边的那个数字指示计算机的网络地址，而其余的数字帮助识别正在发送 (或接收 )信息的团体里面一台特定的计算机。
8.1.2 THE INTERNET,KEY TECHNOLOGY CONCEPTS
Chapter 8 The Internet
计算机专业英语 8-26
The current version of IP is called Version 4,or IPv4.
Because many large corporate and government domains
have been given millions of IP addresses each (to
accommodate their current and future work forces),and
with all the new networks and new Internet-enabled
devices requiring unique IP addresses being attached to
the Internet,a new version of the IP protocol,called IPv6
is being adopted,This scheme contains 128-bit
addresses,or about one quadrillion (1015).
IP现在版本叫做第 4版，或 IPv4。因为许多大公司和政府在各自的域中已给定了数百万个 IP地址 (以适应他们当前和未来的劳动力 )，且由于新网络和新的可上网设备需要独特的 IP地址，新版本 IP协议 IPv6正在得到采用。
这个方案包含 128位的地址,或曰大约 1015个地址。
8.1.2 THE INTERNET,KEY TECHNOLOGY CONCEPTS
Chapter 8 The Internet
计算机专业英语 8-27
Domain Names and URLs,Most people cannot remember 32-
bit numbers,IP addresses can be represented by a natural
language convention called domain names,The domain name
system (DNS) allows expressions such as cnet.com to stand for
numeric IP addresses (cnet.com ’ s numeric IP is
216.200.247.134),Uniform resource locators (URLs),which are
the addresses used by Web browsers to identify the location of
content on the Web,also use domain names as part of the URL.
A typical URL contains the protocol to be used when accessing
the address,followed by its location.
域名和统一资源定位 (URL)。大多数人记不住 32位的数字。 IP地址可由一个自然语言约定 (称为域名 )来表示。域名系统 (DNS)允许像 cnet.com这样的表达代表数值型 IP地址 (cnet.com 的数值型 IP地址是 (216.200.247.134)。
统一的资源定位是网络浏览器用于识别网上内容位置的地址，也使用域名作为它的一部分。一个典型的网址包含访问地址时使用的协议，接着是它的位置。
8.1.2 THE INTERNET,KEY TECHNOLOGY CONCEPTS
Chapter 8 The Internet
计算机专业英语 8-28
Client/Server Computing,While packet switching exploded the
available communications capacity and TCP/IP provided the
communications rules and regulations,it took a revolution in
computing to bring about today’s Internet and the Web,That
revolution is called client/server computing and without it,the
Web—in all its richness—would not exist,In fact,the Internet is a
giant example of client/server computing in which over 70 million
host server computers store Web pages and other content that can
be easily accessed by nearly a million local area networks and
hundreds of millions of client machines worldwide.
客户机 /服务器计算技术。虽然分组交换使有效的通信能力激增，且 TCP/IP
协议提供了通信规则，在计算机技术中，发生了又一次革命才造就了今天的因特网和万维网。这次革命叫做客户机 /服务器计算技术，没有它，万维网及其丰富信息将不会存在。事实上，因特网是客户机 /服务器计算技术的一个巨大实例，其中，超过 7000万部主机服务器计算机储存网页和其他内容，这些网页和内容能被全世界接近一百万个局域网和数亿台客户机容易地访问。
8.1.2 THE INTERNET,KEY TECHNOLOGY CONCEPTS
Chapter 8 The Internet
计算机专业英语 8-29
Client/server computing is a model of computing in which very
powerful personal computers called clients are connected together
in a network together with one or more server computers,These
clients are sufficiently powerful to accomplish complex tasks such
as displaying rich graphics,storing large files,and processing
graphics and sound files,all on a local desktop or handheld device,
Servers are networked computers dedicated to common functions
that the client machines on the network need,such as storing files,
software applications,utility programs such as Web connections,
and printers.
客户机 /服务器计算技术是一种计算模型，其中相当多台被称为客户机的个人计算机联结在一起并与一台或更多的服务器计算机联结在一个网络中。
这些客户机功能足够强大以完成复杂的任务如显示丰富的图形、储存大型文件、并处理图形和声音文件，这些任务全部在当地的台式或手持式装置上完成。服务器是联网的计算机，专门用于提供客户机在网上需要的公共功能,例如储存文件、软件应用、公用程序如网络连接、和打印。
8.1.2 THE INTERNET,KEY TECHNOLOGY CONCEPTS
Chapter 8 The Internet
计算机专业英语 8-30
To appreciate what client/server computing makes
possible,you must understand what preceded it,In the
mainframe computing environment of the 1960s and
1970s,computing power was very expensive and limited.
For instance,the largest commercial mainframes of the
late 1960s had 128k of RAM and 10 megabyte disk drives,
and occupied hundreds of square feet,There was
insufficient computing capacity to support graphics or
color in text documents,let alone sound files or hyper
linked documents and databases.
为了充分理解客户机 /服务器计算技术的作用，你必须了解在它之前的东西。
在 20世纪 60年代和 70年代的大型计算机环境中，计算机能力非常昂贵而有限。比如,60年后期最大的商业化大型机有 128K随机存取存储器和 10兆磁盘驱动器，而且占据数百平方英尺空间。计算能力不足以支持图形和文本中的颜色，更不用说声音文件或超链接文档和数据库。
8.1.2 THE INTERNET,KEY TECHNOLOGY CONCEPTS
Chapter 8 The Internet
计算机专业英语 8-31
With the development of personal computers and local area networks
during the late 1970s and early 1980s,client/server computing became
possible,Client/server computing has many advantages over centralized
mainframe computing,For instance,it is easy to expand capacity by adding
servers and clients,Also,client/ server networks are less vulnerable than
centralized computing architectures,If one server goes down,backup or
mirror servers can pick up the slack; if a client machine is inoperable,the
rest of the network continues operating,Moreover,processing load is
balanced over many powerful smaller machines rather than being
concentrated in a single huge machine that performs processing for
everyone,Both software and hardware in client/server environments can be
built more simply and economically.
20世纪 70年代后期和 80年代初期，随着个人计算机和局域网的发展，客户机 /服务器计算技术成为可能。客户机 /服务器计算技术比中央大型机计算有许多优势。比如，通过增加服务器和客户机，可很容易地扩容。同时，客户机 /服务器网络比中央计算结构不易受损。如果一个服务器被破坏，备用的或镜像服务器能恢复工作；
如果一部客户机不能运转，网络的其部分可继续运行。而且,负荷处理通过许多强大的、较小的机器达到平衡，而不是集中于一部为每个人进行处理的巨型机。在客户机 /服务器环境中，建立软件与硬件都更简单、更经济。
8.1.2 THE INTERNET,KEY TECHNOLOGY CONCEPTS
Chapter 8 The Internet
计算机专业英语 8-32
Today there are about 450 million PCs in existence worldwide,Most of these
PCs can display and process graphics,sound files,and colored text,They
have memories up to 512MB,20 gigabyte hard drives,and occupy about two
square feet,These personal ―supercomputers,‖ when tied together in local
area networks or into large wide area networks such as the Web,make it
possible for millions of people to enjoy,rich” Web documents and
experiences,Soon these capabilities will move to handheld devices such as
the Palms and HP Jornada,and wireless cell phones (much,thinner
clients” ),In the process,more computer processing will be performed by
central servers (reminiscent of mainframe computers of the past).
今天全世界大约有 4.5亿台个人计算机，其中大多数可以显示并且处理图形、声音文件、和彩色文本。他们具有高达 512MB内存,20G(兆字节 )硬盘驱动器，而大约只占 2平方英尺空间。这些个人的“超级计算机”，把它们联结起来接入局域网或大型广域网如因特网，使数以百万计的人们享受“丰富的”网络文件和经验成为可能。这些能力将很快会移植到如 Palms,HP Jornada和无线蜂窝电话等手持式装置中 (很多“瘦客户机” )。在这个过程中，更多的计算机处理将由中央服务器完成
(过去的大型计算机的遗风 )。
8.1.2 THE INTERNET,KEY TECHNOLOGY CONCEPTS
Chapter 8 The Internet
计算机专业英语 8-33
There are many other Internet protocols that provide
services to users in the form of Internet applications that
run on Internet clients and servers,These Internet
services are based on universally accepted protocols—
or standards—that are available to everyone who uses
the Internet,They are not owned by any one organization
but are services that were developed over many years
and given to all Internet users.
有许多其他因特网协议以因特网应用的形式为用户提供服务，
这些因特网应用在客户机和服务器上运行。这些因特网服务以全世界普遍承认的协议或标准为基础，对任何使用因特网的用户有效。他们不为任何一个组织所拥有，而是发展了许多年、
供给所有因特网用户的服务。
8.1.3 Other Internet Protocols And Utility Programs
Chapter 8 The Internet
计算机专业英语 8-34
HTTP,Hypertext Documents,HTTP (short for Hyper Text Transfer
Protocol) is the Internet protocol used for transferring Web pages
(described in the following section),The HTTP protocol runs in the
Application Layer of the TCP/IP model,An HTTP session begins
when a client’s browser requests a Web page from a remote Internet
server,When the server responds by sending the page requested,
the HTTP session for that object ends,Because Web pages may
have many objects on them—graphics,sound or video files,frames,
and so forth—each object must be requested by a separate HTTP
message.
HTTP,超文本文档。 HTTP(超文本传输转移协议的缩写 )是用于传输网页的因特网协议 (下文描述 )。 HTTP协议在 TCP/IP模型中的应用层上运行。当一个客户机的浏览器向远程因特网服务器的一个网页发出请求时,HTTP会话开始。当服务器通过发送所请求的页面回应时，关于这个对象的 HTTP
会话结束。因为网页可能带有许多对象 ——图形、声音或视频文件、帧等 ——每个对象必须由一个独立的 HTTP 信息所请求。
8.1.3 Other Internet Protocols And Utility Programs
Chapter 8 The Internet
计算机专业英语 8-35
SMTP,POP,and IMAP,Sending E-mail,E-mail is one of
the oldest,most important,and frequently used Internet
services,STMP (Simple Mail Transfer Protocol) is the
Internet protocol used to send mail to a server,POP
(Post Office Protocol) is used by the client to retrieve
mail from an Internet server,You can see how your
browser handles SMTP and POP by looking in your
browser’s Preferences or Tools section,where the mail
settings are defined.
SMTP,POP和 IMAP:发送电子邮件。电子邮件是最老、最重要和经常使用的因特网服务之一。 STMP(简单邮件传输协议 )是用于将将邮件发送到服务器的因特网协议。客户机利用 POP(邮局协议 )从因特网服务器上检索邮件。你可以通过察看浏览器上“收藏”和“工具”栏看见你的浏览器如何处理 SMTP和 POP协议,邮件设定在这两栏定义。
8.1.3 Other Internet Protocols And Utility Programs
Chapter 8 The Internet
计算机专业英语 8-36
You can set POP to retrieve e-mail messages from the
server and then delete the messages on the server,or
retain them on the server,IMAP (Internet Message
Access Protocol) is a more current e-mail protocol
supported by many servers and all browsers,IMAP
allows users to search,organize,and filter their mail
prior to downloading it from the server.
你可以设定用 POP协议取回来自服务器的电子邮件信息然后删除服务器上的信息,或在服务器上保留它们。 IMAP(因特网消息访问协议 )是一个由许多服务器和所有的浏览器支持的更通用的电子邮件协议。 IMAP允许使用者在从服务器下载邮件之前搜寻、组织和过滤邮件
8.1.3 Other Internet Protocols And Utility Programs
Chapter 8 The Internet
计算机专业英语 8-37
FTP,Transferring Files,FTP (File Transfer Protocol) is
one of the original Internet services,It is a part of the
TCP/IP protocol and permits users to transfer files from
the server to their client machine,and vice versa,The
files can be documents,programs,or large database
files,FTP is the fastest and most convenient way to
transfer files larger than 1 megabyte,which many mail
servers will not accept.
FTP:传输文件。 FTP(文件传输协议 )是最初的因特网服务之一。
它是 TCP/IP协议的一部份，它允许用户把文件从服务器传送到客户机，反之亦然。文件可以是文档、程序、或大型数据库文件。 FTP是传输大于 1M文件最快速和最方便的方法，而许多邮件服务器将不接受大于 1M的文件
8.1.3 Other Internet Protocols And Utility Programs
Chapter 8 The Internet
计算机专业英语 8-38
SSL,Security,SSL (Secure Sockets Layer) is a protocol
that operates between the Transport and Application
Layers of TCP/IP and secures communications between
the client and the server,SSL helps secure e-commerce
communications and payments through a variety of
techniques such as message encryption and digital
signatures.
SSL:安全性。 SSL(加密套接字协议层 )是一个在 TCP/IP中运行于的传输层和应用层之间的、确保客户机与服务器之间通信安全的协议。通过诸如信息加密和数字签名等多种技术，
SSL促进安全的电子商务通信和支付。
8.1.3 Other Internet Protocols And Utility Programs
Chapter 8 The Internet
计算机专业英语 8-39
Telnet,Running Remote,Telnet is a terminal emulation
program that runs in TCP/IP,You can run Telnet from your
client machine,When you do so,your client emulates a
mainframe computer terminal,(The industry standard
terminals defined in the days of mainframe computing are VT-
52,VT-100,and IBM 3250.) You can then attach yourself to a
computer on the Internet that supports Telnet and run
programs or download files from that computer,Telnet was the
first ―remote work‖ program that permitted users to work on a
computer from a remote location.
Telnet(远程登录 ):远程运行。 Telnet是一个在 TCP/IP中运行的终端模拟程序。你能从你的客户机运行 Telnet。当你这么做的时候,你的客户机模拟一个主机计算机终端。 (定义于大型机计算时代的工业标准终端是 VT-52,VT-100和 IBM 3250)。然后你能接入到一台因特网上支持 Telnet的计算机上，从那部计算机运行程序或下载文件。 Telnet是允许用户在远方的一部计算机上工作的第一个“远程工作”程序。
8.1.3 Other Internet Protocols And Utility Programs
Chapter 8 The Internet
计算机专业英语 8-40
Finger,Finding People,You can find out who is logged
onto a remote network by using Telnet to connect to a
server,and then typing,finger” at the prompt,Finger
is a utility program supported by UNIX computers,When
supported by remote computers,finger can tell you who
is logged in,how long they have been attached,and their
user name,Obviously there are security issues involved
with supporting finger,and most Internet host computers
do not support finger today.
Finger,发现人们。通过使用 Telnet连接到一个服务器上,然后在提示符的键入 "Finger",你能发现谁登录到远程网络。 Finger是一个 UNIX 计算机支持的公用程。当由远程计算机支持时,Finger能告诉你谁登录了、他们已经连上多久和他们的用户名。显然，支持 Finger会涉及安全问题，而且大多数因特网主机今天不支持 Finger。
8.1.3 Other Internet Protocols And Utility Programs
Chapter 8 The Internet
计算机专业英语 8-41
Ping,Testing the Address,You can ―ping‖ a host
computer to check the connection between your client
and the server,The ping (Packet InterNet Groper)
program will also tell you the time it takes for the server
to respond,giving you some idea about the speed of the
server and the Internet at that moment,You can run ping
from the DOS prompt on a personal computer with a
Windows operating system by typing,Ping <domain
name>.
