Chapter 5, Internet Hardware, Software and Communications

morningbreadloafNetworking and Communications

Oct 30, 2013 (3 years and 10 months ago)

130 views



2001 Prentice Hall, Inc. All rights reserved.

Chapter 5, Internet Hardware,
Software and Communications

Outline

5.1

Introduction

5.2

Structure of the Internet

5.3

Hardware


5.3.1

Servers


5.3.2

Communications Media


5.3.3

Storage Area Networks (SANs)

5.4

Connecting to the Internet


5.4.1

Digital Subscriber Lines (DSL)


5.4.2

Broadband


5.4.3

Integrated Services Digital Network (ISDN)



5.4.4

T
-
1 and T
-
3 Lines

5.5

Internet2

5.6

Software


5.6.1

Application Service Providers (ASPs)


5.6.2

Databases



2001 Prentice Hall, Inc. All rights reserved.

Chapter 5, Internet Hardware,
Software and Communications

Outline

5.7

Operating Systems


5.7.1

UNIX


5.7.2

Microsoft Windows


5.7.3

Linux


5.7.4

Mac OS X

5.8

Enhancing Business Communication


5.8.1

Intranets and Extranets


5.8.2

Streaming Audio and Video


5.8.3

Internet Telephony


5.8.4

Web Casting and Webconferencing




2001 Prentice Hall, Inc. All rights reserved.

5.1 Introduction


Connection media


Cost of connecting


Streaming media (audio and video)


Internet telephony


Technologies used to enhance online business
communications



2001 Prentice Hall, Inc. All rights reserved.

5.2 Structure of the Internet


IP address

(Internet Protocol)


Computers use IP addresses to locate other computers on the
Internet


Packet


Source address, a destination address, sequencing
information, error
-
control information and the data to be
delivered to the destination address


Router


Used to move packets across the Internet efficiently





2001 Prentice Hall, Inc. All rights reserved.

5.3 Hardware


The Internet employs many advanced hardware
technologies


Various communications media used to connect hosts


The roles hosts play on the Internet


Servers


Communications Media


Storage Area Networks (SAN)





2001 Prentice Hall, Inc. All rights reserved.

5.3.1 Servers


Server


A host on the Internet that manages network resources and
fulfills requests from clients



Web servers, e
-
mail servers, database servers and file servers


A single server may provide multiple services


A Web server stores Web pages and delivers the
pages to clients upon request


Protocols for delivering information over the Web


Hypertext transfer protocol (HTTP)


File transfer protocol (FTP)


Post office protocol (POP)


Simple mail transfer protocol (SMTP)



2001 Prentice Hall, Inc. All rights reserved.

5.3.2 Communications Media


Communications medium



The hardware that connects computers and other digital
equipment


Bandwidth


Indicates how much data can be transferred through the
medium in a fixed amount of time


Usually measured in bits per second (bps)


Copper wire


The primary communications medium



2001 Prentice Hall, Inc. All rights reserved.

5.3.2 Communications Media


Fiber
-
optic cable


Composed of flexible glass fiber, is thinner and lighter than
traditional copper wire, yet has much wider bandwidth


Uses short bursts of light to represent bits


Optical modem


Modem stands for modulator and demodulator


Translates digital signals from computers into light through a
process called
modulation


Opto chip


Converts the most basic particle of light, the
photon
, into an
electric current


Allows tremendous amounts of data to be sent over fiber
-
optic networks through particles 100 times smaller than the
diameter of a human hair





2001 Prentice Hall, Inc. All rights reserved.

5.3.2 Communications Media


The strength of a signal transmitted over a
communications medium is reduced as the signal
travels farther and farther



Repeater


Can be used to alleviate this problem by amplifying and
retransmitting the signal across segments of copper wire or
fiber
-
optic cable


Transmission costs


Fiber
-
optic cable is more expensive than copper wire


Installation of fiber
-
optic cable is more complicated than
installation of copper wire


