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The companion PowerPoint presentation for Chapter Four (Networks) of the book Police Technology.

The companion PowerPoint presentation for Chapter Four (Networks) of the book Police Technology.

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Networks Networks Presentation Transcript

  • Copyright Protected 2005: Hi Tech Criminal Justice, Raymond E. Foster Police TechnologyPolice Technology Chapter FourChapter Four NetworksNetworks
  • Copyright Protected 2005: Hi Tech Criminal Justice, Raymo Learning ObjectivesLearning Objectives  Understand the importance and use ofUnderstand the importance and use of NetworksNetworks  Understand the different types ofUnderstand the different types of technologies necessary to establish atechnologies necessary to establish a networknetwork  Be exposed to several different types ofBe exposed to several different types of networksnetworks  Understand the necessity for networkUnderstand the necessity for network security and several of the means ofsecurity and several of the means of providing network security.providing network security.
  • Copyright Protected 2005: Hi Tech Criminal Justice, Raymo Network BasicsNetwork Basics  AA networknetwork is aboutis about two or more peopletwo or more people establishing a wayestablishing a way to communicate.to communicate.  There are formalThere are formal and informaland informal networks.networks.
  • Copyright Protected 2005: Hi Tech Criminal Justice, Raymo Network BasicsNetwork Basics  Networks are founded on the concept ofNetworks are founded on the concept of client-server architectureclient-server architecture. Architecture. Architecture refers to the design of a system orrefers to the design of a system or technology.technology.  The individual work station, called aThe individual work station, called a nodenode,, is provided networking services by ais provided networking services by a server.server.
  • Copyright Protected 2005: Hi Tech Criminal Justice, Raymo Network BasicsNetwork Basics  TheThe serverserver is a computer thatis a computer that provides files, printers, andprovides files, printers, and processing power to theprocessing power to the individual workstations. Theindividual workstations. The server is a special type ofserver is a special type of computer linked into acomputer linked into a network. It is used only tonetwork. It is used only to manage the network, sharedmanage the network, shared data, and shared resources.data, and shared resources.
  • Copyright Protected 2005: Hi Tech Criminal Justice, Raymo Why Network?Why Network?  Law enforcement agencies may haveLaw enforcement agencies may have many buildings and offices in differentmany buildings and offices in different physical locations. A network allows themphysical locations. A network allows them to share computer, data, and informationto share computer, data, and information resources. Much of the information usedresources. Much of the information used by law enforcement comes from agenciesby law enforcement comes from agencies outside their organization (e.g., DMV,outside their organization (e.g., DMV, Corrections, other agencies, etc.).Corrections, other agencies, etc.).
  • Copyright Protected 2005: Hi Tech Criminal Justice, Raymo  Networks also provide organizations withNetworks also provide organizations with the capability to back up data. If onethe capability to back up data. If one computer fails, the network can take overcomputer fails, the network can take over the processing load.the processing load. Why Network?Why Network?
  • Copyright Protected 2005: Hi Tech Criminal Justice, Raymo Back to …..Back to ….. Analog and Digital SignalsAnalog and Digital Signals An analog signal weakens as it travelsAn analog signal weakens as it travels through wire because of the resistancethrough wire because of the resistance the signal meets in thethe signal meets in the mediummedium that isthat is carrying it (air, wire, coaxial cable).carrying it (air, wire, coaxial cable). Digital signals are subject to the sameDigital signals are subject to the same decrease in strength as analog signals.decrease in strength as analog signals.
  • Copyright Protected 2005: Hi Tech Criminal Justice, Raymo Digital signals are the primary means ofDigital signals are the primary means of transmitting data communications.transmitting data communications. Digital signals have several advantagesDigital signals have several advantages over analog:over analog:  Fewer errors;Fewer errors;  Can be transmitted at higher speedsCan be transmitted at higher speeds  Peripheral devices are less complexPeripheral devices are less complex.. Back to …..Back to ….. Analog and Digital SignalsAnalog and Digital Signals
  • Copyright Protected 2005: Hi Tech Criminal Justice, Raymo  The analog wave is called aThe analog wave is called a baudbaud.. Bits are essentially added to theBits are essentially added to the analog wave.analog wave.  Public networks tend to run at aboutPublic networks tend to run at about 2,400 baud (waves) per second.2,400 baud (waves) per second. Analog stuffAnalog stuff
