1、中英文資料外文翻譯文獻計算機網絡計算機網絡，通常簡單的被稱作是一種網絡，是一家集電腦和設備為一體的溝通渠道，便于用戶之間的溝通交流和資源共享。網絡可以根據其多種特點來分類。計算機網絡允許資源和信息在互聯設備中共享。目錄1歷史2目的3網絡分類3.1 連接方式3.2 有線技術3.3 無線技術3.4 規模3.5 功能關系(網絡體系結構)3.6 網絡拓撲結構4. 基于物理范圍的各種類型的網絡4.1 局域網4.1.1 個人區域網4.1.2 家中大面積網絡4.2 廣闊的地區網絡4.2.1 校園網絡4.3 大都會區域網4.3.1 企業專用的網絡4.3.2 虛擬專用網絡4.3.3 網際網絡4.4 骨干網4.4

2、.1 全球區域網4.4.2 互聯網44.3 內部網和外部網4.4.4 覆蓋網絡5參考文獻一歷史早期的計算機網絡通信始于20世紀50年代末，包括軍事雷達系統、半自動地面防空系統及其相關的商業航空訂票系統、半自動商業研究環境。1957年俄羅斯向太空發射人造衛星。十八個月后，美國開始設立高級研究計劃局(ARPA)并第一次發射人造衛星。然后用阿帕網上的另外一臺計算機分享了這個信息。這一切的負責者是美國博士萊德里爾克。阿帕網于來于自印度，1969年印度將其名字改為因特網。上世紀60年代，高級研究計劃局(ARPA)開始為美國國防部資助并設計高級研究計劃局網(阿帕網)。因特網的發展始于1969年，20世紀6

3、0年代起開始在此基礎上設計開發，由此，阿帕網演變成現代互聯網。二目的計算機網絡可以被用于各種用途:為通信提供便利:使用網絡，人們很容易通過電子郵件、即時信息、聊天室、電話、視頻電話和視頻會議來進行溝通和交流。共享硬件:在網絡環境下，每臺計算機可以獲取和使用網絡硬件資源，例如打印一份文件可以通過網絡打印機。共享文件：數據和信息: 在網絡環境中，授權用戶可以訪問存儲在其他計算機上的網絡數據和信息。提供進入數據和信息共享存儲設備的能力是許多網絡的一個重要特征。共享軟件:用戶可以連接到遠程計算機的網絡應用程序。信息保存。安全保證。三網絡分類下面的列表顯示用于網絡分類：31連接方式計算機網絡可以據硬件和

4、軟件技術分為用來連接個人設備的網絡，如：光纖、局域網、無線局域網、家用網絡設備、電纜通訊和G.hn（有線家庭網絡標準）等等。以太網的定義，它是由IEEE 802標準，并利用各種媒介，使設備之間進行通信的網絡。經常部署的設備包括網絡集線器、交換機、網橋、路由器。無線局域網技術是使用無線設備進行連接的。這些設備使用無線電波或紅外信號作為一種傳輸媒介。ITU-T（電信標準部門）的G.hn技術使用現有的家庭布線（同軸電纜，電話線和電源線）創建一個高速（可達1Gb/S）局域網。3.2有線技術雙絞線是目前應用最廣泛的通訊媒介。它由銅線扭曲配對而成。普通電話線由兩個絕緣銅導線配對扭成。計算機網絡布線由四對銅

5、電纜構成，可以進行語音結構和數據傳輸。使用雙絞線電纜可以減少交調失真，電磁感應。它的傳輸速度的范圍很廣，從200萬b/s至1億b/s。雙絞線電纜有兩種類型非屏蔽雙絞線(UTP)和屏蔽雙絞線(STP)，它們被用在不同的場合。同軸電纜廣泛用于有線電視系統、寫字樓、和其他工作區域的局域網。該電纜通常由銅或鋁合金絲用帶有高介電常數的靈活性材料絕的緣層包裹，所有這一切都被導電層環繞。絕緣層幫助減少干擾和變形。傳播速度的范圍從2億b/s到超過5億多b/ s。光纖，是由一個或多個細絲狀的玻璃纖維包裹在保護層中。光纖不受電磁輻射。它透過光線延續的傳播速度可以達到上萬億b/s。光纖的傳輸速度比同軸電纜的傳輸速度

