网络工程专业外文翻译--计算机网络
网工英语
计算机网络－局域网（中英文对照）[Local area data networks，normally referred to simply as local area networks or LANs，are used to interconnect distributed communities of computer-based DTEs located within a single building or localized group of buildings.For example，a LAN may be used to interconnect workstations distributed around offices within a single building or a group of buildings such as a university campus.Alternatively，it may be used to interconnect computer-based equipment distributed around a factory or hospital complex[1].Since all the equipment is located within a single establishment，however，LANs are normally installed and maintained by the organization.Hence they are also referred to as private data networks.The main difference between a communication path established using a LAN and a connection made through a public data network is that a LAN normally offers much higher data transmission rates because of the relatively short physical separations involved[2].In the context of the ISO Reference Model for OSI，however，this difference manifests itself only at the lower network dependent layers.In many instances the higher protocol layers in the reference model are the same for both types of network.Before describing the structure and operation of the different types of LAN，it is perhaps helpful to first identify some of the selection issues that must be considered.A summary of some of the these issues is given in Fig. 14-5.It should be stressed that this is only a summary;there are also many possible links between the tips of the branches associated with the figure[3].1.TopologyMost wide area networks，such as the PSTN，use a mesh(sometimes referred to as anetwork)topology.With LANs，however，the limited physical separation of the subscriber DTEs allows simpler topologies to be used.The four topologies in common use are star，bus，ring and hub.The most widespread topology for LANs designed to function as data communication subnetworks for the interconnection of local computer-based equipment is the hub topology, which is a variation of the bus and ring[4].This is shown in Fig. 14-6，sometimes it is called hub/tree topology.2.Transmission mediaTwisted pair，coaxial cable and optical fiber are the three main types of transmission medium used for LANs.3.Medium access control methodsTwo techniques have been adopted for use of the medium access control in the LANs.They arecarrier-sense-multiple-access with collision detection(CSMA/CD)，for bus network topologies，and control token，for use with either bus or ring networks[5].CSMA / CD is used to control multiple-access networks.Each on the network“listens” before attempting to send a message，waiting for the“traffic”to clear[6].If two stations try to send their messages at exactly the same time，a“collision”is detected，an both stations are required to“step back”and try later.Control token is another way of controlling access to a shared transmission medium that is by the use of a control(pertnission)token.This token is passed from one DTE to another according to a defined set of rules understood and adhered to by all DTEs connected to the medium.A DTE may only transmit a frame when it is in possession of the token and，after it has transmined the frame，it passes the token on to allow another DTE to access the tranamission medium.NOTES[1] computer-based是指由计算机控制的，或装有微处理器的。
计算机网络介绍中英文
计算机网络介绍中英文计算机网络基础介绍（英文）AD：Introduction to Computer NetworkComputer network is a system connecting two or more computers. A computer network allows user to exchange data quickly, access and share resources including equipments, application software, and information.Data communications systems are the electronic systems that transmit data over communications lines from one location to another. You might use data communications through your microcomputer to send information to a friend using another computer. You might work for an organization whose computer system is spread throughout a building, or even throughout the country or world. That is, all the parts—input and output units, processor, and storage devices—are in different places and linked by communications. Or you might use telecommunications lines—telephone lines—to tap into information located in an outside data bank. You could then transmit it to your microcomputer for your own reworking and analysis.To attach to a network, a special-purpose hardware component is used to handle all the transmission. The hardware is called a network adapter card or network interface card (NIC), it is a printed circuit board plugged into a computer's bus, and a cable connects it to a network medium.Communications networks differ in geographical size. There are three important types: LANs, MANs, and WANs.Local Area Networks Networks with computers andperipheral devices in close physical proximity—within the same building, for instance—are called local area networks (LANs). Linked by cable-telephone, coaxial, or fiber optic. LANs often use a bus form organization. In a LAN, people can share different equipments, which lower the cost of equipments. LAN may be linked to other LANs or to larger networks by using a network gateway. With the gateway, one LAN may be connected to the LAN of another LAN of another office group. It may also be connected to others in the wide world, even if their configurations are different. Alternatively, a network bridge would be used to connect networks with the same configurations.There is a newly development for LANs: WLAN. A wireless LAN (WLAN) is a flexible data communication system implemented as an extension to, or as an alternative for, a wired LAN within a building or campus. Using electromagnetic waves, WLANs transmit and receive data over the air, minimizing the need for wired connections. Thus, WLANs combine data connectivity with user mobility, and, through simplified configuration, enable movable LANs.Over the recent several years, WLANs have gained strong popularity in a number of vertical markets, including the health-care, retail, manufacturing, warehousing, and academic arenas.These industries have profited from the productivity gains of using hand-held terminals and notebook computers to transmit real-time information to centralized hosts for processing. Today WLANs are becoming more widely recognized as a general-purpose connectivity alternative for a broad range of business customers.Applications for Wireless LANs Wireless LANs frequently augment rather than replace wired LAN networks—oftenproviding the final few meters of connectivity between a backbone network and the mobile user. The following list describes some of the many applications made possible through the power and flexibility of wireless LANs:●Doctors and nurses in hospitals are more productive because hand-held or notebook computers with wireless LAN capability deliver patient information instantly.●Consulting or accounting audit engagement teams or small workgroups increase productivity with quick network setup.●Network managers in dynamic environments minimize the overhead of moves, adds, and changes with wireless LANs, thereby reducing the cost of LAN ownership.●Training sites at corporations and students at universities use wireless connectivity to facilitate access to information, information exchanges, and learning.●Network managers installing networked computers in older buildings find that wireless LANs are a cost-effective network infrastructure solution.●Retail store owners use wireless networks to simply frequent network reconfiguration.●Trade show and branch office workers minimize setup requirements by installing preconfigured wireless LANs needing no local MIS support.●Warehouse workers use wireless LANs to exchange information with central databases and increase their productivity.●Network managers implement wireless LANs to provide backup for mission-critical applications running on wired networks.●Senior executives in conference rooms make quickerdecisions because they have real-time information at their fingertips.The increasingly mobile user also becomes a clear candidate for a wireless LAN. Portable access to wireless networks can be achieved using laptop computers and wireless NICs. This enables the user to travel to various locations–meeting rooms, hallways, lobbies, cafeterias, classrooms, etc.–and still have access to their networked data. Without wireless access, the user would have to carry clumsy cabling and find a network tap to plug into.Metropolitan Area Networks These networks are used as links between office buildings in a city. Cellular phone systems expand the flexibility of MAN by allowing links to car phones and portable phones.Wide Area Networks Wide area networks are countrywide and worldwide networks. Among other kinds of channels, they use microwave relays and satellites to reach users over long distances. One of the most widely used WANs is Internet, which allows users to connect to other users and facilities worldwide.计算机网络基础介绍（译文）计算机网络是连接两个或多个计算机的系统，它允许用户快速地交换数据，访问和共享包括设备、应用软件和信息在内的资源。
计算机网络词汇翻译浅析
计算机网络词汇翻译浅析计算机网络已经成为现代社会中不可或缺的一部分，它使得人们可以在世界各地进行信息交流和数据传输。
在进行计算机网络翻译时，我们需要深入理解各种网络术语的含义和用法。
在本文中，我将就一些常见的计算机网络词汇进行浅析，并提供它们的翻译建议。
1. Internet英文原意：a global computer network providing a variety of information and communication facilities翻译建议：互联网解析：互联网是指连接在一起的全球计算机网络系统，提供各种信息和通信服务。
2. Network英文原意：a group or system of interconnected people or things 翻译建议：网络解析：网络是指相互连接在一起的一组或系统，可以包括计算机、设备和人。
3. Router英文原意：a device that forwards data packets between computer networks翻译建议：路由器解析：路由器是一种设备，用于在不同的计算机网络之间转发数据包。
它通常用于将数据从一个网络发送到另一个网络。
4. Ethernet英文原意：a system for connecting a number of computer systems to form a local area network翻译建议：以太网解析：以太网是一种将多台计算机系统连接在一起形成局域网的系统。
5. Firewall英文原意：a network security system that monitors and controls incoming and outgoing network traffic翻译建议：防火墙解析：防火墙是一种网络安全系统，用于监控和控制进出网络的流量。
