Introduction to Information Technology Turban, Rainer and Potter John Wiley & Sons, Inc. Copyright 2005

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Introduction to Information Technology

Turban, Rainer and Potter

John Wiley & Sons, Inc.

Copyright 2005

Network and Telecommunications
Basics

“ Copyright 2005 John Wiley & Sons Inc.”

TG
4

3

Chapter Outline

The telecommunications system

Network services

Network protocols

Network processing

Types of computer networks






“ Copyright 2005 John Wiley & Sons Inc.”

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Learning Objectives

Describe the component of a telecommunications
system

Describe the eight basic types of communications
media, including their advantages and
disadvantages.

Describe the major types of network services.

Describe the Ethernet and TCP/IP protocols.

Differentiate between client/server computing and
peer
-
to
-
peer computing

Describe the two major types of networks.



“ Copyright 2005 John Wiley & Sons Inc.”

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TG4.1The telecommunications system


Telecommunications system: Combination of
hardware and software that transmits information
(text, data, graphics, and voice) from one location to
another.


Analog signal: Continuous waves that transmit
information by altering the amplitude and frequency of
the waves.


Digital signal: A discrete pulse, either on or off, that
conveys information in a binary form.

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Hardware

Communications media

Communications networks

Communications software

Data communications providers

Communications protocols

Communication applications

The major components of a
telecommunications system:


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Hardware devices that support data
transmission and reception across a
telecommunications system.

Modem:

Device that converts signals from
analog to digital and vice versa.

Communications processors

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2005
John Wiley & Sons Inc.”

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Multiplexer:

Electronic device that allows a
single communications channel to carry data
transmission simultaneously from many
sources.

Front
-
end processor:

A small secondary
computer, dedicated solely to communication,
that manages all routing communications with
peripheral devices.

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2005
John Wiley & Sons Inc.”

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Communication media and channels

Communication channel
. Pathway for
communicating data form one location to
another.

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2005
John Wiley & Sons Inc.”

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Cable media:

Communications channels
that use physical wires or cables to
transmit data and information.

Broadcast ( wireless) media:

Communication channels that use
electromagnetic media (the ‘’airwaves’’) to
transmit data.

Twisted
-
pairs wire:

copper wire twisted
together in pairs used for most business
telephone wiring .



“ Copyright
2005
John Wiley & Sons Inc.”

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Coaxial cable.

Insulated copper wire; used to carry
high
-
speed data traffic and television signals.

Fibber
-

optic cable
. Thousand of very thin filaments of
glass fibers, surround by cladding, that transmit
information via light pulses generated by lasers.

Microwave transmission
. Communication channel that
uses towers to send wireless signals; used for high
-
volume, long
-
distance, point
-
to
-
point communication.



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2005
John Wiley & Sons Inc.”

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Satellite transmission
. Communications
channel that uses orbiting satellites to send
digital transmission point
-
to
-
point.

Propagation delay
. Brief pause between the
sending and receipt of a satellite
transmission.

Global positioning system (GPS).

A wireless
system that uses satellites to enable users to
determine their position anywhere on the
earth.



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2005
John Wiley & Sons Inc.”

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Radio transmission
. Communications channel
that uses radio wave frequencies to send data
directly between transmitters and receivers over
short distances.

Satellite radio (digital radio).

Form of radio
transmission that offers uninterrupted, near CD
-
quality music beamed to your radio from space.

Cellular radio technology
. Use of radio
transmission between cells in geographic
service areas and a mobile telephone switching
office, enabling wireless phone service.



“ Copyright
2005
John Wiley & Sons Inc.”

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Personal communication services (PCS)

technology.
Wireless communication technology that uses lower
-
power, higher
-
frequency radio waves than cellular radio
technology, making PCS devices effective in places
where cellular devices are not.

Infrared.

Red light not commonly visible to human eyes;
can be modulated or pulsed for conveying information.

Bandwidth.

The range of frequencies available in a
communications channel stated in bits per second.



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2005
John Wiley & Sons Inc.”

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TG
4.2
Network services


Computer network
. A system connecting
communications media, hardware, and software
needed of two or more computer systems and/ or
devices.


Switched lined
. Telephone lines through which data
transmissions can be routed or switched to their
destination.


Dedicated lines (leased lines).

telephone line that
provide a constant connection between two devices
and require no switching or dialing.

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2005
John Wiley & Sons Inc.”

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Integrated services digital network (ISDN).

A
high
-
speed technology that allows users to
transfer voice, video, image, and data
simultaneously, over existing telephone lines.

Digital subscriber line (DSL).

A high
-
speed,
digital data
-
transmission technology using
existing analog telephone lines.

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2005
John Wiley & Sons Inc.”

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Cable modem
. A modem that operates over
coaxial cable and offers high
-
speed access to
the Internet or corporate intranets.

Packet switching
. Data transmission
technology that breaks up blocks of text into
small, fixed bundles of data (packets) that are
sent independently through the network.

Frame relay
. A data transmission technology
that is faster and less expensive than packet
switching.

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2005
John Wiley & Sons Inc.”