Fiber
-
optic cable requires fewer repeaters



2001 Prentice Hall, Inc. All rights reserved.

5.3.3 Storage Area Networks


Companies produce large volumes of data to
support sales analysis tools, enterprise resource
planning (ERP) systems, multimedia Web sites
and e
-
commerce systems



Storage Area Network

(SAN)


Provides high
-
capacity, reliable data storage and delivery on
a network



Allows network administrators to collect data in logical
groups on data servers distributed throughout the network


SAN devices store large volumes of data and may also
provide backup and recovery services




2001 Prentice Hall, Inc. All rights reserved.

5.3.3 Storage Area Networks


Mirroring

technology


A SAN device stores redundant copies of data, so that if one
copy is lost or damaged, a mirrored copy can be used


Fiber
-
channel technology



A high
-
speed communications medium based on fiber
-
optic
technology that provides transfer rates of 100 Mbps


Network storage devices providers


EMC


Compaq


StorageNetworks




2001 Prentice Hall, Inc. All rights reserved.

5.4 Connecting to the Internet


Most home users subscribe to an
Internet Service
Provider (ISP)

to connect to the Internet



Some charge fixed monthly fees for Internet access


Some offer free Internet access in return for personal
demographic data



Analog modem


User connects to an ISP using the modem, which then
connects the user to the Internet


Takes digital signals from the computer and turns them into
analog signals


Analog signals can be transmitted over a telephone line just
like a human voice


A modem at the ISP then converts the sound back into a
digital signal that can be transmitted over the Internet




2001 Prentice Hall, Inc. All rights reserved.

5.4 Connecting to the Internet


Free Internet access providers


NetZero


IsFree.com


ACI


Address.com


Web TV


A low
-
cost technology for connecting to the Internet through
the user’s television, instead of a PC



WebTV users can dial into an ISP through a modem to surf
the Web, send and receive e
-
mail and chat with other people


The basic WebTV system includes a wireless keyboard, an
8.6
-
GB, a hard drive and a 56
-
Kbps modem






2001 Prentice Hall, Inc. All rights reserved.

5.4.1 Digital Subscriber Lines


Digital Subscriber Lines (DSL)


Offers high
-
bandwidth Internet access over existing copper
telephone lines



Splits your phone line into three information
-
carrying
channels


DSL connections require special hardware at the local
telephone company’s central office and at the user’s location





2001 Prentice Hall, Inc. All rights reserved.

5.4.1 Digital Subscriber Lines


IAD
(integrated access device)


Provides network connections for high
-
speed Internet
access, as well as connections for multiple voice telephone
lines



ADSL

(asymmetric DSL)


the connection speed for sending data to the Internet
(
upstream
) is slower than the connection speed for receiving
data from the Internet (
downstream
)


VoDSL

(voice over DSL)


Provides voice telephone services and high
-
speed data
access over a single standard telephone line


SDSL

(symmetric DSL)


Transfers data at the same speed both upstream and
downstream






2001 Prentice Hall, Inc. All rights reserved.

5.4.1 Digital Subscriber Lines



2001 Prentice Hall, Inc. All rights reserved.

5.4.2 Broadband


Broadband


A category of high
-
bandwidth Internet service provided
mainly by cable television and telephone companies to home
users


Can handle voice, data and video information


Enables videoconferencing, real
-
time voice and streaming
-
media applications


Always connected, eliminating the need to dial into an ISP


Cable modem


Translates digital signals for transmission over the same
cables that bring cable television to homes and businesses


Connections is shared among many users



2001 Prentice Hall, Inc. All rights reserved.

5.4.3 Integrated Services Digital
Network (ISDN)


ISDN

(Integrated Services Digital Network)


Provides high
-
speed connections to the Internet over both
digital and standard telephone lines


Limited service


Costly connection


Divided into three channels that each perform different tasks


Two bearer channels each support data transfers, while the data
channel is used to transmit routing information


ISDNZone





2001 Prentice Hall, Inc. All rights reserved.

5.4.4 T
-
1 and T
-
3 Lines


T
-
1 line


A dedicated connection that supports data rates of 1.544 Mb
per second


Made up of 24 channels


T
-
3 line


Supports data rates of 43Mbps and is made up of 672
channels that each support 64Kbps