Ping:检测地址。你可以 "Ping"一台主机计算机来检查你的客户机和服务器之间的连结。给出你有关服务器和因特网速度的一些建议，
Ping(Packet InterNet Groper，信息包因特网搜索 )程序还将会告诉你服务器回应所需的时间。你可以在一部具有 Windows操作系统的个人计算机上在 DOS提示符下键入,Ping<域名 >。
8.1.3 Other Internet Protocols And Utility Programs
Chapter 8 The Internet
计算机专业英语 8-42
Tracert,Checking Routes,Tracert is one of a several
route-tracing utilities that allow you to follow the path of
a message you send from your client to a remote
computer on the Internet.
Tracert：检查路径。 Tracert是几种追踪路径的公用程序之一,
它允许你跟踪你在因特网上从客户机向远程计算机发出的信息的路径。
8.1.3 Other Internet Protocols And Utility Programs
Chapter 8 The Internet
计算机专业英语 8-43
New Words & Expressions
substrate n,衬底，基底 middleware n.中间设备,中间件
authentication n.证明,鉴定 repository n,储存库，资料档案库
backbone n.主干,干线 pipeline n,流水线，管线
Mbps n,兆比特每秒 Gbps n,千兆比特每秒
redundancy n.冗余 built-in adj.内置的,嵌入的 n.内置
tier n.一层，一排 curb n.路边
mom and pop shop n,夫妻店 dial-up 拨号上网
narrowband n,窄带 broadband n,宽带
throughput n,吞吐量 objectionable adj.该反对的,不能采用的
modem n.调制解调器 delay n.延迟
aficionado n,狂热爱好者,迷 sovereign adj.统治的 ; n.统治者
Intranet 企业内部互联网 Extranets 企业外部互联网
piggyback n.机载 ; v.搭载
8.2 The Internet Today
Chapter 8 The Internet
计算机专业英语 8-44
Abbreviations
NAP (Network Access Point) 网络访问节点
DSL (digital subscriber line) 数字用户线
Metropolitan Area Exchange (MAE) 城域交换站
W3C (World Wide Web Consortium) 万维网联合会
ISP (Internet Service Provider) Internet服务提供者
ISOC (Internet Society) Internet 协会
IAB (Internet Architectrue Board) Internet架构委员会
IETF (Internet Engineering Task Force) Internet工程任务组
IESG (Internet Engineering Steering Group) Internet工程指导组
8.2 The Internet Today
Chapter 8 The Internet
计算机专业英语 8-45
By 2001,there were approximately 400 million Internet users worldwide,up
from 100 million users at year-end 1997,That figure is projected to continue
to grow to close to 800 million by 2003,One would think that with such
incredible growth,the Internet would be overloaded,However,this has not
been true for several reasons,First,client/server computing is highly
extensible,By simply adding servers and clients,the population of Internet
users can grow indefinitely,Second,the Internet architecture is built in
layers so that each layer can change without disturbing developments in
other layers,For instance,the technology used to move messages through
the Internet can go through radical changes to make service faster without
being disruptive to your desktop applications running on the Internet.
截至 2001年，全世界因特网用户从 1997年底的 1亿上升到大约有 4亿。这个数字计划到 2003年继续增长到 8亿。有人可能会想：以如此令人难以置信的速度增长,因特网会超载。然而，由于几个原因这没有成为现实。首先，客户机 /服务器计算技术可以高度扩展：只需增加服务器和客户机,因特网用户人口能无限增长。其次，因特网是按照层次结构建造的，因此每一层能在不干扰其他层发展的前提下改变。举例来说，用于在因特网上移动信息的技术可以实现根本的改变使服务更快，而不会中断你的台式机在因特网上运行的应用。
8.2 The Internet Today
Chapter 8 The Internet
计算机专业英语 8-46
The Internet can be viewed conceptually as having four layers:
the network technology substrate,transport services and
representation standards,middleware services,and
applications,The network technology substrate is composed of
telecommunications networks and protocols,The transport
layer houses the TCP/IP protocol,The applications layer
contains client applications such as the World Wide Web,e-mail,
and audio or video playback,Middleware is the glue that ties
the applications to the communications networks,and includes
such services as security,authentication,addresses,and storage
repositories.
因特网能被概念性地分为四层：网络技术基体、传送服务和表示标准、中间件服务和应用。网络技术基体由电信网络和协议组成。传送层收容
TCP/IP协议。应用层包含客户机的应用，例如万维网、电子邮件和声频或视频回放。中间件是将应用与通信网络连接起来的粘合剂,并且包括如安全、
验证、地址和存储等服务。
8.2 The Internet Today
Chapter 8 The Internet
计算机专业英语 8-47
Users work with applications (such as e-mail) and rarely
become aware of middleware that operates in the
background,Because all layers use TCP/IP and other
common standards linking all four layers,it is possible
for there to be significant changes in the network layer
without forcing changes in the applications layer,The
network layer is described below.
用户通过应用程序 (例如电子邮件 )工作，很少知道中间件在后台运行。因为各层使用 TCP/IP协议和其他公共标准联结所有四层,所以在网络层发生重大变化而不强迫应用层变化是可能的。网络层在下面描述。
8.2 The Internet Today
Chapter 8 The Internet
计算机专业英语 8-48
Figure 8-3 Internet I network architecture
Chapter 8 The Internet
计算机专业英语 8-49
8.2.1 THE INTERNET BACKBONE
Figure 8-3 illustrates the main physical elements of today’s Internet,The
Internet’s backbone is formed by Network Service Providers (NSPs),which
own and control the major networks,The backbone has been likened to a
giant pipeline that transports data around the world in milliseconds,In the
United States,the backbone is composed entirely of fiber-optic cable
(described more fully below),with bandwidths ranging from 155 Mbps to
2.5 Gbps,Bandwidth measures how much data can be transferred over a
communications medium within a fixed period of time,and is usually
expressed in bits per second (bps),kilobits (thousands of bits) per second
(Kbps),megabits (millions of bits) per second (Mbps),or gigabits (billions of
bits) per second (Gbps).
图 8-3说明了今天因特网的主要物理组成。因特网主干由拥有且控制主要网络的网络服务提供商 (NSPs)形成。主干被比作一个能在几毫秒内将数据传遍全球的巨大通道。在美国，主干完全由光缆 (在文下更完整地描述 )组成，其带宽从 155兆比特 /
秒到 2.5吉比特 /秒。带宽衡量在固定的时间内、通过某种通信媒体能传输多少数据，
通常以每秒位 (bps)、每秒千位 (Kbps)、每秒兆位 (Mbps)或每秒千兆位 (Gbps)来表示。
Chapter 8 The Internet
计算机专业英语 8-50
Connections to other continents are made via a combination of
undersea fiber optic cable and satellite links,The backbones in
foreign countries typically are operated by a mixture of private and
public owners,The U.S,backbone is one of the most developed
because the Internet’s infrastructure was developed here,The
backbone has built-in redundancy so that if one part breaks down,
data can be rerouted to another part of the backbone,Redundancy
refers to multiple duplicate devices and paths in a network.
与其他大陆的连接是经由海底光缆和人造卫星联通的。在外国，
因特网主干是由私营和国有公司共同经营的。美国的因特网主干是 (全世界 )最发达的 (主干 )之一，因为因特网的基础是从这里发展起来的。因特网主干具有内在的冗余，以便如果主干的一部分崩溃,数据可以改行其他部份。冗余指在网络中设备和路径的多重副本。
8.2.1 THE INTERNET BACKBONE
Chapter 8 The Internet
计算机专业英语 8-51
In the United States there are a number of hubs where the backbone
intersects with regional and local networks,and where the backbone
owners connect with one another1,These hubs are called Network
Access Points (NAPs) or Metropolitan Area Exchanges (MAEs),and
use high-speed switching computers to connect the backbone to
regional and local networks,and exchange messages with one
another,The regional and local networks are owned by local Bell
operating companies (RBOCs — pronounced ―ree-bocks‖),and
private telecommunications firms such as MFS Corporation; they
generally are fiber optic networks operating at over 100 Mbps,The
regional networks lease access to Internet Service Providers,private
companies,and government institutions.
在美国，有许多网络中心 ——因特网主干与区域性和地方性网络在此交叉，主干拥有者也在此处彼此连接。这些网络中心被称为网络访问节点 (NAP)或城域交换站
(MAE),而且它们使用高速交换计算机联结主干与地方性和区域性网络、并彼此交换信息。区域性和地方性网络由地方贝尔运营公司 (RBOCs-发音 "ree-bocks")和私营电信公司例如 MFS公司所拥有；它们通常是以超过 100Mbps带宽运行的光纤网络。
区域性网络从因特网服务提供商、私营公司和政府机构租用使用权。
8.2.2 Network access points and metropolitan area exchanges
Chapter 8 The Internet
计算机专业英语 8-52
The Internet backbone connects regional networks,
which in turn provide access to the Internet to Internet
Service Providers,large firms,and government agencies.
因特网主干连接区域性网络,这些区域性网络反过来为因特网服务提供商、大公司和政府机关提供对的因特网的访问。
8.2.2 Network access points and metropolitan area exchanges
Chapter 8 The Internet
计算机专业英语 8-53
8.2.3 CAMPUS NETWORKS
There are an estimated one million campus networks attached to the Internet
worldwide (Computer Industry Almanac Inc.,2001),Campus networks are
generally local area networks operating with a single organization— such as
New York University or Microsoft Corporation,In fact,most large
organizations have hundreds of such local area networks,These
organizations (representing about 60 million workers) are sufficiently large
that they lease access to the Web directly from regional and national carriers,
These local area networks generally are running Ethernet (a local area
network protocol) and have operating systems such as Windows 2000 (NT),
Novell,or others that permit desktop clients to connect to the Internet
through a local Internet server attached to their campus networks,
Connection speeds in campus networks are in the range of 10–100 Mbps to
the desktop.
估计全世界有 100万个校园网联结到因特网 (计算机工业年间鉴公司,2001年 )。校园网通常是一个组织运营的局域网，例如纽约大学或微软公司。事实上，大部分大组织有几百个这样的局域网。这些组织 (代表大约 6亿工人 )足够大，以至于他们直接向区域性和国家通信公司租用对网络的访问。这些局域网通常是运行的以太网 (一种局域网协议 )，并且具有例如 Windows2000(NT),Novell或其他操作系统，允许桌面客户机通过一个连接到校园网的因特网服务器联到因特网。在校园网中，台式机的连接速度在 10-100 Mbps。
Chapter 8 The Internet
计算机专业英语 8-54
8.2.4 INTERNET SERVICE PROVIDERS
The firms that provide the lowest level of service in the multi-
tiered Internet architecture by leasing Internet access to home
owners,small businesses,and some large institutions are called
Internet Service Providers (ISPs)2,ISPs are retail providers—
they deal with ―the last mile of service‖ to the curb,the home,
the business office,About 45 million American households
connect to the Internet through either national or local ISPs,
ISPs typically connect to the Internet and MAEs or NAPs with
high-speed telephone or cable lines (up to 45 Mbps).
在多层次因特网体系中通过向家庭出租因特网访问通道提供最低水平服务的公司、小型企业，和一些大机构叫做因特网服务提供商 (ISP)。因特网服务提供商是零售型供给者 ——他们为街头、家庭、企业办公室处理“最后一步服务”。约 4500万个美国的家庭通过全国性的或地方性的 ISP连接到因特网。因特网服务提供商又利用高速电话或电缆线 (高达 45 Mbps)典型地连接到因特网和城域交换站或网络访问节点。
Chapter 8 The Internet
计算机专业英语 8-55
There are two types of ISP service,narrowband and broadband.
Narrowband service is the traditional telephone modem connection
now operating at 56.6 Kbps (although the actual throughput hovers
around 30 Kbps due to line noise that causes extensive resending of
packets),This is the most common form of connection worldwide.
Broadband service is based on DSL,cable modem,telephone (T1
and T3 lines),and satellite technologies,Broadband—in the context
of Internet service —refers to any communication technology that
permits clients to play streaming audio and video files at acceptable
speeds—generally anything above 100 Kbps.
因特网服务提供商提供两种服务,窄带和宽带。窄带服务是目前以 56.6 Kbps运行的传统电话调制解调器连接 (虽然由于线路噪音造成大量的信息包重新发送,真正的吞吐量徘徊在 30Kbps附近 )。这是全世界最普通的联结形式。宽频服务以数字用户专线、电缆调制解调器，电话 (T1和 T3线 )和人造卫星技术为基础。在因特网服务的环境中，宽频指的是任何允许客户机以可接受的速度运行流型声频和视频文件的通信技术，通常可接受的速度指在 100 Kbps以上。
8.2.4 INTERNET SERVICE PROVIDERS
Chapter 8 The Internet
计算机专业英语 8-56
The term DSL refers to digital subscriber line service,
which is a telephone technology for delivering high-speed
access through ordinary telephone lines found in your home
or business,Service levels range from about 150 Kbps all the
way up to 1 Mbps,DSL service requires that customers live
within two miles (about 4,000 meters) of a neighborhood
telephone switching center.
术语 DSL指数字用户专线服务，是通过在你家或企业所见到的普通电话线传送高速访问的一种电话技术。服务水平从大约从
150Kbps到高达 1Mbps。数字用户专线服务要求客户居住在临近电话交换中心 2英里之内 (大约 4000米 )。
8.2.4 INTERNET SERVICE PROVIDERS
Chapter 8 The Internet
计算机专业英语 8-57
Cable modem refers to a cable television technology that
piggybacks digital access to the Internet on top of the
analog video cable providing television signals to a
home3,Cable modem services ranges from 350 Kbps up
to 1 Mbps,Cable service may degrade if many people in
a neighborhood log on and demand high-speed service
all at once.
电缆调制解调器是一种在向家庭提供电视信号的视频电缆上搭载对因特网进行数字式访问的有线电视技术。电缆调制解调器服务范围从 350 Kbps到 1Mbps。如果临近有许多人同时登录并需要高速服务，缆传服务速度可能降低。
8.2.4 INTERNET SERVICE PROVIDERS
Chapter 8 The Internet
计算机专业英语 8-58
T1 and T3 are international telephone standards for digital
communication,T1 lines offer guaranteed delivery at 1.54
Mbps,while T3 lines offer delivery at 43 Mbps.
T1和 T3是数字通信的国际电话标准。 T1线提供保障 1.54Mbps
的传送,而 T3线提供 43Mbps传送。
8.2.4 INTERNET SERVICE PROVIDERS
Chapter 8 The Internet
计算机专业英语 8-59
8.2.5 INTRANETS AND EXTRANETS
The very same Internet technologies that make it possible to operate a
worldwide public network can also be used by private and government
organizations as internal networks,An intranet is a TCP/IP network located
within a single organization for purposes of communications and
information processing,Many corporations are moving away from
proprietary local area networks such as Windows 2000 and Novell,and
toward a single internal intranet to handle the firm’s information processing
and communication needs,Internet technologies are generally far less
expensive than proprietary networks,and there is a global source of new
applications that can run on intranets,In fact,all the applications available
on the public Internet can be used in private intranets..