6. Server英文原意：a computer or computer program that manages access to a centralized resource or service翻译建议：服务器解析：服务器是一台计算机或计算机程序，用于管理对集中资源或服务的访问。
Computer network中英文对照简介
Computer network计算机网络A computer network is a group of more computers connected to each electronically. This means that the computers can "talk" to each other and that every computer in the network can send information to the others. Usually, this means that the speed of the connection is fast - faster than a normal connection to the Internet.计算机网络是一组多台计算机连接到每个电子。
这意味着计算机可以“讲”给对方，并且每一个在网络上的计算机可以将信息发送到其他。
通常情况下，这意味着连接速度快 - 速度比正常的连接到互联网。
Some basic types of computer networks include:▪ A local area network (often called a LAN) connects two or more computers, and may be called a corporate network in an office or business setting.▪An "internetwork", sometimes called a Wide Area Network (because of the wide distance between networks) connects two or more smaller networks together. The largest internetwork is called the Internet.计算机网络的一些基本类型包括：局域网络（通常被称为一个LAN）连接两个或更多的计算机，并可能被称为一个企业网络，在办公室或业务设置。
计算机类网站网络建设外文翻译、中英文翻译、外文文献翻译
外文翻译Birth of the NetThe Internet has had a relatively brief, but explosive history so far. It grew out of an experiment begun in the 1960's by the U.S. Department of Defense. The DoD wanted to create a computer network that would continue to function in the event of a disaster, such as a nuclear war. If part of the network were damaged or destroyed, the rest of the system still had to work. That network was ARPANET, which linked U.S. scientific and academic researchers. It was the forerunner of today's Internet.In 1985, the National Science Foundation (NSF) created NSFNET, a series of networks for research and education communication. Based on ARPANET protocols, the NSFNET created a national backbone service, provided free to any U.S. research and educational institution. At the same time, regional networks were created to link individual institutions with the national backbone service.NSFNET grew rapidly as people discovered its potential, and as new software applications were created to make access easier. Corporations such as Sprint and MCI began to build their own networks, which they linked to NSFNET. As commercial firms and other regional network providers have taken over the operation of the major Internet arteries, NSF has withdrawn from the backbone business.NSF also coordinated a service called InterNIC, which registered all addresses on the Internet so that data could be routed to the right system. This service has now been taken over by Network Solutions, Inc., in cooperation with NSF.How the Web WorksThe World Wide Web, the graphical portion of the Internet, is the most popular part of the Internet by far. Once you spend time on the Web,you will begin to feel like there is no limit to what you can discover. The Web allows rich and diverse communication by displaying text, graphics, animation, photos, sound and video.So just what is this miraculous creation? The Web physically consists of your personal computer, web browser software, a connection to an Internet service provider, computers called servers that host digital data and routers and switches to direct the flow of information.The Web is known as a client-server system. Your computer is the client; the remote computers that store electronic files are the servers. Here's how it works:Let's say you want to pay a visit to the the Louvre museum website. First you enter the address or URL of the website in your web browser (more about this shortly). Then your browser requests the web page from the web server that hosts the Louvre's site. The Louvre's server sends the data over the Internet to your computer. Your web browser interprets the data, displaying it on your computer screen.The Louvre's website also has links to the sites of other museums, such as the Vatican Museum. When you click your mouse on a link, you access the web server for the Vatican Museum.The "glue" that holds the Web together is called hypertext and hyperlinks. This feature allow electronic files on the Web to be linked so you can easily jump between them. On the Web, you navigate through pages of information based on what interests you at that particular moment, commonly known as browsing or surfing the Net.To access the Web you need web browser software, such as Netscape Navigator or Microsoft Internet Explorer. How does your web browser distinguish between web pages and other files on the Internet? Web pages are written in a computer language called Hypertext Markup Language or HTML.Some Web HistoryThe World Wide Web (WWW) was originally developed in 1990 at CERN, the European Laboratory for Particle Physics. It is now managed by The World Wide Web Consortium, also known as the World Wide Web Initiative.The WWW Consortium is funded by a large number of corporate members, including AT&T, Adobe Systems, Inc., Microsoft Corporation and Sun Microsystems, Inc. Its purpose is to promote the growth of the Web by developing technical specifications and reference software that will be freely available to everyone. The Consortium is run by MIT with INRIA (The French National Institute for Research in Computer Science) acting as European host, in collaboration with CERN.The National Center for Supercomputing Applications (NCSA) at the University of Illinois at Urbana-Champaign, was instrumental in the development of early graphical software utilizing the World Wide Web features created by CERN. NCSA focuses on improving the productivity of researchers by providing software for scientific modeling, analysis, and visualization. The World Wide Web was an obvious way to fulfill that mission. NCSA Mosaic, one of the earliest web browsers, was distributed free to the public. It led directly to the phenomenal growth of the World Wide Web.Understanding Web AddressesYou can think of the World Wide Web as a network of electronic files stored on computers all around the world. Hypertext links these resources together. Uniform Resource Locators or URLs are the addresses used to locate thesefiles. The information contained in a URL gives you the ability to jump from one web page to another with just a click of your mouse. When you type a URL into your browser or click on a hypertext link, your browser is sending a request to a remote computer to download a file.What does a typical URL look like? Here are some examples:/The home page for study english.ftp:///pub/A directory of files at MIT* available for downloading.news:rec.gardens.rosesA newsgroup on rose gardening.The first part of a URL (before the two slashes* tells you the type of resource or method of access at that address. For example:∙http - a hypertext document or directory∙gopher - a gopher document or menu∙ftp - a file available for downloading or a directory of such files∙news - a newsgroup∙telnet - a computer system that you can log into over the Internet∙WAIS* - a database or document in a Wide Area Information Search database∙file - a file located on a local drive (your hard drive)The second part is typically the address of the computer where the data or service is located. Additional parts may specify the names of files, the port to connect to, or the text to search for in a database.You can enter the URL of a site by typing it into the Location bar of your web browser, just under the toolbar.Most browsers record URLs that you want to use again, by adding them to a special menu. In Netscape Navigator, it's called Bookmarks. In Microsoft Explorer, it's called Favorites. Once you add a URL to your list, you can return to that web page simply by clicking on the name in your list, instead of retyping the entire URL.Most of the URLs you will be using start with http which stands for Hypertext Transfer Protocol*. http is the method by which HTML files are transferred over the Web. Here are some other important things to know about URLs:∙ A URL usually has no spaces.∙ A URL always uses forward slashes (//).If you enter a URL incorrectly, your browser will not be able to locate the site or resource you want. Should you get an error message or the wrong site, make sure you typed the address correctly.You can find the URL behind any link by passing your mouse cursor over the link. The pointer will turn into a hand and the URL will appear in the browser's status ba r, usually located at the bottom of your screen.Domain NamesWhen you think of the Internet, you probably think of ".com." Just what do those three letters at the end of a World Wide Web address mean?Every computer that hosts data on the Internet has a unique numerical address. For example, the numerical address for the White House is198.137.240.100. But since few people want to remember long strings of numbers, the Domain Name System (DNS)* was developed. DNS, a critical part of the Internet's technical infrastructure*, correlates* a numerical address to a word. To access the White House website, you could type its number into the address box of your web browser. But most people prefer to use "." In this case, the domain name is . In general, the three-letter domain name suffix* is known as a generictop-level domai n and describes the type of organization. In the last few years, the lines have somewhat blurred* between these categories..com - business (commercial).edu - educational.org - non-profit.mil - military.net - network provider.gov - governmentA domain name always has two or more parts separated by dots and typically consists of some form of an organization's name and the three-letter suffix. For example, the domain name for IBM is ""; the United Nations is "."If a domain name is available, and provided it does not infringe* on an existing trademark, anyone can register the name for $35 a year through Network Solutions, Inc., which is authorized to register .com, .net and .org