Lehrveranstaltung Information Technology Prof. Dr. Marius Dannenberg. Kapitel 2 E-Business Unternehmensinfrastruktur

Steinbeis-Transfer-Institut Business and Engineering Lehrveranstaltung „Information Technology“ Prof. Dr. Marius Dannenberg Kapitel 2 E-Business Unt...
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Steinbeis-Transfer-Institut Business and Engineering

Lehrveranstaltung „Information Technology“ Prof. Dr. Marius Dannenberg

Kapitel 2 E-Business Unternehmensinfrastruktur

Gliederung: LV Information Technology Kapitel 2 E-Business Unternehmensinfrastruktur

1 eBusiness definieren und strukturieren 2 eBusiness Unternehmensinfrastruktur 3 Management Information Systems 4 Web Page Erstellung und Content Management 5 Sell Side eCommerce 6 New Media Marketing 7 eCustomer Relationship Management (eCRM) 8 eMarktforschung 9 Buy Side eCommerce: Electronic Procurement – Beschaffung via Internet 10 eSupply Chain Management (eSCM) 11 ePayment-/eBilling Systeme im Internet 12 Strategisches Innovations- und Technologiemanagement

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By the Year 2000… 4 4 4 4 4

Man will land on Mars Cities will thrive under huge climate controlled domes Travelers will fly from New York to Tokyo in under 2 hours Commuters will strap rockets on their backs and jet to work, or at least commute in small two-seater flying automobiles There will be 200,000 computers in the United States

(From a Wall St. Journal series on the year 2000, published in 1966-67)

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What is eBusiness Infrastructure…?

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Hardware Software Telecommunications and Networks Internet People Data

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Lehrveranstaltung: „E-Commerce und E-Business“ Kapitel 2 E-Business Unternehmensinfrastruktur

2.1 IT-Systems 2.2 Computer Hardware 2.3 Computer Software 2.4 Telecommunications and Networks 2.5 Internet 2.6 Conclusion

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Components of an IT-System (1)

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Components of an IT-System (2)

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Major Roles of IT-Systems IT-Systems provide support for: ƒ Decision Making ƒ Control ƒ Coordination ƒ Analysis ƒ Creation of new Products

Support of Strategic Advantage Support of Managerial Decision Making

Support of Business Operations

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History of the role of IT-Systems 1950-1960 Data Processing Electronic Data Processing

1960-1970 Management Reporting

Management Information Systems

1970-1980 Decision Support

Decision Support Systems Ad hoc Reports

1980-1990

1990-today

Strategic & End User

Electronic Business

End User Computing Exec Info Sys Expert Systems

Electronic Business & Commerce

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New Role of Information Technology in Organizations

ƒ Widening Scope of IT-Systems ƒ Network Revolution and the Internet ƒ New Options for Organizational Design ƒ The Digital Firm: E-Commerce and E-Business

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Gestern: Elektronische Datenverarbeitung IT-Ziele: ƒ ƒ ƒ

Reduktion von Routinearbeiten Auswertung großer Datenmengen Druckmaschine = „Status-Symbol“

Eingabe: Datenerfassung

Kostenträger: Geschäftsleitung

Ausgabe: Papier

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Heute: Informationsverarbeitung IT-Ziele: ƒ Auskunft und End-User-Computing ƒ Eigene DB- und ProgrammServer ƒ Nutzung von PC‘s ƒ Intranet ƒ Internet-Mail-Adressen WAN ƒ Firewalls zum Schutz ƒ Handy-Einsatz Kostenaufteilung an Kostenstellen

LAN

Internet

LAN Seite 12

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Morgen: Globales Info-Zeitalter IT-Ziele: Die richtige Information zum richtigen Zeitpunkt am richtigen Ort • • • • • • •

Internet

IT ist ausgelagert WEB ist ein großer Rechner E-Commerce ad-hoc Systeme Appl. Service Providing (ASP) Mobile Arbeitsplätze Externe Service-Lieferanten

Intern bleiben Service Management und kritische Daten-Server

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Problem: The Solution Gap

Acceptable Deployment Time The Solution Gap Time to Build

1960

1975

2000 Seite 14

Lehrveranstaltung: „E-Commerce und E-Business“ Kapitel 2 E-Business Unternehmensinfrastruktur

2.1 IT-Systems 2.2 Computer Hardware 2.3 Computer Software 2.4 Telecommunications and Networks 2.5 Internet 2.6 Conclusion

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Chapter Objectives ƒ Identify the major types, trends, and uses of microcomputer, midrange, and mainframe computer systems. ƒ Outline the major technologies and uses of computer peripherals for input, output, and storage. ƒ Identify and give examples of the components and functions of a computer system. ƒ Identify the computer systems and peripherals you would acquire or recommend for a business of your choice, and explain the reasons for your selections

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Size and Time in the Computer World How Computers Represent Data BIT: Binary Digit. On/Off, 0/1, Magnetic/Not BYTE: Group of 8 bits for one character Measures of Storage Capacity ƒ ƒ ƒ ƒ ƒ

Byte Kilobyte (KB) Megabyte (MB) Gigabyte (GB) Terabyte (TB)

= 8 Bit = 1,024 (210) Bytes ≅ 103 Bytes = 1,048,576 (220) Bytes ≅ 106 Bytes = 1,073,741,824 (230) Bytes ≅ 109 Bytes 40 = 1,099,511,627,776 (2 ) Bytes ≅ 1012 Bytes

Measures of Speed ƒ ƒ ƒ ƒ

Millisecond Microsecond Nanosecond Picosecond

= 10-3 second = 10-6 second = 10-9 second = 10-12 second

Measuring the rate of data transfer ƒ

Bits per second (bps), Kbps, Mbps

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History of Computing: 1900 – 1959 1900 – 1949: Conception ƒ Computers as electronic “super” calculators, useful only for complex scientific and engineering calculations (World War II).

1950s: Birth of the “Electronic Brain” ƒ “Stored program” computers and programming languages: “Stored program” computers could carry out varied tasks; programming languages were introduced (e.g., COBOL and Fortran). But computers were essentially PCs — one user at a time, communicating with the machine through toggle switches, paper tapes, and punched cards. ƒ Large models involving millions of calculations: Computers could be used for large models involving millions of calculations (planning factory schedules, forecasting the weather, predicting elections). Lack of permanent storage (no disks or tapes) precluded use in day-to-day business activities. During the entire 1950s, only a few dozen machine were sold, each costing hundreds of thousands of dollars (in 1950 money).

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History of Computing: 1960s Infancy of the “Business Machine” (1) Visions of “data-based” organizations ƒ

Modern operating systems and permanent storage: Modern operating systems were developed that allowed the computer to be a shared, constantly available resource. Permanent storage (particularly magnetic disks) allowed databases, which in turn promoted a vision of a “data-based” organization, in which the computer could act as central coordinator for company-wide activities.

Indispensable for preserving large organizations ƒ

By the end of the 1960s computers had become indispensable for large organizations — but, they didn’t change these organizations, they preserved them, keeping them functional as they grew. Large organizations that were previously drowning in paperwork suddenly found that computers allowed them to preserve their existing structures. Rather than changing existing business processes and practices, computers made them faster. The computer made large, complex, centrally-controlled bureaucracies possible — even though all they did was automate many of the inflexibilities and overheads of the past (and added a few of their own).

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History of Computing: 1960s Infancy of the “Business Machine” (2) IT costs money ƒ Modern operating systems and permanent storage: By 1970, organizations were spending millions of dollars on IT, a previously non-existent budget category. Along with the big computers and systems, organizations invested in computer departments, programmers, professional and support staff, and custom applications software.

Sigh of relief ƒ By 1970 it appeared that most companies had finally built most of the applications that made sense. Expensive, probably worth it, and finally containable in cost.

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History of Computing, 1970s: Adolescence – The “Databased” Corporation Technology breakthroughs — in on-line databases, terminals, networks, and large scale permanent storage — caused existing applications to become obsolete and created a need for a whole class of new applications (circa 1970): •



The concepts associated with on-line databases — databases connected to and fed by networked terminals — promised an end to management isolation if management would only: * view information as a key resource; * build a totally consistent, company-wide, database; * ensure that information was entered into and updated in that database as soon as it entered the company. The vision — all of the organization’s information is instantly available in up-to-date, accurate, and consistent form at the touch of a keyboard, allowing faster operations and enabling everyone in the organization to stay in touch with the real world.

IT costs more money (1% or ½ – 10% of budget): • •

The new class of technology cost even more than before, but by the end of the 1970s a rule of thumb was emerging about technology spending: organizations should target 1% of their expense budgets on IT. But the rule was rough, 1% held as an industry average for manufacturing; but 10% of noninterest expense was more the norm for banks, investment houses, and insurance companies. While ½% was closer to the average for retail organizations.

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History of Computing, 1980s: Transition to Maturity – Software Engineering for Mainframes (1) In the 1980s, large computer technology stood still (comparatively): • Although mainframe computers continued to get better, cheaper, and faster, with new features, large computer technology at the end of the 1980s was very similar to technology at the beginning of the decade. A mainframe application built in 1980 looked virtually identical to one built in 1990.

Focus shifted to designing and building applications in some kind of disciplined fashion: • In 1970, organizations had dreams of on-line corporations, wired desktops, totally consistent databases. By, 1980, reality set in — the vision was harder to achieve than anyone imagined.

• In the 1980s, the industry focused on developing the necessary tools, disciplines, and methodologies to make predictably possible the big systems required by the dream. Promised applications had to arrive on schedule and in good working order.

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History of Computing, 1980s: Transition to Maturity – Software Engineering for Mainframes (2) By 1990, organizations had learned (more or less) how to build predictable and reliable big systems — using methodologies that prescribe ways to build highquality systems, and CASE (Computer-Aided Software Engineering) tools to support analysts, designers, and developers in building bigger systems better. • A methodology is a formal prescription for describing how software should be built. They can range from loose frameworks describing basic design approaches to 60-book encyclopedias that define every step and function required to build an application. • Fundamental insight: software design is a formal process. • CASE tools offer ways to use computers to help automate the design process and the associated methodologies.

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History of Computing, 1980s, Version 2: Pesky PCs – Toys or Appliances? By 1985, PCs and their tools (WordStar, 1-2-3 (VisiCalc) and dBase) were starting to make users think in new ways: ƒ First, although they only addressed special needs, these applications also were dramatically easier to learn and use than mainframe applications. And, the tools could be used to build custom applications: • Why wait for MIS to build a forecasting system, when your local hacker can build the same system in three days? • Why wait, when the 3-day system will be easier to use, more flexible and run on cheaper hardware? • And, why wait when the MIS system will take two years, cost tens of thousands of dollars, and then be too expensive to run anyway?

In 1985 PCs were not applicable to business computing: they could not be used to build run-the-business applications: ƒ First (and most important), PC applications couldn’t share data. ƒ Second, they were not capable of handling large amounts of data.

