99 CHAPTER COMMUNICATIONS AND NETWORKS

© 2005 The McGraw-Hill Companies, Inc. All Rights Reserved. 9-2 Competencies Discuss connectivity, the wireless revolution, and communication systems Describe physical and wireless communications channels Discuss connection devices Describe data transmission factors

© 2005 The McGraw-Hill Companies, Inc. All Rights Reserved. 9-3 Competencies cont. Discuss networks and key network terminology Describe the different types of networks Describe network architectures Describe organizational uses of Internet technologies

© 2005 The McGraw-Hill Companies, Inc. All Rights Reserved. 9-4 What is Communication? The process of sharing data, programs, and information between two or more computers

© 2005 The McGraw-Hill Companies, Inc. All Rights Reserved. 9-5 Communications Today

© 2005 The McGraw-Hill Companies, Inc. All Rights Reserved. 9-6 Cont. Applications that depend on the Communication Systems: , instant messaging, internet telephone and electronic commerce. Connectivity: is a concept related to using computer networks to link people and resources. ( you can connect your microcomputer by telephone or other telecommunication link to other computers). Wireless revolution: Allow devices to communicate with one another without any physical connection

© 2005 The McGraw-Hill Companies, Inc. All Rights Reserved. 9-7 Communication Systems Are electronic systems that transmit data from one location to another Basic elements of a communication system: 1- Sending and Receiving Devices ( computers or specialized communication devices). 2- Communication Channel( transmission medium) (physical wire or cable and wireless connection). 3- Connection Devices (communication devices): Act as an interface between the sending and receiving devices and the communication channel, they convert outgoing message into a form and format so that they can travel across the communication channel. 4- Data Transmission specifications: rules and procedures that coordinate the sending and receiving devices( how the message will be send through the communication channel)

© 2005 The McGraw-Hill Companies, Inc. All Rights Reserved. 9-8 Communication Systems Computer Modem Telephone-lines

© 2005 The McGraw-Hill Companies, Inc. All Rights Reserved. 9-9 Communication Channels Channels carry data from one computer to another Two categories of communication channels Physical connection Wireless connection

© 2005 The McGraw-Hill Companies, Inc. All Rights Reserved Physical Connections Solid medium to connect sending and receiving devices Telephone lines ( twisted pair cable) Coaxial cable high frequency transmission cable deliver television signals and connect computer in a network. 80 times the transmission capacity of twisted pair cable Fiber-optic cable Transmit data as pulses of light through tiny tubes of glass times the transmission capacity of twisted pair cable

© 2005 The McGraw-Hill Companies, Inc. All Rights Reserved Wireless Connections Infrared Broadcast radio: Communication uses special sending and receiving towers called Transceivers, send and receive radio signals from wireless devices Microwave: Communication uses high frequency radio waves sending data between buildings in a city Stations used for long distance Bluetooth Satellite Uplink/Downlink Uplink is a term of sending data to a satellite. Downlink is a term of receiving data from a satellite. Global Positioning System: Application of satellite communication Note: Check page 239

© 2005 The McGraw-Hill Companies, Inc. All Rights Reserved More on Satellites Global positioning Network of 24 satellites Owned by the Defense Department Global positioning system (GPS) Devices used to determine location Provides navigational support

© 2005 The McGraw-Hill Companies, Inc. All Rights Reserved Connection Devices Types of signals Analog Digital Types of modems Internal: plug-in circuit board External: wall jack, modem and serial port PC Card: laptop Wireless

© 2005 The McGraw-Hill Companies, Inc. All Rights Reserved Types of Connections Digital subscriber line (DSL) Uses existing phone lines ADSL (Asymmetric digital subscriber line) ADSL services can download at up to 8Mb/s and upload up to 832 kb/s, 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

© 2005 The McGraw-Hill Companies, Inc. All Rights Reserved User Connection Costs & Speeds TypeFeeSpeedSeconds to Get Images Dial-up$1656 kbps45.0 DSL mbps1.7 Cable Modem mbps1.7 Satellite kbps2.8

© 2005 The McGraw-Hill Companies, Inc. All Rights Reserved Bandwidth Measurement of the capacity of the channel Categories Low bandwidths or Voiceband Used for standard telephone communication Medium band Used for minicomputer and mainframe Broadband Used for high capacity transmission Used by DSL, cable & satellite

© 2005 The McGraw-Hill Companies, Inc. All Rights Reserved Protocols Set of communication rules Rules for exchanging data between computers. Standard for Internet: TCP/IP Transmission control protocol/Internet protocol Identifies devices : Identifying sending and receiving devices Each computer on the internet has IP address DNS domain name server convert text to IP address. Reformats information Reformatted or broken into small parts called packets

© 2005 The McGraw-Hill Companies, Inc. All Rights Reserved Networks A computer network is a communication system Connects two or more computers Allows information exchange

© 2005 The McGraw-Hill Companies, Inc. All Rights Reserved Network Terms Node Any device that is connected to a network (Computer or printer) Client: microcomputer Server A node that shares resources with other nodes Hub The center or central node for other nodes Network interface cards (NIC) Network operating system (NOS) Distributed processing This type of system is common in decentralized organization where divisional offices have their own computer Host computer Minicomputer or mainframe computer Network manager Computer specialist or network administrator

© 2005 The McGraw-Hill Companies, Inc. All Rights Reserved Network Types Local area networks 1 mile Home networks Including a common internet connection Metropolitan area networks (MAN) 100 miles connect buildings in a city Wide area networks(WAN)