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Fibber distributed data inference (FDDI).

Data transmission standard based on
high
-
speed, high
-
capacity capabilities of
fiber optics.


Asynchronous transfer mode (ATM).

Data
transmission technology that uses packet
switching and allows for almost unlimited
bandwidth on demand.

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2005
John Wiley & Sons Inc.”

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Switched
-
hub technology
. Data transmission
technology that boots local area networks by adding
an ATM
-
like packet
-
switching capability.

Synchronous optical network (SONET).

An interface
standard for transporting digital signals over fiber
-
optic
lines; allows the integration of transmissions from
multiple vendors.

T
-
carrier System
. A digital transmission system that
defines circuits that operate at different rates, all of
which are multiples of the basic
64
kbps used to
transport a signal voice call.



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2005
John Wiley & Sons Inc.”

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Protocol.

The set of rules and procedures
governing transmission across a network

Ethernet.

The most common network
protocol.


TG
4.3
Network protocols

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2005
John Wiley & Sons Inc.”

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Gigabit Ethernet
. The most common network
protocol in large corporations, which provides
data transmission speeds of one billion bits per
second.

Transmission control protocol / internet protocol
(TCP/IP).

A file transfer protocol that can send
large files of information across sometimes
-

unreliable networks with assurance that the data
will arrive uncorrupted.

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2005
John Wiley & Sons Inc.”

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The ISO
-
OSI model defines how software on different
system communicates at different layers. The model
has seven layers, each having its own well
-
defined
function.

Layer
1
: physical layer
: define the mechanism for
communicating with the transmission media and
interface hardware.

Layer
2
: data link layer
: validates the integrity of the
flow of data.

Layer
3
. network layer:

defines the protocols for data
routing to ensure that information arrives at the correct
destination


The International Standards Organization open
systems interconnection protocol (ISO
-
OSI)

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2005
John Wiley & Sons Inc.”

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Layer
4
: transport layer
: defines the protocols for
structuring messages.

Layer
5
: session layer

: coordinates
communications and maintains the session for as
long as needed including security and log
-
on
functions.

Layer
6
: presentation layer
; defines the way data is
formatted, converted and encoded

Layer
7
: application layer.

Defines the way that
applications programs such as e
-
mail interact with
the network



The International Standards Organization open systems
interconnection protocol (ISO
-
OSI) cont…

“ Copyright
2005
John Wiley & Sons Inc.”

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Distributed processing
. Network architecture that
divides processing work between two or more
computers, linked together in a network.

Client/ server computing
. Form of distributed
processing in which some machines (servers)
perform computing functions for end

user PCs
(clients).

Peer
-

to

peer processing
. A type of client/ server
distributed processing that allows two or more
computers to pool their resources, making each
computer both a client and a server

TG
4.4
Network processing strategies

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2005
John Wiley & Sons Inc.”

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Local area network (LAN).

Network that
connects communications devices in a
limited geographical region (e.g., a
building ), so that every user device on the
network can communicate with every
other device.

Topology.

The physical layout and
connectivity of a network

TG
4.5
Types of computer networks

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2005
John Wiley & Sons Inc.”

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LAN technology

File server.

A repository of various software and data files
for the network, which determines who gets access to what
and in what sequence

Network interface card
. Hardware that specifics the data
transmission rate, the size of message units, the
addressing information attached to each message and
network topology.

Gateway.

A communications processor that connects
dissimilar networks by translating from one set of protocols
to another

Bridge.

A communications processor that connects two
networks of the same type.

Router.

A communications processor that routes message
through several connected LANs or to a wide area network.


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2005
John Wiley & Sons Inc.”

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WLANs: Technologies (e.g., Bluetooth and
wifi) that provide LAN connectivity over short
distance, typically limited to less than
150
meters.


Bluetooth
. A wireless technology that
enables temporary, short
-
range connection
between wireless devices and enables these
devices to communicate with each other via
low
-
power radio frequencies.

Wireless local area networks (WLANs)

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2005
John Wiley & Sons Inc.”

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Wi
-
Fi (Wireless Fidelity).

A wireless technology
that can transmit information at a range up to
300
feet; another name for the
802.11
b
standard on which most WLANs run.

Private branch exchange (PBX). a type of LAN
that controls telephone switching at a company
site.




Wireless local area networks (WLANs)

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2005
John Wiley & Sons Inc.”

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A network, generally are provided by a
common telecommunications carrier, that
covers a wide geographic area.

Value
-
added network (VAN).

A private, data
-
only network that is managed by an outside
third party and used by multiple
organizations to obtain economies in the
cost of network service and network
management.


Wide area networks (WAN)

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2005
John Wiley & Sons Inc.”

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Virtual private network (VPN).

A WAN
operated by a common carrier; provides
a gateway between a corporate LAN
and the Internet.


Tunnelling.

The process of sending data
over the Internet in encrypted form.

Wide area networks (WAN) cont…

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2005
John Wiley & Sons Inc.”

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Enterprise Networking


Interconnected multiple LANs and
WANs.

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2005
John Wiley & Sons Inc.”

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