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Chapter 3 Networks and Telecommunications

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1 Chapter 3 Networks and Telecommunications
Introduction to MIS Chapter 3 Networks and Telecommunications

2 Networks Internal Internet External Teamwork Communication Scheduling
Sharing Internet External Suppliers Customers Banks

3 Outline Introduction Components of a Network Network Structure
Sharing Data Sharing Hardware Sharing Software Components of a Network Computers Media Connection Devices Software Network Structure Shared Media Switched Standards The Internet How the Internet Works Internet 2 Mobile Commerce Global Telecommunications Technical Problems Political Complications Cultural Issues Comment Cases: Specialty Retail Appendix: Creating Web Pages

4 Sharing Data: Transactions
Internet Database Management System and Web Server

5 Sharing Data: Decisions & Searches
Teamwork & joint authorship File Server and Database Team Document Data and Tools Report and Comments

6 Sharing Data: E-mail Internet
2. Message transferred to account on server. 3. Transferred via the Internet to the destination account. 4. Message received when user checks . 1. User creates message.

7 Sharing Data: Calendars
8:00 Mgt meeting 8:30 (open) 9:00 Staff meeting 9:30 Staff meeting 10:00 new meeting

8 Hardware Sharing Printers Storage Processors
tape drive (backup) Corporate or external computer access Workstations Shared Printer Server Files are transferred from workstations to the server. Software automatically copies files to tapes. LAN administrator can restore files if needed.

9 Packet-Switched Networks
Data, Voice, Video All converted to packets Packet has data, destination, and source address Switched services Packets routed as needed Reassembled at destination Voice Sent as packets: B 2 Chicago New York C A 4 1 E Atlanta Dallas 3 5 D Computer Sent as packets: A B C D E

10 Network Components Computers Media Connection devices Internet Servers
Work stations Media Cables Fiber optic Radio Infrared Connection devices Personal Computer Personal Computer LAN card LAN card Internet LAN card LAN card Router or Switch Firewall Shared Printer Server

11 Server Scalability Sun 10000 Sun 3800 Sun Ultra 5
Server farms distribute the workload. Add more computers for more power. Sun 10000 Increasing performance within a product family. Sun 3800 Rack mount server farm. Compaq Sun Ultra 5

12 Network Transmission Media
Electricity Fiber optics Radio waves Fiber Optic Cable Example: Long distance phone lines reflective cladding Twisted Pair Example: Local phone lines glass or plastic Radio or Micro Waves Example: Cellular phones Coaxial Example: Cable TV antenna Shield

13 Fiber Optics Faster More data Less magnetic interference
Long stretches without repeaters 900 copper wires can be replaced by one fiber optic line (for telephone connections).

14 Frequency Spectrum http://www.jsc.mil/images/speccht.jpg
AM: 550K KHz TV: 54M MHz FM: 88M MHz TV: 220M MHz Navy/submarines ELF VLF LF MF HF VHF UHF Microwave Optical 100 1K 100K 1M 10M 100M 1G 10G Hertz All waves behave similarly Sound Radio Micro Light Frequency differences Amount of data Distance Interference / Noise Public Safety: 150M MHz Public Safety: 460M MHz Cellular phones: 800 MHz Cordless phones (some): 900 MHz PCS ET: 2 GHz Pers. Com. Sys (PCS): G GHz

15 Transmission Capacity
A thin fiber optic cable can carry as much data as 900 single copper wires, with minimal interference, and superior tensile strength.

16 The Importance of Bandwidth

17 Shared Connections With shared connections, machines have to take turns, and congestion can slow down all connections. With switched connections, each computer has the full bandwidth of the connection at all times. Performance depends on how fast the switch can handle connections.

18 Time Division A B A C A C A C D
Computers A and B split their messages into packets and share the transmission medium by taking turns sending the data.

19 Frequency Division A B frequency A C C D
3500 Hz C C D Computers A and B split the frequency: A uses a higher spectrum. By listening only to the assigned frequency, multiple transmissions can occur at the same time.

20 Spread Spectrum frequency A B C D
time Sharing a medium by both frequency and time is one method of spread spectrum transmission. It is efficient for many computers because the full bandwidth can be utilized over time and frequency.

21 Wireless Communication
Microwave transmissions are used to provide communications for cellular phones and laptop computers. As prices of phones, portable computers, and communication costs decrease, increasing numbers of workers are choosing wireless technologies.

