1. Technology in Action Chapter 12 Behind the Scenes: Networking and Security in the Business World Copyright © 2012 Pearson Education, Inc. Publishing.

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


Chapter Topics (cont.)

• Types of transmission media• Network software• Network adapters• Moving data in a client/server network• Securing networks


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


Networking Disadvantages

• Networks– Complex– Additional personnel required to maintain

them– Require special equipment and software


Client/Server Networks

• Data flows efficiently

• Servers respond to requests from clients

• Servers perform specific tasks

• Scalable• Centralized


Classifications of Client/Server Networks

• LAN– Local area network– Computers linked over

a small geographic area


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



• PAN– Personal area network– Wireless devices connected in close proximity

to each other• Intranet

– Private corporate network– Protected from the Internet by a firewall



• Extranets– Only certain corporations or individuals can

access– Useful for enabling electronic data

interchange– Use virtual private networks for security


Constructing Client/Server Networks

• Servers• Network

topologies• Transmission

media• Network operating

system software• Network adapters• Network

navigation devices


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


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


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


Network Topologies

• The physical or logical layout of computers, transmission media, and other components

• Types of network topologies– Bus– Ring– Star– Hybrid


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


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


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


Avoiding Data Collisions on an Ethernet Network


Comparing Topologies


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


Choosing a Cable

• Maximum run length• Bandwidth • Bend radius• Cable and installation costs• Susceptibility to interference• Signal transmission methods


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)


Coaxial Cable

• Four components– Copper core– Nonconductive insulating material– Braided metal– Plastic cover


Fiber-Optic Cable

• Components include– Glass or plastic fibers– Cladding– Outer jacket

• Uses light impulses to transmit data

• Immune to interference


Wireless Media802.11 Standard

• In business, wireless media are usually add-ons to a wired network

• Wi-Fi 802.11 standard


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


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


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


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


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


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


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


Network Firewall Layout


Chapter 12 Summary Questions

• What are the advantages of a business network?



• How does a client/server network differ from a peer-to-peer network?



• What are the different classifications of client/server networks?



• What components are needed to construct a client/server network?



• What do the various types of servers do?



• What are the various network topologies (layouts), and why is network topology important in planning a network?



• What types of transmission media are used in client/server networks?



• What software needs to run on computers attached to a client/server network, and how does this software control network communications?



• How do network adapters enable computers to participate in a client/server network?



• What devices assist in moving data around a client/server network?



• What measures are employed to keep large networks secure?


47

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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

1. Technology in Action Chapter 12 Behind the Scenes: Networking and Security in the Business World Copyright © 2012 Pearson Education, Inc. Publishing.

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