使全球性公众网络运转成为可能的、与因特网技术相同的技术也能被私营和政府组织用于内部网络。内联网是一个组织内部用于通信和信息处理的 TCP/IP网络。许多公司正在远离专有局域网例如 Windows 2000和 Novell,并转向一个单一的企业内联网以处理公司的信息和通信需要。因特网技术通常远比专有网络技术价廉，而且拥有一个全球资源获得可在内联网上运行的新应用。事实上，在公用因特网上得到的所有应用都能在专用内联网使用。
Chapter 8 The Internet
计算机专业英语 8-60
8.2.5 INTRANETS AND EXTRANETS
Extranets are formed when firms permit outsiders to access
their internal TCP/IP networks,For instance,General Motors
permits parts suppliers to gain access to GM’s intranet that
contains GM’s production schedules4,In this way,parts
suppliers know exactly when GM needs parts,and where and
when to deliver the parts,
当公司允许局外人访问他们的内部 TCP/IP网络时，外联网就形成了。举例来说，通用汽车公司允许零部件供应商访问公司的内联网，它的内联网包含生产进度。这样，零部件供应商能完全了解通用汽车公司什么时候需要零部件,和到哪里与何时递送零部件。
Chapter 8 The Internet
计算机专业英语 8-61
8.2.6 WHO GOVERNS THE INTERNET?
Aficionados and promoters of the Internet often claim that the
Internet is governed by no one,and indeed cannot be governed,
and that it is inherently above and beyond the law,In fact,the
Internet is tied into a complex web of governing bodies,
national legislatures,and international professional societies,
There is no one governing body that controls activity on the
Internet,Instead,there are several organizations that influence
the system and monitor its operations,Among the governing
bodies of the Internet are:
因特网的热爱者和促进者时常宣称因特网没有被任何人统治,也的确不能被统治,而且还宣称它天生高于法律。事实上，因特网被连入了由管理机构、
国家立法机构和国际专业协会织成的一张复杂的网之中。没有一个管理机构可以控制因特网上的活动，而是有几个组织影响它的系统、监测它的运行。在因特网管理机构中有,
Chapter 8 The Internet
计算机专业英语 8-62
8.2.6 WHO GOVERNS THE INTERNET?
The Internet Architecture Board (IAB),which helps define
the overall structure of the Internet.
The Internet Corporation for Assigned Names and
Numbers (ICANN),which assigns IP addresses,and the
Internet Network Information Center (InterNIC),which
assigns domain names.
The Internet Engineering Steering Group (IESG),which
oversees standard setting with respect to the Internet,
因特网架构委员会 (IAB)帮助定义因特网的总体结构。
因特网域名与地址管理委员会 (ICANN)分配 IP地址；和因特网网络信息中心 (InterNIC)分配域名。
因特网工程指导组 (IESG)监督有关因特网的标准设定。
Chapter 8 The Internet
计算机专业英语 8-63
8.2.6 WHO GOVERNS THE INTERNET?
The Internet Engineering Task Force (IETF),which
forecasts the next step in the growth of the Internet,
keeping watch over its evolution and operation,
The Internet Society (ISOC),which is a consortium of
corporations,government agencies,and nonprofit
organizations that monitors Internet policies and
practices.
The World Wide Web Consortium (W3C),which sets
HTML and other programming standards for the Web.
因特网工程任务组 (IETF)预测因特网成长的下一步,监视它的进化和运行。
因特网协会 (ISOC)是一个公司、政府机关以及监测因特网政策与实践的非营利性组织的联盟。
万维网联合会 (W3C)为万维网设定 HTML和其他编程标准。
Chapter 8 The Internet
计算机专业英语 8-64
8.2.6 WHO GOVERNS THE INTERNET?
While none of these organizations has actual control
over the Internet and how it functions,they can and do
influence government agencies,major network owners,
ISPs,corporations,and software developers with the
goal of keeping the Internet operating as efficiently as
possible.
尽管这些组织中没有一个能真正控制因特网及其如何运行,他们可以就保持因特网尽可能高效运行的目标影响政府机关、主要网络拥有者、公司、因特网服务提供商和软件开发者。
Chapter 8 The Internet
计算机专业英语 8-65
8.2.6 WHO GOVERNS THE INTERNET?
In addition to these professional bodies,the Internet must also
conform to the laws of the sovereign nation-states in which it
operates,as well as the technical infrastructures that exist
within the nation-state,Although in the early years of the
Internet and the Web there was very little legislative or
executive interference,this situation will change in the near
future as the Internet plays a growing role in the distribution of
information and knowledge,including content that some find
objectionable
除了这些专业团体，因特网还必须符合所在的主权民族国家的法律,和这个民族国家存在的技术基础。虽然因特网和万维网在早年很少受到司法与或行政干涉,这种情形在不久的将来就会改变，因为因特网在传播信息和知识方面扮演越来越重要的角色,包括一些有人反对的内容。
Chapter 8 The Internet
计算机专业英语 8-66
New Words & Expressions
congestion n.阻塞 appreciate vt,领会，鉴赏,感激，察觉
circuitous adj.迂回线路的 latency n.等待时间
streaming adj.流型的 ; n.流 synchronous adj.同时的,同步的
jerkiness n.不平稳,颠簸 tag n,标志，特征，标记 [识 ]；标识符
multicasting 多信道广播 diffserve 区别质量的服务
videoconference n.视频会议
Abbreviations
AOL (American On-Line) 美国在线服务公司
NASA (National Aeronautics and Space Administration) (美国 )国家航空航天局
8.3 Internet II,The Future Infrastructure
Chapter 8 The Internet
计算机专业英语 8-67
Much of the Internet’s current infrastructure is several decades
old (equivalent to a century in Internet time),It suffers from a
number of limitations,including,
Bandwidth limitations,There is insufficient capacity throughout
the backbone,the metropolitan switching centers,and most
importantly,to the,last mile” to the house and small business,
The result is slow service (congestion) and a very limited
ability to handle video and voice traffic.
许多因特网现在的基础设施是几十年以前的 (在因特网时代等于一个世纪 )。
它承受许多限制,包括,
带宽限制 。 在主干、城市交换中心和最重要的最终对家庭和小型企业都存在着容量不足的问题。其结果是极慢的服务 (阻塞 )和相当有限的处理音频、
视频的能力。
8.3.1 LIMITATIONS OF INTERNET I
Chapter 8 The Internet
计算机专业英语 8-68
Quality of service limitations,Today’s information packets take a circuitous route to
get to their final destinations,This creates the phenomenon of latency— delays in
messages caused by the uneven flow of information packets through the network,In
the case of e-mail,latency is not noticeable,However,with streaming video and
synchronous communication,such as a telephone call,latency is noticeable to the user
and perceived as ―jerkiness‖ in movies or delays in voice communication,Today’s
Internet uses ―best efforts‖ quality of service,(QOS),which makes no guarantees
about when or whether data will be delivered,and provides each packet with the same
level of service,no matter who the user is or what type of data is contained in the
packet,A higher level of service quality is required if the Internet is to keep expanding
into new services (such as video on demand or telephony).
服务品质限制。今天的信息包需经过迂回路径到达目的地。这就产生了等待时间的现象 ——由于信息包通过网络时流动不畅通引起的信息延迟。就电子邮件来说，等待时间不引人注目。然而对于视频流和同步通信例如电话呼叫，等待时间对使用者是显而易见的并且在电影中感觉到 "抖动 "或在声音通信中感到延迟。今天的因特网使用 "最大努力 "的服务品质,对数据何时或是否被递送没有任何保证；而且无论使用者是谁或信息包中包含什么类型的数据，提供每个信息包相同水平的服务。如果因特网要继续扩大新的服务，就需要较高水平的服务质量 (例如随选视频服务或声音传送 )。
8.3.1 LIMITATIONS OF INTERNET I
Chapter 8 The Internet
计算机专业英语 8-69
Network architecture limitations,Today,a thousand
requests for a single music track from a central server will
result in a thousand efforts by the server to download the
music to each requesting client,This slows down network
performance as the same music track is sent out a
thousand times to clients that might be located in the
same metropolitan area,This is very different from
television,where the program is broadcast once to
millions of homes.
网络结构限制 。今天，对来自一个中央服务器的一个音乐辑发出一千个请求，将会造成服务器为每个请求的客户机下载音乐而动作一千次。当同一个音乐辑被送出一千次到可能位于相同城区的客户机，就减慢了网络性能。
这非常不同于电视,电视节目一次对数以百万计的家庭广播。
8.3.1 LIMITATIONS OF INTERNET I
Chapter 8 The Internet
计算机专业英语 8-70
Language development limitations,HTML,the language
of Web pages,is fine for text and simple graphics,but
poor at defining and communicating ―rich documents‖
such as databases,business documents,or graphics,The
tags used to define an HTML page are fixed and generic.
语言发展限制。 HTML网页语言,对本文和简单的图形是好的,
但在定义和传递如数据库、商业文件或图形等 "富文件 "时是不够的。用于定义 HTML页的标签是固定的和通用的。
8.3.1 LIMITATIONS OF INTERNET I
Chapter 8 The Internet
计算机专业英语 8-71
Now imagine an Internet at least 100 times as powerful as
today’s Internet,an Internet not subjected to the
limitations of bandwidth,protocols,architecture,and
language detailed above,Welcome to the world of Internet
II,and the next generation of e-commerce services and
products.
现在想象一下因特网的功能至少是现在的 100倍,想象一下一个不受上述带宽、协议、结构和语言限制的因特网。欢迎你到因特网 II的世界和下一代电子商务服务与产品的世界。
8.3.1 LIMITATIONS OF INTERNET I
Chapter 8 The Internet
计算机专业英语 8-72
The increased bandwidth and expanded network connections of
the Internet II era will result in benefits beyond faster access and
richer communications,Enhanced reliability and quality of
Internet transmissions will create new business models and
opportunities,Some of the major benefits of these technological
advancements include IP multicasting,latency solutions,
guaranteed service levels,lower error rates,and declining costs.
因特网 II时代增加的带宽与扩大的网络连接造就的利益不只是更快的访问和更丰富的通信。因特网传输的可靠性与质量的提高将会造就新的商业模型和机会。这些技术进步的一些主要的益处包括 IP多信道广播、等待时间解决方案、有保证的服务水平、低错误率和成本的降低。
8.3.3 The larger Internet II technology environment
Chapter 8 The Internet
计算机专业英语 8-73
IP Multicasting,IP multicasting is a set of technologies that enables
efficient delivery of data to many locations on a network,Rather than
making multiple copies of a message intended to be distributed to
multiple recipients at the point of origin of a message,multicasting
initially sends just one message and does not copy it to the individual
recipients until it reaches the closest common point on the network,
thereby minimizing the bandwidth consumed,Network performance
is significantly improved because it isn’t bogged down with the
processing and transmission of several large data files; each
receiving computer doesn’t have to query the transmitting server for
the file.
IP多信道广播。 IP多信道广播是使一组数据向网络中许多位置高效递送的技术。不是将一个信息在源点复制多份向多个接收者分配,多信道广播开始时只是发出一份信息而不向接收者复制，直到它到达网络上最近的公共点，因此使消耗的带宽最少。
因为它不会因处理和传输一些大的数据文件陷入停顿，所以网络型能大大地被改良；
每个接收计算机不必为一个文件向传输服务器发出请求。
8.3.3 The larger Internet II technology environment
Chapter 8 The Internet
计算机专业英语 8-74
Latency Solutions,One of the challenges of packet switching,
where data is divided into chunks and then sent separately to
meet again at the destination,is that the Internet does not
differentiate between high-priority packets,such as video clips,
and those of lower priority,such as self-contained e-mail
messages,Because the packets cannot yet be simultaneously
reassembled,the result is distorted audio and video streams.
等待时间解决方案。将数据分为多块、然后分开传送以便到目的地后再集合的分组交换技术，面临的挑战之一是因特网不区别高优先权信息包如图像修剪,与低优先权信息包如自我包容的电子邮件信息。因为信息包不能然同时重新装配,结果导致声频与视频流失真。
8.3.3 The larger Internet II technology environment
Chapter 8 The Internet
计算机专业英语 8-75
Internet II,however,holds the promise of diffserve,or differentiated
quality of service—a new technology that assigns levels of priority to
packets based on the type of data being transmitted.
Videoconference packets,for example,which need to reach their
destination almost instantaneously,would receive much higher
priority than e-mail messages,In the end,the quality of video and
audio will skyrocket without undue stress on the network,Live and
on-demand TV and video will be possible once Internet II is
completed.
然而因特网 II承诺区别服务品质 ——一种以被传输的数据类型为基础、为信息包分配优先权等级的新技术。例如，视讯会议信息包需要几乎即时到达目的地,将接受比电子邮件信息高的多的优先权。最后，由于在网上没有了过度的压力，视频和声频的质量将猛涨。一旦因特网 II完成，实况和随选电视与视频将成为可能。
8.3.3 The larger Internet II technology environment
Chapter 8 The Internet
计算机专业英语 8-76
Guaranteed Service Levels,In today’s Internet,there is no
service-level guarantee and no way to purchase the right
to move data through the Internet at a fixed pace,The
Internet is democratic—it speeds or slows everyone’s
traffic alike,With Internet II,it will be possible to purchase
the right to move data through the network at a
guaranteed speed in return for higher fees.
有保证的服务水平。在今天的因特网中,没有任何服务水平保证也没有办法购买以固定速度通过因特网移动数据。因特网是民主的 ——它加速或减慢每个人的通信量。通过因特网 II，将可购买以有保障的速度经过网络移动数据的权利，作为对较高费用的回报。
8.3.3 The larger Internet II technology environment
Chapter 8 The Internet
计算机专业英语 8-77
Lower Error Rates,Improved capacity and packet
switching will inevitably impact quality of data
transmissions,reducing error rates and boosting
customer satisfaction.
更低的错误率。改进的能力和分组交换不可避免地影响数据传输的质量，减少错误率而提高客户满意度。
8.3.3 The larger Internet II technology environment
Chapter 8 The Internet
计算机专业英语 8-78
Declining Costs,As the Internet pipeline is upgraded,the
availability of broadband service will expand beyond major
metropolitan areas,significantly reducing the costs of access.
More users means lower cost,as products and technology
catch on in the mass market,Higher volume usage enables
providers to lower the cost of both access devices,or clients,
and the service required to use such products,Both
broadband and wireless service fees are expected to decline as
geographic service areas increase,in part due to competition
for that business.
费用的降低。由于因特网通道升级,宽频服务的有效性将会超过主要大城市的范围，大大地降低访问的费用。较多的使用者意味比较低的费用,如同产品和技术在大众的市场中流行一样。较多的使用准许供应商降低访问设备或客户机的费用和服务必需使用的此类产品费用。随着服务的地理区域增大，预计宽频和无线服务的费用都将降低，部份是由于商业竞争。
8.3.3 The larger Internet II technology environment
Chapter 8 The Internet
计算机专业英语 8-79
英语长句的翻译一、英语长句的分析一般来说,造成长句的原因有三方面,(1) 修饰语过多 ;(2) 并列成分多 ; (3)语言结构层次多。
在分析长句时可以采用下面的方法：
① 找出全句的主语、谓语和宾语,从整体上把握句子的结构。
② 找出句中所有的谓语结构、非谓语动词、介词短语和从句的引导词。
③ 分析从句和短语的功能,例如,是否为主语从句,宾语从句,表语从句等,
若是状语,它是表示时间、原因、结果、还是表示条件等等。
④ 分析词、短语和从句之间的相互关系,例如,定语从句所修饰的先行词是哪一个等。
⑤ 注意插入语等其他成分。
⑥ 注意分析句子中是否有固定词组或固定搭配。
Chapter 8 The Internet
计算机专业英语 8-80
一、英语长句的分析例,For a family of four,for example,it is more convenient
as well as cheaper to sit comfortably at home,with
almost unlimited entertainment available,than to go out
in search of amusement elsewhere.
分析,(1) 该句的骨干结构为 it is more … to do sth than to do sth else.