6、快幾百倍，比雙絞線的速度快上千倍。3.3無線技術地面微波使用地面上的微波發射器和接收器。設備看起來像衛星接受器。地面微波使用的是頻率在千兆赫范圍以內的波，這限制了所有通信線路出現在我們的視線中。中繼站之間的距離大約為30英里。微波天線通常放在建筑物的頂上，例如：塔、丘陵或者山峰的峰頂。通信衛星衛星廣播使用微波通信，而微波傳輸不會因地球大氣層而產生偏轉。衛星安置在太空中，一般在赤道上22000英里(對于同步衛星來說)的高空。這些繞地衛星系統能接收和轉播語音、數據、電視信號。蜂窩技術和個人通信服務系統，使用幾種無線電通訊技術。這類系統被分布到不同的地理區域。每個區域都有低功率發射器或無線電中繼天線

7、裝置來把電話通信從一個地區傳遞到下一個地區。無線LAN,即無線局域網使用高頻無線電技術，類似數字蜂窩和低頻無線電技術。無線局域網使用擴頻技術來實現有限區域內多個設備之間的通信。一個開放式標準的無線電波技術的例子就是IEEE。紅外通信，它能在設備之間進行短距離的不超過10米的點對點(面對面)的信號傳輸，傳輸線路之間不能有障礙。3.4規模網絡通常分為局域網(LAN)、廣域網(WAN)、城域網(MAN)、個人區域網絡(PAN)、虛擬專用網(VPN)、校園局域網(CAN)、存儲區域網絡(SAN)。而其它一些國家，則根據其規模、范圍和目的分類。例如，控制器局域網(CAN)的使用，信任水平和進入權利之間同

8、這些類型的網絡大有不同。局域網往往是專為內部使用的一種組織內部系統和員工個人物理位置的網絡，比如建筑，而廣域網路可以連接物理上獨立的部分，而且可能包括連接一個組織給第三方。3.5功能關系(網絡體系結構)計算機網絡的功能關系可以根據元素中存在的網絡進行分類。如，主動網絡、客戶端服務器、無線自組網絡和點對點(工作組)建筑。3.6網絡拓撲結構計算機網絡分類是根據網絡拓撲結構建立的，如總線網絡，星型網絡，環網，網格。網絡拓撲的協調基于他們在網絡設備上邏輯關系的排列，彼此獨立于物理的安排。即使網絡計算機放置在一個線性安排和被連接到一個集線器，網絡仍是星型拓樸結構，而不是總線網的結構。一個網絡在這方面的視

9、覺和操作特性是不同的。網絡可以基于數據分類的方法以用于傳遞數據，包括數字和模擬網絡。4.基于物理范圍的各種類型的網絡常見的可以確定其規模的計算機網絡類型。4.1局域網局域網(LAN)是一個連接在有限地區的電腦網絡或設備。如家庭、學校、計算機實驗室、辦公樓、或接近的建筑物。每臺計算機或設備，對網絡是一個節點。新的標準ITU-T G.hn也提供一種方法即使用現有的家庭電線（同軸電纜，電話線和電源線）來創建一個有線局域網。 典型的圖書館網絡，在一個分支樹拓撲結構和控制對資源的訪問所有相互關聯的設備必須了解網絡層(第三層)，因為他們要處理多個子網(不同的顏色)的。圖書館里面只有10/100 Mbit

10、/ s的以太網連接到用戶設備和千兆以太網連接到中央路由器，可以稱為“第3層交換機”，因為他們只有從以太網接口才能了解IP。這將是更正確的稱呼他們的接入路由器，在頂部的路由器是一個通訊路由器，它是學生連接到互聯網和學院網絡的接入路由器。局域網的界定特征，和廣域網絡(廣域網的關系)相比較而言，局域網有更高的數據轉移率、小地理范圍,并且不需要租賃電信線路。當前的局域網或其他電氣與電子工程協會 802.3局域網技術操作的速度達10 千兆比特 /秒。這是數據傳輸速率。IEEE已經計劃審查的標準是40到100 千兆比特/秒。個人區域網個人區域網絡(盤)是用于一個人周圍的計算機和使用不同信息技術的設備之間進

