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1
Technology in Action
Chapter 12
Behind the Scenes: Networking and Security in the Business World
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall 2
Chapter Topics
• Advantages of business networks• Client/server vs. peer-to-peer networks• Classifications of client/server networks• Client/server network components• Types of servers• Network topologies
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall 3
Chapter Topics (cont.)
• Types of transmission media• Network software• Network adapters• Moving data in a client/server network• Securing networks
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall 4
Networking Advantages
• Networks– Increase productivity– Enable the sharing of hardware resources– Facilitate knowledge sharing– Enable the sharing of software– Facilitate Internet connectivity– Enable enhanced communication
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Networking Disadvantages
• Networks– Complex– Additional personnel required to maintain
them– Require special equipment and software
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Client/Server Networks
• Data flows efficiently
• Servers respond to requests from clients
• Servers perform specific tasks
• Scalable• Centralized
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Classifications of Client/Server Networks
• LAN– Local area network– Computers linked over
a small geographic area
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Classifications of Client/Server Networks (cont.)
• WAN– Wide area network– Computers linked over
large geographic areas
• MAN– Metropolitan area
network– Computers linked
within a city or county
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall 9
Classifications of Client/Server Networks (cont.)
• PAN– Personal area network– Wireless devices connected in close proximity
to each other• Intranet
– Private corporate network– Protected from the Internet by a firewall
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall 10
Classifications of Client/Server Networks (cont.)
• Extranets– Only certain corporations or individuals can
access– Useful for enabling electronic data
interchange– Use virtual private networks for security
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Constructing Client/Server Networks
• Servers• Network
topologies• Transmission
media• Network operating
system software• Network adapters• Network
navigation devices
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Servers
• The number and types of servers depend on network size and workload
• Dedicated servers– Perform one specific function
• Authentication servers– Keep track of network logins and services
available• File servers
– Store and manage files
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Servers (cont.)• Print servers
– Manage client-requested printing jobs– Create a print queue (prioritize print jobs)
• Application servers– Act as a storage area for application software
• Database servers– Provide clients with access to database
information• E-mail servers
– Process and deliver incoming and outgoing e-mail
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall 14
Servers (cont.)
• Communications servers– Handle communications between networks,
including the Internet– Often the only device on the network directly
connected to the Internet• Web servers
– Host a Web site available through the Internet
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Network Topologies
• The physical or logical layout of computers, transmission media, and other components
• Types of network topologies– Bus– Ring– Star– Hybrid
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Bus Topology
• All nodes are connected in sequence on a single cable
• Networked computers communicate with each other
• One computer transmits data at a time• Becoming obsolete
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Ring Topology
• Nodes are laid out in a ring
• A token (data packet) flows in one direction from device to device
• Recent versions have data transfer rates of up to 100 Mbps
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Star Topology
• Most widely deployed client/server layout
• Nodes connect to a central communications device (switch)
• A node sends a signal to the switch, which retransmits it to the other nodes
• A node accepts only signals addressed to it
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Avoiding Data Collisions on an Ethernet Network
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Comparing Topologies
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Topology Advantages DisadvantagesBus Uses a minimal amount of cabling. Breaks in the cable can disable the network.
Easy, reliable, and inexpensive to install.
Large numbers of users will greatly decrease performance because of high volumes of data traffic.
Ring Allocates access to the network fairly.Adding or removing nodes disables the network.
Performance remains acceptable even with large numbers of users.
Failure of one computer can bring down the entire network.Problems in data transmission can sometimes be difficult to find.
StarFailure of one computer does not affect other computers on the network.
Requires more cable (and possibly higher installation costs) than a bus or ring topology.
Centralized design simplifies troubleshooting and repairs.
The switch is a central point of failure. If it fails, all computers connected to that switch are affected.
Easy to add more computers or groups of computers as needed (high scalability).Performance remains acceptable even with large numbers of users.
Transmission Media
• The routes data takes to flow between devices on a network
• Wired – Twisted-pair– Coaxial– Fiber optic
• Wireless
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Choosing a Cable
• Maximum run length• Bandwidth • Bend radius• Cable and installation costs• Susceptibility to interference• Signal transmission methods
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Twisted-Pair Cable• Pairs of copper wire twisted around each other• Twists make the wires less susceptible to
outside interference• Two types
– Shielded twisted-pair (STP)– Unshielded twisted-pair (UTP)
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Coaxial Cable
• Four components– Copper core– Nonconductive insulating material– Braided metal– Plastic cover
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Fiber-Optic Cable
• Components include– Glass or plastic fibers– Cladding– Outer jacket
• Uses light impulses to transmit data
• Immune to interference
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Wireless Media802.11 Standard
• In business, wireless media are usually add-ons to a wired network
• Wi-Fi 802.11 standard
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Network Operating Systems (NOS)
• Provide services necessary for client computer and server to communicate
• Many modern OSs include NOS client software
• Major network operating systems– Windows Server 2008 R2– UNIX– Linux– Novell SUSE Linux Enterprise
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall 28
Network Adapters• Devices that enable computers to
communicate on a network• Network interface cards (NICs)• Three functions
– Generate network transmission signals– Create data packets– Act as information gatekeepers
• Ethernet compliant• Wireless NICs
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall 29
Network Navigation Devices
• Media access control (MAC) address– Six two-position characters (such as
01:40:87:44:79:A5)– Physical address of network adapter– Internal network identification
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall 30
Network Navigation Devices (cont.)
• Switches and bridges– Send data on a
specific route through the network
– Bridges send data between collision domains
• Routers– Send information
between two networks
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Network Security Threats
• Human errors and mistakes• Malicious human activity
– Current and former employees hacking or planting viruses
• Natural events and disasters– Hurricanes, floods, fire
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Network Security
• Authentication– User ID and password used to access the network– Use of biometric devices– Use of a possessed object for access
• Access privileges– Enable access to certain network systems
• Physical protection measures– Restrict physical access to sensitive network
equipment– Magnetic card readers– Biometric access devices
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Network Security (cont.)
• Firewalls– Prevent access to the network by
unauthorized users– Composed of software, hardware, or both– Screen and validate data packets– Bastion host/proxy server
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Network Firewall Layout
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Chapter 12 Summary Questions
• What are the advantages of a business network?
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall 36
Chapter 12 Summary Questions
• How does a client/server network differ from a peer-to-peer network?
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall 37
Chapter 12 Summary Questions
• What are the different classifications of client/server networks?
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall 38
Chapter 12 Summary Questions
• What components are needed to construct a client/server network?
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall 39
Chapter 12 Summary Questions
• What do the various types of servers do?
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall 40
Chapter 12 Summary Questions
• What are the various network topologies (layouts), and why is network topology important in planning a network?
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall 41
Chapter 12 Summary Questions
• What types of transmission media are used in client/server networks?
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall 42
Chapter 12 Summary Questions
• What software needs to run on computers attached to a client/server network, and how does this software control network communications?
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall 43
Chapter 12 Summary Questions
• How do network adapters enable computers to participate in a client/server network?
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall 44
Chapter 12 Summary Questions
• What devices assist in moving data around a client/server network?
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall 45
Chapter 12 Summary Questions
• What measures are employed to keep large networks secure?
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall 46
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All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic,
mechanical, photocopying, recording, or otherwise, without the prior written permission of the publisher. Printed in the United States of America.
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
47Chapter 12
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