是一个比较结构,而且是在两个不定式之间进行比较。 (2) 该句中共有三个谓语结构,它们之间的关系为,it is more convenient as well as cheaper
to … 为主体结构,但 it是形式主语,真正的主语为第二个谓语结构,to sit
comfortably at home,并与第三个谓语结构 to go out in search of
amusement elsewhere作比较。 (3) 句首的 for a family of four作状语,表示条件 。 另外,还有两个介词短语作插入语,for example,with almost
unlimited entertainment available,其中第二个介词短语作伴随状语,修饰 to sit comfortably at home.
[译文 ]譬如,对于一个四口之家来说,舒舒服服地在家中看电视,就能看到几乎数不清的娱乐节目,这比到外面别的地方去消遣又便宜又方便 。
Chapter 8 The Internet
计算机专业英语 8-81
二、英语长句的翻译英语习惯于用长的句子表达比较复杂的概念,而汉语则不同,常常使用若干短句,
作层次分明的叙述 。 因此,在进行英译汉时,要特别注意英语和汉语之间的差异,将英语的长句分解,翻译成汉语的短句 。 在英语长句的翻译过程中,我们一般采取下列的方法 。
1、顺序法。
当英语长句内容的叙述层次与汉语基本一致时,可以按照英语原文的顺序翻译成汉语。
例,Even when we turn off the beside lamp and are fast asleep,
electricity is working for us,driving our refrigerators,heating our
water,or keeping our rooms air-conditioned.
分析,该句子由一个主句,三个作伴随状语的现在分词以及位于句首的时间状语从句组成,共有五层意思,A.既使在我们关掉了床头灯深深地进入梦乡时 ; B.电仍在为我们工作 ; C,帮我们开动电冰箱 ; D,加热水 ; E.或是室内空调机继续运转。上述五层意思的逻辑关系以及表达的顺序与汉语完全一致,
[译文 ]即使在我们关掉了床头灯深深地进入梦乡时,电仍在为我们工作,帮我们开动电冰箱,把水加热,或使室内空调机继续运转。
Chapter 8 The Internet
计算机专业英语 8-82
二、英语长句的翻译
2,逆序法英语有些长句的表达次序与汉语表达习惯不同,甚至完全相反,
这时必须从原文后面开始翻译。
例,For our purposes we will say e-commerce begins in 1995,
following the appearance of the first banner advertisements
placed by ATT,Volvo,Sprint and others on Hotwired.com in
late October 1994,and the first sales of banner ad space by
Netscape and Infoseek in early 1995.
[译 ]伴随着 ATT,Volvo,Sprint等公司所做的第一例横幅广告于 1994年 10
月下旬出现在 Hotwired.com上，和 1995年初 Netscape与 Infoseek领先出售横幅广告空间，我们会说电子商务是从 1995年开始的。
Chapter 8 The Internet
计算机专业英语 8-83
二、英语长句的翻译
3、分句法有时英语长句中主语或主句与修饰词的关系并不十分密切,翻译时可以按照汉语多用短句的习惯,把长句的从句或短语化成句子,分开来叙述,为了使语意连贯,有时需要适当增加词语。
例,The number of the young people in the United States
who can't read is incredible about one in four.
上句在英语中是一个相对简单的句子,但是如果我们按照原文的句子结构死译,就可能被翻译成,―没有阅读能力的美国青年人的数目令人难以置信约为 1/4。”这样,就使得译文极为不通顺,不符合汉语的表达习惯,因此,我们应该把它译为,
[译文 ]大约有 1/4的美国青年人没有阅读能力,这简直令人难以置信。
Chapter 8 The Internet
计算机专业英语 8-84
二、英语长句的翻译
4,综合法事实上,在翻译一个英语长句时,并不只是单纯地使用一种翻译方法,而是要求我们把各种方法综合使用,这在我们上面所举的例子中也有所体现。尤其是在一些情况下,一些英语长句单纯采用上述任何一种方法都不方便,这就需要我们的仔细分析,或按照时间的先后,或按照逻辑顺序,顺逆结合,主次分明地对全句进行综合处理,以便把英语原文翻译成通顺忠实的汉语句子 。
例,Napster.com,which was established to aid Internet users in
finding and sharing online music files known as MP3 files,is
perhaps the most wellknown example of peer-to-peer e-
commerce,although purists note that Napster is only partially
peer-to-peer because it relies on a central database to show
which users are sharing music files.
译文,Napster.com建立的目标是帮助因特网用户发现并分享在线音乐文件，即人所共知的 MP3文件。尽管纯化论者强调：因为它依赖中央数据库来显示哪一位用户正在分享音乐文件，所以 Napster仅仅是部分对等。但 Napster或许是对等电子商务最著名的实例。
计算机专业英语 8-1
Computer English
Chapter 8 The Internet,Technology
Background
Chapter 8 The Internet
计算机专业英语 8-2
了解 Internet的起源
掌握 Internet的关键技术概念
描述 Internet协议与应用程序的作用
解释当前 Internet的结构
理解当前 Internet的局限
描述 Internet II的潜在作用
掌握英语长句的翻译技巧
Requirements:
Chapter 8 The Internet
计算机专业英语 8-3
8.1 The Internet,Technology Background
New Words & Expressions
hyperlink n.[计 ]超链接 pundit n,空谈家,权威性的评论者
glibly adv.流利地,流畅地 conceptualize v.使有概念
legitimization n.合法化,认为正当 institutional adj.制度上的,机构上的
fledging n.刚会飞的幼鸟,无经验的人 follow-on 继续
slice vt.把,..切成薄片 ; 把,..分成部分 break down 破坏；拆散细分；分类
disabled n.禁止使用的 quad n,四元组
mainframe n.[计 ]主机,大型机 vulnerable adj.易受攻击的,
gigabyte n.十亿字节 (giga-为字首,―十亿” ) supercomputer n.[计 ] 超型计算机
reminiscent adj,怀旧的；回忆的 Domain Name 域名
host computer (host) 主机 instant messaging 即时信息服务
packet-switching 分组交换技术 client/server 客户机 /服务器
circuit switching 线路转接 bit n.[计 ]位,比特
Router [计 ] 路由器 routing algorithm 路径算法
Ethernet n.以太网 token ring networks 令牌环形网
Telnet 远程登录 Finger 查找因特网用户的程序
Ping 测试 IP地址的程序 Tracert 检查路由器程序
UNIX 美国 AT&T公司的操作系统,UNIX操作系统 let alone 更不用说 …
Chapter 8 The Internet
计算机专业英语 8-4
Abbreviations
TCP (Transfer Control Protocol) 传输控制协议
IP(Internet Protocol) 网际协议
FTP (File Transfer Protocol) 文件传输协议
POP (Post Office Protocol)邮局协议
HTTP(Hypertext Transfer Protocol)超文本传输协议
IP address IP地址
URL (Uniform Resource Locator) 统一资源定位
DNS (domain name system) 域名系统
SSL (Security Socket Layer) 加密套接字协议层
RAM (random access memory) 随机存储器
ARPANET (Advanced Research Projects Agency Network) 美国国防部高级研究计划局建立的计算机网
ICANN (Internet Corporation for Assigned Names and Numbers) 因特网域名与地址管理组织
SMTP (Simple Message Transfer Protocol)简单邮件传输协议,用于电子邮件的传输
IMAP (Internet Message Access Protocol) Internet消息访问协议
Chapter 8 The Internet
计算机专业英语 8-5
What is the Internet? Where did it come from,and how did it support
the growth of the World Wide Web? What are the Internet’s most
important operating principles? The Internet is an interconnected
network of thousands of networks and millions of computers
(sometimes called host computers or just hosts) linking businesses,
educational institutions,government agencies,and individuals
together,The Internet provides around 400 million people around the
world (and over 170 million people in the United States) with services
such as e-mail,newsgroups,shopping,research,instant messaging,
music,videos,and news,No one organization controls the Internet or
how it functions,nor is it owned by anybody,yet it has provided the
infrastructure for a transformation in commerce,scientific research,
and culture,
因特网是什么? 它来自何处，和它如何支持万维网的增长? 因特网最重要的运行原则是什么?因特网是成千上万的网络和数以百万计的计算机 (有时被称为主机计算机或主机 )将企业、教育机构、政府机关和个人联结起来的一个互联网络。因特网为全球大约
4亿人 (其中美国 1.7亿多人 )提供诸如电子邮件、新闻讨论组、购物、研究、即时信息、
音乐、视频和新闻等服务。没有任何组织控制因特网或它的运作,它也不被任何人所拥有,尽管它为商业交易、科学研究和文化提供基础设施。
Chapter 8 The Internet
计算机专业英语 8-6
The word Internet is derived from the word internetwork or
the connecting together of two or more computer
networks,The World Wide Web,or Web for short,is one of
the Internet’s most popular services,providing access to
over one billion Web pages,which are documents created
in a programming language called HTML and which can
contain text,graphics,audio,video,and other objects,as
well as,hyperlinks” that permit a user to jump easily
from one page to another,
因特网 (Internet)一词起源于互联网络 (internetwork)或两个或更多的计算机网络联接在一起。全球信息网,或简称万维网,是因特网上最流行的服务之一,提供对 10亿多网页的访问，这些网页是由一种叫做 HTML(超文本链接标示语言 )编程语言生成的文件，
它可以包含本文、图形、声频、视频和其他对象、以及允许用户容易地跳跃到其他网页的“超链接”。
Chapter 8 The Internet
计算机专业英语 8-7
8.1.1 THE EVOLUTION OF THE INTERNET 1961–2000
Internet I—today’s Internet—has evolved over the last
forty years,In this sense,the Internet is not ―new‖; it did
not happen yesterday,Although journalists and pundits
talk glibly about ―Internet‖ time—suggesting a fast-
paced,nearly instant,worldwide global change
mechanism,in fact,it has taken forty years of hard work
to arrive at today’s Internet.
因特网 I——今天的因特网 ——已经发展了四十多年。在这个意义上，因特网不是
“新的”,它不是昨天才发生的事。虽然新闻记者和博学家口若悬河地谈论“因特网”时代 ——指一种快步调的、几乎即时的、全球性的变化机制，事实上，因特网达到今天的水平花费了四十年的艰苦努力。
Chapter 8 The Internet
计算机专业英语 8-8
The history of the Internet can be segmented into three phases,In
the first phase,the Innovation Phase,from 1961 to 1974,the
fundamental building blocks of the Internet were conceptualized and
then realized in actual hardware and software,The basic building
blocks are,packet-switching hardware,client/server computing,and
a communications protocol called TCP/IP (all described more fully
below),The original purpose of the Internet,when it was conceived
in the late 1960s,was to link together large mainframe computers on
college campuses,This kind of one-to-one communication between
campuses was previously only possible through the telephone
system or postal mail.
因特网的历史可以划分为三个阶段。在第一阶段即发明阶段，从 1961年到
1974年，因特网的基本构建模块被概念化并随之用真正的硬件和软件实现。
其基本的构建模块是,分组交换硬件、客户机 /服务器计算技术和一个被称为传输控制协议的通信协议 (它们都将在后文进行全面描述 )。 当在 20世纪
60年代末期构思的时候，因特网最初的目的是将大学校园内的大型计算机联结起来。在校园之间这种一对一的通信先前只有经过电话系统或邮政邮件才可能进行。
8.1.1 THE EVOLUTION OF THE INTERNET 1961–2000
Chapter 8 The Internet
计算机专业英语 8-9
In the second phase,the Institutional Phase,from 1975 to 1995,large
institutions such as the Department of Defense and the National Science
Foundation provided funding and legitimization for the fledging invention
called the Internet,Once the concept of the Internet had been proven in
several government-supported demonstration projects,the Department of
Defense contributed a million dollars to develop the concepts and
demonstration projects into a robust military communications system that
could withstand nuclear war,This effort created what was then called
ARPANET (Advanced Research Projects Agency Network),In 1986,the
National Science Foundation assumed responsibility for the development of
a civilian Internet (then called NSFNet) and began a ten-year-long $200
million expansion program.
在第二阶段即机构化阶段,从 1975年到 1995年，像国防部和国家科学基金委等一些大机构为这项被称为因特网的刚刚起步的发明提供资金并使其合法化。当因特网的概念在一些政府支持的示范性项目中被证实后，国防部提供了一百万美元资金将这个概念和示范性项目发展成为一个可以承受核战的军事通信系统。这个努力产生了以后被称作 ARPANET的东西 (高级研究计划局建立的计算机网 )。在 1986年，国家科学基金委承担了建立民用因特网的任务 (那时叫做 NSFNet)，并且开始了为期十年、耗资 2亿美元的扩展计划。
8.1.1 THE EVOLUTION OF THE INTERNET 1961–2000
Chapter 8 The Internet
计算机专业英语 8-10
In the third phase,the Commercialization Phase,from
1995– 2001,government agencies encouraged private
corporations to take over and expand both the Internet
backbone and local service to ordinary citizens—families
and individuals across America and the world who were
not students on campuses,By 2000,the Internet’s use
had expanded well beyond military installations and
research universities.
在第三阶段即商业化阶段,从 1995年至 2001年，政府机构鼓励私营公司接管并扩展因特网主干和接管为普通市民提供的地方性服务，普通市民包括在全美国和全世界的家庭以及非在校学生等个体。到 2000年，因特网的应用已大大超出了军事设备和大学研究的范围。
8.1.1 THE EVOLUTION OF THE INTERNET 1961–2000
Chapter 8 The Internet
计算机专业英语 8-11
8.1.2 THE INTERNET,KEY TECHNOLOGY CONCEPTS
In 1995,the Federal Networking Council (FNC) took the
step of passing a resolution formally defining the
term Internet,
“Internet” refers to the global information system that—
I,is logically linked together by a globally unique
address space based on the Internet Protocol (IP)
or its subsequent extensions/follow-ons;
在 1995 年，联邦的网络委员会 (FNC)通过了一个关于因特网术语正式定义的决议。
“因特网”是这样的全球信息系统 ——
I,通过以因特网协议或其扩展或继续为基础的、独特的地址空间被逻辑性地联结起来；
Chapter 8 The Internet
计算机专业英语 8-12
8.1.2 THE INTERNET,KEY TECHNOLOGY CONCEPTS
II,is able to support communications using the
Transmission Control Protocol/Internet Protocol
(TCP/IP) suite or its subsequent extensions/follow-
ons,and/or other IP-compatible protocols; and
III,provides,uses or makes accessible,either
publicly or privately,high level services layered on
the communications and related infrastructure
described herein.
II.能够支持使用 TCP/IP(传输控制协议 /因特网协议 )组或其扩展
/继续、和 /或其他与 IP协议 (因特网协议 )兼容的协议进行的通信；并且
III.提供、使用或使可访问此处描述的通信及其相关基础设施
(不论公用的还是专用的 )上分层次的高水平服务。
Chapter 8 The Internet
计算机专业英语 8-13
Based on the definition,the Internet means a network
that uses the IP addressing scheme,supports the
Transmission Control Protocol (TCP),and makes
services available to users much like a telephone system
makes voice and data services available to the public2.
基于这个定义，因特网表示这样一个网络 ——使用 IP地址分配方案、支持传输控制协议，并使用户可以使用多种服务 ——与电话系统使公众能够使用声音和数据服务非常类似。
8.1.2 THE INTERNET,KEY TECHNOLOGY CONCEPTS
Chapter 8 The Internet
计算机专业英语 8-14
Behind this formal definition are three extremely important
concepts that are the basis for understanding the Internet,
packet switching,the TCP/IP communications protocol,and
client/server computing3,Although the Internet has evolved
and changed dramatically in the last 30 years,these three
concepts are at the core of how the Internet functions today and
are the foundation for Internet II.
