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Chapter 9 Communications and Networks McGraw-Hill Copyright © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Computing Essentials 2012: Making IT Work for You Introduction • We live in a truly connected society. • Increased connectivity potentially means increased productivity, especially in business. • You will learn more about the concept of connectivity and the impact of the wireless revolution in this chapter. McGraw-Hill Copyright © 2012 The McGraw-Hill Companies, Inc. All rights reserved. 9-2 Computing Essentials 2012: Making IT Work for You Communications • Computer communications is the process of sharing data, programs, and information between two or more computers • Numerous applications depend on communication systems, including – – – – – McGraw-Hill E-mail Instant messaging Internet telephone Electronic commerce Global positioning systems (GPS) Copyright © 2012 The McGraw-Hill Companies, Inc. All rights reserved. 9-3 Computing Essentials 2012: Making IT Work for You Communications Today • Connectivity uses computer networks to link people and resources • The Wireless Revolution – Single most dramatic change in connectivity and communications has been widespread use of mobile telephones with wireless Internet connectivity McGraw-Hill Copyright © 2012 The McGraw-Hill Companies, Inc. All rights reserved. 9-4 Computing Essentials 2012: Making IT Work for You Communication Systems • Four basic elements – – – – McGraw-Hill Sending and receiving devices Communication channel Connection devices Data transmission specifications Copyright © 2012 The McGraw-Hill Companies, Inc. All rights reserved. 9-5 Computing Essentials 2012: Making IT Work for You Communication Channels • Communication channels carry the data from one computer to another • Two categories of communication channels – Physical connection – Wireless connection McGraw-Hill Copyright © 2012 The McGraw-Hill Companies, Inc. All rights reserved. 9-6 Computing Essentials 2012: Making IT Work for You Physical Connections • Ethernet cable (Twisted pair cable) • Coaxial cable • Fiber-optic cable McGraw-Hill Return Copyright © 2012 The McGraw-Hill Companies, Inc. All rights reserved. 9-7 Computing Essentials 2012: Making IT Work for You Wireless Connections • Radio frequency (RF) – Wi-Fi (wireless fidelity) – Bluetooth (short-range) – WiMax (extends Wi-Fi) • Microwave • Satellite – Global positioning system (GPS) • Infrared – Short distances and line of sight McGraw-Hill Copyright © 2012 The McGraw-Hill Companies, Inc. All rights reserved. 9-8 Computing Essentials 2012: Making IT Work for You Communication Channels Summary McGraw-Hill Copyright © 2012 The McGraw-Hill Companies, Inc. All rights reserved. 9-9 Computing Essentials 2012: Making IT Work for You Connection Device Signals • Types of signals – Analog – Digital McGraw-Hill Copyright © 2012 The McGraw-Hill Companies, Inc. All rights reserved. 9-10 Computing Essentials 2012: Making IT Work for You Connection Devices • Types of modems – Telephone modem – DSL (digital subscriber line) – Cable modem – Wireless modem (WWAN) McGraw-Hill Copyright © 2012 The McGraw-Hill Companies, Inc. All rights reserved. 9-11 Connection Services Computing Essentials 2012: Making IT Work for You • Dial-Up services – Uses phone lines • Leased lines – Replaced by optical carrier (OC) lines • Digital subscriber line (DSL) – Uses phone lines – ADSL is most widely used type of DSL McGraw-Hill • Cable – Uses existing TV cable – Speeds as fast as DSL • Satellite connection services – Use almost anywhere – Slower than DSL and cable modem • Cellular Services – Use 3G and 4G cellular network to provide wireless connectivity Copyright © 2012 The McGraw-Hill Companies, Inc. All rights reserved. 9-12 Computing Essentials 2012: Making IT Work for You Connection Costs and Speeds • Typical user connection costs, bandwidth speeds, and comparable time required to download an image in the USA McGraw-Hill Copyright © 2012 The McGraw-Hill Companies, Inc. All rights reserved. 9-13 Computing Essentials 2012: Making IT Work for You Bandwidth • Measurement of the width or capacity of the communication channel • Categories – – – – McGraw-Hill Voice band (or low bandwidth) Medium band Broadband Baseband Copyright © 2012 The McGraw-Hill Companies, Inc. All rights reserved. 9-14 Computing Essentials 2012: Making IT Work for You Protocols • Communication rules for exchanging data between computers • Internet standard: TCP/IP (Transmission control protocol/Internet protocol) – Identification – unique IP address – Packetization – broken down and reassembled McGraw-Hill Copyright © 2012 The McGraw-Hill Companies, Inc. All rights reserved. 