Transcript File

Telecommunications,
the Internet, &
Wireless Technology
MIS 205 LECTURES
Faculty: MzF
Trends in Telecommunications






New hardware devices; new alternatives for business & nonbusiness communications (e.g., the RIM Blackberry)
Telecommunications deregulation encouraged competition
Dominance of Internet technologies in voice, data, & video
communications
High-speed broadband connections to homes & businesses
Growth in wireless telephone & wireless computer networks
Growing scope of communication-intense products (e.g.,
Internet telephony, mobile commerce)
ADM2372, M Benyoucef, Fall'08
2
Trends in Telecommunications
impact on business






Declining transaction costs
Declining agency costs
Increased agility
Higher quality management decisions
Declining geographical barriers
Declining time barriers (work 24/7)
ADM2372, M Benyoucef, Fall'08
3
ADM2372, M Benyoucef, Fall'08
4
ADM2372, M Benyoucef, Fall'08
5
ADM2372, M Benyoucef, Fall'08
6
ADM2372, M Benyoucef, Fall'08
7
ADM2372, M Benyoucef, Fall'08
8
Components of a Simple Network
Network: 2 or more connected computers
NOS (Network Operating System): routes &
manages communications on the network &
coordinates network resources
NIC: Network Interface Card
Switch: filters & forwards data to specified locations
within a network
Router: send packets of data though different
networks
ADM2372, M Benyoucef, Fall'08
9
Data Communications
what (1)


Data communication: the process of transferring data, information or
commands between 2 computers or between a computer and a terminal
Data communication requires




Transmitter & receiver
Protocol: set of rules
Medium
Message
Medium
Transmitter
Message
Receiver
Protocol
Source: Davis & Benamati, Ecommerce
basics, Addison Wesley, 2002, Page 36
ADM2372, M Benyoucef, Fall'08
10
Data Communications
what (2)

Transmitter/Receiver



Computer, terminal, hardware in general
e.g., PC, Cell phone, PDA, Kiosk, cash register, etc.
Medium

Wired (cable)





Twisted pair of wires (phone)
Coaxial cable (cable TV)
Fiber-optic cable
etc.
Wireless



Radio (laptop with a wireless card, Wireless Fidelity - Wi-Fi)
Satellite
Infrared (wireless keyboard)
ADM2372, M Benyoucef, Fall'08
11
Data Communications
fiber optic cables


Thin strands of clear glass fiber
Data is transformed into pulses of light and sent over the
cable





trillions of bits per second
Faster, lighter, durable, expensive, hard to install
Harder to hack (harder to listen to pulses of light)
Often used as a backbone (i.e., to carry signals to distribution
nodes)
Dense Wave Division Multiplexing (DWDM)


Next-generation optical network
Uses many colors (wavelengths) of light (up to 160)
 even greater capacity
ADM2372, M Benyoucef, Fall'08
12
Data Communications
TCP/IP (1)

Transmission Control Protocol / Internet
Protocol (TCP/IP)



The communications protocol of the Internet
In order for any computer to use the Internet, it
must be equipped with the software that enables
this protocol
TCP/IP is based on “packet switching” - i.e.,
dividing messages into packets and sending
each one individually
ADM2372, M Benyoucef, Fall'08
13
Data Communications
TCP/IP (2) - packet switching
Packet switching:
Technology that breaks
blocks of data into fixed
bundles and routes them
in the most economical
way through any available
channel. Packets are
reassembled once they
reach their destination
ADM2372, M Benyoucef, Fall'08
14
Data Communications
TCP/IP (3)

IP (Internet Protocol)



Specifies the format of packets & addressing scheme
Addresses a packet and drops it in the system
TCP (Transmission Control Protocol)


Enables two hosts to establish a connection for a period
of time to exchange data
Guarantees that packets are delivered in the same order
in which they were sent
ADM2372, M Benyoucef, Fall'08
15
Data Communications
voice over IP (1)





