Download Network and Telecommunications

Networks and
Telecommunications
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Alter – Information Systems
© 2002 Prentice Hall
Opening Case: FedEx
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Tracks each package through each step
from shipper to recipient
Expanded into being a fully integrated
corporate partner that picks up, transports,
warehouses, and delivers a customer’s
finished goods
E-business tools
Alter – Information Systems
© 2002 Prentice Hall
Applying Telecommunications
in Business
TELECOMMUNICATIONS – the
transmission of data between
devices in different locations
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Alter – Information Systems
© 2002 Prentice Hall
Vital Role of Telecommunications
in E-Business
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Telecommunications essential to:
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E-retailers
E-marketplaces
Internet content providers
Internet service providers (ISPs)
Application service providers (ASPs)
Telephone and cable companies
Telecommunication equipment manufacturers
Internet and telecommunications software
firms
Alter – Information Systems
© 2002 Prentice Hall
Convergence of Computing and
Communications
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Reliance of telecommunications on
computers
Role of telecommunications in computing
New wired and wireless transmission
New combinations of data and computing
Alter – Information Systems
© 2002 Prentice Hall
Figure 10.1
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Alter – Information Systems
© 2002 Prentice Hall
Figure 10.2
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Alter – Information Systems
© 2002 Prentice Hall
Types of Networks
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Alter – Information Systems
© 2002 Prentice Hall
A Typical Home Network
Figure 10.3
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Alter – Information Systems
© 2002 Prentice Hall
A Local Area Network (LAN) in a
Business
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LANs connect PCs and other equipment
within a local area
Benefits:
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Sharing equipment
Sharing personal files
Sending messages
Sharing databases
Administering software
Usually wired, but may also be wireless
Alter – Information Systems
© 2002 Prentice Hall
Figure 10.4
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Alter – Information Systems
© 2002 Prentice Hall
A Telephone Network:
Figure 10.6
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Alter – Information Systems
© 2002 Prentice Hall
The Internet (From a User’s
Viewpoint): Figure 10.7
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Alter – Information Systems
© 2002 Prentice Hall
A Wide Area Network (WAN)
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WANs are networks that span a wide
geographical area
Many uses, e.g.,
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Form the communication backbone for large
distributed organizations
Focus on particular transaction processing
application(s)
Transfer and consolidate corporate data, etc.
Alter – Information Systems
© 2002 Prentice Hall
Figure 10.8
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Alter – Information Systems
© 2002 Prentice Hall
Functions and Components of
Telecommunication Networks
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Alter – Information Systems
© 2002 Prentice Hall
Basic Terminology
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Network = a set of devices and
communications channels
 Devices are called nodes
Connectivity = the ability to transmit data
between devices at different locations
Switching = the process of directing a
signal from its source to its destination
Alter – Information Systems
© 2002 Prentice Hall
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Channel = a path along which data are
transmitted
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Wired or wireless
Decoding = converting the data back into
their original form upon arrival at its
destination
Network management = the process of
monitoring the network’s operations,
detecting and repairing faults, and balancing
Alter – Information Systems
traffic
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Figure 10.9
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Alter – Information Systems
© 2002 Prentice Hall
Generating and Receiving Data
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An ever increasing number of different
types of devices can be connected to a
network
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Front-end processor – a specialized
computer that handles network traffic for
another computer
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General purpose
Special purpose
Improves the efficiency of the overall system
Alter – Information Systems
© 2002 Prentice Hall
Transmitting Analog versus Digital
Data
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Data transmission requires that data be
encoded as electrical or optical signals,
and then decoded at destination
Two important factors:
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Are the original data analog or digital?
Are the data transmitted in analog or digital
form?