在这个正式的定义背后，隐含着三个极其重要的概念,分组交换,TCP/IP(传输控制协议 /网际协议 )通信协议和客户机 /服务器计算技术，它们乃是理解因特网的基础。尽管因特网在过去
30年发生了引人注目的进化和变化，但这三个概念仍是今天因特网运转的核心，也是因特网 II的基础。
8.1.2 THE INTERNET,KEY TECHNOLOGY CONCEPTS
Chapter 8 The Internet
计算机专业英语 8-15
Packet Switching,Packet switching is a method of slicing digital
messages into parcels called ―packets,‖ sending the packets
along different communication paths as they become available,
and then reassembling the packets once they arrive at their
destination,Prior to the development of packet switching,early
computer networks used leased,dedicated telephone circuits to
communicate with terminals and other computers,In circuit-
switched networks such as the telephone system,a complete
point-to-point circuit is put together,and then communication
can proceed.
分组交换。分组交换是传输数据的一种方法，它先将数据信息分割成许多称为“分组”的数据信息包；当路径可用时，经过不同的通信路径发送；
当到达目的地后，再将它们组装起来。在分组交换发展之前，早期计算机网络使用租用的专用电话线路和终端与其他计算机进行通信。在线路交换网络如电话系统中，一个完全点对点的线路被连结在一起，然后才能进行通信。
8.1.2 THE INTERNET,KEY TECHNOLOGY CONCEPTS
Chapter 8 The Internet
计算机专业英语 8-16
However,these ―dedicated‖ circuit-switching techniques
were expensive and wasted available communications
capacity—the circuit would be maintained regardless of
whether any data was being sent,For nearly 70% of the
time,a dedicated voice circuit is not being fully used
because of pauses between words and delays in
assembling the circuit segments,both of which
increased the length of time required to find and connect
circuits,A better technology was needed.
然而，这些“专用的”线路交换技术既价格昂贵又浪费有效的通信能力 —
—不论是否有数据输送都需要维持线路。由于字间的停顿和组装时的延迟，
一条专用的声音线路在几乎 70%的时间内没有得到充分利用，而这两种因素都增加寻找和连接线路所需的时间长度。因此需要一种比较好的技术。
8.1.2 THE INTERNET,KEY TECHNOLOGY CONCEPTS
Chapter 8 The Internet
计算机专业英语 8-17
The first book on packet switching was written by Leonard
Kleinrock in 1964,and the technique was further developed by
others in the defense research labs of both the United States and
England,With packet switching,the communications capacity
of a network can be increased by a factor of 100 or more,The
communications capacity of a digital network is measured in
terms of bits per second,Imagine if the gas mileage of your car
went from 15 miles per gallon to 1,500 miles per gallon—all
without changing too much of the car!
第一本关于分组交换的著作是由 Leonard Kleinrock于 1964年所著，美国和英国防卫研究实验室的其他研究人员使这项技术得到进一步发展。由于使用分组交换技术，网络的通信能力提高了 100倍甚至更多。数字网络的通信能力用每秒位来衡量。想象一下汽车行驶的里程，从每加仑汽油行驶
15里提高到每加仑汽油行驶 1500 里 ——而汽车没有太大的改变 !
8.1.2 THE INTERNET,KEY TECHNOLOGY CONCEPTS
Chapter 8 The Internet
计算机专业英语 8-18
In packet-switched networks,messages are first broken down into packets.
Appended to each packet are digital codes that indicate a source address
(the origination point) and a destination address,as well as sequencing
information and error control information for the packet,Rather than being
sent directly to the destination address,in a packet network,the packets
travel from computer to computer until they reach their destination,These
computers are called routers,Routers are special purpose computers that
interconnect the thousands of different computer networks that make up the
Internet and route packets along to their ultimate destination as they travel4.
To ensure that packets take the best available path toward their destination,
the routers use computer programs called routing algorithms.
在分组交换的网络中，信息首先被分解为许多信息包。每个信息包附加数字代码用于指示其源地址 (开始点 )和目的地地址、以及顺序信息和错误控制信息。在分组网络中，信息包不是直接被送到目的地地址,而是在计算机与计算机之间旅行直到它们到达目的地。这些计算机叫做路由器。路由器是一种特殊用途的计算机，它将组成因特网的成千上万个不同计算机网络互相联接起来，并在信息包旅行时将它们的向终极目的地发送。路由器使用一种叫做路由算法的计算机程序，以确保信息包取通向它们目的地的最佳可用路径。
8.1.2 THE INTERNET,KEY TECHNOLOGY CONCEPTS
Chapter 8 The Internet
计算机专业英语 8-19
Packet switching does not require a dedicated circuit but
can make use of any spare capacity that is available on
any of several hundred circuits,Packet switching makes
nearly full use of almost all available communication
lines and capacity,Moreover,if some lines are disabled
or too busy,the packets can be sent on any available line
that eventually leads to the destination point.
分组交换不需要一个专用线路，但是可以利用几百条线路中任何可用的空闲能力。分组交换几乎充分利用了所有可用的通信线路和能力。而且，如果一些线路不通或太忙的话,信息包能在任何可用的、最终通向目的地的线路上传送。
8.1.2 THE INTERNET,KEY TECHNOLOGY CONCEPTS
Chapter 8 The Internet
计算机专业英语 8-20
TCP/IP,While packet switching was an enormous
advance in communications capacity,there was no
universally agreed upon method for breaking up digital
messages into packets,routing them to the proper
address,and then reassembling them into a coherent
message,This was like having a system for producing
stamps,but no postal system (a series of post offices
and a set of addresses).
TCP/IP。尽管分组交换是通信能力的一个巨大进步,但对于将数字信息分解为信息包、将它们传输到适当的地址,然后重新组装为原来的信息，还没有一种公认的方法。这就像有了一个生产邮票的系统,而没有邮政系统 (一系列的邮局和一套住址 )一样。
8.1.2 THE INTERNET,KEY TECHNOLOGY CONCEPTS
Chapter 8 The Internet
计算机专业英语 8-21
TCP/IP answered the problem of what to do with packets on the Internet and
how to handle them,TCP refers to the Transmission Control Protocol (TCP).
IP refers to the Internet Protocol (IP),A protocol is a set of rules for
formatting,ordering,compressing,and error-checking messages,It may
also specify the speed of transmission and means by which devices on the
network will indicate they have stopped sending and/or receiving messages.
Protocols can be implemented in either hardware or software,TCP/IP is
implemented in Web software called server software (described below),TCP
is the agreed upon protocol for transmitting data packets over the Web,TCP
establishes the connections among sending and receiving Web computers,
handles the assembly of packets at the point of transmission,and their
reassembly at the receiving end.
TCP/IP回答了在因特网上用信息包做什么和如何处理信息包的问题。 TCP指传输控制协议,IP表示网际协议。协议是一组用于信息的格式化、次序化、压缩和检查错误的规则。它也可以限定传输速度和网上设备显示它们已停止发送及 (或 )接收信息的方法。协议既可以通过硬件也可通过软件来实现。 TCP/IP(传输控制协议 /网际协议 )通过被称为服务器软件的网络软件来实现 (在下文描述 )。 TCP(传输控制协议 )
是用来在网上传输数据的公认协议。 TCP(传输控制协议 )在发送和接收网络计算机之间建立连接,处理信息包在传输点的组装和在接收端的重新组装。
8.1.2 THE INTERNET,KEY TECHNOLOGY CONCEPTS
Chapter 8 The Internet
计算机专业英语 8-22
TCP/IP is divided into four separate layers,with each
layer handling a different aspect of the communication
problem,The Network Interface Layer is responsible for
placing packets on and receiving them from the network
medium,which could be a Local Area Network (Ethernet)
or Token Ring Network,or other network technology.
TCP/IP(传输控制协议 /网际协议 )被分为四个独立的层,由每层处理通信问题的一个不同方面。网络接口层负责信息包在网络媒体上的排列和接收,网络媒体可能是局域网 (以太网 )、令牌环形网或其他网络技术。
8.1.2 THE INTERNET,KEY TECHNOLOGY CONCEPTS
Chapter 8 The Internet
计算机专业英语 8-23
TCP/IP is independent from any local network technology and can
adapt to changes in the local level,The Internet Layer is responsible
for addressing,packaging,and routing messages on the Internet.
The Transport Layer is responsible for providing communication
with the application by acknowledging and sequencing the packets
to and from the application,The Application Layer provides a wide
variety of applications with the ability to access the services of the
lower layers,Some of the best known applications are Hyper Text
Transfer Protocol (HTTP),File Transfer Protocol (FTP),and Simple
Mail Transfer Protocol (SMTP),all of which we will discuss later in
this chapter.
TCP/IP(传输控制协议 /网际协议 )独立于任何局部网络技术，并能适应在局部水平上的改变。因特网层负责信息的寻址、封装及其在因特网上的路线排定。通过对信息包去与来应用层的确认和排序，传送层负责为应用层提供通信。应用层为许多应用提供访问较低层服务的能力。一些众所周知的应用是超文本传输协议 (HTTP)、文件传输协议 (FTP)和简单邮件传输协议
(SMTP),稍后我们将本章中讨论
8.1.2 THE INTERNET,KEY TECHNOLOGY CONCEPTS
Chapter 8 The Internet
计算机专业英语 8-24
IP Addresses,TCP handles the packetizing and routing
of Internet messages,IP provides the Internet’s
addressing scheme,Every computer connected to the
Internet must be assigned an address — otherwise it
cannot send or receive TCP packets,For instance,when
you sign onto the Internet using a dial-up telephone
modem,your computer is assigned a temporary address
by your Internet Service Provider.
IP地址。 TCP(传输控制协议 )处理因特网信息的分组化和传输路线排定。
IP(网际协议 )提供因特网的地址分配方案。每部连接到因特网的计算机必须分配一个地址，否则它不能够发送或接受 TCP(传输控制协议 )信息包。
举例来说，当你在使用调制解调器拨号上网时，你的计算机由因特网服务提供商分配一个临时地址。
8.1.2 THE INTERNET,KEY TECHNOLOGY CONCEPTS
Chapter 8 The Internet
计算机专业英语 8-25
Internet addresses,known as IP addresses,are 32-bit numbers
that appear as a series of four separate numbers marked off by
periods,such as 201.61.186.227,Each of the four numbers can
range from 0–255,This,dotted quad” addressing scheme
contains up to 4 billion addresses (232),The leftmost number
typically indicates the network address of the computer,while
remaining numbers help to identify the specific computer
within the group that is sending (or receiving ) a message.
因特网地址,即众所周知的 IP地址，是一个 32位的数字，它以一串由园点隔开的四个数字出现,例如 201.61.186.227。四个数字中的每一个都在 0-255
范围内。这个“点分四元组”地址分配方案包含多达到 40亿个地址 (232)。
最左边的那个数字指示计算机的网络地址，而其余的数字帮助识别正在发送 (或接收 )信息的团体里面一台特定的计算机。
8.1.2 THE INTERNET,KEY TECHNOLOGY CONCEPTS
Chapter 8 The Internet
计算机专业英语 8-26
The current version of IP is called Version 4,or IPv4.
Because many large corporate and government domains
have been given millions of IP addresses each (to
accommodate their current and future work forces),and
with all the new networks and new Internet-enabled
devices requiring unique IP addresses being attached to
the Internet,a new version of the IP protocol,called IPv6
is being adopted,This scheme contains 128-bit
addresses,or about one quadrillion (1015).
IP现在版本叫做第 4版，或 IPv4。因为许多大公司和政府在各自的域中已给定了数百万个 IP地址 (以适应他们当前和未来的劳动力 )，且由于新网络和新的可上网设备需要独特的 IP地址，新版本 IP协议 IPv6正在得到采用。
这个方案包含 128位的地址,或曰大约 1015个地址。
8.1.2 THE INTERNET,KEY TECHNOLOGY CONCEPTS
Chapter 8 The Internet
计算机专业英语 8-27
Domain Names and URLs,Most people cannot remember 32-
bit numbers,IP addresses can be represented by a natural
language convention called domain names,The domain name
system (DNS) allows expressions such as cnet.com to stand for
numeric IP addresses (cnet.com ’ s numeric IP is
216.200.247.134),Uniform resource locators (URLs),which are
the addresses used by Web browsers to identify the location of
content on the Web,also use domain names as part of the URL.
A typical URL contains the protocol to be used when accessing
the address,followed by its location.
域名和统一资源定位 (URL)。大多数人记不住 32位的数字。 IP地址可由一个自然语言约定 (称为域名 )来表示。域名系统 (DNS)允许像 cnet.com这样的表达代表数值型 IP地址 (cnet.com 的数值型 IP地址是 (216.200.247.134)。
统一的资源定位是网络浏览器用于识别网上内容位置的地址，也使用域名作为它的一部分。一个典型的网址包含访问地址时使用的协议，接着是它的位置。
8.1.2 THE INTERNET,KEY TECHNOLOGY CONCEPTS
Chapter 8 The Internet
计算机专业英语 8-28
Client/Server Computing,While packet switching exploded the
available communications capacity and TCP/IP provided the
communications rules and regulations,it took a revolution in
computing to bring about today’s Internet and the Web,That
revolution is called client/server computing and without it,the
Web—in all its richness—would not exist,In fact,the Internet is a
giant example of client/server computing in which over 70 million
host server computers store Web pages and other content that can
be easily accessed by nearly a million local area networks and
hundreds of millions of client machines worldwide.
客户机 /服务器计算技术。虽然分组交换使有效的通信能力激增，且 TCP/IP
协议提供了通信规则，在计算机技术中，发生了又一次革命才造就了今天的因特网和万维网。这次革命叫做客户机 /服务器计算技术，没有它，万维网及其丰富信息将不会存在。事实上，因特网是客户机 /服务器计算技术的一个巨大实例，其中，超过 7000万部主机服务器计算机储存网页和其他内容，这些网页和内容能被全世界接近一百万个局域网和数亿台客户机容易地访问。
8.1.2 THE INTERNET,KEY TECHNOLOGY CONCEPTS
Chapter 8 The Internet
计算机专业英语 8-29
Client/server computing is a model of computing in which very
powerful personal computers called clients are connected together
in a network together with one or more server computers,These
clients are sufficiently powerful to accomplish complex tasks such
as displaying rich graphics,storing large files,and processing
graphics and sound files,all on a local desktop or handheld device,
Servers are networked computers dedicated to common functions
that the client machines on the network need,such as storing files,
software applications,utility programs such as Web connections,
and printers.
客户机 /服务器计算技术是一种计算模型，其中相当多台被称为客户机的个人计算机联结在一起并与一台或更多的服务器计算机联结在一个网络中。
这些客户机功能足够强大以完成复杂的任务如显示丰富的图形、储存大型文件、并处理图形和声音文件，这些任务全部在当地的台式或手持式装置上完成。服务器是联网的计算机，专门用于提供客户机在网上需要的公共功能,例如储存文件、软件应用、公用程序如网络连接、和打印。
8.1.2 THE INTERNET,KEY TECHNOLOGY CONCEPTS
Chapter 8 The Internet
计算机专业英语 8-30
To appreciate what client/server computing makes
possible,you must understand what preceded it,In the
mainframe computing environment of the 1960s and
1970s,computing power was very expensive and limited.