domains. You can use the box below to see if a name is a available. Don't be surprised ifthe .com name you want is already taken, however. Of the over 8 million domain names, 85% are .com domains.ICANN, the Internet Corporation for Assigned Names and Numbers, manages the Domain Name System. As of this writing, there are plans to add additional top-level domains, such as .web and .store. When that will actually happen is anybody's guess.To check for, or register a domain name, type it into the search box.It should take this form: In addition to the generic top-level domains, 244 national top-level domains were established for countries and territories*, for example:.au - Australia.ca - Canada.fr - France.de - Germany.uk - United KingdomFor US $275 per name, you can also register an international domain name with Net Names. Be aware that some countries have restrictions for registering names.If you plan to register your own domain name, whether it's a .com or not, keep these tips in mind:The shorter the name, the better. (But it should reflect your family name, interest or business.)The name should be easy to remember.It should be easy to type without making mistakes.Remember, the Internet is global. Ideally, a domain name will "read" in a language other than English.Telephone lines were designed to carry the human voice, not electronic data from a computer. Modems were invented to convert digital computer signals into a form that allows them to travel over the phone lines. Those are the scratchy sounds you hear from a modem's speaker. A modem on theother end of the line can understand it and convert the sounds back into digital information that the computer can understand. By the way, the word modem stands for MOdulator/DEModulator.Buying and using a modem used to be relatively easy. Not too long ago, almost all modems transferred data at a rate of 2400 Bps (bits per second). Today, modems not only run faster, they are also loaded with features like error control and data compression. So, in addition to converting and interpreting signals, modems also act like traffic cops, monitoring and regulating the flow of information. That way, one computer doesn't send information until the receiving computer is ready for it. Each of these features, modulation, error control, and data compression, requires a separate kind of protocol and that's what some of those terms you see like V.32, V.32bis, V.42bis and MNP5 refer to.If your computer didn't come with an internal modem, consider buying an external one, because it is much easier to install and operate. For example, when your modem gets stuck (not an unusual occurrence), you need to turn it off and on to get it working properly. With an internal modem, that means restarting your computer--a waste of time. With an external modem it's as easy as flipping a switch.Here's a tip for you: in most areas, if you have Call Waiting, you can disable it by inserting *70 in front of the number you dial to connect to the Internet (or any online service). This will prevent an incoming call from accidentally kicking you off the line.This table illustrates the relative difference in data transmission speeds for different types of files. A modem's speed is measured in bits per second (bps). A 14.4 modem sends data at 14,400 bits per second. A 28.8 modem is twice as fast, sending and receiving data at a rate of 28,800 bits per second.Until nearly the end of 1995, the conventional wisdom was that 28.8 Kbps was about the fastest speed you could squeeze out of a regular copper telephoneline. Today, you can buy 33.6 Kbps modems, and modems that are capable of 56 Kbps. The key question for you, is knowing what speed modems your Internet service provider (ISP) has. If your ISP has only 28.8 Kbps modems on its end of the line, you could have the fastest modem in the world, and only be able to connect at 28.8 Kbps. Before you invest in a 33.6 Kbps or a 56 Kbps modem, make sure your ISP supports them.Speed It UpThere are faster ways to transmit data by using an ISDN or leased line. In many parts of the U.S., phone companies are offering home ISDN at less than $30 a month. ISDN requires a so-called ISDN adapter instead of a modem, and a phone line with a special connection that allows it to send and receive digital signals. You have to arrange with your phone company to have this equipment installed. For more about ISDN, visit Dan Kegel's ISDN Page.An ISDN line has a data transfer rate of between 57,600 bits per second and 128,000 bits per second, which is at least double the rate of a 28.8 Kbps modem. Leased lines come in two configurations: T1 and T3. A T1 line offers a data transfer rate of 1.54 million bits per second. Unlike ISDN, a T-1 line is a dedicated connection, meaning that it is permanently connected to the Internet. This is useful for web servers or other computers that need to be connected to the Internet all the time. It is possible to lease only a portion of a T-1 line using one of two systems: fractional T-1 or Frame Relay. You can lease them in blocks ranging from 128 Kbps to 1.5 Mbps. The differences are not worth going into in detail, but fractional T-1 will be more expensive at the slower available speeds and Frame Relay will be slightly more expensive as you approach the full T-1 speed of 1.5 Mbps. A T-3 line is significantly faster, at 45 million bits per second. The backbone of the Internet consists of T-3 lines. Leased lines are very expensive and are generally only used by companies whose business is built around the Internet or need to transfer massiveamounts of data. ISDN, on the other hand, is available in some cities for a very reasonable price. Not all phone companies offer residential ISDN service. Check with your local phone company for availability in your area.Cable ModemsA relatively new development is a device that provides high-speed Internet access via a cable TV network. With speeds of up to 36 Mbps, cable modems can download data in seconds that might take fifty times longer with a dial-up connection. Because it works with your TV cable, it doesn't tie up a telephone line. Best of all, it's always on, so there is no need to connect--no more busy signals! This service is now available in some cities in the United States and Europe.The download times in the table above are relative and are meant to give you a general idea of how long it would take to download different sized files at different connection speeds, under the best of circumstances. Many things can interfere with the speed of your file transfer. These can range from excessive line noise on your telephone line and the speed of the web server from which you are downloading files, to the number of other people who are simultaneously trying to access the same file or other files in the same directory.DSLDSL (Digital Subscriber Line) is another high-speed technology that is becoming increasingly popular. DSL lines are always connected to the Internet, so you don't need to dial-up. Typically, data can be transferred at rates up to 1.544 Mbps downstream and about 128 Kbps upstream over ordinary telephone lines. Since a DSL line carries both voice and data, you don't have to install another phone line. You can use your existing line to establish DSLservice, provided service is available in your area and you are within the specified distance from the telephone company's central switching office.DSL service requires a special modem. Prices for equipment, DSL installation and monthly service can vary considerably, so check with your local phone company and Internet service provider. The good news is that prices are coming down as competition heats up.Anatomy of a Web PageA web page is an electronic document written in a computer language called HTML, short for Hypertext Markup Language. Each web page has a unique address, called a URL* or Uniform Resource Locator, which identifies its location on the network.A website has one or more related web pages, depending on how it's designed. Web pages on a site are linked together through a system of hyperlinks* , enabling you to jump between them by clicking on a link. On the Web, you navigate through pages of information according to your interests.Home Sweet Home PageWhen you browse the World Wide Web you'll see the term home page often. Think of a home page as the starting point of a website. Like the table of contents of a book or magazine, the home page usually provides an overview of what you'll find at the website. A site can have one page, many pages or a few long ones, depending on how it's designed. If there isn't a lot of information, the home page may be the only page. But usually you will find at least a few other pages.Web pages vary wildly in design and content, but most use a traditional magazine format. At the top of the page is a masthead* or banner graphic*, then a list of items, such as articles, often with a brief description. The items in the list usually link to other pages on the website, or to other sites. Sometimes these links are highlighted* words in the body of the text, or are arranged in a list, like an index. They can also be a combination* of both. A web page can also have images that link to other content.How can you tell which text are links? Text links appear in a different color from the rest of the text--typically in blue and underlined. When you move yourcursor over a text link or over a graphic link, it will change from an arrow to a hand. The hypertext words often hint* at what you will link to.When you return to a page with a link you've already visited, the hypertext words will often be in a different color, so you know you've already been there. But you can certainly go there again. Don't be surprised though, if the next time you visit a site, the page looks different and the information has changed. The Web is a