information technology in business: telecommunications, networks and internet basics
TRANSCRIPT
MIS 221 2
Learning Objectives
• When you finish this chapter, you will:– Recognize why successful managers must be familiar
with telecommunications concepts and terminology.– Know the principles of communication within a
computer system and among computers.– Be able to identify the major media and devices that
are used in telecommunications.
MIS 221 3
Learning Objectives
– Be able to list and explain the functions of different network layouts and the concept of protocols.
– Understand how telecommunications can improve operations in organizations.
– Know the latest developments in telecommunications media and transmission speeds.
– Understand the historical development of the Internet– Understand the main structural components of the
Internet– Understand how HTML, HTTP, browsers and servers
work together to form the WWW
MIS 221 4
Telecommunications in Business
• Telecommunications
– Any form of long distance communication, including telephone, television and radio
• Telecommunications has improved business in three main ways:
– Better communication– Higher efficiency – Better distribution of data
MIS 221 5
What is Data Communications?
• Data Communications
– Any transfer of data within a computer, between a computer and another device, or between two computers
• Integration– Business are increasingly integrated in their use of
computers, telephony, video and data networks
MIS 221 6
What is a Telecommunications System?
• Compatible hardware and software used to communicate information from one place to another– Will include voice, text, graphics, documents and
video
MIS 221 7
A Generalized Telecommunications System
• Hardware (Host computer, front end communication processor, modem, multiplexor)
• Communications media (Cable or wireless)• Communications software• Data communications providers• Communications protocols• Communications applications (EDI,
videoconferencing, EFT, etc.)
MIS 221 8
Electronic Signals
• Analog– Information imbedded in the changing
characteristics of the wave• Amplitude or frequency based
• Digital– Information imbedded as 1 or 0, on or off
MIS 221 12
Communications Devices
• Modems– Devices that modulate and demodulate signals,
converting from analog to digital and digital to analog
• Multiplexers– Devices that allow several telephones or computers
to transmit data through a single line• Frequency-division multiplexing• Time-division multiplexing
• Front End Processors
MIS 221 13
Channels and Media
• Communication Channel– Physical medium through which data
can be communicated.
• Channel Capacity– Narrow band
– Broadband
MIS 221 14
Channels and Media
• Media– A medium is any means by which data can be
transmitted.
• Transmission speed– A medium’s capacity is determined by the
range of bits per second at which it can operate.
• Baud• Repeater
MIS 221 15
Channels and Media
• Twisted Pair– Telephone line made of a pair of copper wires twisted
to reduce electromagnetic interference (EMI)
• Coaxial Cable– Commonly used for cable television transmission
• More expensive than twisted pair• Greater transmission rate than twisted pair• Much less susceptible to EMI
MIS 221 16
Channels and Media
• Microwaves– High-frequency, short radio-frequency (RF) waves
• Terrestrial microwave• Satellite microwave
• Optical Fiber– Fiber-optic technology uses light instead of electricity
to transmit data.
• Cellular and Wireless– Radio frequency technologies– Fixed or mobile
MIS 221 22
Communication Direction
• Three Modes of Communication Between Devices– Simplex
• One direction only– Half-Duplex
• Both directions, but only one at a time– Full-Duplex
• Simultaneous in both directions
MIS 221 24
Communication Direction
• Asynchronous Communication
– In asynchronous transmission, the devices are not synchronized by any timing aids.
– Advantage• Does not need sophisticated and expensive timing
hardware– Disadvantage
• Overhead, time spent transmitting bits that are not a part of the primary data
MIS 221 26
Communication Modes
• Synchronous Communication– In synchronous communication, data are transmitted
using timing devices.
– Messages are transmitted in packets.
– Advantage of synchronous communication• Overhead in synchronous communication is
significantly smaller than in asynchronous communication.
MIS 221 28
Protocols
• Definition– Rules and procedures governing transmission across
a network• Line access
• Collision avoidance
• TCP/IP– Standard protocol of the Internet and intranets– Transmission Control Protocol/Internet Protocol– Designed for sending large files across unreliable networks– Utilizes packets of information
MIS 221 29
OSI Standard
• Seven Layer Model– Governs peer-to-peer communication
between software at each layer– From physical layer (how bits are transmitted
over a channel)– To application layer (file transfer, security, etc)
MIS 221 31
Networks
• LANs (Local Area Networks)– Networks within a building, or within a group
of adjacent buildings
• WANs (Wide Area Networks)– Networks across significant distances, either within a
single organization or spanning multiple organizations• Value-added networks (VANs)• Wireless communication
MIS 221 33
Networks Devices
• Bridge– Connects two networks at the data link layer
• Router– Connects two networks at network layer– Provides intelligent routing, some network
management functions and security
• Gateways– Connect networks using different protocols
• Switches– Incorporate features of bridges and gateways
MIS 221 34
Other Standards (or lack thereof)
• Operating Systems– No standard exists
• Graphical User Interface– X Windows
• Software Applications– No standard for programming language,
DBMS, etc.
MIS 221 35
Client/Server Computing
• Enabled by proliferation of powerful desktop computers and decentralized servers
• Principle– Processing functions divided between to
separate, distinct computers– One requests services of a server (the
client)– One delivers a service upon request (the
server)
MIS 221 36
Example of Client/Server Computing
• Email– Email client (Outlook) sends request to
POP server for messages– POP Server receives and validates
request to download email– Client processes data received (formats,
displays, stores messages)
MIS 221 37
Example of Client/Server Computing
• Database Transaction– Client program running on PC sends
query to DBMS running on central server– DBMS on server parses and executes
the query– DBMS assembles resulting data (or
status result) and sends it to client– Client receives data and processes it
(displays it, sends message to user, etc)