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Platform Wars In 1985, MIS folks looked at PCs seriously for the first time — and they didn’t like what the saw: • To the MIS folks who were building mission critical apps, PCs were irrelevant. • PCs lacked sophisticated time-sharing and transaction oriented operating systems, had no industrial strength databases, no batch-scheduling facilities, no CASE tools, no modern programming languages. • AND, the little applications being built had none of the fail-safe mechanisms or design methodologies that MIS folks now knew were critical to creating bulletproof applications.

Thus arose the cultural split we all live with today: • A new breed came out of the ‘80s: yesterday teenage hackers and dBase and 1-2-3 programmers have become today’s client/server gurus. • Yesterday’s computer club president is today’s network administrator. • AND, the two sides still don’t talk to each other, the PC professionals and large system professionals still don’t talk to each other — they have different value systems, different technical backgrounds, and different beliefs.

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Here and Now PCs Meet Individual Needs, Not Organizational Needs Mainframe and associated costs up from 1% to 1.5%: ƒ ƒ ƒ

Mainframe systems run the business, but they are hugely expensive, hard to use, inflexible, and time consuming to develop. Still, the systems pay their own way — they run the business. Every transaction, every piece of work done, is justified based on ROI (return on investment). New mainframe systems don’t get built without a business justification.

PCs, a previously nonexistent budget category, have also jumped to 1.5% of organization budgets in 10 years: ƒ

The problem is that PCs can’t be used to run the business: PCs make individuals more productive. They’re easy to use, and application development is relatively quick and flexible. Although individually inexpensive, in the aggregate, they cost as much as mainframes. They require support, network connections and servers, and a variety of other infrastructure and orgware costs. Worst of all, the costs can’t be justified on a ROI basis because PCs meet individual, not organizational, needs.

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Here and Now: Information Costs

Source: Adapted from Vaskevitch (1995: 23-4)

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Trends in Computer System Capabilities First Second Third Fourth Fifth Generation Generation Generation Generation Generation Trend: Toward Smaller, Faster, More Reliable, and Less Costly

Vacuum Vacuum Tubes Tubes

Solid-State Solid-State

Integrated Integrated Circuits Circuits

LSI, LSI, VLSI VLSI MicroMicroprocessors processors

Greater Greater Power, Power, Smaller Smaller Footprint Footprint

Trend: Toward Easy to Purchase, and Easy to Maintain

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Computer System Categories

Super Computer Mainframe Computers Midrange (Mini) Computers

Microcomputers

Network Computer

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Mainframe ƒ ƒ ƒ ƒ ƒ

Largest Enterprise Computer 50 MB to over four GB RAM Commercial, Scientific, Military, Applications Massive Data Complicated Computations

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Midrange (Mini) Computer ƒ ƒ ƒ ƒ

Middle-Range 256 MB to over one GB RAM Universities, Factories, Labs Used as Front-End Processor for Mainframe

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Microcomputer Systems ƒ ƒ ƒ ƒ ƒ ƒ ƒ ƒ ƒ

Workstations Desktop Computers Notebook Computers Handheld Computers (PDA, Information Appliances) 64 MB to over one GB RAM Personal or Business Computers Affordable Many available Components Can be networked

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Network Computers and Terminals Network Computer (Thin Client) NetPC Network Terminal

Benefits:

ƒ Lower purchase cost ƒ Easier maintenance ƒ Easier software distribution and licensing ƒ Computer platform standardization ƒ Reduced end user support requirements ƒ Improved manageability Seite 33

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Supercomputer

ƒ ƒ ƒ ƒ ƒ ƒ

Highly Sophisticated Complex Computations Fastest CPUs Large Simulations State-of-the-art Components Expensive

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Storage Trends Primary Primary Storage Storage

First Second Third Fourth Fifth Generation Generation Generation Generation Generation Magnetic Magnetic Drum Drum

Magnetic Magnetic Core Core

Magnetic Magnetic Core Core

VLSI LSI VLSI LSI Semiconductor Semiconductor Semiconductor Semiconductor Memory Memory Chips Chips Memory Chips Chips Memory

Trend: Towards Large Capacities Using Smaller Microelectronic Circuits Secondary Secondary Storage Storage

Magnetic Magnetic Disk Disk Optical Disk Magnetic Magnetic Tape Tape Magnetic Magnetic Disk Disk Optical Disk Optical Disk Magnetic Tape Tape Magnetic Optical Disk Magnetic Magnetic Disk Disk Magnetic Magnetic Tape Tape Magnetic Tape Magnetic Magnetic Disk Disk Magnetic Drum Drum Magnetic Magnetic Tape Trend: Towards Massive Capacities Using Magnetic and Optical Media

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Common Input Devices ƒ ƒ ƒ ƒ ƒ ƒ ƒ ƒ ƒ ƒ ƒ ƒ

Keyboard Mouse Touch Screen Pointing Devices Pen Based Input Speech Recognition Optical Scanning Magnetic Ink Character Recognition Smart Cards Digital Cameras Source Data Automation Bar codes scanners

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Keyboard Traditional Keyboard

An ergonomic keyboard designed to minimize strain on your hands and wrists

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Pointing Devices ƒ To control an on-screen symbol and to move the insertion point to a particular location or to select programs. Examples for pointing devices are:

• Mouse • Trackball • Touch pad • Pointing Stick • Joystick

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Mouse

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This cordless muse uses infrared remote transmission to communicate with the computer

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Trackball

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Touchpad

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Pointing Stick

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Joystick

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Touch Screen / Pen Input Touch Screen

Pen Input Systems

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Source Data Automation Capture data directly from its original form, the source document ƒ efficiency ƒ accuracy

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Source Data Automation – Image Scanners

Page & image scanners

Hand-held scanners

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The higher the resolution or dots per inch (dpi), the sharper and clearer the resulting image. Today’s scanners have a resolution of at least 600 dpi.

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Source Data Automation – Optical Recognition (Reader)

ƒ ƒ ƒ ƒ

Bar code recognition Optical mark recognition (OMR) Optical character recognition (OCR) Magnetic ink character recognition

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Source Data Automation – Optical Recognition Reader (1) Bar Code

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Source Data Automation – Optical Recognition Reader (2)

Bar Code Readers

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Source Data Automation – Optical Recognition Reader (3) Optical Character Recognition

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Source Data Automation – Optical Recognition Reader (4) OCR characters indicate amount due and account number

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Source Data Automation – Optical Recognition Reader (5) Optical Mark Recognition

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Source Data Automation – Optical Recognition Reader (6) Magnetic Ink Character Recognition

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Multimedia Input Devices

Speech recognition

Digital cameras

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Multimedia Input Devices - A Voice Input System

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Multimedia Input Devices - Digital Camera

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Electronic Whiteboard

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Input Devices: Technology Trends First Second Third Generation Generation Generation

Punched Punched Cards Cards Paper Paper Tape Tape

Punched Punched Cards Cards

Key Key to to Tape/ Tape/ Disk Disk

Fourth Generation

Fifth Generation

Keyboard Keyboard Data Data Entry Entry Pointing Pointing Devices Devices Optical Optical Scanning Scanning

Voice Voice Recognition Recognition Speech Speech and and Touch Touch Devices Devices Handwriting Handwriting Recognition Recognition

Trend: Towards Direct Input Devices that Are More Natural and Easy to Use

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Common Output Devices ƒ Translate bits and bytes into a form that users can understand ƒ A means through which computers communicate with us Video Output ƒ Monitor - Cathode Ray Tube (CRT) ƒ LCD Printed Output ƒ Inkjet ƒ Laser Voice Output ƒ Loud Speaker ƒ Head Set Special Output ƒ ATM’s / POS’s ƒ Virtual Reality

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Video Output Devices - Monitors

Monochrome & Colour ƒ Colour Graphics Adaptor ƒ Extended GA ƒ Video GA ƒ Super VGA ƒ Trident VGA

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Video Output Devices – Flat Panel Displays Liquid Crystal Display (LCD) ƒ Active matrix ƒ Passive matrix Gas plasma monitor

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Video Output Devices – LCD Projectors

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Printed Output Devices – Impact Printers With striking mechanisms ƒ E.g., Dot Matrix Printers

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Printed Output Devices – Non Impact Printers

ƒ Ink Jet Printer

ƒ Laser Printer

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Special Output Devices – ATM’s / POS’s

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Special Output Devices – Virtual Reality

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Output Technology Trends

First Second Third Fourth Fifth Generation Generation Generation Generation Generation

Punched Punched Cards Cards Printed Printed Reports Reports and and Documents Documents

Punched Punched Cards Cards Printed Printed Reports Reports and and Documents Documents

Video Video Displays Displays Video Video Displays Displays Printed Printed Reports Reports Audio Responses Voice Voice Responses Responses Audio Responses Hyperlinked and and Documents Documents Printed Reports Hyperlinked Printed Reports Multimedia Video Video Displays Displays Multimedia and Documents and Documents Documents Documents

Trend: Towards Output Methods that Communicate Naturally, Quickly, and Clearly

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Interactive Multimedia

ƒ Multimedia ƒ Streaming Technology ƒ MP3

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Processing Strategies

Centralized: A single mainframe or midrange computer that performs the processing for multiple users ƒ Mainframe Computing ƒ Personal Computing Distributed: Individual computers are linked through a network sharing of information and computer resources. Needs controls and administration to coordinate the sharing of resources ƒ Client/Server Computing ƒ Peer-to-Peer Computing ƒ Network Computing Seite 73

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Mainframe Computing A single mainframe or midrange computer that performs the processing for multiple users Shortcomings: ƒ Inefficient, since the computer must also control each online user ƒ Total reliance on the central computer ƒ Must balance the workload, to avoid peak-load problems

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Personal Computing

ƒ

ƒ

ƒ

Computers available as a personal tool at any time Graphical user interface (GUI) provides a user friendly interface Modern PCs can support several activities at the same time

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Client / Server Computing Client/server architecture – different processes on the network act as either client or servers Client

Requests

Server

Data, Service

User Interface

Data

Application

Application Function

Function

Network Resources Seite 76

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Client/Server Major Players

USER

CLIENT

SERVER

Client Process

Server Process

System Services

System Services

Hardware

Hardware

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Application Level C/S

Server Process Application Level C/S

Client Process

System Services

Hardware

System Services

Hardware

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System Services Client/Server

Server Process

Client Process

System Services System

System Services

Services C/S

Hardware

Hardware

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Client / Server Computing Advantages ƒ ƒ ƒ

User convenience Technical scalability Greater ability to maintain hardware & software from different vendors

Disadvantages: ƒ ƒ

Increased data and system administration efforts Requires more computing power

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Peer-to-Peer Computing

ƒ

ƒ

ƒ

An alternative to the client/server architecture for small networks Each computer can play the role of server for the other computers in the network Appropriate when the network users mostly do their own work, but occasionally need to exchange data

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Network Computing

Attempts to combine the traditional benefits of centralization with the flexibility & responsiveness of distributed computing Based on stripped down PCs called network computers or thin clients ƒ Contain no hard disk ƒ Data and programs are stored on centralized servers