dynamic* medium. To encourage visitors to return to a site, some web publishers change pages often. That's what makes browsing the Web so excitingA Home (Page) of Your OwnIn the 60s, people asked about your astrological* sign. In the 90s, they want to know your URL. These days, having a web address is almost as important as a street address. Your website is an electronic meeting place for your family, friends and potentially*, millions of people around the world. Building your digital domain can be easier than you may think. Best of all, you may not have to spend a cent. The Web brims with all kinds of free services, from tools to help you build your site, to free graphics, animation and site hosting. All it takes is some time and creativity.Think of your home page as the starting point of your website. Like the table of contents of a book or magazine, the home page is the front door. Your site can have one or more pages, depending on how you design it. If there isn't a lot of information just yet, your site will most likely have only a home page. But the site is sure to grow over time.While web pages vary dramatically* in their design and content, most use a traditional magazine layout. At the top of the page is a banner graphic. Next comes a greeting and a short description of the site. Pictures, text, and links to other websites follow.If the site has more than one page, there's typically a list of items--similar to an index--often with a brief description. The items in the list link to other pages on the website. Sometimes these links are highlighted words in the body of the text. It can also be a combination of both. Additionally, a web page may have images that link to other content.Before you start building your site, do some planning. Think about whom the site is for and what you want to say. Next, gather up the material that you wantto put on the site: write the copy, scan the photos, design or find the graphics. Draw a rough layout on a sheet of paper.While there are no rules you have to follow, there are a few things to keep in mind:∙Start simply. If you are too ambitious at the beginning, you may never get the site off the ground. You can always add to your site.∙Less is better. Most people don't like to read a lot of text online. Break it into small chunks.∙Use restraint. Although you can use wild colors and images for the background of your pages, make sure your visitors will be able to readthe text easily.∙Smaller is better. Most people connect to the Internet with a modem.Since it can take a long time to download large image files, keep the file sizes small.∙Have the rights. Don't put any material on your site unless you are sure you can do it legally. Read Learn the Net's copyright article for moreabout this.Stake Your ClaimNow it's time to roll up your sleeves and start building. Learn the Net Communities provides tools to help you build your site, free web hosting, and a community of other homesteaders.Your Internet service provider may include free web hosting services with an account, one alternative to consider.Decoding Error MessagesAs you surf the Net, you will undoubtedly find that at times you can't access certain websites. Why, you make wonder? Error messages attempt to explain the reason. Unfortunately, these cryptic* messages baffle* most people.We've deciphered* the most common ones you may encounter.400 - Bad RequestProblem: There's something wrong with the address you entered. You may not be authorized* to access the web page, or maybe it no longer exists.Solution: Check the address carefully, especially if the address is long. Make sure that the slashes are correct (they should be forward slashes) and that all the names are properly spelled. Web addresses are case sensitive, socheck that the names are capitalized in your entry as they are in the original reference to the website.401 - UnauthorizedProblem: You can't access a website, because you're not on the guest list, your password is invalid or you have entered your password incorrectly.Solution: If you think you have authorization, try typing your password again. Remember that passwords are case sensitive.403 - ForbiddenProblem: Essentially the same as a 401.Solution: Try entering your password again or move on to another site.404 - Not FoundProblem: Either the web page no longer exists on the server or it is nowhere to be found.Solution: Check the address carefully and try entering it again. You might also see if the site has a search engine and if so, use it to hunt for the document. (It's not uncommon for pages to change their addresses when a website is redesigned.) To get to the home page of the site, delete everything after the domain name and hit the Enter or Return key.503 - Service unavailableProblem: Your Internet service provider (ISP) or your company's Internet connection may be down.Solution: Take a stretch, wait a few minutes and try again. If you still have no luck, phone your ISP or system administrator.Bad file requestProblem: Your web browser may not be able to decipher the online form you want to access. There may also be a technical error in the form.Solution: Consider sending a message to the site's webmaster, providing any technical information you can, such as the browser and version you use.Connection refused by hostProblem: You don't have permission to access the page or your password is incorrect.Solution: Try typing your password again if you think you should have access.Failed DNS lookupProblem: DNS stands for the Domain Name System, which is the system that looks up the name of a website, finds a corresponding number (similar to a phone number), then directs your request to the appropriate web server on theInternet. When the lookup fails, the host server can't be located.Solution: Try clicking on the Reload or Refresh button on your browser toolbar. If this doesn't work, check the address and enter it again. If all else fails, try again later.File contains no dataProblem: The site has no web pages on it.Solution: Check the address and enter it again. If you get the same error message, try again later.Host unavailableProblem: The web server is down.Solution: Try clicking on the Reload or Refresh button. If this doesn't work, try again later.Host unknownProblem: The web server is down, the site may have moved, or you've been disconnected from the Net.Solution: Try clicking on the Reload or Refresh button and check to see that you are still online. If this fails, try using a search engine to find the site. It may have a new address.Network connection refused by the serverProblem: The web server is busy.Solution: Try again in a while.Unable to locate hostProblem: The web server is down or you've been disconnected from the Net.Solution: Try clicking on the Reload or Refresh button and check to see that you are still online.Unable to locate serverProblem: The web server is out-of-business or you may have entered the address incorrectly.Solution: Check the address and try typing it again.Web BrowsersA web browser is the software program you use to access the World Wide Web, the graphical portion of the Internet. The first browser, called NCSA Mosaic, was developed at the National Center for Supercomputing Applications in the early '90s. The easy-to-use point-and-click interface*helped popularize the Web, although few then could imagine the explosive growth that would soon occur.Although many different browsers are available, Microsoft Internet Explorer* and Netscape Navigator* are the two most popular ones. Netscape and Microsoft have put so much money into their browsers that the competition can't keep up. The pitched battle* between the two companies to dominate* the market has lead to continual improvements to the software. Version 4.0 and later releases of either browser are excellent choices. (By the way, both are based on NCSA Mosaic.) You can download Explorer and Navigator for free from each company's website. If you have one browser already, you can test out the other. Also note that there are slight differences between the Windows and MacIntosh* versions.You can surf to your heart's content, but it's easy to get lost in this electronic web. That's where your browser can really help. Browsers come loaded with all sorts of handy features. Fortunately, you can learn the basics in just a few minutes, then take the time to explore the advanced functions.Both Explorer and Navigator have more similarities than differences, so we'll primarily cover those. For the most up-to-date information about the browsers, and a complete tutorial, check the online handbook under the Help menu or go to the websites of the respective* software companies.Browser AnatomyWhen you first launch your web browser, usually by double-clicking on the icon on your desktop, a predefined web page, your home page, will appear. With Netscape Navigator for instance, you will be taken to Netscape's NetCenter.The Toolbar （工具栏）The row of buttons at the top of your web browser, known as the toolbar, helps you travel through the web of possibilities, even keeping track ofwhere you've been. Since the toolbars for Navigator and Explorer differ slightly, we'll first describe what the buttons in common do:o The Back button returns you the previous page you've visited.o Use the Forward button to return to the page you just came from.o Home takes you to whichever home page you've chosen. (If you haven't selected one, it will return you to the default home page,usually the Microsoft or Netscape website.)。
最新计算机网络英语词汇(完美版)
