1、Chapter 9,Communications and Networks,9-2,Competencies (Page 1 of 2),Discuss connectivity, the wireless revolution, and communication systems Describe physical and wireless communications channels Discuss connection devices, including modems, T1, DSL, cable modem, satellite, and cellular connections
2、 Describe data transmission factors, including bandwidths and protocols,Page 246,9-3,Competencies (Page 2 of 2),Discuss networks and key network terminologies1. Describe different types of networks, including local area, metropolitan2 area, and wide area networks. Describe network architectures, inc
3、luding configurations3 and strategies4. Describe organizational uses of Internet technologies, including intranets, extranets, and firewalls.,Page 246,9-4,Introduction,Cell phones and other wireless technologies are allowing us to stay connected in todays world like never before. Increased connectiv
4、ity potentially1 means increased productivity2 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 247,9-5,Communications,The process of sharing data, programs, and information between two or more com
5、puters,Page 248,9-6,Communications Today,Numerous applications depend on communication systemsE-mail, Instant messaging (IM), Internet telephone, and Electronic commerce Connectivity uses computer networks to link people and resources Going wireless has been the most dramatic1 change,Page 248,9-7,Co
6、mmunication Systems,Four basic elements Sending and receiving devices Communication channel Connection devices Data transmission specifications,Page 249,9-8,Communication Channels,Channels carry data from one computer to another Two categories of communication channels Physical connection Wireless c
7、onnection,Page 250,9-9,Physical Connections,Telephone lines(Twisted pair1 cables) Coaxial cable Fiber-optic cable,Page 250,Return,9-10,Wireless Connections,Infrared Broadcast radio Wi-FI (wireless fidelity) 802.11 Microwave Stations Bluetooth Satellite GPS,Page 252,Microwave dish,GPS,Satellite,9-11,
8、Communication Channels Summary,Page 253,9-12,Connection Device Signals,Types of signalsAnalogDigital,Page 253,9-13,Connection Device Types and Transfer Speeds,Types of modems External Internal PC Card Wireless,Page 253,Transfer Speeds,9-14,Connection Service,Dial-Up services Leased lines1 T1, T2, T3
9、 and T4 Digital subscriber line (DSL) Uses existing phone lines One type widely used is ADSL Cable modems Uses existing TV cable Provides speeds as fast as DSL at a lower cost Satellite/air connection services Seven times faster than dial-up Slower than DSL & cable modem Cellular Services Alternativ
10、e2 for mobile devices and laptops Current service areas limited,Page 254,9-15,Typical User Connection Costs & Speeds,Page 255,9-16,Bandwidth,Measurement of the capacity of the channel Categories Voiceband also known as low bandwidth Medium band Broadband Used for high capacity transmission Used by D
11、SL, cable, and satellite,Page 255,9-17,Protocols,Set of communication rules Standard for Internet: TCP/IP (Transmission control protocol/Internet protocol) Identification1 Reformatting2 DNS,Page 256,9-18,Networks,A computer network is a communication system Connects two or more computers Allows info
12、rmation exchange,Page 257,9-19,Computer Networks,Common network terms Node Client Server Hub Network interface cards (NIC) Network operating system (NOS) Distributed processing1 Host computer Network administrator,Page 257,9-20,Network Types,Local area networks Home networks WLAN,AP Metropolitan are
13、a networks Wide area networks,Page 259,LAN,9-21,Network Architecture,Architecture describes how a network is arranged Arrangement is called topology1 Types of network topology Star Bus Ring Hierarchical2,Page 261,9-22,Star Network,Smaller computers linked to a central unit Central unit is called the
14、 network hub Control is maintained by polling1,Page 251,Return,9-23,Bus Network,Each device handles its own communication control There is no host computer Has a common connecting cable called a backbone1,Page 264,Return,9-24,Ring Network,Each device is connected to two other devices No central file
15、 server or computer Useful in a decentralized1 environment,Page 264,Return,9-25,Hierarchical Network,Several computers linked to a central host Computers are hosts to other computers Useful in centralized1 organizations,Page 264,9-26,Principal Network Configurations,Page 265,9-27,Strategies,Strategy
16、 is a way of coordinating the sharing of information and resources Common network strategies Terminal Client/server Peer-to-peer,Page 255,9-28,Organizational Internets,Intranets Private network within an organization Provides information to employees Extranets Private network that connects organizat
17、ions Used to allow suppliers and others access Firewalls Security system Protects against external threats,Page 268,9-29,Careers In IT,Network Administrator Manage a companys LAN and WAN networks Maintain hardware and software Diagnose and repair problems Candidates usually have a bachelors degree i
18、n computer science and practical experience Annual salary is typically between $43,000 and $68,000,Page 270,9-30,A Look to the Future Cars that Monitor and Respond,Pod car (Personalization on Demand) Predicts and responds Designed to learn and adapt to an individuals driving needs and habits,Page 27
19、1,9-31,Discussion 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 278,9-32,Discussion Questions (2 of 2),Define and discuss the four principal network topologies.Define and discuss the three most common network strategies.,Page 278,