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Batch Data Processing

KEYBOARD INPUT

BATCH OF TRANSACTIONS SORTED TRANSACTION FILE

OLD MASTER FILE

VALIDATE AND UPDATE

ERROR REPORTS

NEW MASTER FILE REPORTS

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On-Line Data Processing

TRANSACTIONS

KEYBOARD

IMMEDIATE INPUT

PROCESS / UPDATE MASTER FILE

IMMEDIATE PROCESSING

MASTER FILE

IMMEDIATE FILE UPDATE Seite 84

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Sequential & Parallel Processing Sequential

Parallel Program

Program TASK 1 CPU

CPU

CPU

CPU

TASK 1

TASK 2

TASK 3

RESULT RESULT

Program TASK 2 CPU RESULT

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Hardware Trends Network computing – Java station \ Network PC – stripped down PC (no hard disk) – ideal for running Java applets Total cost of ownership (TCO) – low cost (now competing with sub $1k PCs) Open systems – software is hardware independent A computer chip in everything – household appliances Wireless PDA’s

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Managing Hardware Assets

ƒ Capacity Planning ƒ Scalability ƒ Total Cost of Ownership

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Business Guidelines for Hardware Success Cost Is Only Part of the Story ƒ Many benefits resulting from information systems are intangible and tough to measure • increased productivity • improved decision making • faster customer service Don’t Compromise on Capacity and Reliability ƒ The motto “If it ain’t broke, don’t fix it” does not apply to hardware capacity and reliability Infrastructure, Infrastructure, Infrastructure ƒ Machines no longer work in isolation ƒ All business decisions should consider the technology infrastructure and IS professionals should be prepared to sell its importance to top management Support Is Crucial ƒ When there is a problem, users expect the problem to be fixed almost immediately ƒ Who will provide support? What is the nature of support? When will the support be provided?

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Chapter Summary ƒ A computer system is a system of information processing components that perform input, processing, output, storage and control functions. ƒ The hardware components in a computer include input and output devices, a central processing unit (CPU), and primary and secondary storage. ƒ There are three major categories of computers: microcomputers, midrange computers and mainframe computers ƒ Microcomputers are used as personal computers, but are also interconnected in a variety of telecommunications networks. ƒ Midrange computers are increasingly being used as powerful network servers and for many multi-user business data processing and scientific applications. ƒ Mainframe computers are larger and more powerful and are used to handle information processing needs for large organizations. ƒ Peripheral devices used for input and output come in a variety shape and sizes. Future trends are towards devices that communicate naturally and are quick and easier to use. ƒ Selection of Computer Hardware is a key business decision ƒ Computer Hardware must be appropriate for organization ƒ Many choices and tradeoffs

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2.1 IT-Systems 2.2 Computer Hardware 2.3 Computer Software 2.4 Telecommunications and Networks 2.5 Internet 2.6 Conclusion

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Kapitel 2 E-Business Unternehmensinfrastruktur Kapitel 2.3 Computer Software

Chapter Objectives •

Describe major types of Software



Examine System Software & Operating Systems



Explain Software Evolution



Analyze Major Application Languages



Describe Approaches to Software Development



Identify Software Issues

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Software DETAILED INSTRUCTIONS THAT CONTROL THE OPERATION OF A COMPUTER SYSTEM

3 BASIC FUNCTIONS: ƒ Manage the computer resources of the organization ƒ Provide tools for people to take take advantage of these resources ƒ Act as an intermediary between organizations and stored information

7.3

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Software (1) APPLICATION SOFTWARE SYSTEM SOFTWARE

Controls the operation of computer and its devices. Services as the interface between a user and the computer’ computer’s hardware Operating System: • Language Translators

HARDWARE

• Utility Programs • User Interface • Operating System

Consists of programs designed to perform specific tasks for users popular application software includes: Application Software

Packages Programming Languages

PC Software Tools

Enterprise Software

Groupware

Middleware

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Software (2)

System Software

User Application Software

Hardware

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Systems Software: Operating System

MANAGES & CONTROLS THE ACTIVITIES OF THE COMPUTER

3 MAIN FUNCTIONS (INCLUDES SPECIALIZED CAPABILITIES): ƒ Allocation and assignment of system resources ƒ Scheduling resources and computer jobs ƒ Monitoring computer system activities

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Systems Software: Major Operating Systems

• • • • • •

DOS Windows OS/2 UNIX LINUX MAC OS

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Systems Software: User Interfaces (1) Part of software with which you interact Controls how data and instructions are entered and Information is presented on the screen 2 types of user interfaces: ƒ Command-line ƒ Graphical

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Systems Software: User Interfaces (2) User Interfaces – Command Line

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Systems Software: User Interfaces (3) User Interfaces – Menu-driven

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Systems Software: User Interfaces (4) User Interfaces – Graphical

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Java… the future 4

Java: Developed by Sun Microsystems – object-oriented programming language

4

Applet: tiny program to execute small function

4

Applets downloaded from network or internet – use Word Processor as multiple applets

4

Run on any computer and any operating system

4

Result saved on network, not on PC

4

Only network version of software needs upgrade – costs savings – easy to maintain Seite 101

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Multiprogramming / Multitasking Multiprogramming on a single-user system such as a PC Can run two or more programs on a single computer at the same time Example: Word and Excel TRADITIONAL SINGLEPROGRAM SYSTEM

MULTIPROGRAMMING ENVIRONMENT

PROGRAM 1

UNUSED MEMORY

OPERATING SYSTEM

OPERATING SYSTEM

PROGRAM 1 PROGRAM 2 PROGRAM 3 UNUSED MEMORY Seite 102

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Kapitel 2 E-Business Unternehmensinfrastruktur Kapitel 2.3 Computer Software

Managing Software Assets

USING APPLICATION SERVICE PROVIDERS SOFTWARE MAINTENANCE SELECTING SOFTWARE FOR THE ORGANZIATION

ƒ ƒ ƒ ƒ

APPROPRIATENESS EFFICIENCY COMPATIBILITY SUPPORT

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Chapter Summary

ƒ Selection of Computer Software is a key business ƒ Software must be appropriate for Organization ƒ Many choices and tradeoffs

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2.1 IT-Systems 2.2 Computer Hardware 2.3 Computer Software 2.4 Telecommunications and Networks 2.5 Internet 2.6 Conclusion

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Kapitel 2 E-Business Unternehmensinfrastruktur Kapitel 2.4 Telecommunications and Networks

Chapter Objectives Become familiar with: ƒ The history of communications and information systems ƒ The applications of data communication networks ƒ The major components of networks ƒ The importance of standards ƒ Three key trends in communications and networking ƒ Understand the role of network layers

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Defining Telecommunications

TELECOMMUNICATIONS – the transmission of data from one set of electronic devices over media to another set of geographically separated electronic devices.

Telecommunication includes the transmission of different forms of data such as text, audio, video, images, graphics.

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A Brief History of Telecommunications in the USA 1837 - Samuel Morse exhibited a working telegraph system. 1843 - Alexander Bain patented a printing telegraph. 1876 - Alexander Graham Bell, invented the first telephone capable of practical use. 1879 - first private manual telephone switchboard 1880 - first pay telephone 1915 - first transcontinental telephone service and first transatlantic voice connections. 1934 - Communications Act transferred regulation of interstate telephone traffic from ICC to FCC. 1947 - transistor invented in Bell Labs 1951 - first direct long distance dialing 1962 - first international satellite telephone call 1970 - permitted MCI to provide limited long distance service in competition to AT&T. 1984 - deregulation of AT&T 1980s - public service of digital networks 1990s - cellular telephones commonplace 1996 - U.S. Congress enacted the Telecommunications Act of 1996 1997 - International agreement signed by 68 countries to reduce regulation in TC markets

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Telecommunications Competition and Deregulation Act of 1996: ƒ Practically overnight, the local telephone industry in the U.S. went from a highly regulated and legally restricted monopoly to open competition. ƒ Local service in the U.S. is now open for competition. ƒ RBOCs are now permitted to provide long distance services.

However, is there competition yet ?

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Defining Data Telecommunications

ƒ The movement of computer information from one point to another by means of electrical or optical transmission systems. ƒ Such systems are often called Data Telecommunications Networks or Computer Networks.

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Convergence of Computing and Data Telecommunications ƒ ƒ ƒ ƒ

Reliance of telecommunications on computers Role of telecommunications in computing New wired and wireless transmission New combinations of data and computing

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Kapitel 2 E-Business Unternehmensinfrastruktur Kapitel 2.4 Telecommunications and Networks

Basic Terminology (1) Network: A set of devices and communications channels / a collection of interconnected devices to achieve communication ƒ Devices are called nodes Connectivity: The ability to transmit data between devices at different locations Switching: The process of directing a signal from its source to its destination

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Basic Terminology (2) Decoding: Converting the data back into their original form upon arrival at its destination Network Management: The process of monitoring the network’s operations, detecting and repairing faults, and balancing traffic Protocols: A set of rules and procedures for exchanging information between computers. These rules and procedures ensure efficient and error-free electronic communications between two or more computers.

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Basic Terminology (3) Channel: A path along which data are transmitted (wired or wireless). Channels have five characteristics: 1.

Transmission rate: Rate at which channel carries data from one computer to another

2.

Bandwidth: Volume or capacity of data that a channel can carry

3.

Transmission mode: Ways by which data are transmitted. Two ways include asynchronous (one byte at a time) and synchronous (blocks of bytes).

4.

Transmission direction: Three directions for transmitting data include simplex, half duplex, and full duplex.

5.

Transmission signals: Information travels as analog or digital signals Seite 114

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Kapitel 2 E-Business Unternehmensinfrastruktur Kapitel 2.4 Telecommunications and Networks

Standards

For Telecommunications to be successful, each layer in one computer must be able to communicate with its matching layer in the other computer. This is accomplished by standards.

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The Importance of Standards ƒ Standards are necessary in almost every business and public service entity. ƒ The primary reason for standards is to ensure that hardware and software produced by different vendors can work together. ƒ The use of standards makes it much easier to develop software and hardware that link different networks because software and hardware can be developed one layer at a time.

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Why are standards so important now? More and more consolidation

With consolidation, interoperability becomes a requirement – not just a want! Seite 117

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The Standards Making Process (1) Two types of standards: ƒ Formal standards are developed by an official industry or government body. ƒ Defacto standards emerge in the marketplace and supported by several vendors, but have no official standing.

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The Standards Making Process (2) Formal standardization process has three stages: 1. Specification stage: Developing a nomenclature and identifying the problems to be addressed. 2. Identification of choices stage: Those working on the standard identify the various solutions and choose the optimum solution from among the alternatives. 3. Acceptance, the most difficult stage: Defining the solution and getting recognized industry leaders to agree on a single, uniform solution

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Telecommunications Standards Organizations (1) ƒ International Telecommunications Union Telecommunication Standardization Sector (ITU-TSS) • Technical standard setting organization of the ITU. Formerly called the Consultative Committee on International Telegraph and Telephone (CCITT) • Comprised of representatives of over 150 Postal Telephone and Telegraphs (PTTs), like AT&T, RBOCs, or common carriers.