Alter – Information Systems
© 2002 Prentice Hall
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Analog data, analog signal
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Original signal added to a carrier signal
Used for voice communication
Analog data, digital signal
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Data must be digitized
The digitized data are only an approximation of
the original
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The quality depends on the precision of the
digitizing process
Alter – Information Systems
© 2002 Prentice Hall
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Digital data, analog signal
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Must use a modem at each end
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Superimposes a pattern of 0s and 1s on the carrier
signal
Digital data, digital signal
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Modems are no longer needed
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Digital subscriber line (DSL)
Alter – Information Systems
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Significance of analog vs. digital
transmission
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Digital technology improves the quality of the
transmission
Digital coding allows for error detection and
correction
Digital data can be readily manipulated
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High definition television (HDTV)
Alter – Information Systems
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Directing Data From Source to
Destination
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Dedicated line – a telephone line leased
by a firm, and used exclusively by that firm
Switch – a special purpose computer that
directs incoming messages along a path
Private branch exchange (PBX) – a
special-purpose computer that distributes
calls within a customer’s site
Alter – Information Systems
© 2002 Prentice Hall
Circuit Switching vs. Packet
Switching
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CIRCUIT SWITCHING:
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The method used in telephone networks
Sets up a temporary circuit between the
source and the destination
Resources are reserved for the duration of
the session (call)
Alter – Information Systems
© 2002 Prentice Hall
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PACKET SWITCHING:
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Appropriate when data are transmitted
infrequently from a large number of nodes
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The message is divided into packets
containing control information
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No circuit is established
Provides better sharing of resources
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Used on the Internet
Multiple users share the same resources
Alter – Information Systems
© 2002 Prentice Hall
Figure 10.13
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Alter – Information Systems
© 2002 Prentice Hall
Transmitting Data Through Wire
and Wireless Media
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Bandwidth – corresponds to the capacity
of the transmission channel
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Mbps or Gbps
A major limitation for the information
superhighway
Alter – Information Systems
© 2002 Prentice Hall
Wired Transmission
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TWISTED PAIR
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COAXIAL CABLE
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Used for voice transmission and for low
volume data transmission
Slow
Used in LANs and for data transmissions of
less than 10 miles
Faster and more versatile than twisted pair
Alter – Information Systems
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FIBER OPTIC
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Carries data in the form of light
Extremely fast
Very light
Very difficult to tap into
Very little data loss
Costly
Alter – Information Systems
© 2002 Prentice Hall
Wireless Transmission
Figure 10.16
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Alter – Information Systems
© 2002 Prentice Hall
Telecommunications Standards
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De facto standards – established by the
fact that a product dominates the market,
e.g., Windows
De jure standards – defined by industry
groups or by the government
Many de facto standards become de jure
standards
Alter – Information Systems
© 2002 Prentice Hall
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The OSI (open systems interface)
model is a framework for defining
telecommunications standards
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Covers all aspects of network operations and
management
Developed by the International Standards
Organization (ISO)
Each level in the model is implemented
through protocols
Alter – Information Systems
© 2002 Prentice Hall
Figure 10.18
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Alter – Information Systems
© 2002 Prentice Hall
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TCP/IP (Transmission Control Protocol/
Internet Protocol)
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Used on the Internet
Five layer model
HTML and HTTP are examples of application
layer standards
Open vs. proprietary standards
Alter – Information Systems
© 2002 Prentice Hall
More About Network
Technology
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Alter – Information Systems
© 2002 Prentice Hall
More About LANs
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Main topologies:
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Star – all messages go through a central
node that serves as a switch
Ring – the nodes are linked directly in a
closed loop
Bus – each node is attached to a central
channel called a bus
Alter – Information Systems
© 2002 Prentice Hall
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Token passing:
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One of the most common methods for internal
communication
Used in ring topologies
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Token – a bit pattern that circulates between
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the nodes
To transmit data, a node appends it to the
token
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Alter – Information Systems
© 2002 Prentice Hall
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LANs use two types of transmission:
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Baseband – the entire capacity of the cable
is used to transmit a single digitally encoded
signal
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Ex.: Ethernet
Broadband – the capacity of the cable is
divided into separate frequencies to permit it
to carry several signals at the same time
Alter – Information Systems
© 2002 Prentice Hall
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Interconnection devices – a combination
of hardware and software:
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Routers
Bridges
Gateways
Alter – Information Systems
© 2002 Prentice Hall
More About WANs
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Virtual private networks (VPNs):
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A private network configured within a public
network
Can be built on top of the Internet
Service offered by the telephone companies
and ISPs
Alter – Information Systems
© 2002 Prentice Hall
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Value added networks (VANs):
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Public data networks that “add value” by
transmitting data and by providing access to
commercial databases and software
Use packet switching
Subscription based
Often used in electronic data interchange
(EDI) systems
Alter – Information Systems
© 2002 Prentice Hall
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Public switched data network technologies
(PSDN)
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Data flows through a public network
managed by a telecommunications carrier
Most common technologies:
ISDN (integrated service digital network)
 X.25
 Frame relay
 Asynchronous transfer mode (ATM)
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Alter – Information Systems
© 2002 Prentice Hall
Wireless Networking
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Wireless application protocol (WAP) a standard technology framework for
wireless Internet
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Allows for some of the Internet content to be
accessed by mobile devices
Bluetooth – a fast short-range wireless
technology
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Wireless office
Alter – Information Systems
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IP Telephony
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Voice over the Internet
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Limited by the packet switching technology
currently used by the Internet
Alter – Information Systems
© 2002 Prentice Hall
Telecommunications Policy
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Why should the government permit only some
companies to sell products in a particular line of
business?
What should be the rationale for regulating
telecommunications and setting prices?
Who should be able to use specific public
resources, such as radio frequencies?
To what extent is universal access possible and
to what extent should it be guaranteed?
Alter – Information Systems
© 2002 Prentice Hall