11、行交流的網絡。在個人區域網中使用的設備有個人電腦、打印機、傳真機、電話、PDA、掃描儀甚至是視頻游戲機。一個個人區域網可能包括有線和無線設備。個人區域網的范圍通常延伸到10米。個人有線區域網通常采用USB數據線及高速的序列文件連接來構建,而藍牙通信技術與紅外通信技術則形成了典型的個人無線區域網。家庭區域網絡一個家庭區域網絡(HAN)是一個住宅局域網，一般可用于部署在家里的數字設備之間的通信，如少量的個人電腦及配件，打印機和移動計算設備。它的一種重要功能是是通過有線電視或數字用戶線（DSL）提供的寬帶服務來共享上網，它也可以被稱為一個辦公區域網絡(OAN)。4.2廣域網廣域網(WAN)是覆蓋了一

12、個城市，國家一個很大地理區域的計算機網絡,如城市、國家或跨洲際距離,使用的通信信道是有多種媒體如電話線、電纜和無線電波相結合的信道。廣域網使用的傳輸設備通常是有公共電信運營商提供的，如電話公司。廣域網技術的一般功能體現在開放式系統互連（OSI）參考模型較低的三層:物理層,數據鏈路層和網絡層。校園網校園網是一個在有限的地理區域連接成的局域網(LAN)計算機網絡。網絡設備(交換機、路由器)和傳輸媒體(光纖、銅廠、Cat5布線等)是幾乎完全屬于(校園承租人/所有者的:企業、學校、政府等)。就大學校園的校園網絡建設來說，網絡是將各種各樣的校園建筑，如，學術部門，大學圖書館和學生學員公寓等連在一起的。4

13、.3城域網一個大城市的網絡是一個大型計算機網絡，通常跨越城市或一個大的校園EPN幀中繼廣域網的連接和遠程撥號訪問。VPN用來連接3個辦公室和遠程用戶企業專用網企業網是由企業建設用來互聯公司各個部門的網絡，如生產基地、總部、遠程辦公室、商店等為了共享電腦資源而設立的。虛擬專用網虛擬專用網絡（VPN）是一種特殊的計算機網絡，其中某些節點之間的聯系通過公開式電路連接或通過一些較大的網絡（例如，互聯網）中的虛擬鏈路，而不是通過物理線路。這種通過大型網絡的虛擬專用網使用的數據鏈路層協議被稱為隧道。安全通信是公用因特網中一個常見的應用，但VPN不需要這種明確的安全性能，如認證或者內容加密。例如，VPN可以

14、被用來分離不同用戶在擁有強大安全特性的底層網絡進行通訊時的流量。VPN可能有盡力而為的特性或在VPN客戶端和VPN服務提供者之間有固定的服務等級協定(SLA)。一般來說，VPN拓撲比點對點要復雜的多。互聯網絡一個網際網路使用路由器通過一種常見的路由技術(OSI第三層) 連接兩個或更多的私人計算機。互聯網是許多互聯網絡的一個集合，因此被縮短稱為互聯網。4.4骨干網骨干網絡(BBN)，骨干網絡或網絡骨干是計算機網絡基礎設施的一部分，它連接了不同種類的網絡，并且它提供了不同局域網和不同子網之間進行通信的路徑。骨干網可以將在同一座樓里、不同的建筑物中、校園環境中或國外的不同網絡連接起來。通常，骨干網絡