ƒ International Organization for Standards (ISO) • Member of the ITU, makes technical recommendations about data communications interfaces. Seite 120

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Kapitel 2 E-Business Unternehmensinfrastruktur Kapitel 2.4 Telecommunications and Networks

Telecommunications Standards Organizations (2) ƒ ƒ ƒ ƒ ƒ

American National Standards Institute (ANSI) Institute of Electrical and Electronics Engineers (IEEE) Electronic Industries Association (EIA) National Institute of Standards and Technology (NIST) Electronic Data Interchange (EDI) of Electronic Data Interchange for Administration Commerce and Transport (EDIFACT).

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Data Telecommunications Network

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Example for a Telephone Network

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Kapitel 2 E-Business Unternehmensinfrastruktur Kapitel 2.4 Telecommunications and Networks

Example for a Computer Network

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Functions of the Computer Network Components

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Types of Networks Computer Networks can be classified in many different ways. One of the most common is by geographic scope: ƒ Personal Area Network (PAN): Personal network for one individual to connect several electronic devices with each other. ƒ Local Area Networks (LAN): A group of microcomputers or terminals located in the same general area and connected by a common circuit. Covers a clearly defined small area, such as within or between a few buildings. ƒ Metropolitan Area Networks (MANs): Connects LANs located in different areas to each other and to wide area networks. Typically span from 3 - 30 miles. ƒ Wide Area Networks (WANs): Connects MANs and LANS and are

usually leased from inter-exchange carriers. Typically span hundreds or thousands of miles.

ƒ Global Area Networks (GANs): Connects MANs Seite 126

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Kapitel 2 E-Business Unternehmensinfrastruktur Kapitel 2.4 Telecommunications and Networks

Personal Area Network (PAN)

Quelle: Ericsson

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Local Area Network (LAN)

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Wide Area Network (WAN)

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Types of Networks - Examples

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Common Wide Area Network Designs ƒ Most organizations do not build their own MANs, WANs or GANs by laying cable, building microwave towers, or sending up satellites. Instead most organizations lease circuits from interexchange carriers, and use those to transmit their data. ƒ Once the major connection points one the WAN or GAN have been identified, the next step is to design the circuits that will connect those locations.

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Elements of Networks 1.

Topology – The way in which stations are inter-connected

2.

Switching q Circuit Switching vs. Packet Switching

3.

Transmission Media – Twisted pair, co-ax cable, fiber optic cable – Transmission direction (1-way or 2-way)

4.

Layout and Implementation

5.

Security Seite 132

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Kapitel 2 E-Business Unternehmensinfrastruktur Kapitel 2.4 Telecommunications and Networks

Elements of Networks 1.

Topology

2.

Switching

3.

Transmission Direction

4.

Transmission Media

5.

Connecting Devices

6.

Layout and Implementation

7.

Security Seite 133

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Network Topologies: Ring USER

USER

USER

HOST One way transmission, listen and re-transmit, token ring Seite 134

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Network Topologies: Star

USER

USER

HOST

USER

USER Stations linked to central node, but transmission heard by all users Seite 135

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Kapitel 2 E-Business Unternehmensinfrastruktur Kapitel 2.4 Telecommunications and Networks

Network Topologies: Bus USER

USER

USER

Terminator

Terminator

USER

USER

USER

stations linked to central cable, easy to add new users Seite 136

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Comparing Topologies Ring Activity Cost of expansion Moderate Throughput

Reliability Connectivity Cost

Star Moderate

Bus Low

High Decreases with added node Moderate

Limited by central node

Moderate Decreases with added node

Low

High

Moderate

High Initially Low Low incremental

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Network Topologies: Hybrid

hybrid of ring, star and bus networks Seite 138

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Kapitel 2 E-Business Unternehmensinfrastruktur Kapitel 2.4 Telecommunications and Networks

Elements of Networks 1.

Topology

2.

Switching

3.

Transmission Direction

4.

Transmission Media

5.

Connecting Devices

6.

Layout and Implementation

7.

Security Seite 139

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Elements of Networks: Switching CIRCUIT SWITCHING: ƒ The method used in telephone networks ƒ Sets up a temporary circuit between the source and the destination ƒ Resources are reserved for the duration of the session (call) PACKET SWITCHING: ƒ Appropriate when data are transmitted infrequently from a large number of nodes • Used on the Internet ƒ The message is divided into packets containing control information • No circuit is established ƒ Provides better sharing of resources • Multiple users share the same resources Seite 140

Kapitel 2 E-Business Unternehmensinfrastruktur Kapitel 2.4 Telecommunications and Networks

Circuit Switched vs Packet Switched

3 1 2

Circuit Switched (Verbindungsor.): ƒ Hohe Verbindungsaufbauzeit ƒ Weniger sicher ƒ Geringer Delay ƒ Garantierte Bandbreite

Packet Switched (Paketorientiert): ƒ Keine Verbindungsaufbauzeit ƒ Relativ sicher ƒ Delay und Paketverlust möglich ƒ Keine garantierte Bandbreite

Für Echtzeitanwendungen (Sprache, Video) Beispiele: ISDN, POTS

Zeitunkritische Anwendungen Beispiele: IP, ATM

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Packet Switching

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Elements of Networks 1.

Topology

2.

Switching

3.

Transmission Direction

4.

Transmission Media

5.

Connecting Devices

6.

Layout and Implementation

7.

Security Seite 143

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Transmission Direction

ƒ Simplex ƒ Half-duplex ƒ Full-duplex

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Simplex

Half-duplex

Full-duplex

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Elements of Networks 1.

Topology

2.

Switching

3.

Transmission Direction

4.

Transmission Media

5.

Connecting Devices

6.

Layout and Implementation

7.

Security Seite 146

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Transmission Media Paths that data follows as it is transmitted. Transmission media: ƒ Physical ƒ Wireless Bandwidth – corresponds to the capacity of the transmission channel ƒ MB or GB ƒ A major limitation for the information superhighway

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Kapitel 2 E-Business Unternehmensinfrastruktur Kapitel 2.4 Telecommunications and Networks

Physical (Wired) Transmission Media Twisted Pair Wire ƒ Used for voice transmission and for low volume data transmission ƒ Slow Coaxial Cable ƒ Used in LANs and for data transmissions of less than 10 miles ƒ Faster and more versatile than twisted pair Fiber Optic Cable ƒ Carries data in the form of light ƒ Extremely fast ƒ Very light ƒ Very difficult to tap into ƒ Very little data loss ƒ Costly Seite 148

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Physical (Wired) Transmission Media - Twisted-Pair Wire

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Physical (Wired) Transmission Media - Coaxial Cable

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Kapitel 2 E-Business Unternehmensinfrastruktur Kapitel 2.4 Telecommunications and Networks

Physical (Wired) Transmission Media - Optical Cable

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Physical (Wired) Transmission Media - Summary Twisted pair

Capacity : Range :

1-10 Mbps < 2 KM

Co-axial cable

200 Mbps < 3 KM

Fiber optic cable

10 Gbps Unlimited Seite 152

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Wireless Transmission Media ƒ ƒ ƒ ƒ ƒ

Microwaves Satellite Broadcast Radio Cellular Radio Infrared

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Kapitel 2 E-Business Unternehmensinfrastruktur Kapitel 2.4 Telecommunications and Networks

Wireless Transmission - Microwave

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Wireless Transmission - Satellite

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Wireless Transmission – Microwave and Satellite

Satellite

Microwave

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Wireless Transmission – Cellular Radio The broadcast area for cellular radio is divided into honeycombed-shaped cells, each of which covers a specific geographical area and has its own base station.

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Mobile Kommunikation – Kommunikationsformen (1)

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Mobile Kommunikation – Kommunikationsformen (2) Rahmenbedingungen (Reichweite, Bandbreite, Kosten) führen zu einem Mix an mobilen Kommunikationsformen.

IrDA • Sehr geringer Stromverbrauch

GSM, GPRS, UMTS... • Wide Area Network • Universeller Zugriff

802.11, HiperLAN... • Wireless LAN • Hohe Datenraten

Bluetooth • Sehr kleine Zellen • Ad-hoc Networking • Klein und stromsparend • Geringe Übertragungsleistung

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Mobile Kommunikation - Technologien Mobile Client Application Telephony Client, WAP Browser, SMS Client, Java MIDlet, ...

Java VM Mobile Operating System Symbian EPOC, PalmOS, Microsoft Pocket PC, ...

Mobile Hardware Mobile Phone, Smart Phone, Personal Digital Assistent, Embedded Appliances, ...

Mobile Data Communication CSD, SMS, GPRS UMTS, Bluetooth, IrDA

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Global System for Mobile Communications, GSM (1) ƒ

Mitte der 80er war Mobilfunk auf der Basis analoger und national beschränkter Technologien verfügbar.

ƒ

Seit 1991 ist GSM weltweiter Standard für mobile digitale Kommunikation (2. Generation). Europäischer Standard durch European Telecommunications Standardisation Institute (ETSI).

ƒ

Memorandum of Understanding (MoU): 1988 von 18 europäischen Ländern unterzeichnet, mindestens 2 Netzbetreiber pro Land, Entwicklung gemäß GSMSpezifikation und offene Schnittstellen.

ƒ

Seit 1992 in Betrieb: 401 GSM-Netze in 168 Ländern mit 488 Millionen Nutzern online; zunehmend auch in USA. Europäische Erfolgsstory.

ƒ

GSM unterstützt Sprach- und Datenkommunikation (ISDN-ähnlich).

ƒ

GSM ist leitungsgebunden (Circuit Switched Data, CSD).

ƒ

Übertragungsrate 22 kbit/s brutto, aber nur 9,6 kbit/s netto.

ƒ

Eine SIM-Karte (SIM: Subscriber Identification Module) als Datenspeicher und zur Identifikation.

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Global System for Mobile Communications, GSM (2) ƒ

Über GSM-Mobiltelefone können gleichzeitig Informationen (über SMS-Kanal) und Sprache übermittelt werden.

ƒ

Zurzeit: Viel Sprachkommunikation, wenig Datenkommunikation, Kapazitätsgrenzen in Städten erreicht, 60-80% Prepaid-Karten.

ƒ

Der GSM-Standard sichert bundesweit nahezu flächendeckende Mobilkommunikation für Sprache und Daten. (z.B. SMS, WAP, Cell Broadcast).

ƒ

GSM ist die Basis für die zukünftigen Generationen 2.5G (GPRS, HSCSD, ...) und 3G (UMTS).