Uses IP (Internet protocol) to deliver voice in
digital form
Based on “packet switching” (instead of “circuit
switching” used in regular telephone
communications)
Low cost
Some delay in transmission (compared to circuit
switching)  low sound quality
If high bandwidth  better sound quality
ADM2372, M Benyoucef, Fall'08
16
Data Communications
voice over IP (2)
3
1
2
4
ADM2372, M Benyoucef, Fall'08
5
17
Data Communications
bandwidth (1)

Bandwidth



Measures the amount of data a medium can transmit in a given
period of time
 bps (bits per second)
 Kbps, Mbps or Gbps
 K (1000), M (1 million), G (1 billion)
Baseband: one line, one channel
 most local communications
Broadband: one line, simultaneous channels
 DSL (Digital Subscriber Line)
 Bell

Cable
 Rogers
ADM2372, M Benyoucef, Fall'08
18
Data Communications
modem (1)

Analog signal



Continuous waveform
Voice communications
Digital signal




Discrete waveform
Two states: 0 and 1
On-off electrical pulses
Data communications
ADM2372, M Benyoucef, Fall'08
19
Data Communications
modem (2)


Modem: MOdulation / DEModulation
Translates digital   analog
ADM2372, M Benyoucef, Fall'08
20
Networks
what

A network



consists of two or more computers or other
intelligent devices linked by communication lines
(wired or wireless)
each device is called a node
examples of networks


2 computers sharing a printer
the Internet
ADM2372, M Benyoucef, Fall'08
21
Networks
LAN


LAN (Local Area Network)
Group of interconnected computers or workstations
located in close proximity (e.g., within the same building)
Server
Wiring Closet
Floor 2
Wiring Closet
Floor 1
Basement
ADM2372, M Benyoucef, Fall'08
22
Networks
WAN

WAN (Wide Area Network)





Network of networks
Links geographically distributed computers
Uses broadband public communication services
There is a need to boost and filter the signal
Examples of WANs

Internet, Intranet, Extranet
ADM2372, M Benyoucef, Fall'08
23
Networks
client / server (1)

Server: a computer that controls access to
shared resources


Server hardware (i.e., Dell, IBM, …)


without server software, it is just a client workstation
Server software (MS Server, …)


powerful processor, large memory, large amount of
secondary storage
turns the computer it runs on into a server
Clients

all the other nodes of the network
ADM2372, M Benyoucef, Fall'08
24
Networks
client / server (2)
Server
Client
Client
Printer
File
System
Client/Server
Peer-to-Peer
Client
Client
File
System
Peer
File
System
Peer
File
System
Peer
ADM2372, M Benyoucef, Fall'08
25
Networks
Internet, extranet, intranet
Internet
extranet
intranet
ADM2372, M Benyoucef, Fall'08
26
Networks
Internet (1)

The Internet is a public,
global communications
network that provides
direct connectivity to
anyone


over a LAN via an ISP
(Internet Service Provider)
or
directly via an ISP
ISP: Internet Service Provider
LAN: Local Area Network
T1 Line: High-speed telephone line
Source: http://computer.howstuffworks.com/web-server3.htm
ADM2372, M Benyoucef, Fall'08
27
Networks
Internet (2)

Strategic significance of the Internet




easily accessible
makes communications possible by using
protocols
cost-efficient transfer of data
extensive reach + standardization
 well suited for conducting business
ADM2372, M Benyoucef, Fall'08
28
Networks
Intranet (1)



Corporate LAN or WAN that uses Internet
technology
Secured behind company’s firewalls
Provides Internet capabilities such as




search engines, browsing, tools for communication &
collaboration, etc.
The cost of converting an existing network system
to an intranet is relatively low
Employees can get out on the Internet easily
Outsiders cannot get into the intranet
ADM2372, M Benyoucef, Fall'08
29
Networks
Intranet (2)
Client
Interne
t
Server
Intrane
t
Firewall
E-mail Server
Web Server
Data base
ADM2372, M Benyoucef, Fall'08
30
Networks
Firewall