22 Connecting Networks The need for standards A changing environment
Internet Backbone fiber optic Routers or Switches Switch Hub Hub Radio-based network

23 Shared-Media Network Shared Media Tap

24 Switched Network Switch Servers Workstations/PCs

25 Enterprise Network Internet – ISP Building 1 Building 2 Fiber optic
Switch Servers Workstations/PCs Firewall Internet – ISP Subsidiary

26 Client/Server Network
Peer-to-peer Operating system Multitasking Server Clients Workgroup Printer

27 TCP/IP Reference Model
4. Application 3. Transport (TCP) 2. Internet (IP) 1. Physical Message Header 3 Message Trailer 3 Header 2 Header 3 Header 3 Message Message Trailer 3 Trailer 3 Trailer 2 Header 1 Header 2 Header 3 Header 3 Message Message Trailer 3 Trailer 3 Trailer 2 Trailer 1

28 TCP/IP Reference Application Transport Internet Protocol (IP) Subnet
Mail, Web, FTP Authentication, compression, user services Transport Packetize data and handle lost packets Establish connections through numbered ports Internet Protocol (IP) Route packets to destination Requires unique host addresses: IPv4=32-bit; IPv6=128-bit Requires standards and cooperation Subnet Physical connections Transfers bits with some form of error correction

29 ISO-OSI Reference Model
Layer 7 Application Presentation Session Transport Network Data Link Physical Application Presentation Session Transport Network Data Link Physical Original Data Layer 6 Translate Layer 5 Sign on and resources Layer 4 Data Packet Layer 3 Add routing data R Layer 2 Addresses & Error Check A R C Layer 1 A R C A R C Physical Media

30 Introduction to the Internet
No control Services Mail Telnet FTP WWW WEB searching AltaVista HotBot Lycos WebCrawler Yahoo The Internet

31 How the Internet Works Network service provider (NSP) OC3: 155.52 Mbps
T1: Mbps T3: Mbps Backbone network Internet service provider (ISP) Phone company Phone company Cable company Dial-up: Kbps ISDN: 128 Kbps DSL: Kbps - 6 Mbps Cable: 1 to 10 Mbps Company Web site Individual

32 Internet Connections Backbone providers Phone companies
AT&T GTE Worldcom/MCI Sprint Qwest Network service providers 1998: 39 AGIS Cable & Wireless IBM MCI/Worldcom UUNet Phone companies Regional Bell operating companies (RBOCs) (6) Competitive local exchange carriers (CLECs) (new) Cable companies AT&T Cablevision Regional. Satellite Direct Satellite Starband Internet service providers America Online Microsoft Network Earthlink

33 M-Commerce Internet access everywhere Cell phones PDAs Laptops
Great potential Limited usability Better than voice?

34 Cell Phones and Wireless Communication
Wireless cells work by handing off the wireless connection to the next tower as the caller moves. Connections to multiple towers at one time enables the system to triangulate to get a fairly precise location of the cellular device--even when it is not in a call. Location knowledge will make it possible (although perhaps not desirable) to offer new business opportunities as people move into range.

35 Global Telecommunications
Technical problems Multiple standards Language Developing nations Time zones Limits to space & waves Political complications Transborder data flows Taxes Privacy Accessibility Cultural issues What is an object? Management & control

36 Cases: Specialty Retail

37 Cases: Ben & Jerry’s

38 Appendix: Creating Web Pages
Determine the content. Define a style. Create each page. Text Graphics Link the pages. Test your work. Transfer pages to a Web site.

39 Appendix: Style Sheets
BODY { margin-left: 5px; font: 10pt "Times New Roman", Times, serif; color: black; text-align: left; background-color: #e0ffff; } P { margin-left: 0px; background: transparent; H1 { font: 16pt "Times New Roman", Times, serif; font-weight: bold; Style Sheet Body { … } P {…} Page 3 Page 2 Page1

40 Appendix: Sample HTML <HTML> <HEAD>
<TITLE>Sample HTML Page</TITLE> </HEAD> <BODY> <H1>Section One</H1> <P>This is a sample paragraph on a sample page.</P> </BODY> </HTML>

41 Appendix: Publishing Files
Accessible Web pages Internet or intranet Initial pages Web server Transfer methods: Microsoft Front Page extensions FTP: file transfer protocol Your computer

42 Web Development Hints Start with a tool like Microsoft Word (or Front Page, etc.). Get a good graphics package Keep page size small 30, ,000 bytes typically takes seconds First develop the pages on your own computer. Test all links. Transfer later. Use style sheets. Consistency. Ease of change. Study design elements and art. Formal training/art classes. Study other sites. Watch for and create trends.


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