Communications and Networks Chapter 9 9-1Copyright © 2011 by The McGraw-Hill Companies, Inc. All rights reserved.

Discuss connectivity, the wireless revolution, and communication systems. Describe physical and wireless communications channels. Discuss connection devices, and services including dial- up, DSL, cable, satellite/air, and cellular. Describe data transmission factors, including bandwidths and protocols. Competencies (Page 1 of 2) 9-2 Copyright © 2011 by The McGraw-Hill Companies, Inc. All rights reserved.

Competencies (Page 2 of 2) Discuss networks and key network terminologies. Describe different types of networks, including local, home, wireless, personal, metropolitan, and wide area networks. Describe network architectures, including topologies, and strategies. Describe organization issues related to Internet technologies and network security. 9-3 Copyright © 2011 by The McGraw-Hill Companies, Inc. All rights reserved.

Communications 9-4 The process of sharing data, programs, and information between two or more computers Copyright © 2011 by The McGraw-Hill Companies, Inc. All rights reserved.

Communications Today Numerous applications depend on communication systems— , Instant messaging (IM), Internet telephone, and Electronic commerce Connectivity uses computer networks to link people and resources Going wireless has been the most dramatic change 9-5 Copyright © 2011 by The McGraw-Hill Companies, Inc. All rights reserved.

Communication Systems Four basic elements –Sending and receiving devices –Communication channel –Connection devices –Data transmission specifications 9-6 Copyright © 2011 by The McGraw-Hill Companies, Inc. All rights reserved.

Channels carry data from one computer to another Two categories of communication channels –Physical connectionPhysical connection –Wireless connectionWireless connection Communication Channels 9-7 Copyright © 2011 by The McGraw-Hill Companies, Inc. All rights reserved.

Ethernet cable (Twisted pair cables) Coaxial cable Fiber-optic cable Physical Connections 9-8 Return Copyright © 2011 by The McGraw-Hill Companies, Inc. All rights reserved.

Wireless Connections Radio frequency (RF) –Wi-Fi (wireless fidelity) –Bluetooth Microwave –Line of sight Satellite –GPS Infrared –Short distances –Line of sight 9-9 Copyright © 2011 by The McGraw-Hill Companies, Inc. All rights reserved.

Communication Channels Summary 9-10 Copyright © 2011 by The McGraw-Hill Companies, Inc. All rights reserved.

Types of signals –Analog –Digital Connection Device Signals 9-11 Copyright © 2011 by The McGraw-Hill Companies, Inc. All rights reserved.

Types of modems –Telephone –DSL –Cable –Wireless Connection Devices 9-12 Transfer Speeds Copyright © 2011 by The McGraw-Hill Companies, Inc. All rights reserved.

Dial-Up services Leased lines – T1 –T3 and DS3 have higher capacity Digital subscriber line (DSL) –Uses existing phone lines –One type widely used is ADSL Cable –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 - use 3G cellular network Connection Services 9-13 Copyright © 2011 by The McGraw-Hill Companies, Inc. All rights reserved.

Typical User Connection Costs & Speeds 9-14 Copyright © 2011 by The McGraw-Hill Companies, Inc. All rights reserved.

Measurement of the capacity of the channel Categories –Voice band also known as low bandwidth –Medium band –Broadband –Baseband Bandwidth 9-15 Copyright © 2011 by The McGraw-Hill Companies, Inc. All rights reserved.

Set of communication rules Standard for Internet: TCP/IP (Transmission control protocol/Internet protocol) –Identification –Packetization Protocols 9-16 Copyright © 2011 by The McGraw-Hill Companies, Inc. All rights reserved.

A computer network is a communication system Connects two or more computers Allows information exchange Networks 9-17 Copyright © 2011 by The McGraw-Hill Companies, Inc. All rights reserved.

Computer Networks Node Client Server Directory server Host Switch Network interface cards (NIC) Network operating system (NOS) Network administrator 9-18 Copyright © 2011 by The McGraw-Hill Companies, Inc. All rights reserved.

Local area networks Home networks Wireless LAN Personal Area networks Metropolitan area networks Wide area networks Network Types 9-19 LAN Copyright © 2011 by The McGraw-Hill Companies, Inc. All rights reserved.

Arrangement is called topology Types of network topology –Legacy Star Bus –Current Ring Tree Hybrid Mesh Network Architecture 9-20 Copyright © 2011 by The McGraw-Hill Companies, Inc. All rights reserved.

Star Network Smaller computers linked to a central unit Central unit is called the network switch Control is maintained by routing 9-21 Return Copyright © 2011 by The McGraw-Hill Companies, Inc. All rights reserved.

Bus Network Each device handles its own communication control There is no host Has a common connecting cable called a backbone or bus All communications travel along this bus 9-22 Return Copyright © 2011 by 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 9-23 Return Copyright © 2011 by The McGraw-Hill Companies, Inc. All rights reserved.

Tree Network Several computers linked to a central node Also known as a hierarchical network Useful in centralized organizations 9-24 Copyright © 2011 by The McGraw-Hill Companies, Inc. All rights reserved. Return

Combination of different topologies Large organizations have a complex of smaller networks –Smaller networks use a variety of configurations –Connected together they form a hybrid Hybrid Network 9-25 Copyright © 2011 by The McGraw-Hill Companies, Inc. All rights reserved. Return

Newest type of topology Does not use a specific type of layout Requires that each node have more than one connection to other nodes Wireless technologies are frequently used Mesh Network 9-26 Copyright © 2011 by The McGraw-Hill Companies, Inc. All rights reserved.

Principal Network Configurations 9-27 Copyright © 2011 by The McGraw-Hill Companies, Inc. All rights reserved.

Terminal Client/Server Peer-to-peer Distributed Network Strategies 9-28 Copyright © 2011 by The McGraw-Hill Companies, Inc. All rights reserved.

Organizational Networks Intranets –Private network within an organization –Provides information to employees Extranets –Private network that connects organizations –Used to allow suppliers and others access 9-29 Copyright © 2011 by The McGraw-Hill Companies, Inc. All rights reserved.

Network Security Firewalls –Hardware & software –Protects against external threats Intrusion detection systems (NIDS) Virtual private networks (VPN) 9-30 Copyright © 2011 by The McGraw-Hill Companies, Inc. All rights reserved.