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Kapitel 2 E-Business Unternehmensinfrastruktur Kapitel 2.4 Telecommunications and Networks

GSM - Prinzip zellulare Netze

Quelle: Prof. Zitterbart

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Entwicklungspfade - Mobilfunk

Quelle: Durlacher

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Mobile Kommunikation - Erweiterung der Bandbreite Kanalbündelung: ƒ Belegung mehrerer Zeitschlitze (acht Zeitschlitze im GSM-System), wodurch eine Verachtfachung der Bandbreite möglich ist. ƒ Voraussetzung: Umrüstung der Basisstationen (ca. 10.000 Stück in ganz Deutschland je Netz) und spezielle Endgeräte. Overheadverringerung: ƒ Verzicht auf Fehlererkennung und -korrektur. Steigerung der Nettodatenrate auf 14,4 kbit/s oder sogar 21,4 kbit/s möglich. ƒ Voraussetzung: Gute Funkbedingungen, Umrüstung der Basisstationen und spezielle Endgeräte Höherwertiges Modulationsverfahren: ƒ Erhöht die spektrale Effizienz, ausgedrückt in bit/(Hz x s) und dadurch die Bruttodatenrate von derzeit 22 kbit/s auf 48 kbit/s je Kanal. ƒ Voraussetzung: Umrüstung der Basisstationen und spezielle Endgeräte Seite 165

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Kapitel 2 E-Business Unternehmensinfrastruktur Kapitel 2.4 Telecommunications and Networks

High-Speed Circuit Switched Data (HSCSD) ƒ

Leitungsvermittlung auf GSM-Basis.

ƒ

Nutzt Kanalbündelung und Overheadverringerung.

ƒ

Max. 115,2 kbit/s durch Bündelung von 8 GSM-Kanälen zu je 14,4 kbit/s.

ƒ

GSM-Netze haben jedoch nur Gateways zum Festnetz mit max. 64 kbit/s.

ƒ

Praktische Implementierung: 4 Kanäle (= 57,6 kbit/s).

ƒ

Gilt als wesentlich geeigneter für GSM-1800-Netze (= E-Netze in Deutschland), da dort mehr Frequensspektrum zur Verfügung steht und die Kapazität noch nicht so hoch ausgelastet ist.

ƒ

Deutschland: ƒ

Durch E-Plus angeboten (Bezahlung aller Kanäle nach herkömmlichen Datentarif?).

ƒ

Regelbetrieb seit Frühjahr 2000 mit 36,4 kbit/s.

ƒ

Commitment anderer Netzbetreiber in Deutschland?

ƒ

Bislang geringe Zahl von verfügbaren Endgeräten.

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General Packet Radio Service (GPRS) ƒ

Erster paketorientierter Datendienst im GSM-Netz

ƒ

Always on Verbindung und volumenabhängige Tarifierung.

ƒ

Nur geringe Anpassungen in der GSM-Infrastruktur nötig

ƒ

Bündelung von bis zu 8 Time-Slots

ƒ

Nutzt Kanalbündelung und Overheadverringerung.

ƒ

Overheadvariabilität erlaubt Datenraten von 9,05 / 13,4 / 15,6 und 21,4 kbit/s je Kanal.

ƒ

Max. 171,2 kbit/s durch Bündelung von 8 Kanälen zu je 21,4 kbit/s.

ƒ

Praktische Implementierung startet mit 4 Kanälen zu 13,4 kbit/s (= 53,6 kbit/s).

ƒ

Shared-Medium-Effekt führt zu Aufteilung der Gesamtkapazität auf mehrere Nutzer - Quality of Service (QoS) kann daher nicht garantiert werden.

ƒ

Ideal für den mobilen Internetzugang.

ƒ

Dürfte von allen Netzbetreibern in Deutschland angeboten werden.

Seite 167

Kapitel 2 E-Business Unternehmensinfrastruktur Kapitel 2.4 Telecommunications and Networks

Enhanced Data Rates for GSM Evolution (EDGE) ƒ

Neues Modulationsverfahren.

ƒ

Wird zusätzlich zur Kanalbündelung und Overheadreduktion angewendet.

ƒ

Je Zeitschlitz sind dann 48 kbit/s möglich (= 384 kbit/s insgesamt)

ƒ

Grundsätzliche Handicaps von GPRS und HSCSD bleiben jedoch erhalten - lediglich die theoretische Spitzendatenrate wird gesteigert.

ƒ

Paketvermittlung: Enhanced GPRS (EGPRS)

ƒ

Leitungsvermittlung: Enhanced Circuit Switched Data (ECSD)

(Interessant für alle Netzbetreiber, die keine UMTS-Lizenz erhalten haben. Netzbetreiber mit UMTS-Lizenz werden diese Technik wahrscheinlich nicht einführen.) Seite 168

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Kapitel 2 E-Business Unternehmensinfrastruktur Kapitel 2.4 Telecommunications and Networks

Universal Mobile Telecommunications System, UMTS (1) ƒ

Neue Übertragungstechnologie (CDMA), bietet mehr Bandbreite

ƒ

Neues Frenquenzspektrum (UMTSLizenzen)

ƒ

Leitungs- und Paketvermittelt

ƒ

Datenübertragungsrate max. 2Mbit/s

ƒ

Neue Dienste möglich

Seite 169

Quelle: Nokia

Kapitel 2 E-Business Unternehmensinfrastruktur Kapitel 2.4 Telecommunications and Networks

Universal Mobile Telecommunications System, UMTS (2) ƒ

Europäischer Standard für theoretisch 2,048 Mbit/s

ƒ

Realistische Szenarien (Beginn 2002/3?):

ƒ

ƒ

144 kbit/s aus mobilen Umgebungen heraus in großen Zellen (dünnbesiedelte Gebiete).

ƒ

384 kbit/s aus mobilen Umgebungen heraus in kleinen Zellen (Ballungsräume).

ƒ

2,048 Mbit/s aus stationären Umgebungen.

Herausforderungen für UMTS technischer und wirtschaftlicher Art: ƒ

Synergien aus bestehenden GSM-Netzen geringer als erwartet, dadurch neues Netz erforderlich.

ƒ

UMTS-Technologie komplexer als erwartet.

ƒ

Know-How-Problem.

ƒ

Kapazitätsproblem in existierenden Netzen ist durch Sprache entstanden, nicht durch Daten.

ƒ

UMTS-Frequenzspektrum wird zunächst für Telefonie in Ballungsgebieten benötigt.

Seite 170

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Vergleich Mobilfunksysteme GSM / CSD

GSM / HSCSD

GSM / GPRS

GSM / HSCSD mit EDGE

GSM / GPRS mit EDGE

UMTS

Modus

Leitungsvermittelt

Leitungsvermittelt

Paketvermittelt

Leitungsvermittelt

Paketvermittelt

Leitungs- und Paketvermittelt

Max. Bandbreite

14,4 kbit/s

115,2 kbit/s

171,2 kbit/s

384 kbit/s

384 kbit/s

2,048 Mbit/s

Bandbreite f. Nutzer

9,6 kbit/s

36,4 kbit/s

Lastabhängig ca. 10-20 kbit/s

384 kbit/s ?

Lastabhängig bis 100 kbit/s

144 kbit/s 384 kbit/s 2,048 Mbit/s

Genutzte Verfahren

-

Bündelung Overheadred.

Bündelung Overheadred.

Alle

Alle

Alle

Anwendungen

Fax, einfache Datenübertr.

Echtzeitverkehr Downloads

Burstartiger Verkehr

Echtzeitverkehr Downloads

Burstartiger Verkehr

Div.

2001 ?

Testbed: 1999 Betriebsnetze: 2002

2002 ?

Januar 2003 ?

Teststart

1992

Herbst 1999

Herbst 1999

2001 ?

Betriebsstart

1993

Frühjahr 2000

2001

2002 ?

Seite 171

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Seite 172

Quelle: Durlacher

Kapitel 2 E-Business Unternehmensinfrastruktur Kapitel 2.4 Telecommunications and Networks

Mobile Kommunikation - Rahmenbedingungen Schwächen Zukunft

Aktueller Stand

Präsentation

Kosten

• Keine einheitliche Entwicklungsumgebung zur Implementierung mobiler Dienste

Eingabe

Speicher

• Im Vergleich zum „fixed Computing“ höhere Verbindungskosten zum Internet

Rechenleistung

Datenübertragung

Seite 173

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Wireless Networking Standards

ƒ

Bluetooth – a fast short-range wireless technology •

ƒ

Wireless office

Wireless application protocol (WAP) - a standard technology framework for wireless Internet •

Allows for some of the Internet content to be accessed by mobile devices

Seite 174

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Problematik vor Bluethooth

Verschiedene VerschiedeneSysteme Systeme zum zumErfassen Erfassenvon von

••Adressen Adressen ••Telefonnummern Telefonnummern ••Termine Termine ••Memos, Memos,etc etc

Seite 175

Kapitel 2 E-Business Unternehmensinfrastruktur Kapitel 2.4 Telecommunications and Networks

Herkömmliche Lösungen

Seite 176

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Herkömmliche Lösungen – Verbindung über Kabel ƒ Ein Kabel verbindet zwei oder mehr Geräte. ƒ Mehrere Standards verfügbar: ƒ Serielle oder Parallele Kabel, ISDN Kabel, Stromkabel, USB (Daten+Strom). ƒ Aber auch viele proprietäre Lösungen. ƒ Vorteil: ƒ Geringe Kosten und weite Verbreitung. ƒ Problem: ƒ Kabelsalat? ƒ Ad-hoc Verbindungen? Seite 177

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Kapitel 2 E-Business Unternehmensinfrastruktur Kapitel 2.4 Telecommunications and Networks

Bluetooth: Ein globaler Standard für die kabellose Kommunikation?

Personal Area Network (PAN)

Seite 178

Kapitel 2 E-Business Unternehmensinfrastruktur Kapitel 2.4 Telecommunications and Networks

Was ist Bluetooth? Harald Blaatand “Bluetooth” II ƒ King of Denmark 940-981 ƒ Son of Gorm the Old (King of Denmark) and Thyra Danebod (daughter of King Ethelred of England). ƒ Harald controlled Denmark and Norway. This is one of two Runic stones erected in his capital city of Jelling (central Jutland).

Seite 179

Kapitel 2 E-Business Unternehmensinfrastruktur Kapitel 2.4 Telecommunications and Networks

Definition Bluetooth ... und dient der Realisierung eines Personal Area Network (PAN) ... ein Industriestandard (ohne Lizenzkosten)

... für die kabellose Verbindung (funkbasiert)

... von 2 oder mehreren (Netzwerk)

... für Sprache und Daten (auch gleichzeitig)

... auf kurze Entfernung (Picoversion: bis 10 m)

... beliebigen Geräten (Notebook, Handy, PDA...)

„Bluetooth ist ein internationaler Standard, der Funkverbindungen zwischen unterschiedlichen mobilen und stationären Geräten ermöglicht. Über Bluetooth können Computer und zugehörige Peripheriegeräte, digitale Kameras, Mobiltelefone, PDAs, Internet-Zugangsgeräte Modems, ISDN-Adapter etc.) und in Zukunft auch Haussteuerungsanlagen und Geräte in Automobilen drahtlos miteinander kommunizieren.“ (Quelle: www.bluetooth.elsa.com)

Seite 180

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The Headset is Bluetooth-enabled

Seite 181

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Bluetooth - Special Interest Group (SIG) ƒ

Konsortium aus Firmen, die den Bluetooth-Standard definieren.