[A]Alphamosic Graphics字母镶嵌图形Active Directory动态目录ADSI动态目录服务接口Autosizing自动调整大小Anonymous FTP 匿名文件传输Access Control 访问控制ARP地址解析协议API 应用程序界面ACL 访问控制表Attenuation 衰减ARP 地址解析协议Adapter 适配器Average seek time 平均寻道时间Authorization 授权，认证Adapter 适配器A3D 3D定位音效技术Acrobat Adobe阅读软件AC97 音响数字/模拟转换ACL 访问控制表A3D Aureal声音技术ATAPI AT附件包接口aliasing 混淆utoexec.bat 自动批处理文件API 应用程序设计接口ASP服务器开发专用脚本ADSL 非对称数字用户线路AVI 影音文件ADSL 非对称数字用户环线Algorithm 算法Alpha DEC公司微处理器Authorwsre Authorware 多媒体创作软件AMI BIOS BIOS基本输入/输出系统AGP 加速图形接口Aactive matrix 动态矩阵Aactive Network 动态网络Authentication and Authorization 鉴别与授权Auditing 审计，计审At Work Architecture，Microsoft Microsoft 的At Work体系结构[B]BISDN宽带综合业务数字网BRI基本速率接口BIS商务信息系统Bundled Software捆绑软件Bluetooth蓝牙Back Door 后门Bridge 网桥Bit 比特Backup 备份Beta Test Beta测试Bookmark 书签BASIC 编程语言B2B 商务对商务Bandwidth 带宽BBS 电子布告栏系统Beta 测试第二版bit 位Bug 程序缺陷、臭虫Byte－Oriented Protocol 面向字节规程Bus Topology 总线拓扑Bursts 突发传送Burst Mode，NetWare NetWare的突发方式Bulletin Board System 公告牌系统Brouter（Bridge／router）桥路器（桥接器／路由器）Broadcast Storm 广播风暴Broadcast 广播Broadband Services 宽带（通信）服务Broadband ISDN 宽带综合业务数字网Bridging 桥接Breakout BoX 中断盒Border Gateway Protocol 边界网关协议BNC Connector BNC连接器Block Suballocation 磁盘块再分配Bit－Oriented Protocol 面向位协议BITNET BITNET网Bindery 装订Binary Synchronous Communications 二进制同步通信（规程）Bell Operating Companies 贝尔运营公司Bell modem Standards 贝尔调制解调器标准Bellman－Ford Distance－Vector Routing Algorithm Bellman－Ford距离向量[C]CFTV付费电视CDMA码分多址技术CRC循环冗余检查CD-ROM只读光盘机CMIP 通用管理信息协议Cable 电缆Cable Modem 电缆调制解调器Chipset 芯片组CNNIC 中国互联网络信息中心CRT 阴极射线管Cache 高速缓冲存储器Client/Server 客户机/服务器Cookie 网络小甜饼Cache 高速缓冲存储器CMOS 可读写芯片CGI 公共网关接口Cryptography 密码术；密码学Corporation for Open Systems 开放系统公司Copper Distributed Data Interface 铜质分布式数据接口Cooperative Accessing 协同处理Controlled Access Unit 受控访问单元Contention 争用Container Objects 所有者对象Connection－Oriented and Connectionless Protocols 面向连接和无连接协议Connectionless Network Protocol 无连接网络协议Connectionless and Connection－Oriented Transactions 无连接和面向连接事务Configuration Management 配置管理Conditioning 调节Concentrator Devices 集中器设备Compression Techniques 压缩技术Compound Documents 复合文档Complex Instruction Set Computer 复杂指令系统计算机Communication Services 通信服务Communication Server 通信服务器Communication Controller 通信控制器Communication 通信Common Programming Interface for Communication IBM IBM的通信公用编程接口Common Open Software Environment 公用开放软件环境Common Object Request Broker Architecture 公用对象请求代管者体系结构Common Object Model 公用对象模型[D]Dvorak Keyboard Dvorak键盘DDR双倍速率SDRAMDAO 数据访问对象Daemon 后台程序DTR 数据终端就绪DASD 直接访问存储设备DMI 桌面管理界面DPI 打印分辨率DHCP动态主机配置协议Driver 驱动程序DDN 数字数据网络DRAM 动态随机存取内存DSL 数字用户环线Desktop 桌面、台式电脑Download 下载Digital camera Digital camera 数码相机Dynamic Routing 动态路由选择Dynamic Data Exchange 动态数据交换Duplex Transmission 双工传输Duplexed Systems 双工系统Downsizing 向下规模化，下移DOS Requester，NetWare NetWare礑OS请求解释器Domains 域Domain Name Service 域名服务Document Management 文档管理Document Interchange Standards 文档交换标准Distributed System Object Model 分布式系统对象模型Distributed Relational Database Architecture 分布式关系数据库体系结构Distributed Queue Dual Bus 分布式队列双总线Distributed Processing 分布式处理Distributed Objects EveryWhere（DOE），SunSoft SunSoft的全分布式对象Distributed Object Management Systems 分布式对象管理系统Distributed Object Management Facility （DOMF），Hewlett－Packard HP的分布式对象管理设施Distributed Name Service，DEC DEC的分布式命名服务Distributed Management Environment 分布式管理环境Distributed Management 分布式管理Distributed File Systems 分布式文件系统Distributed File System，OSF DCE OSF DCE 的分布式文件系统Distributed Database 分布式数据库Distributed Computing Environment（DCE），OSF 开放软件基金会（OSF）的分布式计算环境[E]Edge Device 边界设备Email Filter 电子邮件过滤器EPP 增强型并行端口Extranet 外联网EISA总线扩展工业标准结构External Bus 外部总线EDO RAM 动态存储器Ethernet 以太网Email client 电子邮件客户端程序Exterior Gateway Protocols 外部网关协议Extended Industry Standard Architecture Bus 扩展工业标准体系结构（EISA）总线EtherTalk EtherTalk 适配器Ethernet100VG－AnyLAN（Voice Grade）100VG－AnyLAN（语音级）以太网Ethernet 100Base－X 100Base－X以太网Ethernet 10BaSe－T（Twisted－pair）10Base －T（双绞线）以太网Ethernet 10Base－5（Thicknet）10Base－5（粗电缆）以太网Ethernet 10Base－2（Thinnet）10Base－2（细电缆）以太网Ethernet 以太网Error Detection and Correction 检错和纠错Enterprise System Connections（SCON），IBM IBM的企业级系统连接Enterprise System Architecture，IBM IBM的企业级系统体系结构Enterprise Networks 企业网Enterprise Management Architecture，DEC DEC的企业（点）管理体系结构End System－to－Intermediate System（ES－IS）Routing 端系统对中间系统Encryption 加密Encina Encina应用程序Encapsulation 封装E－Mail电子函件Elevator Seeking 电梯式查找［寻道］算法Electronic Software Distribution（ESD）and Licensing 电子软件分发（ESD）和特许（ESL）Electronic Mail Broadcasts to a Roaming Computer 对漫游计算机的电子函件广播Electronic Mail 电子函件Electronic Industries Association 电子工业协会Electronic Data Interchange 电子数据交换Electromagnetic Interference 电磁干扰EISA（Extended Industry Standard Architecture）Bus EISA（扩展工业标准体系结构）总线EIA／TIA 568 Commercial Building Wiring Standard EIA／TIA 568 商用建[F]File Server文件服务器FCC & BCC转发与密送Flash动画制作软件Failback 自动恢复FAT 文件分配表FTP Server 文件传输服务器Fax modem 传真调制解调器FDDI 光纤分布式数据接口FAT 文件分配表FLASH 动感网页制作工具FTP 文件传输协议FAT32 32位文件分配表Firewall 防火墙Flash FlashFull－Duplex Transmissions 全双工传输Front－End System 前端（台）系统Front－End Processor 前端（台）处理机Frequency Division Multiplexing 频分多路复用Frames in Communication 通信帧Frame Relay 帧中继Fractional T1／Fractional T3 部分T1／部分T3Forwarding 转发Flow Control Methods 流控方法FINGER FINGER实用程序Filtering 筛选，过滤File Transfer Protocol 文件传输协议File Transfer Access and Management 文件传输访问和管理File Systems in the Network Environment 网络环境中的文件系统File Systems，Distributed 分布式文件系统Filesharing 文件共享File Server 文件服务器Fileand Directory Permissions，Windows NT Windows NT的文件和目录许File and Directory Attributes，NetWare NetWare的文件和目录属性Fiber Channel 光纤通道Fiber－Optic Cable 光缆Fiber Distributed Data Interface 光纤分布式数据接口Federated Naming Services，SunSoft ONC SunSoft ONC的联合命名服务Federated Database 联合数据库Federal Information Processing Standards 联邦信息处理标准FAX Servers 传真服务器[G]GPRS通用分组无线业务GPRS通用分组无线业务3G 第三代移动通信GUI 图形用户界面Gateway 网关Groupware 群件Groups 组Grounding Problems 接地问题Government OSI Profile 政府OSI框架文件Glue，Oracle Oracle的Glue解决方法Global Naming Services 全局命名服务Gateway－to－Gateway Protocol 网关对网关协议Gateway 网关，信关[H]HDF 层次型数据格式Hardware 硬件HTTP 超文本传输协议Hacker 黑客HTML超文本标记语言HUB 集线器HTTP 超文本传输协议HTML 超文本链接标示语言Hard Disk 硬盘Hubs Hub，集线器，集中器Hub Management Interface Hub管理接口Hot Fix，Novell NetWare Novell NetWare的热修复Host 主机Horizontal Wiring System 水平布线系统Hop 跳跃（计）数，过路数，中继数Homogeneous Network Environments 同构网络环境Home Directory 私人目录High－Speed Serial Interface 高速串行接口High－Speed Networking 高速联网高速网包括传输速度高于在1990年前占主导地位的传统传输速度的LAN和WHigh Performance Routing（HPR），IBM IBM 的高性能路由选择High Performance Parallel Interface 高性能并行接口High Performance File System 高性能文件系统High－Level Data Link Control 高级数据链路控制（规程）High Capacity Storage System（HCSS），Novell NetWare Novell NetWare的大容量存储系统High－bit－rate Digital Subscriber Line 高位速率数字用户专用线Heterogeneous Network Environments 异构网络环境Hermes，Microsoft Microsoft的企业网管理系统Handshaking 握手，联络，信号交换Half－Duplex Transmission 半双工传输[I]IMAP4信息访问协议4Insert Mode插入模式iPAQ Pocket PCIIS Internet信息服务器IB 智能大厦IrDA 红外线传输装置IIS 网络信息服务器IA 信息家电INF File 适配器安装信息文件Instructions Cache 指令缓存INF File 信息文件Internet backbone Internet骨干网Interface 界面Icon 图标Icon 图标Icon 图标Icon 图标Icon 图标IT 信息技术产业Internal Bus 内部总线IIS Internet信息服务器IT 信息技术IDE 集成驱动电子设备IP 网络协议IRC 互联网中转聊天ICP 互联网内容提供商ICP 互联网内容提供商Isohronous Service 等时服务IS－IS Interdomain Routing Protocol IS－IS 域间路由选择协议ISDN／B－ISDN 综合业务数字网／宽带综合业务数字网Iridium System 铱系统Interrupts 中断Interprocess Communication 进程间通信Interoperability 互操作性，互用性Internetwork Routing 网间路由选择Internetwork Packet Exchange 网间分组交换Internetworking 网络互联Internet Protocol Internet网络协议，因特网协议Internet Engineering Task Force Internet工程任务组Internet Internet网因特网[J]JPEG 联合图像专家组规范JSP网页控制技术Java编程语言Jukebox Optical Storage Device 自动换盘光盘存储设备Jabber 超时传输，Jabber传输[K]Key recovry 密钥恢复Knowbots Knowbots智能程序Key Encryption Technology 密钥加密技术Kernel 操作系统内核Kermit Kermit文件运输协议Kerberos Authentication Kerberos鉴别[L]LCD 液晶显示屏Light Cabel 光缆Leased line 专线LPT 打印终端LPT 打印终端接口LAN 局域网LU 6．2 LU 6．2协议Lotus Notes Lotus的Notes软件Logons and Logon Accounts 用户登录和登录帐号Login Scripts 登录原语Logical Units 逻辑单元Logical Links 逻辑链路LocalTalk LocalTalk网Local Procedure Calls 本地过程调用Local Loops 局部环路Local Groups 本地组Local Exchange Carrier 本地交换电信局Local Area Transport 局域传输协议Local Area NetWorks 局域网Local Access and Transport Area 本地访问和传输区域Load－Balancing Bridges 负载平衡桥接器，负载平衡网桥Link State Routing 链路状态路由选择Link Services Protocol，NetWare NetWare的链路服务协议Link Layer 链路层Link Access Procedure 链路访问规程Line Conditioning 线路调节Licensing Server API 许可证服务器API Legacy Systems 保留系统Leased Line 租用线路Learning Bridges 自学习桥接器Leaf Objects 叶对象Layered Architecture 分层体系结构Large Internetwork Packet Exchange 大型网间分组交换Laptop Connections 膝上机联网LAN Workplace Products，Novell Novell的LAN Workplace产品，Novell的局域网Workplace产品LAN Troubleshooting 局域网故障诊断LANtastic LANtastic局域网操作系统LAN Server 局域网服务器LAN Requester 局域网请求解释器LAN Manager，Microsoft Microsoft的局域网管理器，Microsoft的LAN Manager[M]Mosaic 摩塞克浏览器MO 磁性光盘Mac OS Mac操作系统MO 磁光盘MCSE 微软认证系统工程师MUD 分配角色的游戏环境Mainbus 系统总线Mainboard 主板MAN 城域网Memory Stick Memory Stick 存储棒MSI MSI 微星科技Multistation Access Unit 多站访问部件Multipurpose Internet Mail Extension Internet 多功能邮件传递扩展标准Multiprotocol Transport Network（MPTN），IBM IBM的多协议传输网络Multiprotocol Router 多协议路由器Multiprotocol Networks 多协议网络Multiprocessor Systems 多处理器系统Multiprocessing 多处理器处理Multiplexing 多路复用技术Multimedia 多媒体Multidrop（Multipoint）Connection 多点连接MOTIS（Message Oriented Text Interchange System）MOTIS（面向消息的文本交换系统）Motif Motif 工具Modems 调制解调器Mobile Computing 移动计算Mirroring 镜像Middleware 中间件Microwave Communication 微波通信Micro－to－Mainframe Connectivity 微型计算机到大型计算机的互联性Microsoft At Work Architecture Microsoft At Work体系结构Microsegmentation 微分段Microkernel 微内核Microcom Networking Protocol（MNP）Microcom的联网协议MicroChannel Architecture（MCA）Bus 微通道体系结构（MCA）总线Metropolitan Area Networks 城域网Messaging Application Programming Interface 消息应用程序编程接口Messaging API，Inter－Application 应用程序间的消息传递APIMessaging API，E－mail E－mail的消息传递APIMessage Transfer Agent 消息传送代理Message Queuing Interface（MAI），IBM IBM 的消息排队接口[N]NOC网络操作中心NAT网址解析NOC网络操作中心NAT 网址解析NDIS 网络驱动程序接口Network Architecture 网络体系结构NSR 渲染引擎NFS 网络文件系统NAT 网址转换NWLink IPX/SPX协议微软执行部分NetBIOS 网络基本输入/输出系统Network interface card 网卡NTFS（New Technology File System）NTFS （新技术文件系统）Novell Novell公司Node 节点，结点，网点Network Troubleshooting 网络故障诊断与维修Network Service Protocol，DEC DEC网络服务协议Networks 网络NetWork Management 网络管理Network Layer，OSI Model OSI模型的网络层Network Interface Card 网络接口卡Networking Blueprint 联网方案Network File System 网络文件系统Network Dynamic