外文文獻(xiàn)—計(jì)算機(jī)網(wǎng)絡(luò)

1、英文原文：Computer networkA 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 us

2、ers to share resources. Networks may be classified according to a wide variety of characteristics. A computer network allows sharing of resources and information among interconnected devices. History ： Early networks of

3、communicating computers included the military radar system Semi-Automatic Ground Environment (SAGE) and its relative the commercial airline reservation system Semi-Automatic Business Research Environment (SABRE),started

4、 in the late 1950s.[1][2] When Russia launched His SPUTNIK Satellite in Space In 1957.The American Started Agency Names ADVANCE RESEARCH PROJECT AGENCY (ARPA) & launched THis 1st Satellite Within 18 Month After Estab

5、lishment.Then Sharing Of TheInformation InAnother 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 th

6、e 1960s, the Advanced Research Projects Agency (ARPA) started funding the design of the Advanced Research Projects Agency Network (ARPANET) for the United States Department of Defense. Development of the network began i

7、n 1969, based on designs developed during the 1960s.[3] The ARPANET evolved into the modern Internet. Purpose ： Computer networks can be used for a variety of purposes: Facilitating communications. Using a network, peop

8、le 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 a

9、ccess and 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

10、 stored on other computers on the network. The capability of providing access to data and information on shared storage devices is an important feature of many networks. Sharing software.： Users connected to a network m

11、ay run application programs on remote computers. information preservation Security Network classification The following list presents categories used for classifying networks. Connection method ：Computer networks can b

12、e classified according to the voice, data, and TV signals. Cellular and PCS systems – Use several radio communications technologies. The systems are divided to different geographic areas. Each area has a low-power trans

13、mitter 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

14、technology. Wireless 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 ,

15、 which can transmit signals between devices within small distances not more than 10 meters peer to peer or ( face to face ) without any body in the line of transmitting. Scale：Networks are often classified as local area

16、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), and others, depending on their s

17、cale, 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

18、 systems and employees in individual physical locations, such as a building, while WANs may connect physically separate parts of an organization and may include connections to third parties. Functional relationship (net

19、work architecture) ：Computer networks may be classified according to the functional relationships which exist amongthe elements of the network,e.g., active networking, client–server, Wireless ad hoc network andpeer-to-p

20、eer (workgroup) architecture. Network topology ： Main article: Network topology Computer networks may be classified according to the network topology upon which the network is based, such as bus network, star network, r

21、ing 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 a

22、re physically placed in a linear arrangement and are connected to a hub, the network has a star topology, rather than a bus topology. In this regard the visual and operational characteristics of a network are distinct.

23、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 scopeCommon types of computer networks may be identified by

24、 their scale. Local area network：A 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 positio