ƒ

Beginn 1998.

ƒ

Key-Player sind Ericsson, IBM, Intel, Nokia, Toshiba, Lucent sowie Motorola.

ƒ

Über 2100 Firmen unterstützen den Standard.

ƒ

Standard 1.0 bereits Mitte 1999, Version 1.1 Ende 2000 verabschiedet. Erste Produkte bereits verfügbar.

ƒ

Endgeräte von unterschiedlichen Herstellern sollen miteinander kommunizieren (z.B. PCs, PDAs, Mobiles, Stereoanlagen, Haushaltsgeräte etc.).

ƒ

Ziel der Entwicklung von Bluetooth: ƒ

Reduzierung der vielfältigen Schnittstellen

ƒ

Übertragung von Daten auf kurze Distanzen

ƒ

Ersetzen von Kabeln (und Steckern)

Seite 182

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Bluetooth - Überblick Eigenschaften

ƒ ƒ ƒ ƒ ƒ ƒ ƒ ƒ ƒ

2.4 GHz-Band 1 Mbit/s brutto 1/10 mW Sendeleistung Überall anwendbar Geringer Stromverbrauch Daumennagelgroßer Chip Ad-hoc Networking Integrierte Sicherheit Gebührenfrei

ƒ ƒ ƒ ƒ ƒ ƒ ƒ ƒ

Große Datenmengen 10/100 m Reichweite Auch Flughafen, Bahnhof, ... Sehr robust Kleine Batteriegröße Kleine Größe Automatische Kommunikation Sichere Kommunikation

Seite 183

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Kapitel 2 E-Business Unternehmensinfrastruktur Kapitel 2.4 Telecommunications and Networks

Bluetooth - Technische Aspekte ƒ

Genutztes Frequenzband (2,402GHz-2,480GHz) ist weltweit freigegeben (keine Lizenzgebühren).

ƒ

Aber viele andere Geräte agieren auch in diesem Frequenzbereich (Mikrowellen, medizinische Geräte, DECT, 802.11b).

ƒ

Frequenzband ausgiebig getestet, daher weit einsetzbar (z.B. Lufthansa erlaubt Nutzung des 2,4GHz Bereichs während des Flugbetriebs).

ƒ

Aufwendige Kodierung bei der physischen Verbindung (1600 Frequenzwechsel pro Sekunde). Sehr robust, schnelle und zuverlässige Übertragung von Daten.

ƒ

Keine Sichtverbindung notwendig (vgl. Infrarot)

ƒ

Bruttogeschwindigkeit von 1 Mbit/s

ƒ

Datenübertragung bis 720 Kbps (ISDN: 64Kbps).

Seite 184

Kapitel 2 E-Business Unternehmensinfrastruktur Kapitel 2.4 Telecommunications and Networks

Bluetooth - Technische Aspekte ƒ

Ziel: Massenproduktion (1,7 Milliarden Stück im Jahr 2005) ermöglicht geringere Kosten (10 Mark pro Stück).

ƒ

Geringer Stromverbrauch macht Einsatz auch in sehr kleinen Geräten möglich.

ƒ

ƒ

10 Meter Reichweite; 1 mW Sendeleistung (1 mW im Gegensatz zu 800-2000 mW bei GSM-Handys)

ƒ

100 Meter Reichweite; 100mW Sendeleistung (Long-Range-Bluetooth)

Bluetooth Endgeräte finden sich automatisch. ƒ

ƒ

PDA synchronisiert sich mit PC beim Eintreten in den Raum.

Integriertes Sicherheitskonzept: ƒ

Eigener PDA synchronisiert sich nicht mit jedem PDA auf der Straße.

Seite 185

Kapitel 2 E-Business Unternehmensinfrastruktur Kapitel 2.4 Telecommunications and Networks

Bluetooth - Typischer Ablauf (1) Private Private PIN PINdes des Anwenders Anwenders

Bluetooth Bluetooth Chip Chip

ƒ

Jeder Bluetooth Chip hat eine weltweit eindeutige Nummer.

ƒ

Nach der Aktivierung sucht das Geräte nach anderen Bluetooth-Stationen.

ƒ

Wurde ein anderes Gerät gefunden, muss der Anwender eine PIN eingeben, um die Kommunikation freizuschalten.

ƒ

Danach tauschen die Bluetooth-Geräte Profile aus und Verschlüsselung Verschlüsselungdurch durch Zufallszahlen suchen damit nach gemeinsamen Funktionen/Daten. Zufallszahlen Gesamte weitere Kommunikation wird über 128BitSchlüssel kodiert.

ƒ

Seite 186

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Kapitel 2 E-Business Unternehmensinfrastruktur Kapitel 2.4 Telecommunications and Networks

Bluetooth - Typischer Ablauf (2) Ericsson Bluetooth Modul: 33 * 17 * 4 mm

Seite 187

Kapitel 2 E-Business Unternehmensinfrastruktur Kapitel 2.4 Telecommunications and Networks

Bluetooth - Profile

Synchronisation

Object Exchange

Headset LAN Access

Intercom

Dial-up Networking Seite 188

Kapitel 2 E-Business Unternehmensinfrastruktur Kapitel 2.4 Telecommunications and Networks

Bluetooth Szenarien: 3 in 1-Telefon ƒ

Nur noch ein Endgerät für verschiedene Szenarien der Sprachkommunikation: ƒ

Telefonieren über Mobilfunkanbieter: Fungiert als normales Handy (keine Nutzung der Bluetooth-Technologie).

ƒ

Telefonieren über Festnetz: Zu Hause über Bluetooth Verbindung mit einer Festnetzstation (geringere Gesprächkosten).

ƒ

Interngespräche: Gespräche sind im Personal Area Network (10m) über Bluetooth möglich (keine Gesprächskosten). Seite 189

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Kapitel 2 E-Business Unternehmensinfrastruktur Kapitel 2.4 Telecommunications and Networks

Bluetooth Szenarien – Verbindung Notebook und Handy

Internet

UnternehmensNetzwerk

Mobilnetz

GSM

9,6 kBit/s

HSCSD

57,6 kBit/s

GPRS

115 kBit/s

EDGE

384 kBit/s

UMTS

2 MBit/s

max. 721 kBit/s

Bluetooth Link

Seite 190

Kapitel 2 E-Business Unternehmensinfrastruktur Kapitel 2.4 Telecommunications and Networks

Bluetooth Szenarien - Internet-Bridge Zugang zum Internet zu jeder Zeit. Ein Rechner bestimmt den nächsten und kostengünstigsten Zugangspunkt ins Internet. Dies kann sein:

ƒ Das Handy im Koffer. ƒ Die Festnetzstation in der Wohnung. ƒ Der kostenlose Zugangsknoten in der Wartehalle eines Hotels. ƒ usw.

Seite 191

Kapitel 2 E-Business Unternehmensinfrastruktur Kapitel 2.4 Telecommunications and Networks

Bluetooth Szenarien - Datenaustausch

ƒ

Während eines Zusammentreffens können beliebige Datenobjekte (Kalender-Meetings, AdreßbuchKontaktinformationen, Dateien) ausgetauscht werden.

ƒ

In Bluetooth werden Standards definiert, die bewirken, dass versendete Datenobjekte auch in der korrespondierenden Applikation auftauchen (Meetings erscheinen im Kalender).

Seite 192

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Kapitel 2 E-Business Unternehmensinfrastruktur Kapitel 2.4 Telecommunications and Networks

Bluetooth Szenarien - Automatische Synchronisation ƒ

Idee: Alle Geräte im PAN haben den selben Datenbestand (Adressen, Meetings, etc.).

ƒ

Dazu synchronisieren sich alle Endgeräte beim Eintritt in das PAN automatisch miteinander.

ƒ

Der Synchronisationsprozess bleibt transparent.

ƒ

Erweckt den Anschein, man habe einen virtuellen Speicher, den man über beliebige Endgeräte manipulieren kann. Seite 193

Kapitel 2 E-Business Unternehmensinfrastruktur Kapitel 2.4 Telecommunications and Networks

Bluetooth Szenarien – Sharing: Gemeinsame Nutzung von Ressourcen

Seite 194

Kapitel 2 E-Business Unternehmensinfrastruktur Kapitel 2.4 Telecommunications and Networks

Bluetooth Szenarien - Kopfhörer

Verbindet Kopfhörer bei Bedarf mit beliebigem Endgerät (Handy, PC, Bürotelefon, CD Spieler, etc.).

Siehe: www.ericsson.com/infocenter/news/Bluetooth_headset.html

Seite 195

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Kapitel 2 E-Business Unternehmensinfrastruktur Kapitel 2.4 Telecommunications and Networks

Bluetooth Szenarien - Bilderübertragung Digitale Kameras, die Bilder per Bluetooth und Handy verschicken.

GSM UMTS

Seite 196

Kapitel 2 E-Business Unternehmensinfrastruktur Kapitel 2.4 Telecommunications and Networks

Bluetooth - Anwendungen Bluetooth • Sehr kleine Zellen • Ad-hoc Netzwerk-fähig • Klein und Energie-effizient • Sehr hohe TN-Dichte möglich • Geringe Sendeleistung • Billig und interoperabel • Sehr sicher Gut für Zahlungsabwicklung

Ortsabhängige Dienste im lokalen Umfeld Nahkommunikation Kleine und leichte Geräte

In Flugzeugen Hot Spots und Kliniken

Seite 197

Kapitel 2 E-Business Unternehmensinfrastruktur Kapitel 2.4 Telecommunications and Networks

Bluetooth-Produkte: - Ericsson R520 Erstes Tri-Band (900/1800/1900) GSM Handy mit ƒ HSCSD (bis zu 56,7Kbs Datenverbindung - Leitung), ƒ GPRS (bis 115Kbs Datenverbindung - Paket), ƒ WAP Browser, ƒ Bluetooth (bis zu 720Kbs Datenverbindung), ƒ IrDA (bis zu 4Mbs Datenverbindung), ƒ Spracherkennung (Kein Tastendruck notwendig) und ƒ Kombination mit Ericsson Headset oder spezieller PC Card zum drahtlosen Zugang zu Remote Access Services.

Seite 198

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Kapitel 2 E-Business Unternehmensinfrastruktur Kapitel 2.4 Telecommunications and Networks

Bluetooth-Produkte: Anoto Pen ƒ

Äußerlich normaler Kugelschreiber.

ƒ

Stift schreibt mir spezieller Tinte, die von eingebauter Infrarot-Kamera gelesen wird.

ƒ

Integrierte Texterkennung auf geschriebenen Text.

ƒ

Zeichen werden per Bluetooth an Laptop, Handheld etc. direkt weitergereicht.

ƒ

Mails, Texte usw. können wie gewohnt handschriftlich geschrieben werden.