9-15 Computing Essentials 2012: Making IT Work for You Networks • A computer network is a communication system that connects two or more computers • Allows exchange of information and resources McGraw-Hill Copyright © 2012 The McGraw-Hill Companies, Inc. All rights reserved. 9-16 Computing Essentials 2012: Making IT Work for You Computer Networks • • • • • • • Node Client Server Directory server Host Switch Network interface cards (NIC) • Network operating systems (NOS) • Network administrator McGraw-Hill Copyright © 2012 The McGraw-Hill Companies, Inc. All rights reserved. 9-17 Computing Essentials 2012: Making IT Work for You Network Types • Local area network (LAN) • Home network • Wireless LAN (WLAN) • Metropolitan area network (MAN) • Wide area network (WAN) McGraw-Hill Copyright © 2012 The McGraw-Hill Companies, Inc. All rights reserved. 9-18 Computing Essentials 2012: Making IT Work for You Network Architecture • Arrangement is called topology • Types of network topology – Legacy • Bus • Ring – Current McGraw-Hill • • • • Star Tree Hybrid Mesh Copyright © 2012 The McGraw-Hill Companies, Inc. All rights reserved. 9-19 Computing Essentials 2012: Making IT Work for You Bus Network • Each device is connected to a common cable, called a bus or backbone • All communications travel along this bus • There is no host; messages are passed device-to-device in a sequence McGraw-Hill Return Copyright © 2012 The McGraw-Hill Companies, Inc. All rights reserved. 9-20 Computing Essentials 2012: Making IT Work for You Ring Network • Each device is connected to two other devices • No central file server or computer • Useful in a decentralized environment McGraw-Hill Return Copyright © 2012 The McGraw-Hill Companies, Inc. All rights reserved. 9-21 Computing Essentials 2012: Making IT Work for You Star Network • Most widely used network topology for both homes and large businesses • Each device connects directly to a central network switch McGraw-Hill Return Copyright © 2012 The McGraw-Hill Companies, Inc. All rights reserved. 9-22 Computing Essentials 2012: Making IT Work for You Tree Network • Each device is connected to a central node, either directly or through subordinate nodes • Also known as a hierarchical network McGraw-Hill Return Copyright © 2012 The McGraw-Hill Companies, Inc. All rights reserved. 9-23 Computing Essentials 2012: Making IT Work for You Hybrid Network • Combination of different topologies • Large organizations have a complex network of smaller networks – These smaller networks use a variety of configurations – When connected together, they form a hybrid McGraw-Hill Return Copyright © 2012 The McGraw-Hill Companies, Inc. All rights reserved. 9-24 Computing Essentials 2012: Making IT Work for You Mesh Network • Does not use a specific physical layout, but requires that each node have more than one connection to other nodes • Wireless technologies are frequently used McGraw-Hill Copyright © 2012 The McGraw-Hill Companies, Inc. All rights reserved. 9-25 Computing Essentials 2012: Making IT Work for You Network Topologies McGraw-Hill Copyright © 2012 The McGraw-Hill Companies, Inc. All rights reserved. 9-26 Computing Essentials 2012: Making IT Work for You Network Strategies • • • • Terminal server network Client/server network Peer-to-peer (P2P) network Distributed processing network McGraw-Hill Terminal Server Client/Server Peer-to-Peer Copyright © 2012 The McGraw-Hill Companies, Inc. All rights reserved. 9-27 Computing Essentials 2012: Making IT Work for You Organizational Networks • Intranets – Private network within an organization – Works like the Internet, where employees use browsers to access Web sites and Web pages • Extranets – Private network that connects organizations – Works like the Internet, but provides suppliers and other trusted partners with limited access to the organization’s networks McGraw-Hill Copyright © 2012 The McGraw-Hill Companies, Inc. All rights reserved. 9-28 Computing Essentials 2012: Making IT Work for You Network Security • Firewalls – Combination of hardware and software – Proxy server provides pass-through access – Protects against external threats • Intrusion detection systems (NIDS) • Virtual private networks (VPN) – Creates a secure private network connection between your computer and the organization McGraw-Hill Copyright © 2012 The McGraw-Hill Companies, Inc. All rights reserved. 9-29 Chapter 9 Communications and Networks STUDY p274 – 279 VISUAL SUMMARY MULTIPLE CHOICE Q’s McGraw-Hill KEY TERMS MATCHING Q’s Copyright © 2012 The McGraw-Hill Companies, Inc. All rights reserved.