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1、McGraw-Hill/IrwinCopyright 2008 by The McGraw-Hill Companies, Inc. All rights reserved.Chapter 9Communications and NetworksCompetencies (Page 1 of 2)Discuss connectivity, the wireless revolution, and communication systemsDescribe physical and wireless communications channelsDiscuss connection device
2、s, including modems, T1, DSL, cable modem, satellite, and cellular connectionsDescribe data transmission factors, including bandwidths and protocolsPage 2462Competencies (Page 2 of 2)Discuss networks and key network terminologies.Describe different types of networks, including local area, metropolit
3、an area, and wide area networks.Describe network architectures, including configurations and strategies.Describe organizational uses of Internet technologies, including intranets, extranets, and firewalls.Page 2463Introduction Cell phones and other wireless technologies are allowing us to stay conne
4、cted in todays world like never before. Increased connectivity potentially means increased productivity especially in the business world. You will learn more about the concept of connectivity and the impact of the wireless revolution in this chapter.Page 2474CommunicationsThe process of sharing data
5、, programs, and information between two or more computersPage 2485Communications Today Numerous applications depend on communication systemsE-mail, Instant messaging (IM), Internet telephone, and Electronic commerceConnectivity uses computer networks to link people and resourcesGoing wireless has be
6、en the most dramatic changePage 2486Communication SystemsFour basic elements Sending and receiving devicesCommunication channelConnection devicesData transmission specificationsPage 2497Communication Channels Channels carry data from one computer to another Two categories of communication channelsPh
7、ysical connection Wireless connectionPage 2508Physical ConnectionsTelephone lines(Twisted pair cables)Coaxial cableFiber-optic cable Page 250Return9Wireless Connections InfraredBroadcast radioWi-FI (wireless fidelity) 802.11MicrowaveStationsBluetoothSatelliteGPSPage 252Microwave dishGPS Satellite10C
8、ommunication Channels SummaryPage 25311Connection Device SignalsTypes of signalsAnalogDigitalPage 25312Connection Device Types and Transfer SpeedsTypes of modemsExternalInternalPC CardWirelessPage 253Transfer Speeds 13Connection ServiceDial-Up servicesLeased lines T1, T2, T3 and T4Digital subscriber
9、 line (DSL)Uses existing phone lines One type widely used is ADSL Cable modemsUses existing TV cable Provides speeds as fast as DSL at a lower costSatellite/air connection services Seven times faster than dial-upSlower than DSL & cable modemCellular ServicesAlternative for mobile devices and laptops
10、Current service areas limited Page 25414Typical User Connection Costs & SpeedsPage 25515BandwidthMeasurement of the capacity of the channelCategories Voiceband also known as low bandwidthMedium band BroadbandUsed for high capacity transmissionUsed by DSL, cable, and satellitePage 25516ProtocolsSet o
11、f communication rulesStandard for Internet: TCP/IP (Transmission control protocol/Internet protocol)Identification Reformatting Page 25617NetworksA computer network is a communication systemConnects two or more computersAllows information exchange Page 25718Computer NetworksCommon network termsNodeC
12、lientServerHubNetwork interface cards (NIC)Network operating system (NOS)Distributed processingHost computerNetwork administratorPage 257Computer Networks Connect Computers19Network TypesLocal area networksHome networksWLANMetropolitan area networksWide area networksPage 259LAN20Network Architecture
13、Architecture describes how a network is arrangedArrangement is called topologyTypes of network topologyStarBusRingHierarchicalPage 26121Star Network Smaller computers linked to a central unitCentral unit is called the network hubControl is maintained by pollingPage 251Return22Bus Network Each device
14、 handles its own communication controlThere is no host computerHas a common connecting cable called a backbonePage 264Return23Ring Network Each device is connected to two other devicesNo central file server or computerUseful in a decentralized environment Page 264Return24Hierarchical Network Several
15、 computers linked to a central hostComputers are hosts to other computersUseful in centralized organizations Page 26425Principal Network ConfigurationsPage 26526StrategiesStrategy is a way of coordinating the sharing of information and resourcesCommon network strategiesTerminalClient/serverPeer-to-p
16、eerPage 25527 Organizational InternetsIntranetsPrivate network within an organizationProvides information to employeesExtranetsPrivate network that connects organizationsUsed to allow suppliers and others access FirewallsSecurity system Protects against external threats Page 26828Careers In ITNetwor
17、k AdministratorManage a companys LAN and WAN networksMaintain hardware and softwareDiagnose and repair problemsCandidates usually have a bachelors degree in computer science and practical experienceAnnual salary is typically between $43,000 and $68,000Page 27029A Look to the FutureCars that Monitor
18、and RespondPod car (Personalization on Demand)Predicts and responds Designed to learn and adapt to an individuals driving needs and habits Page 27130Discussion Questions (1 of 2)Define and discuss connectivity, the wireless revolution, and communications.Identify and describe the various physical and wireless communication channels.Identify the standard Internet protocol and discuss its essential features.Page 27831Discussion Questions (2 of 2) Define and discuss the four principal network topologies.Define and discuss the three most common network strategies.Page 27832谢谢观赏！谢谢观赏！