ƒ

Hilfreich bei kleinen Eingabemedien, Alternative zur Spracherkennung. Seite 199

Kapitel 2 E-Business Unternehmensinfrastruktur Kapitel 2.4 Telecommunications and Networks

Bluetooth - Zukünftige Entwicklung ƒ Prognosen stark schwankend • IDC: 2003 -> 90 % Notebooks mit Bluetooth • Intel: 2005 -> 80 % Notebooks mit Bluetooth ƒ Weiterentwicklung des Standards • Höhere Datenrate (2 - 10 Mbit/s) • Höhere Energieeffizienz

Seite 200

Kapitel 2 E-Business Unternehmensinfrastruktur Kapitel 2.4 Telecommunications and Networks

Seite 201

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Kapitel 2 E-Business Unternehmensinfrastruktur Kapitel 2.4 Telecommunications and Networks

Bluetooth – Vorteile (1) ¾ Bluetooth... ¾ ... ist mit niedrigen Kosten verbunden. ¾ ... benötigt wenig Energie.

¾ ... bietet schnelle und verläßliche digitale Übertragungen. ¾ ... machst lästige Kabel überflüssig. ¾ ... erfordert keine Sichtverbindung zw. den Geräten. Seite 202

Kapitel 2 E-Business Unternehmensinfrastruktur Kapitel 2.4 Telecommunications and Networks

Bluetooth – Vorteile (2) ¾ Bluetooth... ¾ ... bietet einen enormen Grad an Freiheit. ¾ ... ist einfach zu bedienen und läßt sich unbemerkt integrieren. ¾ ... ist sehr vielseitig, da es einen universellen Standard schafft. ¾ ... erhöht Komfort und Sicherheit. ¾ ... hat eine hohe Verläßlichkeit (Vermeidung von Kabelbrüchen). Seite 203

Kapitel 2 E-Business Unternehmensinfrastruktur Kapitel 2.4 Telecommunications and Networks

Bluetooth - Nachteile ¾ Bluetooth... ¾ ... hat z.Zt. noch hohe Nachrüstkosten. ¾ ... arbeitet auf derselben Frequenz wie Wireless LANs (mögliche Kollisionsprobleme) ¾ ... wird nicht von jedem Gerät mit allen Profilen unterstützt. ¾ ... hat in der laufenden Generation eine problematische Chipgröße.

Seite 204

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Bluetooth – Ausblick

Seite 205

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Wireless LANs Vorteile: ƒ

Räumlich flexibel innerhalb eines Empfangsbereichs

ƒ

Ad-hoc-Netzwerke ohne vorherige Planung machbar

ƒ

Keine Verkabelungsprobleme (z.B.historische Gebäude,Feuerschutz, Ästhetik)

ƒ

Weniger anfällig gegenüber Katastrophen wie Erdbeben, Feuer - und auch unachtsamen Benutzern, die Stecker ziehen!

Nachteile: ƒ

Übertragungsraten derzeit bei (10 Mbit/s)

ƒ

Viele proprietäre Lösungen, Standards beginnen sich erst langsam durchzusetzen

ƒ

Müssen viele nationale Regelungen beachten, wenn sie mit Funk arbeiten, globale Regelungen werden erst langsam geschaffen (z.B. IMT-2000)

Seite 206

Kapitel 2 E-Business Unternehmensinfrastruktur Kapitel 2.4 Telecommunications and Networks

Wireless LANs - Entwicklungsziele ƒ

Weltweite Funktion

ƒ

Möglichst geringe Leistungsaufnahme wegen Batteriebetrieb

ƒ

Betrieb ohne Sondergenehmigungen bzw. Lizenzen möglich

ƒ

Robuste Übertragungstechnik

ƒ

Vereinfachung der (spontanen) Zusammenarbeit bei Treffen

ƒ

Einfache Handhabung und Verwaltung

ƒ

Schutz bereits getätigter Investitionen im Festnetzbereich

ƒ

Sicherheit hinsichtlich Abhören vertraulicher Daten und auch hinsichtlich der Emissionen

ƒ

Transparenz hinsichtlich der Anwendungen und Protokolle höherer Schichten Seite 207

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Wireless LANs: - Infrastrukur- und Ad hoc-Netzwerke

Seite 208

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IEEE 802.11 ƒ

IEEE-Standard (Institute of Electrical and Electronics Engineers), vgl. IEEE 802.3 (Ethernet), IEEE 802.5 (Token Ring)

ƒ

Verschiedene Standards, 802.11, 802.11 b, 802.11 a

ƒ

Übertragungsband: 2,4 GHz (weltweit) (802.11 a: 5 GHz)

ƒ

Bandbreite: 1 - 11 Mbit/s (brutto)

ƒ

40 - 128 Bit Verschlüsselung (WEP)

ƒ

Sendeleistung max. 100 mW Seite 209

Kapitel 2 E-Business Unternehmensinfrastruktur Kapitel 2.4 Telecommunications and Networks

IEEE 802.11 - Infrastrukturnetz

Seite 210

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Kapitel 2 E-Business Unternehmensinfrastruktur Kapitel 2.4 Telecommunications and Networks

Funktechnologien - Gegenüberstellung Reichweite 500-1000 km

Satellitenfunk

10-50 km

1-6 km

10-500 m

GSMFunkmodem DECT

5-15 m 1-1,5 m

GPRS

Power Bluetooth Bluetooth

IEEE 802.11

HIPERLAN/2

IrDA Kilobit - Bereich

Megabit - Bereich

Bandbreite Seite 211

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Wireless Trends

Seite 212

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Narrowband Integrated Services Digital Network (N-ISDN) ƒ The first generation of Integrated services digital network (ISDN), commonly called narrowband ISDN (N-ISDN), combines voice, video, and data over the same digital circuit. ƒ ISDN has long been more of a concept than a reliable service in North America. ƒ Acceptance has been slowed because equipment vendors and common carriers conflicting interpretations of ISDN standards. ƒ ISDN has been a success in Europe ƒ Voice/data/video are transportable over a single switched digital connection ƒ Temporary connections can be constructed and terminated as needed (not dedicated) ƒ Narrowband ISDN offers the following type of service: • Basic rate interface (BRI, basic access service or 2B+D) provides two 64 Kbps bearer (B) channels and one 16 Kbps control signaling (D) channel. • One advantage of BRI is it can be installed over existing telephones lines. (if less than 3.5 miles).

Seite 213

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Local Loop Transmission - N-ISDN

Voice

Voice ISDN

ISDN ISDN network

Data

Data

Codec

Codec

Video

Video

Seite 214

Kapitel 2 E-Business Unternehmensinfrastruktur Kapitel 2.4 Telecommunications and Networks

Wide Area Networking using ISDN Technology router

LAN hub

ISDN terminal adapter ISDN PC adapter card

LAN hub server

ISDN BRI service

4 x 128 Kbps

512 Kbps

router

ISDN IMUX

analog phone ISDN Service

ISDN BRI service 4 x 128 Kbps ISDN PC adapter card

analog phone

router

512 Kbps ISDN IMUX

LAN hub remote access server

ISDN terminal adapter

ISDN terminal adapter

router

server

LAN hub

Seite 215

Kapitel 2 E-Business Unternehmensinfrastruktur Kapitel 2.4 Telecommunications and Networks

Broadband Integrated Services Digital Network (B-ISDN) ƒ The second generation of ISDN is called Broadband ISDN (B-ISDN). ƒ B-ISDN is currently offered in three services: • Full duplex channel at 155.2 Mbps. • Full duplex channel at 622.08 Mbps. • Asymmetrical service with two simplex channels (Upstream at 155.2 Mbps, downstream at 622.08 Mbps).

Seite 216

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Local Loop Transmission - Asymmetric Digital Subscriber Line (ADSL) ƒ Works over PSTN at higher frequencies on same copper pair ƒ Asymmetric since upstream data-rate is lower than downstream datarate. ADSL Technology Implementation Local Carrier Central Office HOME

Central Office voice switch

10baseT ethernet NIC up to 640 Kbps

POTS

Central Office data switch

PSTN

up to 6 Mbps

ADSL modem

Rack mounted ADSL modems

analog phone

Internet

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Local Loop Transmission - Cable Modems Two kinds: ƒ Provide upstream bandwidth over PSTN and provide downstream bandwidth over installed cable (CATV) ƒ Modify CATV architecture to support simultaneous upstream and downstream transmission (30 Mbps downstream, 768 Kbps upstream) Cable Modem Installation Cable Company Headend HOME 10baseT ethernet NIC

modem pool

upstream commands sent through analog modem

cable video transmission equipment

PSTN 10baseT data

modem

cable data switch cable router

television signals television

cable modem

shared 30 Mbps shared 768 Kbps

Internet

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Elements of Networks 1.

Topology

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Connecting Devices

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Layout and Implementation

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Connecting Devices • Modem • Hub • Bridge • Switch • Router • Brouter • Gateway

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Modem (1) ‘Modulation’ & ‘Demodulation’ ƒ Internal & External ƒ Digital to Analog to Digital ƒ A cable modem

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Modem (2)

Analog signal

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Hubs ƒ Operating at the physical layer, hubs are very simple devices that pass all traffic in both directions between the LAN sections they link. ƒ They may connect different types of cable, but use the same data link and network protocol. ƒ Strictly speaking, hubs are not considered part of a backbone network, but are usually repeaters or amplifiers.

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Bridges ƒ Bridges operate at the data link layer. They connect two LAN segments that use the same data link and network protocol. They may use the same or different types of cables. ƒ Bridges “learn” whether to forward packets, and only forward those messages that need to go to other network segments.

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Bridges ƒ If a bridge receives a packet with a destination address that is not in the address table, it forwards the packet to all networks or network segments except the one on which it was received. ƒ Bridges are a combination of both hardware and software, typically a “black box” that sits between the two networks, but can also be a computer with special software.

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Switches ƒ Like bridges, switches operate at the data link layer. Switches connect two or more computers or network segments that use the same data link and network protocol. They may connect the same or different types of cable.

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Switches Switches operate at the same layers as bridges but differ from them in two ways: ƒ First, most switches enable all ports to be in use simultaneously, making them faster than bridges. ƒ Second, unlike bridges, switches don’t learn addresses, and need to have addresses defined. There are two types of switches: ƒ Cut-through switches examine the destination of the incoming packet and immediately connect the port with the incoming message to the correct outgoing port. ƒ Store-and-forward switches copy the incoming packet into memory before processing the destination address. Seite 227

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Routers ƒ Routers operate at the network layer. Routers connect two or more LANs that use the same or different data link protocols, but the same network protocol. ƒ Routers may be “black boxes,” computers with several NICs, or special network modules in computers. ƒ In general they perform more processing on each message than bridges and therefore operate more slowly. ƒ Routers choose the best route between networks when there are several possible routes between them. ƒ Routers also only process messages specifically addressed to it, unlike bridges. ƒ Routers make no changes to the network layer packet and user data it receives. Seite 228

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Routers

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Brouters ƒ Brouters are devices that combine the functions of both bridges and routers. These operate at both the data link and network layers. A brouter connects both same and different data link type network LAN segments. ƒ It is as fast as a bridge for same data link type networks, but can also connect different data link type networks.