15、的承載能力大于連接到它上面的網絡。在一家擁有分布在不同區域子公司的大公司里，可能有骨干網將不同的區域連接在一起，例如，如果一個服務器集群系統需要被公司內坐落于各種不同的地理位置的部門訪問。將不同部門連接在一起的那部分網絡(例如:局域網，無線網)經常被稱作網絡骨干。在骨干網絡的設計中經常會考慮到網絡擁塞的問題。不應將骨干網絡和因特網骨干混同。全球區域網絡全球區域網絡(GAN)是一個用于支持通過任意數量的無線局域網、衛星覆蓋區域等進行移動通信的網絡。移動通信的主要挑戰是處理從一個覆蓋地區轉到另一個地區的用戶通信。電氣與電子工程協會802項目涉及一系列地面無線局域網。互聯網互聯網是一個全球性的聯結政

16、府、學術、公司、公共領域和私人計算機系統的網絡。它基于互聯網的網絡技術協議組件。這繼承了由美國國防部開發研制的高等研究計劃署網絡(阿帕網)。互聯網也是萬維網(WWW)的通信主干。內部網和外部網內部網和外部網是一個計算機網絡的延伸部分，它通常是一個局域網。內部網是一系列網絡的集合，它使用網際協議和基于網際協議的工具，如瀏覽器和文件傳輸應用程序，他們由單一管理實體進行管理。管理實體只對授權的用戶開放內聯網。通常內部網是一個機構的內部網絡。一個大的內聯網一般會有至少一個網絡服務器，為用戶提供組織過的信息。外部網被限制在單一的組織或實體的范圍內，通常它也會被限制連接到一個或多個組織或實體。但不一定是受

17、信任的組織或實體，例如公司的客戶可能獲得企業內部網的訪問權限，同時從安全的觀點來講客戶可能不會被認為是可信賴的。從技術上講，外部網也被分類為CAN、MAN、WAN或者其他類型的網絡。盡管外聯網不能只包括單一的一個局域網，它必須擁有至少一個與外部網絡的連接。覆蓋網絡覆蓋網絡是一個建立在另一個計算機上面網絡上面的虛擬網絡。覆蓋網絡中的每個節點通過虛擬的或者邏輯上的鏈接相連，每個節點都對應一條路徑，或者在底層網絡通過許多物理鏈接來連接網絡。覆蓋網絡的樣本: 在SONET光纖上的IPComputer networkFrom Wikipedia, the free encyclopedia"C

18、omputer networks" redirects here. For the periodical, see Computer Networks (journal).A computer network, often simply referred to as a network, is a collection of computers and devices interconnected by communications channels that facilitate communications among users and allows users to shar

19、e resources. Networks may be classified according to a wide variety of characteristics. A computer network allows sharing of resources and information among interconnected devices.Contents1 History2 Purpose3 Network classification3.1 Connection method3.2 Wired technologies3.3 Wireless technologies3.

20、4 Scale3.5 Functional relationship (network architecture)3.6 Network topology4 Types of networks based on physical scope4.1 Local area network4.1.1 Personal area network4.1.2 Home area network4.2 Wide area network4.2.1 Campus network4.3 Metropolitan area network4.3.1 Enterprise private network4.3.2

21、Virtual private network4.3.3 Internetwork4.4 Backbone network4.4.1 Global area network4.4.2 Internet4.4.3 Intranets and extranets4.4.4 Overlay network5 ReferencesHistoryEarly networks of communicating computers included the military radar system Semi-Automatic Ground Environment (SAGE) and its relat

22、ive the commercial airline reservation system Semi-Automatic Business Research Environment (SABRE), started in the late 1950s.12When Russia launched His SPUTNIK Satellite in Space In 1957.The American Started Agency Names ADVANCE RESEARCH PROJECT AGENCY (ARPA) & launched His 1st Satellite Within

23、 18 Month After Establishment.Then Sharing Of The Information In Another Computer They Use ARPANET.And This All Responsibility On America's Dr.LIED LIEDER.Then in 1969,ARPANET Comes in INDIA And INDIAN Switched This Name To NETWORK. In the 1960s, the Advanced Research Projects Agency (ARPA) star

24、ted funding the design of the Advanced Research Projects Agency Network (ARPANET) for the United States Department of Defense. Development of the network began in 1969, based on designs developed during the 1960s.3 The ARPANET evolved into the modern Internet.PurposeComputer networks can be used for

25、 a variety of purposes:Facilitating communications. Using a network, people can communicate efficiently and easily via email, instant messaging, chat rooms, telephone, video telephone calls, and video conferencing.Sharing hardware. In a networked environment, each computer on a network may access an

26、d use hardware resources on the network, such as printing a document on a shared network printer.Sharing files, data, and information. In a network environment, authorized user may access data and information stored on other computers on the network. The capability of providing access to data and in

27、formation on shared storage devices is an important feature of many networks.Sharing software. Users connected to a network may run application programs on remote computers.Information preservation.Security. Network classificationThe following list presents categories used for classifying networks.