Data Exchange 网络动态数据交换Network Driver Standards 网络驱动程序标准Network Driver Interface Specification 网络驱动程序接口规范NetWork Control Program 网络控制程序Network Architecture 网络体系结构NetWare Volumes NetWare的（文件）卷宗NetWare Shell NetWare工作站外壳程序NetWare SFT Level ⅢNetWare的三级系统容错NetWare Products NetWare软件产品NetWare Loadable Module NetWare的可装入模块NetWare Link Service Protocol NetWare的链路服务协议NetWare Electronic Software Distribution NetWare的电子软件分发NetWare Disks，Partitions，and Volumes NetWare的磁盘、分区和卷宗NetWare Core Protocol NetWare的核心协议NetWare NetWare网络操作系统NetView，IBM IBM的NetView网络管理系统NetLS（Network License Server）NetLS（网络许可权服务器）[O]OEM原装备生产厂商OH调制解调器连线OSD 屏幕视控系统OAW 光学辅助温式技术OA 办公自动化Open Source 开放源代码OSF／1，Open Software Foundation 开放软件基金会OSF／1操作系统OS／2 OS／2操作系统Organization Containers 机构包容器对象Optical Libraries 光盘库，光盘存储库Optical Fiber 光纤Open View Management System，Hewlett－Packard HP的Open VieW管理系统Open Systems Interconnection（OSI）Model 开放式系统互联（OSI）模型Open Systems 开放式系统Open Software Foundation（OSF）开放软件基金会（OSF）Open Shortest Path First（OSPF）Protocol 优先开放最短路径（OSPF）协议Open Network Computing（ONC），SunSoft SunSoft的开放式网络计算环境Open Messaging Interface（OMI）开放消息传递接口Open Document Architecture 开放文档体系结构OpenDoc Alliance，Apple Apple的OpenDoc 联盟OPEN DECconnect Structured Wiring 开放DECconnect结构化布线系统OpenData－link Interface 开放数据链路接口Open Database Connectivity（ODBC），Microsoft Microsoft的开放式数据库互联性Open Collaborative Environment（OCE），Apple Apple的开放协作环境On－line Transaction Processing 联机（在线）事务处理Objects，NetWare Directory Services NetWare 目录服务中的对象Objects 对象，目标，实体Object Request Broker 对象请求代管者Object－Oriented echnology 面向对象技术Object－Oriented Interfaces and Operating Systems 面向对象接口和操作系统Object－Oriented Database 面向对象数据库Object Management Group 对象管理组织Object Management Architecture 对象管理体系结构Object Linkingand Embedding 对象链接与嵌入Object Broker，DEC DEC的对象代理者软件，DEC的Object Broker软件[P]Packetsniffer包嗅探器PHP4嵌入式脚本描述语言Push Technology推技术PVM并行虚拟机Path 路径、通路PKI 公开密钥基础设施Pull-down Menu 下拉菜单PAP 密码验证协议PnP 即插即用PCL 打印机指令语言PDS 个人数字系统PCI 周边元件扩展接口POP3 高级网络协议PHP 服务器端编程语言Plasma Display Plasma Display 等离子显示器Punchdown Block 穿孔板，分线盒Pulse－Code Modulation 脉码调制，脉冲代码调制Public Switched Data NetWork 公共交换数据网Public Key Cryptographic Systems 公开密钥加密系统Public Data NetWorks（PDNs）公用数据网（PDN）PU2．1 物理单元（PU）2．1Protocol Stack 协议栈Protocols，Communication 通信协议Protocol Data Unit 协议数据单元Protocol Converters 协议转换器Protocol Analyzers 协议分析器（程序）Protected of Data 数据的保护Protected Mode （受）保护模式Properties of Objects 对象的性质，对象的特性Propagation Delay 传播延迟Project DOE（Distributed Objects Everywhere）企业（工程）DOE（全分布式对象）Private Network 私用网，专用网Private Key Cryptography 私用密钥密码学Privacy Enhanced Mail增强安全的私人函件Print Server 打印服务器Printingon NetWare Networks NetWare网上打印（服务）Premises Distribution System 规整化布线系统Preemptive Multitasking 抢先多任务处理PowerPC PowerPC微处理里器系列PowerOpen Environment PowerOpen环境Q]Quadrature Amplitude Modulation 正交振幅调制，正交调幅[R]RDRAM高频DRAMRAID冗余独立磁盘阵列Registry 注册表RISC CPU 精简指令集CPURegistry 注册表RDRAM Rambus动态随机存取内存RSA Data Security RSA数据安全性RSA数据安全性Routing Protocols 路由选择协议Routing Information Protocol 路由选择信息协议Routing，OSI OSI的路由选择Routing，NetWare NetWare的路由选择Routing，Internet Internet路由选择Routing，IBM IBM路由选择Routing，AppleTalk AppleTalk路由选择AppleTalk路由选择Routers 路由器RJ－11and RJ－45 Connections RJ－11和RJ －45连接Ring Network Topology 环网拓扑结构环网拓扑结构Rights（Permissions）in Windows NT Windows NT权限（准许权限）Rightsin Windows for Workgroups Windows for Workgroups中的权限Rightsin Novell NetWare Novell NetWare中的权限RG－62 Coaxial Cable RG－62同轴电缆RG－58 Coaxial Cable RG－58同轴电缆Replication 复制Repeater 中继器，重复器Remote Procedure Call 远程过程调用Remote Access Software 远程访问软件Regional Bell Operating Companies（RBOC）地方贝尔运营公司Redundant Arrays of Inexpensive Disks （RAID）廉价磁盘冗余阵列Reduced Instruction Set Computer 精简指令系统（集）计算机Redirector 重定向器（程序）RAM Mobile Data RAM 移动数据公司[S]SSL安全套层SAA系统应用架构SMP 对称多处理结构SET 安全电子商务协议SNA 系统网络结构Subnet 子网SSL 安全套接层协议Server 服务器SMP 对称式多处理器Serial Interface 串行接口SOHO 小型办公与家庭办公Scanner 扫描仪Search Engine 搜索引擎Screen Saver 屏幕保护程序Socket 7 接口结构SONET 同步光纤网SMTP 简单邮件传送协议SCSI 小型计算机系统接口SGRAM 同步图形动态随机存取内存SDRAM 同步动态随机存取内存SystemView，IBM IBM的SystemView网络管理系统Systems Network Architecture（SNA），IBMIBM 系统网络体系结构Systems Application Architecture 系统应用体系结构System Object Model（SOM），IBM IBM的系统对象模型（SOM）System Fault Tolerance 系统容错Synchronous Optical Network 同步光纤网Synchronous Data Link Control 同步数据链路控制（规程）Synchronous Communication 同步通信Symmetrical Multiprocessing 对称多处理Switching Hubs 交换式集线器Switched Virtual Circuit 交换式虚电路Switched Services 交换式服务Switched Multimegabit Data Service 交换式多兆位数据服务Switched－56 Services Switched－56服务，交换式56服务Surge Suppressors 浪涌电压抑制器，电涌抑制器Supervisor 超级用户，监管员SunOS，SunSoft SunSoft的SunOS操作系统SunNet Manager，Sun Microsystems，Inc．Sun公司的SunNet ManagerSun Microsystems，Inc．Sun 微系统公司SunLink Network Sunlink网[T]TFT 有源矩阵彩色显示器TFTP 小文件传输协议Transport layer 传输层Taskbar 任务条Twisted－Pair Cable 双绞线，双绞线电缆Tuxedo，UNIX System Laboratories UNIX系统实验室的Tuxedo中间件Tunneling 管道传送，隧道，管道传输Trustees 受托者Troubleshooting 故障诊断与维修，排错Trivial File Transfer Protocol 普通文件运输协议Transport Protocol 传输协议Transport Layer Interface 运输层接口Transport Layer，OSI Model OSI模型的运输层Transmission Media，Methods，and Equipment 传输介质、方法和设备Transmission Control Protocol／Internet Protocol 传输控制协议／Internet协议Transfer Rates 传输率Transceiver，Ethernet 以太网收发器，以太网的接收发送器Transaction Processing 事务处理Topology 拓扑结构Token Ring NetWork 令牌环网Token Bus NetWork 令牌总线网Token and Token Passing Access Methods 令牌和令牌传递访问方式Time Synchronization Services 时间同步服务Time Domain Reflectometer 时域反射计（仪，器）Throughput 吞吐率，处理能力Threads 线程Testing Equipment and Techniques 测试设备和技术Terminator 终端器，终结器，终止器Terminal Servers 终端服务器Terminal 终端Telnet Telnet程序Telenet Telenet网Telecommunication 电信，远程通信Technical Office Protocol 技术办公系统协议TeamLinks，DEC DEC的群件TeamLinks Taligent Taligent公司T1／T3 Services T1／T3服务[U]UDA统一数据读取UML 统一建模语言UTP 无屏蔽双绞线URL 统一资源定位格式UPS 不间断电源Ultra DMA 33 同步DMA协定UNIX 32位操作系统UNIX 操作系统USB 通用串行总线Users and Groups 用户和（小）组User Datagram Protocol 用户数据报协议User Agent 用户代理USENET USENET网Unshielded Twisted Pair 非屏蔽双绞线UNIX－to－UNIX Copy Program UNIX系统间文件拷贝程序UNIX System Laboratories UNIX系统实验室UNIX International UNIX国际UNIX UNIX操作系统Unit of Work 作业单元，工作单元Uninterruptible Power Supply 不间断电源Unified Network Management Architecture （UNMA），AT＆T AT＆T的统一网络管理体系结构[V]Virtual Desktop虚拟桌面VoxML语音标记语言Video Compression 视频压缩Virtual reality 虚拟现实VOD 视频传播系统VESA 视频电子标准协会VRML 虚拟现实建模语言VESA 视频电子标准Volume Spanning 卷宗的跨越Volumes，NetWare NetWare的卷宗Virtual Terminal（VT）虚拟终端Virtual Telecommunication Access Method 虚拟远程通信访问方法Virtually Integrated Technical Architecture Lifecycle 虚拟集成技术体系结构生命周期Virtual File Systems 虚拟文件系统Virtual Data Networks 虚拟数据网Virtual Circuit 虚电路VINES，Banyan Banyan的VINES操作系统Videoconferencing and Desktop Video 电视会议和台式（桌面）视频系统Very Small Aperture Terminals（VSATs）卫星小站电路设备Vertical Wiring 垂直布线系统Vendor Independent Messaging （VIM），Lotus Lotus 的厂商无关消息传递应用程序编程接口“V dot”Standards，CCITT CCITT（ITU）的“V点”标准VAX，Digital Equipment Corporation（DEC）数字设备公司（DEC）的VAXValue－Added Carrier 增值网[W]WINS IP解析WYSIWYG 所见即所得WEB VOD WEB视频点播Wizard 向导Wavetable 波表合成Windows CE 操作系统WAP 无线应用协议Workstation 工作站Workplace OS Workplace操作系统Workgroups 工作组，（用户）组Workflow Software 工作流软件Wiring 布线Wireless Mobile Communication 无线移动通信Wireless LAN Communication 无线局域网通信Windows Telephony Application Interface Windows 电话应用程序接口Windows Sockets API Windows套节字（嵌套字）APIWindows Open System Architecture（WOSA）Windows开放式系统体系结构（WOSA）Windows NT Advanced Server，Microsoft Microsoft的Windows NT高级服务器操作系统Windows NT，Microsoft Microsoft的Windows NT操作系统Windows for Workgroups，Microsoft Microsoft的Windows for Workgroups操作系统Wide Area Networks 广域网WHOIS（“Who Is”）WHOIS数据库[X]XUL扩展用户接口语言XON/XOFF异步通信协议X2/DSL调制解调器XSLT XSL变换描述XUL 扩展用户接口语言XQL XML查询语言XML 扩展标签语言X Window X窗口，X Windows图形用户接口X／Open X／Open公司，X／Open国际联盟有限公司XMODEM Protocol XMODEM协议Xerox Network System Xerox网络系统X．500 Directory Services X．500目录服务X．400 Message Handling System X．400消息处理系统X．25 X．25 协议[Y]Ymodem Ymodem协议[Z]Zmodem Zmodem协议Zip Drive Zip驱动器ZIP 压缩文件格式Zone Multicast Address，AppleTalk AppleTalk的区广播地址Zone Information Table（ZIT），AppleTalk AppleTalk 的区信息表Zone Information Protocol（ZIP），AppleTalkAppleTalk的区信息协议Zone，AppleTalk AppleTalk 的区，AppleTalk 的域ZMODEM Protocol ZMODEM 协议。
网络工程师常用英文单词和缩写翻译
ARPARNET(Internet) ：阿帕网ICCC ：国际计算机通信会议CCITT ：国际电报电话咨询委员会SNA ：系统网络体系结构(IBM)DNA ：数字网络体系结构(DEC)CSMA/CD ：载波监听多路访问/冲突检测(Xerox) NGI ：下一代INTERNETInternet2 ：第二代INTERNETTCP/IP SNA SPX/IPX AppleTalk ：网络协议NII ：国家信息基础设施(信息高速公路)GII ：全球信息基础设施MIPS ：PC的处理能力Petabit ：10^15BIT/SCu芯片: ：铜OC48 ：光缆通信SDH ：同步数字复用WDH ：波分复用ADSL ：不对称数字用户服务线HFE/HFC：结构和Cable-modem 机顶盒PCS ：便携式智能终端CODEC ：编码解码器ASK(amplitude shift keying) ：幅移键控法FSK(frequency shift keying) ：频移键控法PSK(phase shift keying) ：相移键控法NRZ (Non return to zero) ：不归零制PCM(pulse code modulation) ：脉冲代码调制nonlinear encoding ：非线性编程FDM ：频分多路复用TDM ：时分多路复用STDM ：统计时分多路复用DS0 ：64kb/sDS1 ：24DS0DS1C ：48DS0DS2 ：96DS0DS3 ：762DS0DS4 ：4032DS0CSU(channel service unit) ：信道服务部件SONET/SDH ：同步光纤网络接口LRC ：纵向冗余校验CRC ：循环冗余校验ARQ ：自动重发请求ACK ：确认NAK ：不确认preamble ：前文postamble ：后文ITU ：国际电信联合会character-oriented ：面向字符bit-oriented ：面向位SYNC ：同步字符HDLC ：面向位的方案SDLC ：面向位的方案bit-stuffing ：位插入STP ：屏蔽双绞线UTP ：非屏蔽双绞线RG-58A/U ：标准RG-11 ：用于10BASE5RG-59U ：75欧0.25INCH CATVRG-62U ：9欧0.25INCH ARCnet10BASE5 ：IEEE802.3RG-59U ：0.25inch CATVRG-62U ：0.25inch ARCnetLED(light emitting diobe) ：发光二级管ILD(injection laster diobe) ：注入型激光二级管PIN ：检波器APD ：检波器intensity modulation ：亮度调制line of sight ：可视通路CCITT V.28(EIA RS232C) ：非平衡型CCITT V.10/X.26(EIA RS423A) ：新的非平衡型CCITT V.11/X.27(EIA RS422A) ：新的平衡型TD ：发送数据RD ：接收数据XON/XOFF ：流控制Automatic Repeat Request Protocol ：自动重发请求Send and wait ARQ:continuous ：ARQ停等ARQ Ward Christensen ：人名Kermit ：协议circuit switching ：线路交换packet switching ：分组交换virtual circuit ：虚电路ATM(asynchronous transfer mode) ：异步传输模式ATDM ：异步时分多路复用packetizer ：打包器VPI(vritual path identifier) ：虚路径标识VCI(virtual channel identifier) ：虚通道标识syntax ：语法semantics ：语义timing ：定时OSI(open system interconnection) ：开放系统session ：会话synchronization ：同步activity management ：活动管理AE ：应用实体UE ：用户元素CASE ：公共应用服务元素SASE ：特定应用服务元素VT ：虚拟终端JIM ：作业传送和操作reverved ：保留echo ：回送discard ：丢弃active users ：活动用户daytime ：白天netstat(who is up of