计算机英语(Chapter 5 LANs AND WANs)教程文件.ppt

Describe the characteristics of PANs, NANs, MANs and WANs. Diagram the five most common network topology. List the types of cables and other links used by data communication network. Make list of network devices and explain the role of each one. Section A Network Building Blocks What is the purpose of network? In the early years , most computers is function as standalone units. A network allows data transmission between computers. Additionally, a computer network makes it possible to share software application and hardware devices. How are computer networks classified? Networks can be classified according to size and geographic scope. - PAN (Personal Area Networks) - NAN (Neighborhood Area Networks) - LAN (Local Area Networks) - MAN (Metropolitan Area Networks) - WAN (Wide Area Networks) What is the difference between a network client and a server? Network devices can function as clients and servers, A server is a computer that provides services for clients. What connect the nodes of a network? Data travel from one network device to another over a cable or air. Bandwidth is the transmission capacity of a communications channel. The bandwidth of digital channel is measured by bits/second (bps). LAN: 10/100Mbps Modem: 54Mbps What is a protocol? Communication protocol refers to a set of rules for efficiently transmitting data from one network node to another. The best-known communications protocol is probably TCP/IP. How does data travel over a network? In Shannons model, data from source is encoded and sent as signals over communication channel to destination. When signal arrives destination, it is decoded. The transmission signal can be disrupted by inference. What is packet? A packet is a parcel of data that is sent across a computer network. Each parcel contains the address of sender, destination address, serial number, and some data. What is MAC address? A MAC address is a unique number assigned to net