28、Connection methodComputer networks can be classified according to the hardware and software technology that is used to interconnect the individual devices in the network, such as optical fiber, Ethernet, wireless LAN, HomePNA, power line communication or G.hn.Ethernet as it is defined by IEEE 802 ut

29、ilizes various standards and mediums that enable communication between devices. Frequently deployed devices include hubs, switches, bridges, or routers. Wireless LAN technology is designed to connect devices without wiring. These devices use radio waves or infrared signals as a transmission medium.

30、ITU-T G.hn technology uses existing home wiring (coaxial cable, phone lines and power lines) to create a high-speed (up to 1 Gigabit/s) local area network. Wired technologiesTwisted pair wire is the most widely used medium for telecommunication. Twisted-pair cabling consist of copper wires that are

31、twisted into pairs. Ordinary telephone wires consist of two insulated copper wires twisted into pairs. Computer networking cabling consist of 4 pairs of copper cabling that can be utilized for both voice and data transmission. The use of two wires twisted together helps to reduce crosstalk and elect

32、romagnetic induction. The transmission speed ranges from 2 million bits per second to 100 million bits per second. Twisted pair cabling comes in two forms which are Unshielded Twisted Pair (UTP) and Shielded twisted-pair (STP) which are rated in categories which are manufactured in different increme

33、nts for various scenarios.Coaxial cable is widely used for cable television systems, office buildings, and other work-sites for local area networks. The cables consist of copper or aluminum wire wrapped with insulating layer typically of a flexible material with a high dielectric constant, all of wh

34、ich are surrounded by a conductive layer. The layers of insulation help minimize interference and distortion. Transmission speed range from 200 million to more than 500 million bits per second.Optical fiber cable consists of one or more filaments of glass fiber wrapped in protective layers. It trans

35、mits light which can travel over extended distances. Fiber-optic cables are not affected by electromagnetic radiation. Transmission speed may reach trillions of bits per second. The transmission speed of fiber optics is hundreds of times faster than for coaxial cables and thousands of times faster t

36、han a twisted-pair wire.citation neededWireless technologiesTerrestrial microwave Terrestrial microwaves use Earth-based transmitter and receiver. The equipment looks similar to satellite dishes. Terrestrial microwaves use low-gigahertz range, which limits all communications to line-of-sight. Path b

37、etween relay stations spaced approx, 30 miles apart. Microwave antennas are usually placed on top of buildings, towers, hills, and mountain peaks.Communications satellites The satellites use microwave radio as their telecommunications medium which are not deflected by the Earth's atmosphere. The

38、 satellites are stationed in space, typically 22,000 miles (for geosynchronous satellites) above the equator. These Earth-orbiting systems are capable of receiving and relaying voice, data, and TV signals.Cellular and PCS systems Use several radio communications technologies. The systems are divided

39、 to different geographic areas. Each area has a low-power transmitter or radio relay antenna device to relay calls from one area to the next area.Wireless LANs Wireless local area network use a high-frequency radio technology similar to digital cellular and a low-frequency radio technology. Wireless

40、 LANs use spread spectrum technology to enable communication between multiple devices in a limited area. An example of open-standards wireless radio-wave technology is IEEE.Infrared communication , which can transmit signals between devices within small distances not more than 10 meters peer to peer

41、 or ( face to face ) without any body in the line of transmitting.ScaleNetworks are often classified as local area network (LAN), wide area network (WAN), metropolitan area network (MAN), personal area network (PAN), virtual private network (VPN), campus area network (CAN), storage area network (SAN

