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710: Foundations of Information Systems

Chapter 4: TelecommunicationsAnd Networks

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Telecommunication Systems

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Transmission Media

• Twisted-Pair Wire– Telephone wire, Cat 5

• Coaxial Cable– Cable TV cable

• Fiber-Optic Cable– 20 x price of twisted pair,

1000 x capacity

• Microwave Signals– ’No, you don’t get toasted!’– Satellites, line-of-sight

• Infrared and Radio Signals– Wireless, short distance

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Media Types

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Data Processing Strategies

• Centralized Processing– all processing occurs in a single location

or facility• Decentralized Processing

– processing devices are placed at various remote locations

• Distributed Processing– computers are placed at remote

locations and connected via telecommunication devices

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Terminal-to-Host Connection

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File Server Connection

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Client/Server Connection

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Client/Server Processing• Cooperation Through Message

Exchange

– Client program sends Request message, such as a database retrieval request

– Server program sends a Response message to deliver the requested information or an explanation for failure

Client Machine Server

Client ProgramServer

Program

Request

Response

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Networks

• Local Area Network (LAN)– Connect computers in a single building or

campus– Distances typically less than 1,000 meters

• Wide Area Networks (WAN)– Connects computers across long distances– Typically several hundred kilometers– Example: Internet

• Metropolitan Area Networks (MAN)– Connects computers in the same city– Up to 100 kilometers (often much less)

Not in Book

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Network Types

• Ethernet– Very popular, Cheap 10/100/1000 Mbps– Usually short distances

• Asynchronous Transfer Mode (ATM)– Good for multimedia. Used for Internet access. – Up to 622 Mbps over long distances

• Bluetooth– For connecting devices (printer, mouse etc) to

PC. Short range, piconet, Max 1 Mbps

• More wireless on next slide...

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Wireless alphabet soup

Spec Range Speed Frequency

802.11b(WiFi)

75 m 11 Mbps 2.4 GHzRisks interference w/ cordless phones

802.11a(WiFi-5)

30 m 54 Mbps 5 GHzLess interference

802.11g 75 m 54 Mbps 2.4 GHzBackwards compatible w/802.11b

• 802.11i – security standard (authentication and encryption)• 802.1x – authentication

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The Internet

Traffic travels across routers between LANs

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Technological Underpinnings• Internet Management

– No owner! Managed by negotiation and non-binding contracts. May not continue to work.

– Internet Engineering Task Force (www.ietf.org) decides on technical standards

– World Wide Web Consortium (www.w3c.org) sets HTML and HTTP standards

• Backbone network (gigabit connection)– Check

http://global.mci.com/about/network/global_presence/global/ (just one company)

– Or: http://www.caida.org/tools/visualization/mapnet/Backbones/

• Network Addressing– IP numbers: e.g. 140.252.13.33 (32 bits = 4 billion

addresses)– The internet is running out of addresses!– Long-term solution: IP v6 (128 bits = 3.4 * 1038 addresses)

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More Technology…

• Domain Names– Text version of IP address (translated by DNS)– Country domains (.dk, .uk, .de, .us) and

generic domains (.com, .net, .org). USA also has .mil, .gov, and .edu.

– NEW: .aero, .biz, .coop, .info, .museum, .pro, .name

– Managed by ICANN (www.icann.org)

• Network Access– No-one controls access!– Most people connect through an ISP

• AOL and MSN largest ISPs (even though they are Online Services (OLSs)

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Internet Protocols

• Internet Protocol (IP): standard that enables traffic to be routed from one network to another as needed

• Transport Control Protocol (TCP): rules that computers on a network use to establish and break connections

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Internet Communication• E-mail (first time in

1971!)– One of the most popular

activities on the Internet!– Becoming official

business communication mode

– ListServ (http://www.lsoft.com/lists/listref.html)

• Newsgroups (Usenet)– Go to

http://www.google.com/grphp?hl=en

– Being outpaced by web-based fora

• Telnet• FTP

• Streaming– Internet Radio, Internet

TV• Real-Time Streaming

– Videoconferencing• Chatting/IM• Online collaboration• Internet Telephony

(VoIP)• Web log (blog)• Rich Site Summary

(RSS) – a.k.a. RDF Site Summary

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World Wide Web (www)• Hyper Text Transfer Protocol (HTTP)• Hyper Text Markup Language (HTML)

– And derivatives/alternatives• SGML, DHTML, XML

• URL• Browser• Search engines

– Google most popular– Categories: Web crawlers (e.g. Google), categorized (e.g.

Yahoo), Meta-search (search many engines)– Info on search engines: www.searchenginewatch.com

• Review Question: What’s the difference between the Internet and the Web?

http://www.uwosh.edu

Developed in 1989

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Internet Worldwide Trends

• Rapid worldwide growth continues• Main use in

– North America, Europe, Australia

• Some use in– Asia, Middle East, Eastern Europe, South America

• Virtually no use– Africa (90% in South Africa)

• 80% of all international connections from Asia, Africa, S. America go directly to a US city

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Worldwide Trends

• Online Population in million vs. World Population– Online: Jan. 2000 and Feb. 2002, Offline:

Mid-2000

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Intranets and Extranets

• Intranet– An internal corporate network

built using Internet and World Wide Web standards and products; used by the employees of the organization to access corporate information.

• Extranet– A network that links selected

resources of the intranet of a company with its customers, suppliers, or other business partners; based on Web technologies.

• Accessed by on-site employees

• Passwords needed

• Most company info can be put on intranet

• Accessed by off-site employees and business partners

• Passwords needed

• Example: Online banking, TitanWeb

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Intranet and Extranet• Both use internet

standards– Web pages, HTTP-

protocol

• Intranet– Within a company

• Extranet– Outside access to a

company’s intranet or specific web pages

– Security: Virtual Private Networks (VPN)

– Examples: TitanWeb, Online Banking, E-procurement systems

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Electronic Data Interchange (EDI)

• A system to electronically transfer business documents– Orders, bills, confirmations etc– ’Structured e-mail messages’

• Agreements/partnerships are set up in advance

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Issues in EDI

• Data Standards– ANSI X.12: Used in the US– EDIFACT: Defined by UN. Used in much of the

rest of the world– XML/EDI may help in the future

• http://www.geocities.com/WallStreet/Floor/5815/

– Companies must use the same standard to communicate

– Standards can be tailored to fit industries or individual businesses

• Mostly for large companies– May force smaller business partners to use

EDI

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Issues in EDI

• Two Network Standards• Value Added Network (VAN)

– Pro: High security, high capacity– Con: Price, incompatible hardware,

only large companies

• Internet– Pro: Cheap, ubiqutous, easy to use– Con: Security, capacity

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Virtual Private Network

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Encryption

Very important in E-commerce

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Next Week

• Lecture– Chapter 5 and 6: E-commerce, Transaction

Processing Systems, Management Information Systems, and ERP

• Presentations– Teams 1, 2 and 3

• Assignments– Assignment 2 due from Teams 4 - 8