Firewall: hardware & software that isolate the
company’s intranet from the internet
Controls external access to the company’s
servers
Most firewalls work by screening packets

Examples



Only allow packets originating from inside the company
Accept http but no ftp or telnet
Reject MP3 files and adult content
ADM2372, M Benyoucef, Fall'08
31
Networks
VPN

Virtual Private Network

Provides secure transport of
private communications over the
public Internet

Less expensive, more flexible,
greater bandwidth than non-IP
networks

Creates tunnels of secured data
flows using encryption
 if intercepted, messages
cannot be interpreted
Internet
Point
B
Point
A
ADM2372, M Benyoucef, Fall'08
32
What is encryption?
Receiver
Sender
Encrypt
Cipher Text
Clear Text
Decrypt
Cipher Text
Clear Text
 Secret Key encryption
 A single key, known to both parties
ADM2372, M Benyoucef, Fall'08
33
What is encryption?
A simple Caesar-shift substitution Cipher
Plain text
ATTACK AT DAWN
Base alphabet ABCDEFGHIJKLMNOPQRSTUVWXYZ
Shift one letter BCDEFGHIJKLMNOPQRSTUVWXYZA
Cipher text
BUUBDL BU EBXO
[ Source: E-commerce Basics, by Davis & Benamati, Addison Wesley, 2003 ]
ADM2372, M Benyoucef, Fall'08
34
Networks
Extranet

Network that uses a VPN to link intranets
in different locations over the Internet; an
“extended intranet”

The protected environment of an extranet
allows partners to collaborate & share
info securely
ADM2372, M Benyoucef, Fall'08
35
The WWW (1)

Before 1990




1993: Mosaic





E-mail, FTP, telnet
Text based
UNIX commands
First browser
User friendly, graphical interface
Point & click
Will later become Netscape
1995: Netscape went public

The WWW (World Wide Web): standardized protocols for
creating, naming, linking & accessing Internet content
ADM2372, M Benyoucef, Fall'08
36
The WWW (2)

Browser


software that runs on the
client’s computer, requests &
displays web pages
Interne
t
Web server


Browser
software that runs on the host
computer and manages web
pages
Application server

software that manages the
interaction between the web
server and the organization’s
Information systems
ADM2372, M Benyoucef, Fall'08
Web
Server
Application
Server
Organizational
Information Systems:
Applications & Databases
37
The WWW (3)

URL (Uniform Resource Locator)

the address of a resource on the World Wide Web
http://www.uottawa.ca
Top level domain
(others: com, org, UK, …)
Hypertext Transfer Protocol:
rules used for exchanging web
pages between the browser and
the web server.
Local domain
(others: bell, umontreal, etc.)
Conventional name for the
public web server, name of the
program that runs on the host
ADM2372, M Benyoucef, Fall'08
38
The WWW (4)
LAN
Server
Browser
1
7
2
6
Internet
Client workstation
3
Downloading
a web page
5
4
Web
Server
Web
pages
Host Computer
ADM2372, M Benyoucef, Fall'08
39
The Wireless Revolution
Bluetooth



A wireless networking
standard for creating
Personal Area
Networks (PAN)
Links devices within a
10 meter range
Uses low power radio
based communication
at up to 722 Mbps
ADM2372, M Benyoucef, Fall'08
40
The Wireless Revolution
Wi-Fi (Wireless Fidelity)

For wireless LANs





54Mbps (10 to 30 meters
range)
11Mbps (30 to 50 meters
range)
Security issues
Possibility of interferences
(from wireless phones, other
wireless LANs, etc.)
WiMax (Worldwide
Interoperability for Microwave
Access)


Range: up to 50 kilometers
Speed: up to 75 Mbps
ADM2372, M Benyoucef, Fall'08
41