42、), and others, depending on their scale, scope and purpose, e.g., controller area network (CAN) usage, trust level, and access right often differ between these types of networks. LANs tend to be designed for internal use by an organization's internal systems and employees in individual physical

43、locations, such as a building, while WANs may connect physically separate parts of an organization and may include connections to third parties. Functional relationship (network architecture)Computer networks may be classified according to the functional relationships which exist among the elements

44、of the network, e.g., active networking, clientserver, Wireless ad hoc network and peer-to-peer (workgroup) architecture.Network topologyMain article: Network topologyComputer networks may be classified according to the network topology upon which the network is based, such as bus network, star netw

45、ork, ring network, mesh network. Network topology is the coordination by which devices in the network are arranged in their logical relations to one another, independent of physical arrangement. Even if networked computers are physically placed in a linear arrangement and are connected to a hub, the

46、 network has a star topology, rather than a bus topology. In this regard the visual and operational characteristics of a network are distinct. Networks may be classified based on the method of data used to convey the data, these include digital and analog networks.Types of networks based on physical

47、 scopeCommon types of computer networks may be identified by their scale. Local area networkA local area network (LAN) is a network that connects computers and devices in a limited geographical area such as home, school, computer laboratory, office building, or closely positioned group of buildings.

48、 Each computer or device on the network is a node. Current wired LANs are most likely to be based on Ethernet technology, although new standards like ITU-T G.hn also provide a way to create a wired LAN using existing home wires (coaxial cables, phone lines and power lines).4Typical library network,

49、in a branching tree topology and controlled access to resourcesAll interconnected devices must understand the network layer (layer 3), because they are handling multiple subnets (the different colors). Those inside the library, which have only 10/100 Mbit/s Ethernet connections to the user device an

50、d a Gigabit Ethernet connection to the central router, could be called "layer 3 switches" because they only have Ethernet interfaces and must understand IP. It would be more correct to call them access routers, where the router at the top is a distribution router that connects to the Inter

51、net and academic networks' customer access routers.The defining characteristics of LANs, in contrast to WANs (Wide Area Networks), include their higher data transfer rates, smaller geographic range, and no need for leased telecommunication lines. Current Ethernet or other IEEE 802.3 LAN technolo

52、gies operate at speeds up to 10 Gbit/s. This is the data transfer rate. IEEE has projects investigating the standardization of 40 and 100 Gbit/s.5Personal area networkA personal area network (PAN) is a computer network used for communication among computer and different information technological dev

53、ices close to one person. Some examples of devices that are used in a PAN are personal computers, printers, fax machines, telephones, PDAs, scanners, and even video game consoles. A PAN may include wired and wireless devices. The reach of a PAN typically extends to 10 meters.6 A wired PAN is usually

54、 constructed with USB and Firewire connections while technologies such as Bluetooth and infrared communication typically form a wireless PAN. Home area networkA home area network (HAN) is a residential LAN which is used for communication between digital devices typically deployed in the home, usuall

55、y a small number of personal computers and accessories, such as printers and mobile computing devices. An important function is the sharing of Internet access, often a broadband service through a CATV or Digital Subscriber Line (DSL) provider. It can also be referred to as an office area network (OA

56、N). Wide area networkA wide area network (WAN) is a computer network that covers a large geographic area such as a city, country, or spans even intercontinental distances, using a communications channel that combines many types of media such as telephone lines, cables, and air waves. A WAN often use

57、s transmission facilities provided by common carriers, such as telephone companies. WAN technologies generally function at the lower three layers of the OSI reference model: the physical layer, the data link layer, and the network layer.Campus networkA campus network is a computer network made up of

58、 an interconnection of local area networks (LAN's) within a limited geographical area. The networking equipments (switches, routers) and transmission media (optical fiber, copper plant, Cat5 cabling etc.) are almost entirely owned (by the campus tenant / owner: an enterprise, university, government etc.).In the case of a university campus-based campus network, the network is likely to link a variety of campus buildings including; academic departments, the university library and student residence halls.Metr