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Communication Networks

Reading:Laudon & Laudonchapter 6

Additional Reading:Brien & Marakaschapter 6

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OutlineTelecommunication and Networking

Current TrendsComputer Network

Key Digital Networking TechnologiesCommunication Network TopologiesThe Global Internet

Addressing and ArchitectureGovernanceFuture Trends

Internet and E-commerce

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HRO500 Guest Rooms, 28 floorsDistance from central Osaka

ProblemsPressures to adapt in a competitive industryOutdated communication methods

SolutionsImplement a mobile wireless LANto provide integrated voice and datacoverage across the entire hotelWireless Handheld or Notebook PCs → Ability to access the info online anywhere in hotel and respond accurately and immediatelyProvide immediate/before service from past record, memorable serviceSavings → 60 hrs per year per staff member or total 4800 hrs annuallyIntel Centrino and Intel XScale technologies capable of handling phone calls as well as data communication allowed employees to access information from anywhere in the hotelDemonstrates IT’s role in hastening the communication and flow of informationIllustrates digital technology’s role contemporary networking

Hyatt Hotels – Wireless Networking

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ConvergenceTelephone Networks and Computer Networks

Single digital network using Internet standardsCable companies providing voice service

BroadbandMore than 60% U.S. Internet users → BroadbandCost of Service ↓

Broadband WirelessVoice and data communication as well as Internet access are increasingly taking place over broadband wireless platforms

Mobile Wireless Access → Fastest growing form of internet access (2008 – 96% ↑)

Trends – Networking and Telecom

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Internet2Next generation of the Internet – Network of Networks1996 to 2006High-performance backbone network – different infrastructure

BW → 2.5 - 9.6 Gbps200 universities, scientific institutions, communications corporations →Part of Internet2Never, Not intended to replace Internet, test bedPurpose → Develop roadmap, next stage of innovation for current internetNew addressing protocol, satellite quality videoMost Connections → Abilene

Network backbone, 10 GbpsVideo Conferencing, Multicasting, Remote Applications, Speed ↑ & BW ↑

IPv6Internet population growth, Out of available IP address – 2013New version, 128 bit addresses, more than new quadrillion (2^128) possible addresses, IPv4 – 32bitsRoughly 5,000 addresses for every square micrometer of the earth's surface, sufficiently large for the indefinite future

Trends – Networking and Telecom

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NetworkAn interconnected chain, group or system

Number of possible connections (N → Nodes)N*(N-1)

If 10 computers on a network → 10 * 9 = 90 possible connections

Metcalfe’s LawThe usefulness of a network equals the square of number of usersOn a small network, a change in technology affects technology onlyOn a large network like the Internet, a change in technology affects social, political and economic systems

Network Concept

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Two or More Connected ComputersMajor Components in Simple Network

Client computer Server computerNetwork interfaces (NICs)Connection mediumNetwork operating system

Routes & manages communication on networkCoordinates network resourcesExample → Server software’s, Novell NetWare, Linux, Microsoft Windows Server

HubSends packet of data to all connected devices

SwitchMore intelligence, can filter and forward data to specified destination on network

RoutersDevice used to route packets of data through different networks, ensuring that data sent gets to the correct address

Computer Network

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SwitchMakes connections between telecommunications circuits in a network

RouterIntelligent communications processor that interconnects networks based on different protocols

GatewayConnects networks using different communications Connection medium

Computer Network

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SwitchMakes connections between telecommunications circuits in a network

RouterIntelligent communications processor that interconnects networks based on different protocols

GatewayConnects networks using different communications Connection medium

Computer Network

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Can IncludeHundreds of local area networks (LANs) linked to firmwide corporate networkVarious powerful servers

Web siteCorporate intranet, extranetBackend systems

Mobile wireless LANs (Wi-Fi networks)Videoconferencing systemTelephone networkWireless cell phones

Network in Large Companies

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Network in Large Companies

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Client/Server ComputingClients → End user personal computers or networked computersServers → Manage NetworksInterconnected by LANs, Distributed computing modelProcessing shared between clients and serversServer sets rules of communication for network and provides every client with an address so others can find it on the networkHas largely replaced centralized mainframe computingThe Internet → Largest implementation of client/server computing