© 2005 The McGraw-Hill Companies, Inc. All Rights Reserved Network Architecture Architecture describes how a network is arranged Arrangement is called topology Types of network topology Star Bus Ring Hierarchical

© 2005 The McGraw-Hill Companies, Inc. All Rights Reserved Star Network Smaller computers linked to a central unit Central unit is called the network hub

© 2005 The McGraw-Hill Companies, Inc. All Rights Reserved Bus Network Each device handles its own communication control There is no host computer Has a common connecting cable called a backbone

© 2005 The McGraw-Hill Companies, Inc. All Rights Reserved Ring Network Each device is connected to two other devices No central file server or computer Useful in a decentralized environment

© 2005 The McGraw-Hill Companies, Inc. All Rights Reserved Hierarchical Network Several computers linked to a central host Computers are hosts to other computers Useful in centralized organizations

© 2005 The McGraw-Hill Companies, Inc. All Rights Reserved Strategies Strategy is a way of coordinating the sharing of information and resources Common network strategies Terminal Processing power is centralized in one large computer, usually a mainframe. Many airline reservation systems are terminal systems. A large central computer maintain all the airline schedule. Client/server Use one computer to coordinate and supply services to other nodes on the network. The server provides access to resources such as web pages, database. Peer-to-peer Nodes have equal authority and can act as both clients and servers, for example one microcomputer can obtain files located on another microcomputer and can also provide files to other microcomputers

© 2005 The McGraw-Hill Companies, Inc. All Rights Reserved Organizational Internets

© 2005 The McGraw-Hill Companies, Inc. All Rights Reserved Internets and Extranets Intranets Private network within an organization Provides information to employees Extranets Private network that connects organizations Used to allow suppliers and others access Firewalls Security system Protects against external threats

© 2005 The McGraw-Hill Companies, Inc. All Rights Reserved A Look to the Future Wireless Robotic Car Pod car (Personalization on Demand) Predicts and responds Designed to learn and adapt to an individual's driving needs and habits

© 2005 The McGraw-Hill Companies, Inc. All Rights Reserved Key Terms (239) analog signal (240) application server (243) asymmetric digital subscriber line (ADSL) (241) backbone (249) bandwidth (241) base station (245) bits per second (bps) (240) Bluetooth (239) broadcast radio (238) broadband (242) bus (249) bus network (249) cable modem (241) cellular phone system (245) client (243)

© 2005 The McGraw-Hill Companies, Inc. All Rights Reserved Key Terms client/server network system (251) coaxial cable (238) communications (246) communication channel (237) communication device (237) communication server (243) communication system (237) computer network (243) connection device (237) connectivity (236) database server (243) data transmission specification (237) dedicated server (243)

© 2005 The McGraw-Hill Companies, Inc. All Rights Reserved Key Terms demodulation (240) dial-up service (240) digital signal (240) digital subscriber line (DSL) (241) dish (239) Distributed data processing system (249) distributed processing (243) Domain name server (DNS) (242) downlink (239) external modem (240) extranet (243) fiber-optic cable (238) file server (243) firewall (253) Gnutella (252)

© 2005 The McGraw-Hill Companies, Inc. All Rights Reserved Key Terms global positioning (239) global positioning system (GPS) (239) hierarchical network (249) home network (245) host computer (243) hub (243) hybrid network (249) infrared (238) internal modem (240) intranet (253) IP address (Internet Protocol address) (242) LAN adapter (243) line of sight communication (238) Local area network (LAN) (244)

© 2005 The McGraw-Hill Companies, Inc. All Rights Reserved Key Terms low bandwidth (241) medium band (242) metropolitan area network (MAN) (245) microwave (239) microwave station (239) modem (240) modulation (240) Napster (251) network administrator (243) network architecture (248) network gateway (244) network hub (248) network interface card (NIC) (243) network manager (243)

© 2005 The McGraw-Hill Companies, Inc. All Rights Reserved Key Terms network operating system (NOS) (243) node (243) packet (242) PC card modem (240) peer-to-peer network system (252) polling (248) printer server (243) protocol (242) proxy server (254) receiving device (237) regional network (245) ring network (249) satellite (239) Satellite/air connection service (241) sending device (237)

© 2005 The McGraw-Hill Companies, Inc. All Rights Reserved Key Terms server (243) star network (248) strategy (250) TCP/IP (transmission control protocol/Internet protocol) (242) telephone line (238) terminal network system (250) time-sharing system (249) T1, T2, T3, T4 lines (240) topology (248) transceiver (238) transfer speed (240) transfer rate (240) transmission medium (237)

© 2005 The McGraw-Hill Companies, Inc. All Rights Reserved Key Terms twisted pair (238) uplink (239) voiceband (241) voice grade (241) Web server (243) wide area network (WAN) (245) Wi-FI (wireless fidelity) (239) wireless LAN (WLAN) (245) wireless modem (240) wireless receiver (245)

© 2005 The McGraw-Hill Companies, Inc. All Rights Reserved FAQs What is fiber-optic cable? My Palm Pilot uses Bluetooth. What is it? What is a modem? What is DSL? How does it work? How fast is broadband bandwidth? What is a local area network? What is meant by peer-to-peer?

© 2005 The McGraw-Hill Companies, Inc. All Rights Reserved Discussion Questions Discuss what is meant by the wireless revolution. Discuss the four types of service connections. Discuss the advantages and disadvantages of the four network topologies. Explain the connections in a home network. Describe the different network topologies. Describe a GPS system.