For instance,the largest commercial mainframes of the
late 1960s had 128k of RAM and 10 megabyte disk drives,
and occupied hundreds of square feet,There was
insufficient computing capacity to support graphics or
color in text documents,let alone sound files or hyper
linked documents and databases.
为了充分理解客户机 /服务器计算技术的作用，你必须了解在它之前的东西。
在 20世纪 60年代和 70年代的大型计算机环境中，计算机能力非常昂贵而有限。比如,60年后期最大的商业化大型机有 128K随机存取存储器和 10兆磁盘驱动器，而且占据数百平方英尺空间。计算能力不足以支持图形和文本中的颜色，更不用说声音文件或超链接文档和数据库。
8.1.2 THE INTERNET,KEY TECHNOLOGY CONCEPTS
Chapter 8 The Internet
计算机专业英语 8-31
With the development of personal computers and local area networks
during the late 1970s and early 1980s,client/server computing became
possible,Client/server computing has many advantages over centralized
mainframe computing,For instance,it is easy to expand capacity by adding
servers and clients,Also,client/ server networks are less vulnerable than
centralized computing architectures,If one server goes down,backup or
mirror servers can pick up the slack; if a client machine is inoperable,the
rest of the network continues operating,Moreover,processing load is
balanced over many powerful smaller machines rather than being
concentrated in a single huge machine that performs processing for
everyone,Both software and hardware in client/server environments can be
built more simply and economically.
20世纪 70年代后期和 80年代初期，随着个人计算机和局域网的发展，客户机 /服务器计算技术成为可能。客户机 /服务器计算技术比中央大型机计算有许多优势。比如，通过增加服务器和客户机，可很容易地扩容。同时，客户机 /服务器网络比中央计算结构不易受损。如果一个服务器被破坏，备用的或镜像服务器能恢复工作；
如果一部客户机不能运转，网络的其部分可继续运行。而且,负荷处理通过许多强大的、较小的机器达到平衡，而不是集中于一部为每个人进行处理的巨型机。在客户机 /服务器环境中，建立软件与硬件都更简单、更经济。
8.1.2 THE INTERNET,KEY TECHNOLOGY CONCEPTS
Chapter 8 The Internet
计算机专业英语 8-32
Today there are about 450 million PCs in existence worldwide,Most of these
PCs can display and process graphics,sound files,and colored text,They
have memories up to 512MB,20 gigabyte hard drives,and occupy about two
square feet,These personal ―supercomputers,‖ when tied together in local
area networks or into large wide area networks such as the Web,make it
possible for millions of people to enjoy,rich” Web documents and
experiences,Soon these capabilities will move to handheld devices such as
the Palms and HP Jornada,and wireless cell phones (much,thinner
clients” ),In the process,more computer processing will be performed by
central servers (reminiscent of mainframe computers of the past).
今天全世界大约有 4.5亿台个人计算机，其中大多数可以显示并且处理图形、声音文件、和彩色文本。他们具有高达 512MB内存,20G(兆字节 )硬盘驱动器，而大约只占 2平方英尺空间。这些个人的“超级计算机”，把它们联结起来接入局域网或大型广域网如因特网，使数以百万计的人们享受“丰富的”网络文件和经验成为可能。这些能力将很快会移植到如 Palms,HP Jornada和无线蜂窝电话等手持式装置中 (很多“瘦客户机” )。在这个过程中，更多的计算机处理将由中央服务器完成
(过去的大型计算机的遗风 )。
8.1.2 THE INTERNET,KEY TECHNOLOGY CONCEPTS
Chapter 8 The Internet
计算机专业英语 8-33
There are many other Internet protocols that provide
services to users in the form of Internet applications that
run on Internet clients and servers,These Internet
services are based on universally accepted protocols—
or standards—that are available to everyone who uses
the Internet,They are not owned by any one organization
but are services that were developed over many years
and given to all Internet users.
有许多其他因特网协议以因特网应用的形式为用户提供服务，
这些因特网应用在客户机和服务器上运行。这些因特网服务以全世界普遍承认的协议或标准为基础，对任何使用因特网的用户有效。他们不为任何一个组织所拥有，而是发展了许多年、
供给所有因特网用户的服务。
8.1.3 Other Internet Protocols And Utility Programs
Chapter 8 The Internet
计算机专业英语 8-34
HTTP,Hypertext Documents,HTTP (short for Hyper Text Transfer
Protocol) is the Internet protocol used for transferring Web pages
(described in the following section),The HTTP protocol runs in the
Application Layer of the TCP/IP model,An HTTP session begins
when a client’s browser requests a Web page from a remote Internet
server,When the server responds by sending the page requested,
the HTTP session for that object ends,Because Web pages may
have many objects on them—graphics,sound or video files,frames,
and so forth—each object must be requested by a separate HTTP
message.
HTTP,超文本文档。 HTTP(超文本传输转移协议的缩写 )是用于传输网页的因特网协议 (下文描述 )。 HTTP协议在 TCP/IP模型中的应用层上运行。当一个客户机的浏览器向远程因特网服务器的一个网页发出请求时,HTTP会话开始。当服务器通过发送所请求的页面回应时，关于这个对象的 HTTP
会话结束。因为网页可能带有许多对象 ——图形、声音或视频文件、帧等 ——每个对象必须由一个独立的 HTTP 信息所请求。
8.1.3 Other Internet Protocols And Utility Programs
Chapter 8 The Internet
计算机专业英语 8-35
SMTP,POP,and IMAP,Sending E-mail,E-mail is one of
the oldest,most important,and frequently used Internet
services,STMP (Simple Mail Transfer Protocol) is the
Internet protocol used to send mail to a server,POP
(Post Office Protocol) is used by the client to retrieve
mail from an Internet server,You can see how your
browser handles SMTP and POP by looking in your
browser’s Preferences or Tools section,where the mail
settings are defined.
SMTP,POP和 IMAP:发送电子邮件。电子邮件是最老、最重要和经常使用的因特网服务之一。 STMP(简单邮件传输协议 )是用于将将邮件发送到服务器的因特网协议。客户机利用 POP(邮局协议 )从因特网服务器上检索邮件。你可以通过察看浏览器上“收藏”和“工具”栏看见你的浏览器如何处理 SMTP和 POP协议,邮件设定在这两栏定义。
8.1.3 Other Internet Protocols And Utility Programs
Chapter 8 The Internet
计算机专业英语 8-36
You can set POP to retrieve e-mail messages from the
server and then delete the messages on the server,or
retain them on the server,IMAP (Internet Message
Access Protocol) is a more current e-mail protocol
supported by many servers and all browsers,IMAP
allows users to search,organize,and filter their mail
prior to downloading it from the server.
你可以设定用 POP协议取回来自服务器的电子邮件信息然后删除服务器上的信息,或在服务器上保留它们。 IMAP(因特网消息访问协议 )是一个由许多服务器和所有的浏览器支持的更通用的电子邮件协议。 IMAP允许使用者在从服务器下载邮件之前搜寻、组织和过滤邮件
8.1.3 Other Internet Protocols And Utility Programs
Chapter 8 The Internet
计算机专业英语 8-37
FTP,Transferring Files,FTP (File Transfer Protocol) is
one of the original Internet services,It is a part of the
TCP/IP protocol and permits users to transfer files from
the server to their client machine,and vice versa,The
files can be documents,programs,or large database
files,FTP is the fastest and most convenient way to
transfer files larger than 1 megabyte,which many mail
servers will not accept.
FTP:传输文件。 FTP(文件传输协议 )是最初的因特网服务之一。
它是 TCP/IP协议的一部份，它允许用户把文件从服务器传送到客户机，反之亦然。文件可以是文档、程序、或大型数据库文件。 FTP是传输大于 1M文件最快速和最方便的方法，而许多邮件服务器将不接受大于 1M的文件
8.1.3 Other Internet Protocols And Utility Programs
Chapter 8 The Internet
计算机专业英语 8-38
SSL,Security,SSL (Secure Sockets Layer) is a protocol
that operates between the Transport and Application
Layers of TCP/IP and secures communications between
the client and the server,SSL helps secure e-commerce
communications and payments through a variety of
techniques such as message encryption and digital
signatures.
SSL:安全性。 SSL(加密套接字协议层 )是一个在 TCP/IP中运行于的传输层和应用层之间的、确保客户机与服务器之间通信安全的协议。通过诸如信息加密和数字签名等多种技术，
SSL促进安全的电子商务通信和支付。
8.1.3 Other Internet Protocols And Utility Programs
Chapter 8 The Internet
计算机专业英语 8-39
Telnet,Running Remote,Telnet is a terminal emulation
program that runs in TCP/IP,You can run Telnet from your
client machine,When you do so,your client emulates a
mainframe computer terminal,(The industry standard
terminals defined in the days of mainframe computing are VT-
52,VT-100,and IBM 3250.) You can then attach yourself to a
computer on the Internet that supports Telnet and run
programs or download files from that computer,Telnet was the
first ―remote work‖ program that permitted users to work on a
computer from a remote location.
Telnet(远程登录 ):远程运行。 Telnet是一个在 TCP/IP中运行的终端模拟程序。你能从你的客户机运行 Telnet。当你这么做的时候,你的客户机模拟一个主机计算机终端。 (定义于大型机计算时代的工业标准终端是 VT-52,VT-100和 IBM 3250)。然后你能接入到一台因特网上支持 Telnet的计算机上，从那部计算机运行程序或下载文件。 Telnet是允许用户在远方的一部计算机上工作的第一个“远程工作”程序。
8.1.3 Other Internet Protocols And Utility Programs
Chapter 8 The Internet
计算机专业英语 8-40
Finger,Finding People,You can find out who is logged
onto a remote network by using Telnet to connect to a
server,and then typing,finger” at the prompt,Finger
is a utility program supported by UNIX computers,When
supported by remote computers,finger can tell you who
is logged in,how long they have been attached,and their
user name,Obviously there are security issues involved
with supporting finger,and most Internet host computers
do not support finger today.
Finger,发现人们。通过使用 Telnet连接到一个服务器上,然后在提示符的键入 "Finger",你能发现谁登录到远程网络。 Finger是一个 UNIX 计算机支持的公用程。当由远程计算机支持时,Finger能告诉你谁登录了、他们已经连上多久和他们的用户名。显然，支持 Finger会涉及安全问题，而且大多数因特网主机今天不支持 Finger。
8.1.3 Other Internet Protocols And Utility Programs
Chapter 8 The Internet
计算机专业英语 8-41
Ping,Testing the Address,You can ―ping‖ a host
computer to check the connection between your client
and the server,The ping (Packet InterNet Groper)
program will also tell you the time it takes for the server
to respond,giving you some idea about the speed of the
server and the Internet at that moment,You can run ping
from the DOS prompt on a personal computer with a
Windows operating system by typing,Ping <domain
name>.
Ping:检测地址。你可以 "Ping"一台主机计算机来检查你的客户机和服务器之间的连结。给出你有关服务器和因特网速度的一些建议，
Ping(Packet InterNet Groper，信息包因特网搜索 )程序还将会告诉你服务器回应所需的时间。你可以在一部具有 Windows操作系统的个人计算机上在 DOS提示符下键入,Ping<域名 >。
8.1.3 Other Internet Protocols And Utility Programs
Chapter 8 The Internet
计算机专业英语 8-42
Tracert,Checking Routes,Tracert is one of a several
route-tracing utilities that allow you to follow the path of
a message you send from your client to a remote
computer on the Internet.
Tracert：检查路径。 Tracert是几种追踪路径的公用程序之一,
它允许你跟踪你在因特网上从客户机向远程计算机发出的信息的路径。
8.1.3 Other Internet Protocols And Utility Programs
Chapter 8 The Internet
计算机专业英语 8-43
New Words & Expressions
substrate n,衬底，基底 middleware n.中间设备,中间件
authentication n.证明,鉴定 repository n,储存库，资料档案库
backbone n.主干,干线 pipeline n,流水线，管线
Mbps n,兆比特每秒 Gbps n,千兆比特每秒
redundancy n.冗余 built-in adj.内置的,嵌入的 n.内置
tier n.一层，一排 curb n.路边
mom and pop shop n,夫妻店 dial-up 拨号上网
narrowband n,窄带 broadband n,宽带
throughput n,吞吐量 objectionable adj.该反对的,不能采用的
modem n.调制解调器 delay n.延迟
aficionado n,狂热爱好者,迷 sovereign adj.统治的 ; n.统治者
Intranet 企业内部互联网 Extranets 企业外部互联网
piggyback n.机载 ; v.搭载
8.2 The Internet Today
Chapter 8 The Internet
计算机专业英语 8-44
Abbreviations
NAP (Network Access Point) 网络访问节点
DSL (digital subscriber line) 数字用户线
Metropolitan Area Exchange (MAE) 城域交换站
W3C (World Wide Web Consortium) 万维网联合会
ISP (Internet Service Provider) Internet服务提供者
ISOC (Internet Society) Internet 协会
IAB (Internet Architectrue Board) Internet架构委员会
IETF (Internet Engineering Task Force) Internet工程任务组
IESG (Internet Engineering Steering Group) Internet工程指导组
8.2 The Internet Today
Chapter 8 The Internet
计算机专业英语 8-45
By 2001,there were approximately 400 million Internet users worldwide,up
from 100 million users at year-end 1997,That figure is projected to continue
to grow to close to 800 million by 2003,One would think that with such
incredible growth,the Internet would be overloaded,However,this has not
been true for several reasons,First,client/server computing is highly
extensible,By simply adding servers and clients,the population of Internet
users can grow indefinitely,Second,the Internet architecture is built in
layers so that each layer can change without disturbing developments in
other layers,For instance,the technology used to move messages through
the Internet can go through radical changes to make service faster without
being disruptive to your desktop applications running on the Internet.
截至 2001年，全世界因特网用户从 1997年底的 1亿上升到大约有 4亿。这个数字计划到 2003年继续增长到 8亿。有人可能会想：以如此令人难以置信的速度增长,因特网会超载。然而，由于几个原因这没有成为现实。首先，客户机 /服务器计算技术可以高度扩展：只需增加服务器和客户机,因特网用户人口能无限增长。其次，因特网是按照层次结构建造的，因此每一层能在不干扰其他层发展的前提下改变。举例来说，用于在因特网上移动信息的技术可以实现根本的改变使服务更快，而不会中断你的台式机在因特网上运行的应用。
8.2 The Internet Today
Chapter 8 The Internet
计算机专业英语 8-46
The Internet can be viewed conceptually as having four layers:
the network technology substrate,transport services and
representation standards,middleware services,and
applications,The network technology substrate is composed of
telecommunications networks and protocols,The transport
layer houses the TCP/IP protocol,The applications layer
contains client applications such as the World Wide Web,e-mail,
and audio or video playback,Middleware is the glue that ties
the applications to the communications networks,and includes
such services as security,authentication,addresses,and storage
repositories.
因特网能被概念性地分为四层：网络技术基体、传送服务和表示标准、中间件服务和应用。网络技术基体由电信网络和协议组成。传送层收容
TCP/IP协议。应用层包含客户机的应用，例如万维网、电子邮件和声频或视频回放。中间件是将应用与通信网络连接起来的粘合剂,并且包括如安全、
验证、地址和存储等服务。
8.2 The Internet Today
Chapter 8 The Internet
计算机专业英语 8-47
Users work with applications (such as e-mail) and rarely
become aware of middleware that operates in the
background,Because all layers use TCP/IP and other
common standards linking all four layers,it is possible
for there to be significant changes in the network layer
without forcing changes in the applications layer,The
network layer is described below.