NETSTAT)qotd(quote of the day)日期引用chargen(character generator)字符发送器nameserver(domani name server)域名服务器bootps(bootstrap protocol server/client)引导协议服务器/客户机tftp(trivial file transfer)简单文件传送sunrpc(sun microsystems RPC)SUN公司NTP:network time protocol网络时间协议SNMP(SNMP net monitor)SNMP网络监控器SNMP traps陷井biffunix comsatdaemone.g timed daemonsyslogsystem logURG紧急字段可用ACK确认字段可用请求急迫操作RST连接复位SYN同步序号FIN发送方字节流结束Manchester曼彻斯特编码FDDI(fiber distributed data interface)光纤分布数据接口TTRT目标标记循环时间aggregation of multiple link segments多重链接分段聚合协议MAN(metropolitan area network plus)城域网CSMA/CD(carrier sense multiple access/collision detection) 载波监听Token bus令牌总线Token ring令牌环SAP服务访问点request indictaion response confirmationLLC PDULLC协议数据单元DSAP address目地服务访问点地址字段SSAP address源服务访问点地址字段XID交换标识SABME置扩充的异步平衡方式DISC断开连接DM断开FRMR帧拒收solt timeAUI连接单元接口MAU介质连接接口MDI介质相关接口PMA物理介质接口SFD起始定界符PAD填充字段FCS帧校验序列PLS物理层收发信号slot time时间Inter Frame Gap 帧attempt limit最大重传次数back off limit避免算法参数Jam size阻塞参数max frame size最大帧address size地址collaspsed backone 折叠式主干网BSS基本服务集ESS扩展服务集DFW-MAC分布式基础无线MAC IFS帧间空隙SIFS:短PIFSDIFS分布协调CTS发送清除DQDB(IEEE802.6)分布式队列双总线TDM时分复用TMS多时分交换TSI时间片互换TST网络机构TSSST STS SSTSS TSTST网络机构PSTN公用交换电话网public switched telephone network详细PBX:private branch exchange专用交换网PABX;private automatic branch exchange自动交换机CBX:computerized branch exchange程控交换SLIP:serial line IP串行IPLCP(link control protocol)链路控制协议NCP:network control protocol网络控制协议BRI基本速率接口PRI群速率接口LAPB:line access protocol balanced链路访问协议平衡registration登录interrupt中断LAP F link access procedure for frame-mode bearer serivesrotate不知道recovery恢复discard丢弃retransmission重传switched access交换访问intergated access集成访问alerting警告progress进展AALATM适配层GFC总流控cell rate decoupling信元率去耦SDH同步数字级PDH准国步数字级GSM:group special mobile移动通讯NSS网络子系统OMC-R操作维护中心BSS基站子系统BSC基站控制器BTS基站收发信机MS移动站SIM:subscriber identity module 标识模块MSCHLR归属位置寄存器VLR访问位置寄存器AUC鉴权中心EIR设备识别寄存器OMC-S操作维护中心SC短消息中心WAP无线应用协议WAE无线应用层WSP会话层WTP事务层WTLS安全层WDP传输层MAP移动应用部分WML无线标记语言SSL:secure sockets layer安全套接层PCS个人通信业务PCN个人通信网GEO对地静止轨道NON-GE0(MEO,LEO)不清楚ITU国际电信联盟VSAT:very small aperture -terminal 甚小天线终端LEOS低轨道卫星通信系统中继器bridge网桥router路由器gateway网关ONsemble stackable 10BASE可叠加组合型集线器transparent bridge传输桥source routing bridge源路径桥broadcast storm广播风暴encapsulation封装translation bridging转换桥接方式SRT源地址选择透明桥offset偏移more flag标识ICMPINTERNET控制报文协议SPF:shortest path first最短路径IGP:interior gateway protocol核心网关协议EGP:exterior gateway protocol 扩展网关协议RIP:routing information protocol 路由信息协议OSPF开放最短径优先协议acquisition request获取请求acquisition confirm获取确认cease中止poll轮询IPX/SPX internetwork packet exchange/sequented packet exchange NOVELLinterpreter解释器redirector重定向器SFT system fault tolerant系统容错ELS entry level solution不认识ODI开放数据链路接口NDIS network device interface specification网络设备接口...DDCS数据库管理和分布数据库连接服务DCE:distributed computing environment分布计算环境OSF:open software foundation开放软件基金PWS:peer web serviceWEB服务器OEM原始设备制造商RAS远程访问服务IIS:Internet Information serverINTERNET信息服务WINS:windows internet name systemWINDOWS命名服务NTDS:windows NT directory serverNT目录服务TDI传输驱动程序接口schedule++应用程序,预约本COSE:common open software environment普通开放软件环境RPC远程过程调用SNMP:simple network management protocol简单网管协议SMI:structer of management information管理信息结构SMT:station management管理站SMTP:simple mail transfer protocol简单邮件传输协议SNA:system network architectureIBM网络SNR:signal noise ratio信噪比SONENT:synchronous optical network同步光纤网络SPE:synchronous payload envelope同步PAYLOAD信CMIS/CMIP公共管理信息服务/协议CMISE公共管理信息服务agent代理IMT:inductive modeling technology不知道plaintext明文ciphertext脱密encryption加密decryption解密symmetric key cryptography对称加密asymmetric key cryptography不对称加密public key公钥private key私钥DES:data encryption standard数据加密标准IDEA:international data encryption algorithm 国际加密算法PIN:personal identification number个人标识符session key会话层密钥KDC:key distribuetion center密钥分发中心sign签名seal封装certificate证书certificate authority CA证书权威机构OSF开放软件中心AFS:andrew file system分布式文件系统ticket凭证authenticatior身份认证timestamp时间标记reply attack检测重放攻击realm域PKI公钥基础设施certificate hierarchy证书层次结构across certificate交叉证书security domain安全领域cerfificate revoke list(CRL)证书层次结构LDAP:light weight directory access protocol 协议access matrix访问矩阵ACL:access control list访问列表reference monitor引用监控器course grained粗粒度访问控制medium grained中粒度访问控制fine grained细粒度访问控制CORBA面向对象的分布系统应用MQ报文队列VPN虚拟专网IPSEC:IP security安全IPSA:security association安全??encopulation security payload封装安全负载AH:authentication header鉴别报头IKE:Internet key exchange交换rogue programs捣乱程序IPSP:IP security protocol安全IKMP:internet key managemetn protocol 协议IESGInternet工程领导小组SHA安全散列算法MAC:message authentication code代码CBC密码块链接SSL安全套接层协议cerfificate verify证书检验报文PEM私用强化邮件PGP:pretty good privacy好的private保密authenticated已认证SEPP安全电子付费协议SET安全电子交易middleware中间件GSS-API通用安全服务SNP安全网络编程BWD:browser web database浏览WEBplugin插入件basic authentication scheme不知道digest authentication scheme摘要认证方法open group:the open group research institute研究所DCE:distributed computing environment分布式计算机环境SLP:secure local proxy安全局部代理SDG:secure domain proxy安全域代理OMG:object management group目标管理组CORBS:common object request broker architecture 不清楚authentication鉴别access control访问控制data confidnetiality保密data integrity数据完整性non-reputation防止否认enciphermant加密机制digital signature mechanisms数据完整性authentication mechanisms路由控制机制notarization mechanisms公证trusted function可信security labels安全标记event dectection事件检测security audit trail安全审计跟踪security recovery安全恢复TCSEC:trusted computer system evaluation criteria标准TCSEC TNI:trusted network interpretation of the TCSEC 标准TCSEC TDI:trusted database interpretation of the TCSEC 标准ITSEC:information technology security evaluation标准CC:command criteria for IT security evaluation安全classified criteria for secruity protection中国安全of computer information system中国安全GB17859-1999国标TCB:trusted computing baseSNMP:simple network management protocol网管ICMP:internet control message protocol互联网控制信息协议ARP:address resolution protocol地址解析协议TCP:transmission control protocol传输控制协议UDP:user datagram protocol用户数据报协议SMTP:simple mail transfer protocol简单邮件传输DNS:domain name service服务器NSP:name service protocol服务器TElnet:telcommunication networkTELEGP:exterior gateway protocol外部网关连接器协议IGP:inter gateway protocol内部网关连接器协议SLIP串行接口协议PPP点对点协议UNICAST单播地址cluster群集地址multicast组播地址scable model可伸缩模型integrated model集成模型OLAP联机分析工具NAS:network applications supportDEC公司的工具NWC:newwave computingHP工具OCCA:open cooperative computing architecture 开放合作计算体系结构DAA:distributed application architectureDG的分布应用体系结构COSE:common opensystem enviroment通用开放系统环境CDE:common desktop enviroment通用桌面环境DCE分布式计算环境RPC远程过程调用DME分布管理环境OSE/APP开放系统环境应用可移植框架ODA开放文件体系结构ODL开放文件语言。
计算机网络中英文对照外文翻译文献
中英文资料外文翻译计算机网络计算机网络，通常简单的被称作是一种网络，是一家集电脑和设备为一体的沟通渠道，便于用户之间的沟通交流和资源共享。
网络可以根据其多种特点来分类。
计算机网络允许资源和信息在互联设备中共享。
一．历史早期的计算机网络通信始于20世纪50年代末，包括军事雷达系统、半自动地面防空系统及其相关的商业航空订票系统、半自动商业研究环境。
1957年俄罗斯向太空发射人造卫星。
十八个月后，美国开始设立高级研究计划局(ARPA)并第一次发射人造卫星。
然后用阿帕网上的另外一台计算机分享了这个信息。
这一切的负责者是美国博士莱德里尔克。
阿帕网于来于自印度，1969年印度将其名字改为因特网。
上世纪60年代，高级研究计划局(ARPA)开始为美国国防部资助并设计高级研究计划局网(阿帕网)。
因特网的发展始于1969年，20世纪60年代起开始在此基础上设计开发，由此，阿帕网演变成现代互联网。
二．目的计算机网络可以被用于各种用途:为通信提供便利:使用网络，人们很容易通过电子邮件、即时信息、聊天室、电话、视频电话和视频会议来进行沟通和交流。
共享硬件:在网络环境下，每台计算机可以获取和使用网络硬件资源，例如打印一份文件可以通过网络打印机。
共享文件：数据和信息: 在网络环境中，授权用户可以访问存储在其他计算机上的网络数据和信息。
提供进入数据和信息共享存储设备的能力是许多网络的一个重要特征。
共享软件:用户可以连接到远程计算机的网络应用程序。
信息保存。
安全保证。
三．网络分类下面的列表显示用于网络分类：3．1连接方式计算机网络可以据硬件和软件技术分为用来连接个人设备的网络，如：光纤、局域网、无线局域网、家用网络设备、电缆通讯和G.hn（有线家庭网络标准）等等。
以太网的定义，它是由IEEE 802标准，并利用各种媒介，使设备之间进行通信的网络。
经常部署的设备包括网络集线器、交换机、网桥、路由器。
无线局域网技术是使用无线设备进行连接的。
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外文原文：COMPUTER NETWORKSDATE COMMUNICATIONSOne of the functions of the host computer is to store the applications programs for the various secondaries.The end equipment which either generates the digital information for transmission or uses the received digital data can be computer ,printers ,keyboards, CRTs, and so on. This equipment generally manipulates digital information internally in word units—all the bits that make up a word in a particular piece of equipment are transferred in parallel. Digital data, when transmitted, are in serial form. Parallel transmission of an 8-bit word require eight pairs of transmission lines—not at all cost-effective. Data terminal (DTE) is a general phrase encompassing all of the circuitry necessary to perform parallel-to-serial and serial-to-parallel conversions for transmission and reception respectively and for data link management. The UART (Universal Asynchronous Receiver/Transmitter) and USART (Universal Asynchronous/Asynchronous Receiver/Transmitter) are the devices that perform the parallel-to-serial and serial-to-parallel conversions. The primary DTE includes a line control unit (LCU or LinCo) which controls the flow of information in a multipoint data link system. A station controller (STACO) is the corresponding that belonged to the subscriber in a data link system. Between the DTEs, starting with the modems, was communications equipment owned and maintained by Telco property.Data communications equipment (DCE) accepts the serial data stream from the DTE and converts it to some form of analog signal suitable for transmission on voice-grade lined. At the receive end, the DCE performs the reverse function of converting the received analog signal to a serial digital data stream. The simplest form of DCE is a modem (modulator/demodulator) or data set. At the transmit end, the modem can be considered a form of digital-to-analog converter, while at the receive end, it can considered a form of analog-to-digital converter. The most common of modulation by modems are frequency shift keying (FSK), phase shift keying (PSK), and quadrature amplitude modulation (QAM). This is a typically data transmission mode using the analog telephone lines. If you transmit data bydigital channel (sometimes it is called “Digital T-carrier”), a pulse Code Modulation (PCM) equipment must be used. A microwave transmission system can also be used for the data communication. Finally, you can use the satellite communication system for data transmission.If