Technology Guide 4 Telecommunications and the Internet T4-1

Technology Guide 4Telecommunications

andthe Internet

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IT for ManagementProf. Efraim Turban

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Telecommunication Concepts

• Telecommunication– long-distance communication through the

use of common carriers, including telephone, television, and radio.

• Data Communications– Electronic collection, exchange, and

processing of data or information, including text, pictures, voice, and other information that is digitally coded and intelligible to a variety of electronic machines


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Telecommunication System

HostComputer

HostComputer

PC orTerminal

PC orTerminal

MultiplexorMultiplexor

ModemModem

HostComputer

HostComputer

PC orTerminal

PC orTerminal

MultiplexorMultiplexor

ModemModem

Hardware

Front endprocessor

Receiver

Telecommunicationmedia

(channels)


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Electronic Signals

• Analog Signals– continuous waves that “carry” information

by altering the characteristics of the waves– amplitude and frequency

• Digital Signals– discrete on-off pulses that convey

information in terms of 1s and 0s, just like the central processing unit in computers


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Database andDatabase Management Systems• Database

– an organized logical grouping of related files– no data redundancy, data isolation, and data

inconsistency

• Database Management Systems (DBMS)– a program that provides access to a database– permits an organization to centralize data,

manage them efficiently, and provide access to the stored data by application programs


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Communication Processors

• Modem– Performs modulation and

demodulation

– Modulation convert information from digital to analog

– Demodulation convert information form analog to digital


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Communication Processors

• Multiplexor– An electronic device that allows a single

communications channel to carry data transmissions simultaneously from many sources

• Front-end Processor– A specialized computer that managers

all routing communications with peripheral devices


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Communications Media (Channels)

• Cable Media– Twisted-pair wire consists of strands of copper wire

twisted in pairs

– Coaxial cable consists of insulated copper wire, and is much less susceptible to electrical interference and can carry much more data than twisted-pair wire

– Fiber Optics consists of thousands of very thin filaments of glass fibers

– Photonics generates and harnesses light and other forms of radiant energy whose quantum unit


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• Wireless Media– Microwave– Satellite

• geostationary earth orbit (GEO); medium earth orbit (MEO); and low earth orbit (LEO)

– Global Positioning Systems– Radio– Infrared


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• Wireless Media– Cellular Radio Technology

• Wireless Application Protocol (WAP); Wireless Markup Language (WML)

– Mobile Computer

– Personal Communication service

– Personal Digital Assistants


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Characteristics of Communication Media

• Transmission Speed– bandwidth : the range of frequencies available

in any communications channel– bit per second (bps) : the unit of measurement– channel capacity : narrowband, voiceband, and

broadband– baud rate : the amount of data that can be

transmitted through a communications channel

• Optical Networking– dense wave division multiplexing (DWDM)


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Transmission Direction

• Simplex Data Transmission– uses only one direction only

• Half-duplex Transmission– uses only one circuit, but it is used in

both directions

• Full-duplex Transmission– uses two circuit for communications –

one for each direction simultaneously


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Transmission Mode

• Asynchronous Transmission– only one character is transmitted or received

at a time– inherently inefficient

• Synchronous Transmission– a group of characters is sent over a

communications link in a continuous bit stream while data transfer is controlled by a timing signal initiated by the sending device


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Transmission Accuracy

• Telephone line cables may be mishandled by repair personnel, accidentally cut by construction workers, or subjected to power surges while data are being transmitted.

• Accuracy controls consist of bits called parity bits that are like check sums aded to characters and/or blocks of characters at the sending end of the line.


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Protocols

• Protocol is a set of rules and procedures governing transmission across a network

• Transmission Control Protocol/Internet Protocol (TCP/IP) is a file transfer protocol that can send large files of information n across sometimes unreliable networks with assurance that he data will arrive in uncorrupted form


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Communication Standards• Network Standards

– physical layer, data link layer, network layer, transport layer, session layer, presentation layer, and application layer

– System Network architecture (SNA) standard

• Transmission Standards– fiber distributed data interface (FDDI), asynchronous

transfer mode (ATM), switch hub technologies, and Integrated services digital network (ISDN)

• Software Standards– Operating systems, graphical user interface standard,

software application standards


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Interfaces

• Parallel Data Transfer– most often used for local communication, employs

a communications interface with a series of dedicated wires, each serving one purpose