T
-
1 and T
-
3 lines can be used for both voice and
data communication


Everythingt1.com




2001 Prentice Hall, Inc. All rights reserved.

5.5 Internet2


Consortium developing next generation of the
Internet


Abeline


A high
-
speed network currently used by Internet2 consortium
members, will soon be able to transfer 2.4 gigabits of data per
second


Teleimmersion


Allows users in different locations to share information in real
time

even 3D images


Virtual laboratory


Enable researchers worldwide to collaborate on projects


Digital libraries


Storage of audio and video files, enabling a search for a movie
by a line from its soundtrack.



2001 Prentice Hall, Inc. All rights reserved.

5.6 Software


Application Service Providers


Databases



2001 Prentice Hall, Inc. All rights reserved.

5.6.1 Application Service Provider


Provide customized business software applications
over the Internet


Maintains and updates the application as necessary


Companies can eliminate the costs associated with
developing and maintaining business applications


Virtual private networks

(VPNs)


Allow customers to connect to their applications securely
over the Internet


VPNs use the
point
-
to
-
point tunneling protocol (PPTP)

to
create a secure channel of communication between the
customer and the ASP



2001 Prentice Hall, Inc. All rights reserved.

5.6.2 Databases


Database


An integrated collection of data



Database management system

(
DBMS)



Provides mechanisms for storing and organizing data in a
manner that facilitates satisfying sophisticated queries and
data manipulations


Structured Query Language
(SQL


Almost universally used with relational database systems to
make
queries

(i.e., to request information that satisfies given
criteria) and manipulate data



2001 Prentice Hall, Inc. All rights reserved.

5.6.2 Databases


Relational database model



A logical representation of the data that allows the
relationships between the data to be considered
independently of the physical implementation of the data
structures



Popular enterprise
-
level relational database
systems:


Microsoft Sequel Server


Oracle



Sybase



DB2



Informix



2001 Prentice Hall, Inc. All rights reserved.

5.7 Operating Systems


Operating system (OS)


Software that manages the resources on a computer


Multiuser OS


Allows more than one user to run programs simultaneously


Multiprocessor OS


Controls a computer that has many hardware CPUs


Multitasking OS


Allows multiple applications to run simultaneously


Multithreading OS


Allows an individual program to specify that several activities
should be performed in parallel


Major operating systems used in desktop
computers are UNIX , Linux , Macintosh and
Windows





2001 Prentice Hall, Inc. All rights reserved.

5.7.1 Unix


Multics


“All things to all people”



Bell Laboratories, General Electric and Project MAC


Unix


Developed by Bell Laboratories after leaving the Multics
project


First version written in assembly language



Unique design and coherence



Met the needs of programmers who were building software
and of administrators who control software development
efforts





2001 Prentice Hall, Inc. All rights reserved.

5.7.1 Unix


University of California at Berkley


From time sharing to systems appropriate for studying
distributed computing environments



Sun Microsystems


Sun OS


Include facilities for supporting a graphics, window
-
based,
mouse
-
oriented interface


Provided facilities for diskless workstations to use the
network for file storing, sharing and paging


The Open Group


Controls the specification for UNIX and holds the trademark



www.unix
-
systems.org




2001 Prentice Hall, Inc. All rights reserved.

5.7.2 Microsoft Windows


The most popular operating system in the world


Introduced in 1984 with graphical user interface (GUI) added to the
DOS system


Windows 2.0


Failed to make a large impact in the market


Took too long to open applications, change screens, etc.