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Gateways ƒ Gateways operate at the network layer and use network layer addresses in processing messages. ƒ Gateways connect two or more LANs that use the same or different (usually different) data link and network protocols. The may connect the same or different kings of cable. ƒ Gateways process only those messages explicitly addressed to them. ƒ Gateways translate one network protocol into another, translate data formats, and open sessions between application programs, thus overcoming both hardware and software incompatibilities. ƒ A gateway may be a stand-alone microcomputer with special software or even a special circuit card in the network server. ƒ One of the most common uses of gateways is to enable LANs that use TCP/IP and Ethernet to communicate with IBM mainframes that use SNA. ƒ The gateway provides both the basic system interconnection and the necessary translation between the protocols in both directions. Seite 231

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Gateways

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Elements of Networks 1.

Topology

2.

Switching

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Transmission Direction

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Transmission Media

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Connecting Devices

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Layout and Implementation Issues

4 4 4 4 4 4 4 4 4

Distance (some media are limited) Range of services (data, voice, video) Security (encryption) Multiple access (capacity issues) Utilization (light vs. heavy use) Cost justifiable (per user) Installation (centralized) Allow for growth and expansion (people / equipment) Facilitate service and maintenance (upgrades)

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Budget Considerations 4

4

4

4

Hardware – Dedicated file server? estimate $6k min – NT servers $15k- $30k – $150 per workstation for network interface card – Active Hub? estimate $80/port - $140/port (managed) Software – File server, Novell Netware v4 “street” $48-$70 per user Installation – Electronic classrooms ~ $320 per connection Network administrator ($880/user/year- 1/50 users) Seite 235

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Elements of Networks 1.

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Transmission Direction

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Connecting Devices

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Layout and Implementation

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Security ƒ

Firewall

ƒ

Viren Scanner

ƒ

Ad Blocker

ƒ

Spyware Remover

ƒ

Spam Blocker

ƒ

Etc. Seite 237

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Kapitel 2 E-Business Unternehmensinfrastruktur Kapitel 2.4 Telecommunications and Networks

Future Trends in Telecommunications and Networking Between now and the year 2010, data communications will grow faster and become more important than computer processing itself. There are three major trends driving the future of communications and networking: ƒ Trend 1: Pervasive Networking ƒ Trend 2: The Integration of Voice, Video and Data ƒ Trend 3: New Information Services

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Trend 1: Pervasive Networking (1) ƒ In the future, communications networks will be everywhere. ƒ This pervasive networking means that virtually any computer will be able to communicate with any other computer in the world. ƒ This will increase telecommuting in which employees perform some or all of their work at home instead of going to the office each day.

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Trend 1: Pervasive Networking (2) ƒ Cellular telephone networks will begin to compete directly with the current wired telephone network ƒ Pervasive networking will also increase the use of electronic data interchange (EDI), the paperless transmission of business documents between companies ƒ The Internet has experienced such rapid growth that it now connects millions of computers in virtually every country in the world

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Trend 2: The Integration of Voice, Video and Data

ƒ The integration of voice and data is largely complete in wide area networks. ƒ The integration of video into computer networks has been much slower, partly due to past legal restrictions, and partly due to the immense communications needs of video.

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Trend 3: New Information Services

ƒ The World Wide Web has changed the nature of computing so now that almost anyone with a computer can be their own publisher. ƒ Never before in the history of the human race has so much knowledge and information been available to ordinary citizens.

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2.1 IT-Systems 2.2 Computer Hardware 2.3 Computer Software 2.4 Telecommunications and Networks 2.5 Internet 2.6 Conclusion

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Kapitel 2 E-Business Unternehmensinfrastruktur 2.5 Internet

The Internet ƒ Began as government connection of universities ƒ Internet Service Provider (ISP): Organization connected to Internet, leases temporary connections to subscribers ƒ No one owns the Internet, no formal Organization Today the Internet is the world’s largest network

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Organisation des Internet Kein zentraler Eigentümer, keine zentrale Leitung:

⇒ Dezentraler Aufbau Einschränkung: einheitliche Standards:

⇒ Zentrale Institutionen zur Standardisierung und Koordination des Netzbetriebes: • Internet Society (http://www.isoc.org) zur globalen Verwaltung und Koordination • Internet Network Information Center (http://www.internic.net) zur zentralen Adreßverwaltung

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Internet Nutzer weltweit (2001)

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Internet Nutzer weltweit (Prognose bis 2004)

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International: Internet-Nutzerdichte (2000)

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Durchschnittlicher jährlicher Anstieg der Internet-Nutzer

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Internet-Nutzer in der BRD (1997 – 2001)

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Internet-Nutzer-Zahlen verschiedener Studien im Vergleich

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BRD: Internet-Nutzung nach Bundesländern (Mai/Juni 2001)

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BRD: Internet-Nutzung nach Alter (2001)

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BRD: Internet-Nutzung nach Alter (1998 – 2001)

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Internet-Nutzer nach Geschlecht (2001)

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Internet-Nutzung nach Haushaltseinkommen

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Gruppen überdurchschnittlicher Internet-Nutzer

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Internet verdrängt klassische Kommunikationsformen

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The Internet - From a User’s Viewpoint (1)

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How the Internet Works

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The Open Architecture of the Internet

ƒ Independent networks should not require any internal changes in order to be connected to the network. ƒ Packets that do not arrive at their destinations must be retransmitted from their source network. ƒ The router computers do not retain information about the packets that they handle. ƒ No global control exists over the network.

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Kapitel 2 E-Business Unternehmensinfrastruktur 2.5 Internet

The TCP/IP Internet Protocol

Protocol - a collection of rules for formatting, ordering, and errorchecking data sent across a network TCP/IP - the two protocols that support the Internet operation ƒ Transmission Control Protocol (TCP) ƒ Internet Protocol (IP)

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Other Internet Protocols Hypertext Transfer Protocol (HTTP): ƒ Communications standard used to transfer Web pages. Responsible for transferring and displaying Web pages SMTP, POP, and IMAP: ƒ Protocols associated with sending and retrieving e-mail File Transfer Protocol (FTP): ƒ Transfers files between TCP/IP-connected computers

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IP Address and Domain Names ƒ IP Address – numerical number for all Internet addresses (126.204.89.56) ƒ Uniform Resource Locator (URL) - address of specific Internet resource, e.g.: http://www.adobe.com ƒ Domain Name – www.adobe.com http://www.prenhall.com/laudon PROTOCOL FOR THE WEB EXTENSION HOST COMPUTER

DIRECTORY

DOMAIN NAME

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Internet Applications/Capabilities Electronic Mail: ƒ Person-to-Person messaging, Document Sharing, most popular form of communication Telnet: ƒ Log on one computer, work on another. Allows users to log on to a remote computer that is attached to the Internet FTP: ƒ Transfer files from computer to computer. Fast way to deliver digital business information from one computer to another Usernet Newsgroups: ƒ Electronic bulletin boards for discussion groups Internet Relay Chat:

ƒ Interactive conversations World Wide Web (WWW): Seite 265

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Traditional vs. Hyperlinked Document Pages

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Client/Server Structure of the WWW

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Message Flow Between a Web Client and Server

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Web Client/Server Communication Three-Tiered Client/Server ƒ First tier is the client ƒ Second tier is the Web server ƒ Third tier are the applications and their databases (example: catalog with search)

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Internet, Intranets, and Extranets (1) Das Internet: Mit Internet wird das physikalische Netzwerk bezeichnet, das Computer auf der ganzen Welt miteinander verbindet. Es umfasst eine Infrastruktur von Netzwerk-Servern und Widearea-Kommunikationsleitungen, die dazu dienen, die enorme Menge an Informationen im Internet aufzunehmen und zu übermitteln. Das Intranet: Ein Netzwerk innerhalb eines Unternehmens, das mithilfe der gewohnten Tools des Internets wie Webbrowsern den Zugriff auf firmeninterne Informationen erlaubt. Nur die Mitarbeiter des Unternehmens haben Zugang zum Intranet, das durch Sicherheitsvorkehrungen (Passwort) geschützt ist. Über Intranets können z.B. aktuelle Preislisten, Telefonverzeichnisse, Formulare oder Wissensdatenbanken zur Verfügung gestellt werden. Weiterhin ist es denkbar, dass Mitarbeiter bestimmte Aufgaben (z.B. das Ändern ihrer Personaldaten nach einem Umzug) via Selbstbedienung erledigen. Insgesamt kann man mit Intranets also sowohl die Informationsversorgung verbessern, als auch Einsparungen erzielen. Das Extranet: Ein Extranet entsteht durch die Erweiterung des Intranets über das Unternehmen hinaus auf Kunden, Zulieferer, Geschäftspartner oder sogar Konkurrenten. Auch das Extranet ist durch Sicherheitsvorkehrungen (Passwort) geschützt, um zu verhindern, dass jeder Internet-Nutzer Zugriff darauf nehmen kann. Extranets zielen v.a. auf Serviceverbesserung und Rationalisierung ab. Quelle: in Anlehnung an Chaffey et al., 200, S. 34 ff.

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Internet, Intranets, and Extranets (2) Intranets – an internal Internet: ƒ ƒ ƒ ƒ ƒ ƒ ƒ ƒ

Internal Network - Only selected individuals are allowed access Fully based on Internet-Technology Overcomes Computer Platform Differences Low-cost way to distribute corporate information Collect and group information for external dissemination Infrastructure requirements are usually in place if PCs are on a LAN Often installed on existing Network Infrastructure Firewall - Security System to Prevent Invasion of Private Networks

Extranets: ƒ Connect companies with suppliers or other business partners ƒ Provide the infrastructure for the coordination of purchases, EDI, and communications ƒ Use the Internet for communicating among themselves Seite 271

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Internet, Intranets, and Extranets (3) Example of an Extranet-Infrastructure DATABASES CUSTOMER

SUPPLIER

INTERNET

FIREWALL

SERVER

BUSINESS PARTNER CLIENTS

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Internet, Intranets, and Extranets (4) Virtual Private Network (VPN): ƒ Uses public networks and protocols to send sensitive data by using “tunneling” or “encapsulation” - private passageways through the Internet ƒ Designed to save money and create a competitive advantage by alliances formed with cooperating companies ƒ Can be built on top of the Internet ƒ Service offered by the telephone companies and ISPs

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Secure VPN Extranet

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Internet Connections Options and Tradeoffs

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Readings Dannenberg/Barthel, Effiziente Marktforschung, Bonn, 2002, S. 51-74.

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Telecommunications in Organizations

4 4 4 4 4 4 4 4 4

Electronic Business Electronic Commerce Intranets ~ Extranets Facilitating inter-organizational systems (IOS) Electronic Data Interchange (EDI) GPS Systems (Tracking) Groupware (Lotus Notes) International Call Centers Virtual Private Networks (VPNs)

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