– both data and control signals are transmitted simultaneously

• Serial Data Transfer– most often used for long-distance communications,

is bit by bit rather than many bits in parallel


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Network Topology

• Bus Network– nodes are arranged along a single length of

twisted-pair wire, coaxial cable, or fiber optic cable that can be extended at he ends

• Rink Network– nodes are arranged along the transmission path

so that a signal passes through one station at a time before returning to its originating node

• Star Network– a central node that connects to each of the other

nodes by a single, point-to-point link


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Local Area Networks (LAN)

• LAN connects two or more communicating devices within a short distance– Gateway is a communications processor that

can connect dissimilar net works by translating for one set of protocols to another

– Bridge connects two networks of the same type– Router routes messages through several

connected LANs or to a WAN

• Private Branch Exchange (PBX)


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Wide Area Networks (WANs)

• Value-Added Networks (VAN)– private, multipath, data-only, third-party-

managed networks that can provide economies in the cost of service and network management

• Frame Relay– a shared network service that packages data into

“frames” that are similar to packets

• Virtual Private Network (VPN)– a set of hardware and software that provides a

gateway between a corporate LAN and the internet


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Network Processing

• Point-to-Point Connection– two devices on a network are

directly connected

• Peer-to-Peer Connection– two devices have the same relative

standing, as with two microcomputers


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Client/Server Architecture

• Presentation Component– the application interface or how the

application appears to the user

• Applications Logic– created by the business rules of the

application

• Data Management Component – consists of the storage and management

of the data needed by the application


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Types ofClient/Server Architecture

• Distributed Presentation

• Remote Presentation

• Distributed Function

• Remote Data Management

• Distributed Data Management


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Peer-to-Peer Architecture

• Network information is stored on a centralized file server and made available to ma clients, the Information stored across peer-to-peer networks is uniquely decentralized.

• Popular peer-to-peer network operating systems include Microsoft’s Windows 95 and 98, Windows NT, Artisoft’s LANtastic, and Netware Lite.


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Open Systems andEnterprise Networking

• Connectivity– the ability of the various computer resources to communicate

with each other through network devices without human intervention

• Portability– the ability to move applications, data, and even people form

one system to another with minimal adjustments• Interoperability

– the ability of systems to work together by sharing applications, data, nd computer resources.

• Scalability– the ability to run applications unchanged on any open system

where the hardware can range form a laptop PC to a supper computer


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Open Systems andEnterprise Networking

• Embedded LANs– open systems and connectivity have

enabled networks to completely span organization

– Most firms have multiple LANs and may have multiple WANs, which are interconnected to form an enterprisewide network


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Internet

• Basic Characteristics and Capabilities– Accessing the Internet

• access an internet-connected file server on your organization’s LAN

• log into the Internet from your home• wireless connections

– TV as a channel to the Internet• a special connection device, and a

telephone connection


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Internet

• The TCP/IP Protocol– procedures and rules for transferring data

across the internet• Internet Resources

– access libraries and conduct research– access to large databases– access to online magazines

• Wide Area Information Servers (WAIS)– an Internet directory designed to help end users

find and retrieve information over the networks by providing efficient search methods


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Internet

• The World Wide Web– a vast connection of interconnected pages of

information that are stored on computers around the world that are connected to the internet

• Bowser– a set of standards for storing, retrieving,and

manipulating information• Hyperlinks

– links to internal or external documents• Web Site : a computer network• Web Page : a document


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Internet

• Creating Web Documents– HyperText Markup Language (HTML)– Java

• Search Engines– enable you to locate information by using

key words in the same way that you would search online library resources

• Internet Addresses– uniform resource locator (URL)– hypertext transfer protocol (HTP)


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Internet

• Gopher– a “burrowing tool” that provides access to a

wide range of textual information available on the Internet

• Downloading Software and Files– cheapware, freeware, and shareware– file transfer protocol (FTP)

• Electronic Mall (e-mall)– allows multiple-access communication

delivered exclusively on a computer network


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Internet

• Chat Programs– allow you to send messages to people at the same time

• Newsgroup– organized in a directory and are divided into

categories and subcategories• Mailing Lists

– subscribe : add e-mail name and address– unsubscribe : remove the e-mail name and address

• Electronic Bulletin Boards– allow people leave messages for other people and

receive massive amounts of information• Portals

– a Web site designed to offer Internet services

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