Windows 3.0


Achieved widespread success


Windows 95


Introduced a new graphical user interface and increased
performance


Windows 98, Windows NT and Windows 2000, WinXP, and Vista



2001 Prentice Hall, Inc. All rights reserved.

5.7.3 Linux


Linux


A UNIX
-
like operating system that has been developed by
volunteers worldwide



Initially developed by Linus Torvalds


Greatest success on the server
-
side


Version 1.0


Released in 1994, gained market share to become one of the
world’s most widely used operating systems


The Gnome Foundation


Founded to develop a free Linux
-
based desktop environment
and a free application framework to compete with Microsoft
Office for the desktop
-
computer environment



2001 Prentice Hall, Inc. All rights reserved.

5.7.3 Linux


Open source software


Freely available source code, so that anyone can use, customize
and make updates to the software


Kernel


The core of the operating system



Most of the applications that run on Linux are freely
available over the Internet and on many CD
-
ROM
distributions



GNU General Public License
(GPL)


One of the most widely used open
-
source licenses


Requires that the source code for GPL
-
licensed software, as well
as the source code for any modifications or improvements to that
software, is made freely available to the public



2001 Prentice Hall, Inc. All rights reserved.

Microsoft.NET


Microsoft.NET


Weaves together the operating system, the Internet and each
device to create applications and services to be accessed
anytime, anywhere, from any device



Could potentially support UNIX and Linux


Building and maintaining .NET components


Windows.NET


Visual Studio.NET


Integrated development environment (IDE)


.NET Enterprise Servers and the .NET framework



.NET applications will be built with XML



2001 Prentice Hall, Inc. All rights reserved.

5.7.4 Mac OSX


Achieved great success in the 1980s, dominating
the market for GUI
-
based personal computers



One of the first widely available systems to use a
window
-
based (i.e., a GUI) interface, a mouse and
icons



Release of Windows challenged MacIntosh sales


Mac

OS X operating system


Core was built using industry open standards based on Unix


Aqua


New Mac OS X interface






2001 Prentice Hall, Inc. All rights reserved.

Internet Appliances


Internet appliances



Desktop devices designed specifically for connecting to the
Internet


iPAQ Home Internet Appliance


Netpliance i
-
opener


Devices allow you to browser the Web, send and
receive e
-
mail and access streaming media online


Limited functionality






2001 Prentice Hall, Inc. All rights reserved.

5.8 Enhancing Business
Communication


Intranets


Extranets


Streaming audio and video


Internet telephony


Makes PC
-
to
-
PC and PC
-
to
-
phone calls possible,
dramatically reducing the cost of communication


Web casting


Virtual conferencing


Wireless technology



2001 Prentice Hall, Inc. All rights reserved.

5.8.1 Intranets and Extranets


Intranet


An organization’s internal network that uses the TCP/IP
protocols of the Internet


Only authorized parties, such as the organization's
employees, have access to an organization’s intranet



Used to store internal information


Extranet



An intranet that is also accessible by authorized external
parties who are not members or employees of the
organization


Members or employees might have unrestricted access to
information on the extranet, whereas customers or vendors
might have access to a limited subset of that information





2001 Prentice Hall, Inc. All rights reserved.

5.8.2 Streaming Audio and Video


Streaming technologies


Allow users to send and process audio and video data
continuously



Allows users to start playing the audio or video file while it
is still downloading



Users can play music over the Internet


Users can watch a small video on a Web site



2001 Prentice Hall, Inc. All rights reserved.

5.8.2 Streaming Audio and Video

RealPlayer dialog. (Copyright© 1995
-
2000 Realnetworks, Inc. All Rights Reserved. RealNetworks,

Real.com
, RealPlayer are trademarks registered trademarks of of RealNetworks, Inc.)



2001 Prentice Hall, Inc. All rights reserved.

5.8.3 Internet Telephony


Internet telephony


Enables communication over the Internet, allowing you to
use your PC as a telephone


Cost efficient


Net2Phone


Service allows you to make free PC
-
to
-
telephone calls
within the United States, and international calls at
discounted rates


Net2Phone and other Internet telephony services are not
always compatible with systems running firewalls


ClickTogether

service allows companies to add personalized
voice capabilities to a Web site







2001 Prentice Hall, Inc. All rights reserved.

5.8.4 Webcasting and Web
Conferencing


Webcasting


Broadcasting over the Web


Businesses can stream seminars, conferences, shows, sales
presentations and more though their Web sites


Live or prerecorded


Web conferencing


Allows businesses to meet and collaborate online, in real
time from anywhere in the world


Evoke


Webcasting and Web conferencing