用户通过应用程序 (例如电子邮件 )工作，很少知道中间件在后台运行。因为各层使用 TCP/IP协议和其他公共标准联结所有四层,所以在网络层发生重大变化而不强迫应用层变化是可能的。网络层在下面描述。
8.2 The Internet Today
Chapter 8 The Internet
计算机专业英语 8-48
Figure 8-3 Internet I network architecture
Chapter 8 The Internet
计算机专业英语 8-49
8.2.1 THE INTERNET BACKBONE
Figure 8-3 illustrates the main physical elements of today’s Internet,The
Internet’s backbone is formed by Network Service Providers (NSPs),which
own and control the major networks,The backbone has been likened to a
giant pipeline that transports data around the world in milliseconds,In the
United States,the backbone is composed entirely of fiber-optic cable
(described more fully below),with bandwidths ranging from 155 Mbps to
2.5 Gbps,Bandwidth measures how much data can be transferred over a
communications medium within a fixed period of time,and is usually
expressed in bits per second (bps),kilobits (thousands of bits) per second
(Kbps),megabits (millions of bits) per second (Mbps),or gigabits (billions of
bits) per second (Gbps).
图 8-3说明了今天因特网的主要物理组成。因特网主干由拥有且控制主要网络的网络服务提供商 (NSPs)形成。主干被比作一个能在几毫秒内将数据传遍全球的巨大通道。在美国，主干完全由光缆 (在文下更完整地描述 )组成，其带宽从 155兆比特 /
秒到 2.5吉比特 /秒。带宽衡量在固定的时间内、通过某种通信媒体能传输多少数据，
通常以每秒位 (bps)、每秒千位 (Kbps)、每秒兆位 (Mbps)或每秒千兆位 (Gbps)来表示。
Chapter 8 The Internet
计算机专业英语 8-50
Connections to other continents are made via a combination of
undersea fiber optic cable and satellite links,The backbones in
foreign countries typically are operated by a mixture of private and
public owners,The U.S,backbone is one of the most developed
because the Internet’s infrastructure was developed here,The
backbone has built-in redundancy so that if one part breaks down,
data can be rerouted to another part of the backbone,Redundancy
refers to multiple duplicate devices and paths in a network.
与其他大陆的连接是经由海底光缆和人造卫星联通的。在外国，
因特网主干是由私营和国有公司共同经营的。美国的因特网主干是 (全世界 )最发达的 (主干 )之一，因为因特网的基础是从这里发展起来的。因特网主干具有内在的冗余，以便如果主干的一部分崩溃,数据可以改行其他部份。冗余指在网络中设备和路径的多重副本。
8.2.1 THE INTERNET BACKBONE
Chapter 8 The Internet
计算机专业英语 8-51
In the United States there are a number of hubs where the backbone
intersects with regional and local networks,and where the backbone
owners connect with one another1,These hubs are called Network
Access Points (NAPs) or Metropolitan Area Exchanges (MAEs),and
use high-speed switching computers to connect the backbone to
regional and local networks,and exchange messages with one
another,The regional and local networks are owned by local Bell
operating companies (RBOCs — pronounced ―ree-bocks‖),and
private telecommunications firms such as MFS Corporation; they
generally are fiber optic networks operating at over 100 Mbps,The
regional networks lease access to Internet Service Providers,private
companies,and government institutions.
在美国，有许多网络中心 ——因特网主干与区域性和地方性网络在此交叉，主干拥有者也在此处彼此连接。这些网络中心被称为网络访问节点 (NAP)或城域交换站
(MAE),而且它们使用高速交换计算机联结主干与地方性和区域性网络、并彼此交换信息。区域性和地方性网络由地方贝尔运营公司 (RBOCs-发音 "ree-bocks")和私营电信公司例如 MFS公司所拥有；它们通常是以超过 100Mbps带宽运行的光纤网络。
区域性网络从因特网服务提供商、私营公司和政府机构租用使用权。
8.2.2 Network access points and metropolitan area exchanges
Chapter 8 The Internet
计算机专业英语 8-52
The Internet backbone connects regional networks,
which in turn provide access to the Internet to Internet
Service Providers,large firms,and government agencies.
因特网主干连接区域性网络,这些区域性网络反过来为因特网服务提供商、大公司和政府机关提供对的因特网的访问。
8.2.2 Network access points and metropolitan area exchanges
Chapter 8 The Internet
计算机专业英语 8-53
8.2.3 CAMPUS NETWORKS
There are an estimated one million campus networks attached to the Internet
worldwide (Computer Industry Almanac Inc.,2001),Campus networks are
generally local area networks operating with a single organization— such as
New York University or Microsoft Corporation,In fact,most large
organizations have hundreds of such local area networks,These
organizations (representing about 60 million workers) are sufficiently large
that they lease access to the Web directly from regional and national carriers,
These local area networks generally are running Ethernet (a local area
network protocol) and have operating systems such as Windows 2000 (NT),
Novell,or others that permit desktop clients to connect to the Internet
through a local Internet server attached to their campus networks,
Connection speeds in campus networks are in the range of 10–100 Mbps to
the desktop.
估计全世界有 100万个校园网联结到因特网 (计算机工业年间鉴公司,2001年 )。校园网通常是一个组织运营的局域网，例如纽约大学或微软公司。事实上，大部分大组织有几百个这样的局域网。这些组织 (代表大约 6亿工人 )足够大，以至于他们直接向区域性和国家通信公司租用对网络的访问。这些局域网通常是运行的以太网 (一种局域网协议 )，并且具有例如 Windows2000(NT),Novell或其他操作系统，允许桌面客户机通过一个连接到校园网的因特网服务器联到因特网。在校园网中，台式机的连接速度在 10-100 Mbps。
Chapter 8 The Internet
计算机专业英语 8-54
8.2.4 INTERNET SERVICE PROVIDERS
The firms that provide the lowest level of service in the multi-
tiered Internet architecture by leasing Internet access to home
owners,small businesses,and some large institutions are called
Internet Service Providers (ISPs)2,ISPs are retail providers—
they deal with ―the last mile of service‖ to the curb,the home,
the business office,About 45 million American households
connect to the Internet through either national or local ISPs,
ISPs typically connect to the Internet and MAEs or NAPs with
high-speed telephone or cable lines (up to 45 Mbps).
在多层次因特网体系中通过向家庭出租因特网访问通道提供最低水平服务的公司、小型企业，和一些大机构叫做因特网服务提供商 (ISP)。因特网服务提供商是零售型供给者 ——他们为街头、家庭、企业办公室处理“最后一步服务”。约 4500万个美国的家庭通过全国性的或地方性的 ISP连接到因特网。因特网服务提供商又利用高速电话或电缆线 (高达 45 Mbps)典型地连接到因特网和城域交换站或网络访问节点。
Chapter 8 The Internet
计算机专业英语 8-55
There are two types of ISP service,narrowband and broadband.
Narrowband service is the traditional telephone modem connection
now operating at 56.6 Kbps (although the actual throughput hovers
around 30 Kbps due to line noise that causes extensive resending of
packets),This is the most common form of connection worldwide.
Broadband service is based on DSL,cable modem,telephone (T1
and T3 lines),and satellite technologies,Broadband—in the context
of Internet service —refers to any communication technology that
permits clients to play streaming audio and video files at acceptable
speeds—generally anything above 100 Kbps.
因特网服务提供商提供两种服务,窄带和宽带。窄带服务是目前以 56.6 Kbps运行的传统电话调制解调器连接 (虽然由于线路噪音造成大量的信息包重新发送,真正的吞吐量徘徊在 30Kbps附近 )。这是全世界最普通的联结形式。宽频服务以数字用户专线、电缆调制解调器，电话 (T1和 T3线 )和人造卫星技术为基础。在因特网服务的环境中，宽频指的是任何允许客户机以可接受的速度运行流型声频和视频文件的通信技术，通常可接受的速度指在 100 Kbps以上。
8.2.4 INTERNET SERVICE PROVIDERS
Chapter 8 The Internet
计算机专业英语 8-56
The term DSL refers to digital subscriber line service,
which is a telephone technology for delivering high-speed
access through ordinary telephone lines found in your home
or business,Service levels range from about 150 Kbps all the
way up to 1 Mbps,DSL service requires that customers live
within two miles (about 4,000 meters) of a neighborhood
telephone switching center.
术语 DSL指数字用户专线服务，是通过在你家或企业所见到的普通电话线传送高速访问的一种电话技术。服务水平从大约从
150Kbps到高达 1Mbps。数字用户专线服务要求客户居住在临近电话交换中心 2英里之内 (大约 4000米 )。
8.2.4 INTERNET SERVICE PROVIDERS
Chapter 8 The Internet
计算机专业英语 8-57
Cable modem refers to a cable television technology that
piggybacks digital access to the Internet on top of the
analog video cable providing television signals to a
home3,Cable modem services ranges from 350 Kbps up
to 1 Mbps,Cable service may degrade if many people in
a neighborhood log on and demand high-speed service
all at once.
电缆调制解调器是一种在向家庭提供电视信号的视频电缆上搭载对因特网进行数字式访问的有线电视技术。电缆调制解调器服务范围从 350 Kbps到 1Mbps。如果临近有许多人同时登录并需要高速服务，缆传服务速度可能降低。
8.2.4 INTERNET SERVICE PROVIDERS
Chapter 8 The Internet
计算机专业英语 8-58
T1 and T3 are international telephone standards for digital
communication,T1 lines offer guaranteed delivery at 1.54
Mbps,while T3 lines offer delivery at 43 Mbps.
T1和 T3是数字通信的国际电话标准。 T1线提供保障 1.54Mbps
的传送,而 T3线提供 43Mbps传送。
8.2.4 INTERNET SERVICE PROVIDERS
Chapter 8 The Internet
计算机专业英语 8-59
8.2.5 INTRANETS AND EXTRANETS
The very same Internet technologies that make it possible to operate a
worldwide public network can also be used by private and government
organizations as internal networks,An intranet is a TCP/IP network located
within a single organization for purposes of communications and
information processing,Many corporations are moving away from
proprietary local area networks such as Windows 2000 and Novell,and
toward a single internal intranet to handle the firm’s information processing
and communication needs,Internet technologies are generally far less
expensive than proprietary networks,and there is a global source of new
applications that can run on intranets,In fact,all the applications available
on the public Internet can be used in private intranets..
使全球性公众网络运转成为可能的、与因特网技术相同的技术也能被私营和政府组织用于内部网络。内联网是一个组织内部用于通信和信息处理的 TCP/IP网络。许多公司正在远离专有局域网例如 Windows 2000和 Novell,并转向一个单一的企业内联网以处理公司的信息和通信需要。因特网技术通常远比专有网络技术价廉，而且拥有一个全球资源获得可在内联网上运行的新应用。事实上，在公用因特网上得到的所有应用都能在专用内联网使用。
Chapter 8 The Internet
计算机专业英语 8-60
8.2.5 INTRANETS AND EXTRANETS
Extranets are formed when firms permit outsiders to access
their internal TCP/IP networks,For instance,General Motors
permits parts suppliers to gain access to GM’s intranet that
contains GM’s production schedules4,In this way,parts
suppliers know exactly when GM needs parts,and where and
when to deliver the parts,
当公司允许局外人访问他们的内部 TCP/IP网络时，外联网就形成了。举例来说，通用汽车公司允许零部件供应商访问公司的内联网，它的内联网包含生产进度。这样，零部件供应商能完全了解通用汽车公司什么时候需要零部件,和到哪里与何时递送零部件。
Chapter 8 The Internet
计算机专业英语 8-61
8.2.6 WHO GOVERNS THE INTERNET?
Aficionados and promoters of the Internet often claim that the
Internet is governed by no one,and indeed cannot be governed,
and that it is inherently above and beyond the law,In fact,the
Internet is tied into a complex web of governing bodies,
national legislatures,and international professional societies,
There is no one governing body that controls activity on the
Internet,Instead,there are several organizations that influence
the system and monitor its operations,Among the governing
bodies of the Internet are:
因特网的热爱者和促进者时常宣称因特网没有被任何人统治,也的确不能被统治,而且还宣称它天生高于法律。事实上，因特网被连入了由管理机构、
国家立法机构和国际专业协会织成的一张复杂的网之中。没有一个管理机构可以控制因特网上的活动，而是有几个组织影响它的系统、监测它的运行。在因特网管理机构中有,
Chapter 8 The Internet
计算机专业英语 8-62
8.2.6 WHO GOVERNS THE INTERNET?
The Internet Architecture Board (IAB),which helps define
the overall structure of the Internet.
The Internet Corporation for Assigned Names and
Numbers (ICANN),which assigns IP addresses,and the
Internet Network Information Center (InterNIC),which
assigns domain names.
The Internet Engineering Steering Group (IESG),which
oversees standard setting with respect to the Internet,
因特网架构委员会 (IAB)帮助定义因特网的总体结构。
因特网域名与地址管理委员会 (ICANN)分配 IP地址；和因特网网络信息中心 (InterNIC)分配域名。
因特网工程指导组 (IESG)监督有关因特网的标准设定。
Chapter 8 The Internet
计算机专业英语 8-63
8.2.6 WHO GOVERNS THE INTERNET?
The Internet Engineering Task Force (IETF),which
forecasts the next step in the growth of the Internet,
keeping watch over its evolution and operation,
The Internet Society (ISOC),which is a consortium of
corporations,government agencies,and nonprofit
organizations that monitors Internet policies and
practices.
The World Wide Web Consortium (W3C),which sets
HTML and other programming standards for the Web.
因特网工程任务组 (IETF)预测因特网成长的下一步,监视它的进化和运行。
因特网协会 (ISOC)是一个公司、政府机关以及监测因特网政策与实践的非营利性组织的联盟。
万维网联合会 (W3C)为万维网设定 HTML和其他编程标准。
Chapter 8 The Internet
计算机专业英语 8-64
8.2.6 WHO GOVERNS THE INTERNET?
While none of these organizations has actual control
over the Internet and how it functions,they can and do
influence government agencies,major network owners,
ISPs,corporations,and software developers with the
goal of keeping the Internet operating as efficiently as
possible.
尽管这些组织中没有一个能真正控制因特网及其如何运行,他们可以就保持因特网尽可能高效运行的目标影响政府机关、主要网络拥有者、公司、因特网服务提供商和软件开发者。
Chapter 8 The Internet
计算机专业英语 8-65
8.2.6 WHO GOVERNS THE INTERNET?
In addition to these professional bodies,the Internet must also
conform to the laws of the sovereign nation-states in which it
operates,as well as the technical infrastructures that exist
within the nation-state,Although in the early years of the
Internet and the Web there was very little legislative or
executive interference,this situation will change in the near
future as the Internet plays a growing role in the distribution of
information and knowledge,including content that some find
objectionable
除了这些专业团体，因特网还必须符合所在的主权民族国家的法律,和这个民族国家存在的技术基础。虽然因特网和万维网在早年很少受到司法与或行政干涉,这种情形在不久的将来就会改变，因为因特网在传播信息和知识方面扮演越来越重要的角色,包括一些有人反对的内容。
Chapter 8 The Internet
计算机专业英语 8-66
New Words & Expressions
congestion n.阻塞 appreciate vt,领会，鉴赏,感激，察觉
circuitous adj.迂回线路的 latency n.等待时间
streaming adj.流型的 ; n.流 synchronous adj.同时的,同步的
jerkiness n.不平稳,颠簸 tag n,标志，特征，标记 [识 ]；标识符
multicasting 多信道广播 diffserve 区别质量的服务
videoconference n.视频会议
Abbreviations
AOL (American On-Line) 美国在线服务公司
NASA (National Aeronautics and Space Administration) (美国 )国家航空航天局
8.3 Internet II,The Future Infrastructure
Chapter 8 The Internet
计算机专业英语 8-67
Much of the Internet’s current infrastructure is several decades
old (equivalent to a century in Internet time),It suffers from a
number of limitations,including,
Bandwidth limitations,There is insufficient capacity throughout
the backbone,the metropolitan switching centers,and most
importantly,to the,last mile” to the house and small business,
The result is slow service (congestion) and a very limited
ability to handle video and voice traffic.
