Download Networking Technologies

"Part I Understanding Information Systems Technology"
I
5
NETWORKING
TECHNOLOGIES
Information Systems Technology
Ross Malaga
Copyright © 2005 Prentice Hall, Inc.
5-1
LEARNING GOALS
• Describe the components of a telecommunications system.
• Compare and contrast the various types of transmission
media
• Identify and explain the various types of computer networks.
• Identify and describe the role of the major hardware items
used in networks.
• Describe the importance of networking protocols and identify
the major ones used in business.
• Identify and describe the role of software used in networks.
• Describe the function of telecommunications services.
• Explain the importance of network planning and the major
components of a network plan.
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Bead Bar Consultant
Networking Needs
• Meredith – How to build a network when there is no
premises wiring?
• Suzanne – Need to connect all locations
• Leda – Connectivity would allow easier exchange of ideas
with franchisees
• Mitch – Remote access to corporate network from anywhere
• Julia – Minimize costs and improve data collection and
communications with all locations
• Miriam – Electronic sales data and marketing materials
• Rachel – Work flow systems to reduce paperwork
• Jim – Use of electronic forms instead of paper forms
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Telecommunications Systems
• Purpose – to transmit data from one location to another
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Voice data
Computer data
Video data
Any data
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Transmission media
Network topology
Data communications hardware
Protocols used in system
Network software
Telecommunications services
• Major components
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Data Format for Network
Transmission
• Data inside computers is in digital form
• Networks transmit two forms of data
– Analog – voice over telephone
– Digital – data over ISDN telephone line
• Analog network cannot carry digital data
– Most of existing telephone system is an analog network
• Conversion of digital data to analog format (when
necessary)
– Modulation
• Amplitude modulation
• Frequency modulation
– Convert on one end of transmission; de-convert on other end
– Modulation–demodulation, or modem for short
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How Modems Work
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Bandwidth
• The measure of capacity of transmission media
• Bits per second (bps)
– Kilobits per second
• Modem communications over telephone lines
– Megabits per second
• Most existing local area networks
– Gigabits per second
• High speed data networks
– Internet backbone
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Network Media
• Physical media
– Electrical signal
• Wire
– Twisted pair
» Phone System
» LAN
– Coaxial
• Signal interference
– Optical signal
• Fiber optic cable
– Thin glass fibers surrounded by coating
– Uses lasers for light source
– Very fast
– Physical media require installation of cable
• Expensive
• Time consuming
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Network Media
• Wireless media
– Radio frequency
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Low power radio waves
Affected by electromagnetic interference
Highly vulnerable to snooping
Conflicting standards
– IEEE 802.11a, b, and G
• Limited distance
– Terrestrial microwave
• Tower
• Satellite
– Geosynchronous – GEO
– Medium earth orbit – MEO
– Low earth orbit – LEO
– Infrared
• Close proximity and “line of sight” location required
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Media Types and Speed
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Computer Networks
• Two or more computers that are connected for the
purpose of sharing data
– File sharing (e.g. MP3s)
– E-mail
– Database sharing
• Computer must be connected to the network media
– Network interface card (NIC)
– Each NIC has its own unique address
• Once connected to the network, the computer (or other
device) becomes a network node
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Transmitting Data in a Network
• Circuit switched network
– Entire circuit from end to end must be open and available
– Guarantees message goes through
– Any one segment along the way goes down, the circuit is
disabled
• Packet switched network
– Message data divided into small pieces called packets, each
with destination address and packet id
– Special network hardware routes packets to destination where
message is reassembled
– More fault tolerant than circuit switched networks
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Network Topologies
• The configurations of network components
• Widely used network topologies
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Bus
Star
Ring
Mesh
Tree
Hybrid
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Bus Network Topology
• Most simple network topology
• All devices connected to a common central
cable
• Inexpensive
• Easily expanded
• If cable fails, the entire network will shut down
• Bus is topology used most widely in businesses
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Bus Network Topology (Continued)
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Star Network Topology
• Star topology is centered around central routing
device called a hub
• All network nodes connect to the hub
• Easy to install and update
• If hub fails, network fails
• Hub can also be a bottleneck
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Ring Network Topology
• Each node connected to two other nodes in a
ring
• Similar to the buss, but with the ends of the buss
connected together
• More reliable than buss or star
– If one node fails, data rerouted around failed node
• Expensive and difficult to install
– Usually used by larger organizations who can afford
the expense and to whom the reliability is very
important
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Ring Network Topology (Continued)
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Mesh Network Topology
• Every node connected to every other node
• Fast
• Reliable
– No hub or bus to fail
– If one device goes down, it is the only node affected
• Expensive
– Every node must be wired to every other node
• Difficult to add nodes
– If there are 32 nodes in a mesh network and you
wish to add a new node, how many new cables must
you add? Copyright © 2005 Prentice Hall, Inc.