Key Network Technologies

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Packet SwitchingMethod of slicing digital messages into parcels (packets)Sends packets along different communication paths as they become available, and then reassembling packets at destinationPrevious circuit-switched networks required assembly of complete point-to-point circuit

Expensive, Wasted communication capacity

Packet switching more efficient use of network’s communications capacit

Key Network Technologies

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Packet Switching Communication

Key Network Technologies

Data are grouped into small packets, transmitted independently over various Communications channelsReassembled at their final destination

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Network Topologies (Structure of Network)Star → ties end user computers to a central computerRing → ties local computer processors together in a ring on a relatively equal basisBus → local processors share the same comm channel

Computer Network

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Open Systems Interconnection Model (OSI)A seven-layer model that serves as a standard model for networkarchitecturesModel for how messages should be transmitted between two points in a networkEach layer adds functions

TCP/IP and ConnectivityConnectivity between computers enabled by protocolsProtocols → Different components in network communicate with each other by adhering to common set of rulesTransmission Control Protocol/Internet Protocol

Common worldwide standard that is basis for InternetTCP → Movement of data between computes, establish connection, sequences transfer of packets, acknowledges packet sentIP → Responsible for delivery of packets, disassembling and reassembling of packets

A five layer telecommunications protocol used by the Internet

Key Network Technologies

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OSI (7 layer) Communication NetworkTCP/IP (5 layer)

Key Network Technologies

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TCP/IPPostal system → finds your house addresses, delivers your mail (packets)IP4 → Current IP addressing protocol, 32 bit Internet address valueFirst Part identifies the network on which the host residesSecond part identifies the particular host on networkFour decimal numbers separated by periodValid addresses can range from 0.0.0.0 to 255.255.255.255 (4.3 billion addresses)

Key Network Technologies

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TCP/IP (IP4)

Class E addresses Reserved → Research Organizations, ExperimentsLimited broadcast address → 255.255.255.255

One sender to many recipients, all the nodes on LANLoopback IP address → 127.0.0.1, Adapter intercepts and sends back to application, network behavior Private Addresses (reserved range for intranet, free usage)

Key Network Technologies

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IPv6128 bit addressGenerally written in hhhh:hhhh:hhhh:hhhh:hhhh:hhhh:hhhh:hhhhE3D7:0000:0000:0000:51F4:9BC8:C0A8:6420 Shorthand Notation → E3D7::51F4:9BC8:C0A8:6420 Mixed Notation → E3D7::51F4:9BC8:158.132.11.186Only two reserved addresses in IPv6

0:0:0:0:0:0:0 → Internal for protocol implementation0:0:0:0:0:0:1 → Loopback address (similar to 127.0.0.1 in IPv4)

Key Network Technologies

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InternetOver 46 million servers (2004)710 – 945 million users (2004)No central computer systemNo governing bodyNo one owns it

Key Network Technologies

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What is Internet?Internet Addressing and Architecture

The Domain Name SystemHierarchical structureTop-level domains

Internet Architecture and GovernanceNo One Owns Internet!Worldwide Internet Policies → Professional & Government Bodies

IAB, ICANN, W3C

The Global Internet

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Domain Name System

The Global Internet

The Domain Name System is a hierarchical system with a root domain, top-level domains, second-level domains, and host computers at the third level.

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Internet ServicesE-mailChatting and instant messagingNewsgroupsTelnetFile Transfer Protocol (FTP)World Wide WebVoIPVirtual private network (VPN)

The Global Internet

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Client/Server Computing on Internet

The Global Internet

Client computers running Web browser and other software can access an array of services on servers over the Internet. These services may all run on a single server or on multiple specialized servers.

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How Voice over IP Works?

The Global Internet

An VoIP phone call digitizes and breaks up a voice message into data packets that may travel along different routes before being reassembled at the final destination. A processor nearest the call’s destination, called a gateway, arranges the packets in the proper order and directs them to the telephone number of the receiver or the IP address of the receiving computer.