许多因特网现在的基础设施是几十年以前的 (在因特网时代等于一个世纪 )。
它承受许多限制,包括,
带宽限制 。 在主干、城市交换中心和最重要的最终对家庭和小型企业都存在着容量不足的问题。其结果是极慢的服务 (阻塞 )和相当有限的处理音频、
视频的能力。
8.3.1 LIMITATIONS OF INTERNET I
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计算机专业英语 8-68
Quality of service limitations,Today’s information packets take a circuitous route to
get to their final destinations,This creates the phenomenon of latency— delays in
messages caused by the uneven flow of information packets through the network,In
the case of e-mail,latency is not noticeable,However,with streaming video and
synchronous communication,such as a telephone call,latency is noticeable to the user
and perceived as ―jerkiness‖ in movies or delays in voice communication,Today’s
Internet uses ―best efforts‖ quality of service,(QOS),which makes no guarantees
about when or whether data will be delivered,and provides each packet with the same
level of service,no matter who the user is or what type of data is contained in the
packet,A higher level of service quality is required if the Internet is to keep expanding
into new services (such as video on demand or telephony).
服务品质限制。今天的信息包需经过迂回路径到达目的地。这就产生了等待时间的现象 ——由于信息包通过网络时流动不畅通引起的信息延迟。就电子邮件来说，等待时间不引人注目。然而对于视频流和同步通信例如电话呼叫，等待时间对使用者是显而易见的并且在电影中感觉到 "抖动 "或在声音通信中感到延迟。今天的因特网使用 "最大努力 "的服务品质,对数据何时或是否被递送没有任何保证；而且无论使用者是谁或信息包中包含什么类型的数据，提供每个信息包相同水平的服务。如果因特网要继续扩大新的服务，就需要较高水平的服务质量 (例如随选视频服务或声音传送 )。
8.3.1 LIMITATIONS OF INTERNET I
Chapter 8 The Internet
计算机专业英语 8-69
Network architecture limitations,Today,a thousand
requests for a single music track from a central server will
result in a thousand efforts by the server to download the
music to each requesting client,This slows down network
performance as the same music track is sent out a
thousand times to clients that might be located in the
same metropolitan area,This is very different from
television,where the program is broadcast once to
millions of homes.
网络结构限制 。今天，对来自一个中央服务器的一个音乐辑发出一千个请求，将会造成服务器为每个请求的客户机下载音乐而动作一千次。当同一个音乐辑被送出一千次到可能位于相同城区的客户机，就减慢了网络性能。
这非常不同于电视,电视节目一次对数以百万计的家庭广播。
8.3.1 LIMITATIONS OF INTERNET I
Chapter 8 The Internet
计算机专业英语 8-70
Language development limitations,HTML,the language
of Web pages,is fine for text and simple graphics,but
poor at defining and communicating ―rich documents‖
such as databases,business documents,or graphics,The
tags used to define an HTML page are fixed and generic.
语言发展限制。 HTML网页语言,对本文和简单的图形是好的,
但在定义和传递如数据库、商业文件或图形等 "富文件 "时是不够的。用于定义 HTML页的标签是固定的和通用的。
8.3.1 LIMITATIONS OF INTERNET I
Chapter 8 The Internet
计算机专业英语 8-71
Now imagine an Internet at least 100 times as powerful as
today’s Internet,an Internet not subjected to the
limitations of bandwidth,protocols,architecture,and
language detailed above,Welcome to the world of Internet
II,and the next generation of e-commerce services and
products.
现在想象一下因特网的功能至少是现在的 100倍,想象一下一个不受上述带宽、协议、结构和语言限制的因特网。欢迎你到因特网 II的世界和下一代电子商务服务与产品的世界。
8.3.1 LIMITATIONS OF INTERNET I
Chapter 8 The Internet
计算机专业英语 8-72
The increased bandwidth and expanded network connections of
the Internet II era will result in benefits beyond faster access and
richer communications,Enhanced reliability and quality of
Internet transmissions will create new business models and
opportunities,Some of the major benefits of these technological
advancements include IP multicasting,latency solutions,
guaranteed service levels,lower error rates,and declining costs.
因特网 II时代增加的带宽与扩大的网络连接造就的利益不只是更快的访问和更丰富的通信。因特网传输的可靠性与质量的提高将会造就新的商业模型和机会。这些技术进步的一些主要的益处包括 IP多信道广播、等待时间解决方案、有保证的服务水平、低错误率和成本的降低。
8.3.3 The larger Internet II technology environment
Chapter 8 The Internet
计算机专业英语 8-73
IP Multicasting,IP multicasting is a set of technologies that enables
efficient delivery of data to many locations on a network,Rather than
making multiple copies of a message intended to be distributed to
multiple recipients at the point of origin of a message,multicasting
initially sends just one message and does not copy it to the individual
recipients until it reaches the closest common point on the network,
thereby minimizing the bandwidth consumed,Network performance
is significantly improved because it isn’t bogged down with the
processing and transmission of several large data files; each
receiving computer doesn’t have to query the transmitting server for
the file.
IP多信道广播。 IP多信道广播是使一组数据向网络中许多位置高效递送的技术。不是将一个信息在源点复制多份向多个接收者分配,多信道广播开始时只是发出一份信息而不向接收者复制，直到它到达网络上最近的公共点，因此使消耗的带宽最少。
因为它不会因处理和传输一些大的数据文件陷入停顿，所以网络型能大大地被改良；
每个接收计算机不必为一个文件向传输服务器发出请求。
8.3.3 The larger Internet II technology environment
Chapter 8 The Internet
计算机专业英语 8-74
Latency Solutions,One of the challenges of packet switching,
where data is divided into chunks and then sent separately to
meet again at the destination,is that the Internet does not
differentiate between high-priority packets,such as video clips,
and those of lower priority,such as self-contained e-mail
messages,Because the packets cannot yet be simultaneously
reassembled,the result is distorted audio and video streams.
等待时间解决方案。将数据分为多块、然后分开传送以便到目的地后再集合的分组交换技术，面临的挑战之一是因特网不区别高优先权信息包如图像修剪,与低优先权信息包如自我包容的电子邮件信息。因为信息包不能然同时重新装配,结果导致声频与视频流失真。
8.3.3 The larger Internet II technology environment
Chapter 8 The Internet
计算机专业英语 8-75
Internet II,however,holds the promise of diffserve,or differentiated
quality of service—a new technology that assigns levels of priority to
packets based on the type of data being transmitted.
Videoconference packets,for example,which need to reach their
destination almost instantaneously,would receive much higher
priority than e-mail messages,In the end,the quality of video and
audio will skyrocket without undue stress on the network,Live and
on-demand TV and video will be possible once Internet II is
completed.
然而因特网 II承诺区别服务品质 ——一种以被传输的数据类型为基础、为信息包分配优先权等级的新技术。例如，视讯会议信息包需要几乎即时到达目的地,将接受比电子邮件信息高的多的优先权。最后，由于在网上没有了过度的压力，视频和声频的质量将猛涨。一旦因特网 II完成，实况和随选电视与视频将成为可能。
8.3.3 The larger Internet II technology environment
Chapter 8 The Internet
计算机专业英语 8-76
Guaranteed Service Levels,In today’s Internet,there is no
service-level guarantee and no way to purchase the right
to move data through the Internet at a fixed pace,The
Internet is democratic—it speeds or slows everyone’s
traffic alike,With Internet II,it will be possible to purchase
the right to move data through the network at a
guaranteed speed in return for higher fees.
有保证的服务水平。在今天的因特网中,没有任何服务水平保证也没有办法购买以固定速度通过因特网移动数据。因特网是民主的 ——它加速或减慢每个人的通信量。通过因特网 II，将可购买以有保障的速度经过网络移动数据的权利，作为对较高费用的回报。
8.3.3 The larger Internet II technology environment
Chapter 8 The Internet
计算机专业英语 8-77
Lower Error Rates,Improved capacity and packet
switching will inevitably impact quality of data
transmissions,reducing error rates and boosting
customer satisfaction.
更低的错误率。改进的能力和分组交换不可避免地影响数据传输的质量，减少错误率而提高客户满意度。
8.3.3 The larger Internet II technology environment
Chapter 8 The Internet
计算机专业英语 8-78
Declining Costs,As the Internet pipeline is upgraded,the
availability of broadband service will expand beyond major
metropolitan areas,significantly reducing the costs of access.
More users means lower cost,as products and technology
catch on in the mass market,Higher volume usage enables
providers to lower the cost of both access devices,or clients,
and the service required to use such products,Both
broadband and wireless service fees are expected to decline as
geographic service areas increase,in part due to competition
for that business.
费用的降低。由于因特网通道升级,宽频服务的有效性将会超过主要大城市的范围，大大地降低访问的费用。较多的使用者意味比较低的费用,如同产品和技术在大众的市场中流行一样。较多的使用准许供应商降低访问设备或客户机的费用和服务必需使用的此类产品费用。随着服务的地理区域增大，预计宽频和无线服务的费用都将降低，部份是由于商业竞争。
8.3.3 The larger Internet II technology environment
Chapter 8 The Internet
计算机专业英语 8-79
英语长句的翻译一、英语长句的分析一般来说,造成长句的原因有三方面,(1) 修饰语过多 ;(2) 并列成分多 ; (3)语言结构层次多。
在分析长句时可以采用下面的方法：
① 找出全句的主语、谓语和宾语,从整体上把握句子的结构。
② 找出句中所有的谓语结构、非谓语动词、介词短语和从句的引导词。
③ 分析从句和短语的功能,例如,是否为主语从句,宾语从句,表语从句等,
若是状语,它是表示时间、原因、结果、还是表示条件等等。
④ 分析词、短语和从句之间的相互关系,例如,定语从句所修饰的先行词是哪一个等。
⑤ 注意插入语等其他成分。
⑥ 注意分析句子中是否有固定词组或固定搭配。
Chapter 8 The Internet
计算机专业英语 8-80
一、英语长句的分析例,For a family of four,for example,it is more convenient
as well as cheaper to sit comfortably at home,with
almost unlimited entertainment available,than to go out
in search of amusement elsewhere.
分析,(1) 该句的骨干结构为 it is more … to do sth than to do sth else.
是一个比较结构,而且是在两个不定式之间进行比较。 (2) 该句中共有三个谓语结构,它们之间的关系为,it is more convenient as well as cheaper
to … 为主体结构,但 it是形式主语,真正的主语为第二个谓语结构,to sit
comfortably at home,并与第三个谓语结构 to go out in search of
amusement elsewhere作比较。 (3) 句首的 for a family of four作状语,表示条件 。 另外,还有两个介词短语作插入语,for example,with almost
unlimited entertainment available,其中第二个介词短语作伴随状语,修饰 to sit comfortably at home.
[译文 ]譬如,对于一个四口之家来说,舒舒服服地在家中看电视,就能看到几乎数不清的娱乐节目,这比到外面别的地方去消遣又便宜又方便 。
Chapter 8 The Internet
计算机专业英语 8-81
二、英语长句的翻译英语习惯于用长的句子表达比较复杂的概念,而汉语则不同,常常使用若干短句,
作层次分明的叙述 。 因此,在进行英译汉时,要特别注意英语和汉语之间的差异,将英语的长句分解,翻译成汉语的短句 。 在英语长句的翻译过程中,我们一般采取下列的方法 。
1、顺序法。
当英语长句内容的叙述层次与汉语基本一致时,可以按照英语原文的顺序翻译成汉语。
例,Even when we turn off the beside lamp and are fast asleep,
electricity is working for us,driving our refrigerators,heating our
water,or keeping our rooms air-conditioned.
分析,该句子由一个主句,三个作伴随状语的现在分词以及位于句首的时间状语从句组成,共有五层意思,A.既使在我们关掉了床头灯深深地进入梦乡时 ; B.电仍在为我们工作 ; C,帮我们开动电冰箱 ; D,加热水 ; E.或是室内空调机继续运转。上述五层意思的逻辑关系以及表达的顺序与汉语完全一致,
[译文 ]即使在我们关掉了床头灯深深地进入梦乡时,电仍在为我们工作,帮我们开动电冰箱,把水加热,或使室内空调机继续运转。
Chapter 8 The Internet
计算机专业英语 8-82
二、英语长句的翻译
2,逆序法英语有些长句的表达次序与汉语表达习惯不同,甚至完全相反,
这时必须从原文后面开始翻译。
例,For our purposes we will say e-commerce begins in 1995,
following the appearance of the first banner advertisements
placed by ATT,Volvo,Sprint and others on Hotwired.com in
late October 1994,and the first sales of banner ad space by
Netscape and Infoseek in early 1995.
[译 ]伴随着 ATT,Volvo,Sprint等公司所做的第一例横幅广告于 1994年 10
月下旬出现在 Hotwired.com上，和 1995年初 Netscape与 Infoseek领先出售横幅广告空间，我们会说电子商务是从 1995年开始的。
Chapter 8 The Internet
计算机专业英语 8-83
二、英语长句的翻译
3、分句法有时英语长句中主语或主句与修饰词的关系并不十分密切,翻译时可以按照汉语多用短句的习惯,把长句的从句或短语化成句子,分开来叙述,为了使语意连贯,有时需要适当增加词语。
例,The number of the young people in the United States
who can't read is incredible about one in four.
上句在英语中是一个相对简单的句子,但是如果我们按照原文的句子结构死译,就可能被翻译成,―没有阅读能力的美国青年人的数目令人难以置信约为 1/4。”这样,就使得译文极为不通顺,不符合汉语的表达习惯,因此,我们应该把它译为,
[译文 ]大约有 1/4的美国青年人没有阅读能力,这简直令人难以置信。
Chapter 8 The Internet
计算机专业英语 8-84
二、英语长句的翻译
4,综合法事实上,在翻译一个英语长句时,并不只是单纯地使用一种翻译方法,而是要求我们把各种方法综合使用,这在我们上面所举的例子中也有所体现。尤其是在一些情况下,一些英语长句单纯采用上述任何一种方法都不方便,这就需要我们的仔细分析,或按照时间的先后,或按照逻辑顺序,顺逆结合,主次分明地对全句进行综合处理,以便把英语原文翻译成通顺忠实的汉语句子 。
例,Napster.com,which was established to aid Internet users in
finding and sharing online music files known as MP3 files,is
perhaps the most wellknown example of peer-to-peer e-
commerce,although purists note that Napster is only partially
peer-to-peer because it relies on a central database to show
which users are sharing music files.
译文,Napster.com建立的目标是帮助因特网用户发现并分享在线音乐文件，即人所共知的 MP3文件。尽管纯化论者强调：因为它依赖中央数据库来显示哪一位用户正在分享音乐文件，所以 Napster仅仅是部分对等。但 Napster或许是对等电子商务最著名的实例。