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Tree Network Topology
• Combination of bus and star
• Two or more star networks connected using a
bus for the backbone
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Hybrid Topologies
• Combine two or more of the other topologies
• Bus used for LANs and ring used for campus
backbone linking LANs together
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Network Architecture
• Defines how network functions at a logical level
• Two primary types
– Client-server
– Peer-to-peer (P2P)
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Client-server Network Architecture
• Nodes are either clients or servers
• Clients use services
• Servers provide services
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Access to shared data
E-mail
Printing
FAX
• Client software on client node cooperates with
server software on server node
– WWW is largest client server application
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Peer-to-Peer Network Architecture
• All nodes on the network are equal.
• Any node can be both a client and a server.
• Napster was an example of a P2P network used
to share MP3 files.
• Windows printer and file sharing use P2P.
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Local Area Networks (LANs)
• Computer network where the nodes are all in
close proximity
– Department
– Floor in office building
– Small business building
• Provides access to shared resources
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Servers
Printers
Databases
Internet access
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Larger Networks
• Campus area network (CAN)
– Connects LANs within a limited geographic area
• School
• Corporate campus
• Military installation
• Metropolitan area network (MAN)
– Within a town or city
• Wide area network (WAN)
– Two or more LANs that are geographically separate
but linked through a public telephone network
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Data Communications Hardware
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NIC
Hub
Modem
Router – special hardware in packet switched
networks that determines optimal routing path
for packets
• Gateway – converts data from one standard to
another; allows connections of disparate
networks
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Protocols
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An agreed upon set of rules that govern
communications in a network
TCP/IP
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The protocol suite for the Internet
Transmission Control Protocol (TCP)
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Provides a reliable byte-stream transfer service between two endpoints
on an internet
Internet Protocol (IP)
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Defines a delivery mechanism for packets of data sent between all
systems on an Internet
Widely used by business, even for internal networks
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Protocols (Continued)
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Ethernet
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A set of rules for constructing message in a local network
Most widely used protocol for transmitting data over LANs
Listen before talk
Simple
Inexpensive
Flexible
Collisions
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High message volume greatly reduces transmission speed
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Protocols (Continued)
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Token Ring
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Also a set of rules for constructing message in a
local network
Only one node “talks” at a time
Complex
Expensive
More fault tolerant than Ethernet
No collisions
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Transmission speed unaffected by message volume
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Network Software
• Network operating system
– Novell NetWare
– Microsoft Windows Server 2003
• Network management software
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Helps ensure security of network
Monitors performance
Helps administrators reconfigure network
Remote administration via push technology
• Network monitoring software
– Packet sniffers – see data as it moves over network
– Keystroke monitors – see what users are doing
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Telecommunications Services
• Value Added Networks (VANs)
– Proprietary networks built using common carriers
– Provide enhanced services
• Video conferencing
• Electronic data interchange (EDI)
• Virtual Private Networks (VPNs)
– Use encryption to provide a secure end-to-end connection
over common carriers or the Internet
– Remote access to internal networks w/o dialup
• Leased lines
– High speed, long distance data transfer
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Leased Line Comparisons
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Bead Bar Consultant
• How can the Bead Bar use networking technologies?
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Meredith – Wireless connections
Suzanne – Connect all studios to org. software
Leda – Remote access to org. software for franchisees
Mitch – Can we access from onboard ships, also?
Julia – Cost benefits of wireless networking
Miriam – Improved inventory control due to more rapid
transmission of sales and inventory data
– Rachel – Improved efficiency
– Jim – Will we need a network administrator? How about
new policies and procedures for using and accessing the
network?
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Learning Goals Summary
In this chapter you have learned:
 The components of a telecommunications system
 To compare and contrast the various types of transmission
media
 To identify and explain the characteristics of various types of
computer networks
 To identify and describe the role of the major hardware items
used in networks
 The importance of networking protocols and identify the
major ones used in business
 To identify and describe the role of software used in networks
 The function of telecommunications services
 The importance of network planning and the major
components of a network plan
Copyright © 2005 Prentice Hall, Inc.
5-41