the cables and signal levels used to interconnect the DTE and DCE were left unregulated, the variations generated would probably be proportional to the number of manufacturers. Electronics industries Association (EIA) , an organization of manufactures with establishing the DTE and modem. This is a 25-pincable whose pins have designated functions and specified signal levels. The RS-232C is anticipated to be replaced by an update standard.ARCHITECTURE OF COMPUTER NETWORKSComputer network is a complex consisting of two or more conned computing units, it is used for the purpose of data communication and resource resource sharing. Design of a network and its logical structure should comply with a set of design principles, including the organization of functions and the description of data formats and procedure. This is the network architecture and so called as a set of layers and protocols, because the architecture is a layer-based.In the next two sections we will discuss two important network architectures, the OSI reference model and the TCP/IP reference model.1.The OSI Reference ModelThe OSI model is shown in Fig.14-2(minus the physical medium). This model is based on a proposal developed by the International Standards Organizations (OSI) as the first step toward international standardization of the protocols used in the various layers. The model is called the ISO OSI (Open System Interconnection) Reference Model because it deals with connecting open systems--that is, systems that are open for communication with other systems, We will usually just call it the OSI model for short.The OSI model has seven has seven layers. Note that the OSI model itself is not a network architecture because it does not specify the exact services and protocols to be used in each layer. It just tells what each layer should do. However , However, ISO has also produced standards for all the layers, although these are not part of the reference model itself. Each one has been published as a separate international standard.2.The TCP/IP Reference ModelThe TCP/IP reference model is an early transport protocol which was designed by the US Department of Defence (DOD) around in 1978. It is often claimed that it gave rise the OSI “connectionless”mode of operation. TCP/IP is still used extensively and is called as a industrial standard of internet work in fact, TCP/IP has two parts: TCP and IP. TCP means it is on the transport layer and IP means it is on the network layer separately.(1)There are two end-to-end protocols in the transport layer, one of which is TCP(Transmission Control Protocol) , another is UDP (User Datagram Protocol).TCP is a connection-oriented protocol that allows a byte stream originating onone machine to be delivered without error on any other machine in the internet.UDP is an unreliable, connectionless protocol for application that do not wantTCP’s sequencing of flows control flow control and wish to provide their own.(2)The network layer defines an official packet format and protocol called IP(Internet protocol). The job of the network layer is to deliver IP packets wherethey are supposed to go.The TCP/IP Reference Model is shown in Fig.14.3. On top of the transport layer is the application layer, It contains all the higher-level protocols. The early ones included virtual terminal (TELNET), (FTP), electronic mail (SMTP) and domain name service(DNS).WIDE AREA NETWORKA wide area network, or WAN, spans a large geographical area, often a country or continent . It contains a collection of machines intended for running user (i. e. , application) programs. We will follow traditional usage and call these machines hosts. By a communication subnet, or just subnet for short. The job of the subnet is to carry messages from host to host, just as the telephone system carries words from speaker to listener. By separating the pure communication aspects of the network (the subnet) from the application aspects (the hosts), the complete network design is greatly simplified. Relation between hosts and the subnet is shown in Fig.14-4.One of many methods that can be used to categorize wide area networks is with respect to the flow of information on a transmission facility. If we use this method to categorize wide area networks, we can group them into three basic types: circuit switched, leased line and packet switched.1.CIRCUIT SWITCHED NETWORKSThe most popular type of network and the one almost all readers use on a daily basis is a circuit switched network. The public switched telephone network, however, is not limited to the telephone company, By purchasing appropriate switching equipment, any organization can construct their own internal circuit switched network and, if desired, provide one or more interfaces to the public switched network to allow voice and data transmission to flow between the public network and their private internal network2．LEASED LINE NETWORKSThis is a dedicated network connected by leased lines. Leased line is a communications line reserved for the exclusive use of a leasing customer without inter-exchange switching arrangements. Leased or private lines are dedicated to the user. This advantage is that the terminal or computer is a always physically connected to the line. Very short response times are met with service.3.PACKET SWITCHING NETWORKSA packet network is constructed through the use of equipment that assembles and disassembles packets, equipment that routes packet, and transmission facilities used to route packets from the originator to the destination device. Some types of data terminal equipment (DTE) can create their own packets, while other types of DTE require the conversion of their protocol into packets through the use of a packet assembler / disassemble (PAD). Packets are routed through the network by packet switches. Packet switches examine the destination of packets as they flow through the network and transfer the packets onto trunks interconnecting switches based upon the packet destination destination and network activity.Many older pubic networks follow a standard called X.25. It was developed during 1970s by CCITT to provide an interface between public packet-switched network and their customers.CCITT Recommendation X.25 controls the access from a packet mode DTE, such as aterminal device or computer system capable of forming packets, to the DCE at a packet mode. CCITT Recommendation X.28 controls the interface between non-packet mode devices that cannot interface between the PAD and the host computer. CCITT Recommendation X.3 specifies the parameter settings on the PAD and X.75 specifies the interface between packet network.LOCAL AREA NETWORKLocal area data network , normally referred to simply as local area network or LANs, are used to interconnect distributed communities of computer-based DTEs located within a building or localized group of building. For example, a LAN may be used to interconnect workstations distributed around offices within a single building or a group of buildings such as a university campus. Alternatively, it may be complex. Since all the equipment is located within a single establishment, however, LANs are normally installed and maintained by the organization. Hence they are also referred to as private data networks.The main difference between a communication path established using a LAN and a connection made through a public data network is that a LAN normally offers much higher date transmission rates because of the relatively short physical separations involved. In the context of the ISO Reference Model for OSI, however, this difference manifests itself only at the lower network dependent layers. In many instances the higher protocol layers in the reference model are the same for both types of network.Before describing the structure and operation of the different types of LAN, it is perhaps helpful to first identify some of the selection issues that must be considered. It should be stressed that this is only a summary; there are also many possible links between the tips of the branches associated with the figure.1.TopologyMost wide area networks, such as the PSTN, use a mesh (sometimes referred to as a network) topology. With LANs, however, the limited physical separation of the subscriber DTEs allows simpler topologies to be used. The four topologies in common use are star, bus ,ring and hub.The most widespread topology for LANs designed to function as data communication subnetworks for the interconnection of local computer-based equipment is the hub topology, which is a variation a variation of the bus and ring. Sometimes it is called hub/tree topology.2. Transmission mediaTwisted pair, coaxial cable and optical fiber are the three main type of transmission medium used for LANs.3. Medium access control methodsTwo techniques have been adopted for use of the medium access control in the LANs. They are carrier-sense-multiple-access with collision detection (CSMA/CD), for bus network topologies, and control token, for use with either bus or ring networks.CSMA/CD is used to control multiple-access networks. Each on the network “listens”before attempting to send a message, waiting for the “traffic” to clear. If two stations try to sent their messages at exactly the same time, a “collision” is detected, and both stations are required to “step back” and try later.Control token is another way of controlling access to a shared transmission medium that is by the use of a control (permission) token. This token is passed form one DTE to another according to a defined set of rules understood and adhered to by all DTEs connected to the medium. ADTE may only transmit a frame when it is in possession of the token and, after it has transmitted the frame, it passed the token on to allow another DTE to access the transmission medium.中文译文：计算机网络14.1 数据通信图14-1是数据通信链路的简化框图。