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Technology in Action
Chapter 12
Behind the Scenes: Networking and
Security in the Business World
Copyright © 2011 Pearson Education, Inc. Publishing as Prentice Hall
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Chapter Topics
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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
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Chapter Topics (cont.)
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Types of transmission media
Network software
Network adapters
Moving data in a client/server network
Securing networks
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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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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
• WAN
– Wide area
network
– Computers
linked over large
geographic
areas
• MAN
– Metropolitan
area network
– Computers
linked within a
city or county
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Classifications of
Client/Server Networks
• PAN
– Personal area network
– Wireless devices connected in close proximity
to each other
• Intranet
– Private corporate network
– Protected from the Internet by a firewall
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Classifications of
Client/Server Networks
• 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
• 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
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Servers
• 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 Technologies
Topology
Bus
Advantages
Disadvantages
Uses a minimal amount of cabling.
Breaks in the cable can disable the network.
Large numbers of users will greatly decrease
performance because of high volumes of data
traffic.
Adding or removing nodes disables the
network.
Failure of one computer can bring down the
entire network.
Problems in data transmission can
sometimes be difficult to find.
Easy, reliable, and inexpensive to install.
Ring
Star
Allocates access to the network fairly.
Performance remains acceptable even
with large numbers of users.
Failure of one computer does not affect
other computers on the network.
Centralized design simplifies
troubleshooting and repairs.
Requires more cable (and possibly higher
installation costs) than a bus or ring topology.
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.
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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
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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 Media
802.11 Standard
• In business, wireless media are usually
add-ons to a wired network
• Wi-Fi 802.11 standard
– 802.11g
– 802.11n
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Network Operating
Systems (NOS)
• Provide the protocol that controls the
communication among devices on the
network
• Many modern OSs include NOS client
software
• Major network operating systems
– Windows Server 2008
– UNIX
– Novell SUSE Linux Enterprise
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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
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Network Navigation Devices
• Media access control (MAC) address
– Six two-digit numbers (such as
01:40:87:44:79:A5)
– Physical address of network adapter
– Internal network identification
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Network Navigation Devices
• Repeaters
– Amplify a signal and
retransmit it
– Extend cable runs
• Hubs
– Transmit signals; have
multiple ports
• Receive a signal from a
device
• Reconstruct the signal
• Transmit the signal to
all ports on the hub
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Network Navigation Devices
• 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
• Firewalls
– Prevent access to the network by
unauthorized users
– Composed of software and/or hardware
– 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?
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Chapter 12 Summary Questions
• How does a client/server network differ
from a peer-to-peer network?
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Chapter 12 Summary Questions
• What are the different classifications of
client/server networks?
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Chapter 12 Summary Questions
• What components are needed to construct
a client/server network?
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Chapter 12 Summary Questions
• What do the various types of servers do?
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Chapter 12 Summary Questions
• What are the various network topologies
(layouts), and why is network topology
important in planning a network?
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Chapter 12 Summary Questions
• What types of transmission media are
used in client/server networks?
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Chapter 12 Summary Questions
• What software needs to be running on
computers attached to a client/server
network, and how does this software
control network communications?
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Chapter 12 Summary Questions
• How do network adapters enable
computers to participate in a client/server
network?
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Chapter 12 Summary Questions
• What devices assist in moving data
around a client/server network?
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Chapter 12 Summary Questions
• What measures are employed to keep
large networks secure?
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Copyright © 2011 Pearson Education, Inc.
Publishing as Prentice Hall
Chapter 12
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