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A secure network that uses the Internet as its backbone but relies on firewalls, encryption and other security

A pipe traveling through the Internet

Virtual Private Network

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Virtual Private Network Using Internet

The Global Internet

This VPN is a private network of computers linked using a secure “tunnel” connection over the Internet. It protects data transmitted over the public Internet by encoding the data and “wrapping” them within the Internet Protocol (IP). By adding a wrapper around a network message to hide its content, organizations can create a private connection that travels through the public Internet.

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Thin ClientsNetwork computers and other clients provide a browser-based user interface

Network Computing

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People Monitoring Employees on Networks: People Monitoring Employees on Networks: UnethicalUnethical or or Good BusinessGood Business??

Question - Should managers monitor employee e-mail and Internet usage? Why or why not?

Corporate misuse, abuse of email for personal reasons is explodingEmployees who use company resources for work not related to the company are, in essence, engaged in “service theft.”Companies are in business to generate profits for their shareholders. Managers certainly should be concerned with the loss of time and employee productivity, the additional traffic it creates on their networks that inhibits the efficiency for real business purposes, lost revenue or missed opportunities, as well as overcharging clients because of lost employee efficiencies. The company itself is responsible for the use of its resources and what employees do while using themAdverse publicity can seriously affect a company and could even result in very expensive lawsuitsCompanies also fear e-mail leakage of trade secrets. Other legal and regulatory problems involve the safe keeping of all e-mails that are generated on corporate equipment. This information must be retained for specific time periods and may be requested as evidence in a lawsuit

Case StudyCase Study – Monitoring Employees

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Describe an effective e-mail and Web use policy for a company

Effective e-mail and Web use policy must be carefully designedand clearly communicated to all persons who use these corporate resources

There are a number of different policies - Some companies allow absolutely no personal use of corporate networks whereas others allow some degree of activity that is easily monitored

A good policy will detail exactly what type of activity is acceptableand what is not allowed

Clearly articulate sanctions that will be followed for any and all offenses in relation to the policy

Most of all, rules for Internet usage should be tailored to specific business needs and organizational cultures

Case StudyCase Study – Monitoring Employees

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Explore the Web site of online employee monitoring software such as SpectorSoft, NetVizor, SpyTech, or Activity Monitor and answer the following questions

What employee activities does this software track? What can an employer learn about an employee by using this software?

SpectorSoft Web site - The Spector Pro keylogger will instantly inform you whenever they type, or even simply view, any alert words or phrases that you specify

Spector Pro continuously looks for alert words in everything they type, every web site they visit, all chats/Instant Messages and in each email sent or received. Every time a keyword is detected, Spector Pro will immediately email you a detailed report of when, where and how the keyword was used

Case StudyCase Study – Monitoring Employees

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How can businesses benefit from using this software?Testimonials → With Spector Pro, we were immediately able to discover which employees were non-productive. Not only has Spector Pro helped us weed out lazy workers, it also helped to uncover fraud in some of our departments

In addition, this program has also allowed us to realize and resolve training issues we've experienced with our internal software

Spector Pro is very stealthy, has no noticeable effect on system performance and provides excellent return on investment

Case StudyCase Study – Monitoring Employees

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Hypertext Markup Language (HTML):Formats documents for display on Web

Hypertext Transfer Protocol (HTTP): Communications standard used for transferring Web pages

Uniform resource locators (URLs): Addresses of Web pages

Example → http://www.megacorp.com/content/features/082602.html

Web serversSoftware for locating and managing Web pages

World Wide Web

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Search EnginesStarted in early 1990s as relatively simple software programs using keyword indexesIn 1994 two Stanford students → Hand selected list of web pages

Yet Another Hierarchical Officious Oracle – Yahoo! In 1998, two another Stanford students released first version of Google

Not only index each page’s word but also ranked search results → PageRankAlso combination of key words → Foundation of Google

Major source of Internet advertising revenue via search engine marketing, using complex algorithms and page ranking techniques to locate results

Shopping Bots Use intelligent agent software for searching Internet for shoppinginformationMySimon or Google Product Search

Filter and retrieve info about products of interest, negotiate price/delivery terms, evaluate competitive products using criteria

Semantic Web Collaborative effort to make Web searching more efficient by reducing the amount of human involvement in searching for and processing Web information

World Wide Web

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How Google Works?

