Chapter 6

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Managing
Telecommunications

Chapter 6


Information Systems Management In Practice 5E

McNurlin & Sprague


Copyright 2002 by

Prentice Hall, Inc.

6
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2

How are telecommunications


analogous to highway systems?


The flow

of information within and among the
corporate office, departments, and individuals
analogous to traffic on a highway.


Building of systems

-

IS department responsible
for designing, building, and maintaining IS in same
way as government is for the streets, roads, and
highways.


Managed by users

-

both systems are managed by
users, not builders.


Standards

-

must be issued for highway (enforced
by police) and message traffic

Copyright 2002 by

Prentice Hall, Inc.

6
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3

The Evolving Telecommunications
Scene


New telecommunications infrastructure
is being built


The telecom industry is being
transformed



Copyright 2002 by

Prentice Hall, Inc.

6
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4

The Internet is the Network of
Choice


The Internet has arrived for business
use: Beginning in 1994, because of
the invention of WWW
-

a hyper
-
linked graphical layer of the Net.
Funded by DOD in 1960, intended for
electronic shipment of large scientific
and research files. Built as a
distributed network, without a
controlling node.

Copyright 2002 by

Prentice Hall, Inc.

6
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5

OSI Reference Model


The worldwide telephone system has been so
effective in connecting people because it has
been based on common standards worldwide.


Closed vs. open networks
: closed network
-

one
that is offered by one supplier and to which only
the products of that supplier can be attached.
Open networks are based on international
standards so products of many manufacturers
can be attached.


Seven layer OSI reference model guides the
development for computer networks.

Copyright 2002 by

Prentice Hall, Inc.

6
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6

OSI Reference Model


Analogy of mailing a letter
:
-

see Figure 6
-
2


Control information (address and type of
delivery) is on the envelope
-

determines the
services provided by the next lower layer and
addressing information for next lower layer.
When a layer receives a “message” from the next
higher layer, it performs the requested services
and “wraps” the message in its own layer of
control information. It passes the “bundle” to the
layer directly below it. On the receiving end, a
layer receiving a bundle from a lower layer
unwraps the outermost layer of control
information, interprets the information, and acts
on it.

Copyright 2002 by

Prentice Hall, Inc.

6
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7

OSI Reference Model:

The Seven Layers


7
-

Application Layer
: contains the protocols
embedded in the applications used, e.g., HTTP, FTP
for transferring files in Internet, X.500 Directory
Services, X.400 Mail Handling, postscript


6
-

Presentation
: translate data to and from
language and format of 7; e.g. NetBIOS to
communicate among peripherals


5
-

Session
: control the dialog for a session and
acts as a moderator and sees that messages are
sent as directed; e.g., Secure Sockets Layer (SSL)
to provide Internet security

Copyright 2002 by

Prentice Hall, Inc.

6
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8


4
-

Transport Layer
: handle flow control and
ensure integrity of each message,
resequencing portions of data packets to
ensure reliable packet delivery; TCP
-
Transmission Control Protocol


3
-

Network Layer
: route packets to their
destination; IP
-

Internet Protocol, allows
packets to traverse an “Internet”

OSI Reference Model:

The Seven Layers

Copyright 2002 by

Prentice Hall, Inc.

6
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9


2
-

Logical Link
: protocols do error
correction; LAN protocols, such as
Ethernet and Token Ring, work here


1
-

Physical Layer
: defines the physical
connection of the devices to the network;
defines electrical and mechanical
characteristics of connections,
characteristics of transmission wires
(e.g., DS1, coax)

OSI Reference Model:

The Seven Layers

Copyright 2002 by

Prentice Hall, Inc.

6
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10


Wireless

will be the leading access
technology because people are mobile,
PC may be next era cell phone



Personal area networks (PANs)


LANs


The last mile


Long distance


M
-
commerce

Wireless is the Next Frontier

Copyright 2002 by

Prentice Hall, Inc.

6
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11

To connect a laptop computer to a cell
phone or to connect computers in a room
creating an ad hoc LAN or to create a PAN
in one’s office



PAN is a short distance network (30 ft.)



Uses:


Synchronize a laptop and a PDA


Dispense money to a toll booth

Wireless is the Next Frontier:
Personal Area Networks (PANs)

Copyright 2002 by

Prentice Hall, Inc.

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12


Advantage
: used in hazardous environments,
where no wiring ducts available, disaster
recovery, and temporary installations.

1. Infrared light LANs
-

transmit at frequencies in
the lowest frequency in the light spectrum.
Transmitters and receivers in sight with each
other. Wide BW. Can be licensed anywhere.

2. Narrowband radio frequency (RF)
-

transmit
on a center frequency. RF transmitters must
be licensed, government regulates radio
signals.

Wireless is the Next Frontier:
LANs

Copyright 2002 by

Prentice Hall, Inc.

6
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13


Spread Spectrum LANs use RF bands that are
allocated to wireless nets by FCC, signal is spread
by transmitting a chirp pattern, receiver accepts
signals it can decode. RF
-
noisy environment.


Wireless LANs topologies
-

see Figure 6.5

1. Peer Level System: Each unit communicated with
every other unit. Low cost and no master control
needed. Breaks down as traffic grows.

2. Centrally Controlled System (client
-
server):
Central controller is linked to a wired LAN.
Control unit handles all communications, and has
centralized network management and access
control.

Wireless is the Next Frontier:
LANs

Copyright 2002 by

Prentice Hall, Inc.

6
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14


Uses RF technology between a home or
business and a telephone company’s
central office.


Also called “fixed wireless,” this
technology is being used in developing
countries and remote locations in place of
wire line.


Networks are rapidly deployed


Less costly


Wireless is the Next Frontier:
Wireless Local Loops

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Prentice Hall, Inc.

6
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15


The most familiar wide area wireless
technology is cell phones.


Standards


Global Systems for Mobile Communications
(GMS)


Time division for Multiple Access (TDMA)


Code Division Multiple Access (CDMA)

Wireless is the Next Frontier:
Wireless Long Distance

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Prentice Hall, Inc.

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16


Technologies:


1G, first generation cell phones used
analog technology and circuit switching


2G, second generation cell phones use


Digital technology and circuit switching


Carry data and messages using short
messaging service (SMS)


2.5G Upcoming, will extend 2G digital
technologies (GSM, CDMA and TDMA)


3G Upcoming, will provide WANs for PCs
and multimedia

Wireless is the Next Frontier:
Wireless Long Distance

Copyright 2002 by

Prentice Hall, Inc.

6
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17


M
-
Commerce stands for “Mobile
Commerce”


Objective: Being able to conduct
commerce digitally from wireless devices


Technology: Cellular radio technology at
higher frequencies than cell phones.
Transmitters and receivers have lower
power, thus cells are smaller.

Wireless is the Next Frontier:

M
-
Commerce

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Prentice Hall, Inc.

6
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18


Wireless services used for LANs and
PCSs are in the microwave range.
Are they safe for humans?


Is Wireless Safe?

Copyright 2002 by

Prentice Hall, Inc.

6
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19

The IS Department plays three roles:

1.
Create the telecom architecture for the
enterprise


Connectivity


Interoperability

2.
Operate the network

3.
Stay close to the forefront of the field

The Role of the IS Department

Copyright 2002 by

Prentice Hall, Inc.

6
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20

The Telecom world is:


Big and getting bigger


Complex

The telecom world has caused a great
impact in the new economy


E
-
mail, Web sites, transactions, and business

Generations of Internet economy


Wired


Unwired

Conclusion