World Wide Web

The Google search engine is continuously crawling the Web, indexing the content of each page, calculating its popularity, and storing the pages so that it can respond quickly to user requests to see a page. The entire process takes about one-half second.

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Major Web Search Engines

World Wide Web

Google is the most popular search engine on the Web, handling 56 percent of all Web searches.

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Web 2.0Started in early 1990s as relatively simple software programs using keyword indexes

Second-generation interactive Internet-based services for people to collaborate, share information, and create new services online

Blogs → Chronological, informal Web sites created by individuals using easy-to-use weblog publishing tools

RSS (Really Simple Syndication) → Syndicates Web content so aggregator software can pull content for use in another setting or viewing later, mashups

Wikis → Collaborative web sites where visitors can add, delete, or modify content on the site

World Wide Web

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IntranetUse existing network infrastructure with Internet connectivity standards software developed for the WebCreate networked applications that can run on many types of computersProtected by firewalls

ExtranetAllow authorized vendors and customers access to an internal intranetUsed for collaborationAlso subject to firewall protection

The Global Internet

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Wireless DevicesPDAs, BlackBerry, smart phonesInstant availability of Info from field – Inventory level ↓

Cellular SystemsCompeting standards for cellular service

United States → CDMAMost of rest of world → GSM

Third-generation (3G) networksHigher transmission speeds suitable for broadband Internet access384 Kbps (Mobile), 2Mbps (Stationary), Available in HK, Japan, S. Korea, Taiwan, Singapore, N. Europe, Not yet in USA(?)

The Wireless Revolution

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Bluetooth Network (PAN)Short-range wireless technologyTo connect PC to peripherals such as printer

Within a small 30-foot (10-meter) area

The Wireless Revolution

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Wireless Computer Network and AccessBluetooth (802.15)

Links up to 8 devices in 10-m area using low-power, radio-based communicationUseful for personal networking (PANs)FedEx drivers, handheld → computers → cellularNo docking of handheld units in transmitters, saves 20 million $ year

Wi-Fi (802.11)Set of standards: 802.11a, 802.11b, 802.11g, 802.11nUsed for wireless LAN and wireless Internet accessAlso known as Wi-Fi → Wireless for FidelityUse access points → Device with radio receiver/transmitter for connecting wireless devices to a wired LANHotspots → One or more access points in public place to provide maximum wireless coverage for a specific areaWeak security features, Susceptibility to Interference (n, MIMO)

The Wireless Revolution

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An 802.11 Wireless LANRadio waves to transmit network signals from the wired network to the client adapters

The Wireless Revolution

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Wireless Computer Network and AccessWiMax (802.16)

Wi-Fi range < 300 feet from base stationsWiMax → Worldwide Interoperability for Microwave Access802.16 → 75 Mbps, Robust Security & QOSLinks Wireless access range of 31 milesRequire WiMax (Rooftop) antennas

Broadband Cellular WirelessMany cell services offer Wi-Fi capabilities for Internet accessNo Wi-Fi hotspot?, Small card (Laptop) → 3G, 300-500 Kbps

The Wireless Revolution

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Wireless Sensor NetworksNetworks of hundreds or thousands of interconnected wireless devices embedded into physical environment to provide measurements of many points over large spacesUsed to monitor building security, detect hazardous substances in air, monitor environmental changes, traffic, or military activityDevices have built-in processing, storage, and radio frequency sensors and antennasRequire low-power, long-lasting batteries and ability to endure in the field without maintenance

The Wireless Revolution

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Wireless Sensor Networks

The Wireless Revolution

The small circles represent lower-level nodes and the larger circles represent high-end nodes. Lower-level nodes forward data to each other or to higher-level nodes, which transmit data more rapidly and speed up network performance.