  • Copyright Protected 2005: Hi Tech Criminal Justice, Raymo  Our technology adds more bits to eachOur technology adds more bits to each baud generally in multiples of four.baud generally in multiples of four.  A 2,400 baud analog signal that addsA 2,400 baud analog signal that adds 12 bits to each baud would give an12 bits to each baud would give an effective transmission rate of 28,800effective transmission rate of 28,800 bits per second (BPS).bits per second (BPS). Analog stuffAnalog stuff This about Modem Speed!
  • Copyright Protected 2005: Hi Tech Criminal Justice, Raymo One of the schemes commonly used toOne of the schemes commonly used to prevent data corruption isprevent data corruption is bit paritybit parity..  Take a stream of binary, add up theTake a stream of binary, add up the numbers, you get an odd or an even number.numbers, you get an odd or an even number.  Add a digit at the end of the data to indicateAdd a digit at the end of the data to indicate if the sum is odd or even.if the sum is odd or even.  The receiving computer compares the sumThe receiving computer compares the sum of the data stream to the bit parity digit.of the data stream to the bit parity digit. Error DetectionError Detection
  • Copyright Protected 2005: Hi Tech Criminal Justice, Raymo Information travels between computersInformation travels between computers in a network in one of three ways:in a network in one of three ways:  Simplex transmissionSimplex transmission – information– information travels in one direction onlytravels in one direction only  Half-duplexHalf-duplex – information travels in– information travels in both directions, one way at a timeboth directions, one way at a time  Full duplexFull duplex – data is transmitted in– data is transmitted in both directions simultaneouslyboth directions simultaneously Data TransmissionData Transmission
  • Copyright Protected 2005: Hi Tech Criminal Justice, Raymo Designing a NetworkDesigning a Network Look at three things:Look at three things:  TheThe fastest throughput and responsefastest throughput and response time possibletime possible  TheThe least-cost pathleast-cost path – the data flows– the data flows through the fewest devices possiblethrough the fewest devices possible  Design reliabilityDesign reliability
  • Copyright Protected 2005: Hi Tech Criminal Justice, Raymo Things That ConnectThings That Connect Networks accomplish data transfer with aNetworks accomplish data transfer with a concept calledconcept called packet switchingpacket switching..  Unused (available) portions of aUnused (available) portions of a network are chosennetwork are chosen  Data passes through the most efficientData passes through the most efficient available meansavailable means
  • Copyright Protected 2005: Hi Tech Criminal Justice, Raymo In networks, the connection point betweenIn networks, the connection point between your computer and the network is commonlyyour computer and the network is commonly aa modemmodem.. Modems have becomeModems have become asymmetric digitalasymmetric digital subscriber line (ADSL).subscriber line (ADSL). The wordThe word asymmetrical is used because these modemsasymmetrical is used because these modems send data faster in one direction than thesend data faster in one direction than the other.other. Things That ConnectThings That Connect
  • Copyright Protected 2005: Hi Tech Criminal Justice, Raymo Most homes and offices have a dedicated copperMost homes and offices have a dedicated copper wire running between them and the telephonewire running between them and the telephone company’s central office.company’s central office.  The copper wire can carry far more data than theThe copper wire can carry far more data than the 3,000 Hz signal of a typical telephone conversation3,000 Hz signal of a typical telephone conversation  The copper wire can act as a purely digital high-speedThe copper wire can act as a purely digital high-speed transmission channel (1 million bps).transmission channel (1 million bps).  The same line can transmit both a telephoneThe same line can transmit both a telephone conversation and the digital data.conversation and the digital data. Asymmetric Digital SubscriberAsymmetric Digital Subscriber Line -Line - DSLDSL
  • Copyright Protected 2005: Hi Tech Criminal Justice, Raymo Other waysOther ways of connecting to a networkof connecting to a network  Use aUse a hubhub  Most hubs include aMost hubs include a switchswitch. A switch. A switch determines how data will travel along itsdetermines how data will travel along its path to the intended destination – to lookpath to the intended destination – to look for the optimal routefor the optimal route  AA routerrouter is like a switch. A router is ais like a switch. A router is a bridge between two networks. Thebridge between two networks. The router determines the best path betweenrouter determines the best path between two different networkstwo different networks
  • Copyright Protected 2005: Hi Tech Criminal Justice, Raymo  AA remote switchremote switch is one that is at youris one that is at your location but controlled by someone else atlocation but controlled by someone else at different location.different location.  AA trunktrunk is a circuit between different typesis a circuit between different types of switching equipment.of switching equipment.  MiddlewareMiddleware describes a software that isdescribes a software that is used to connect different applications (theused to connect different applications (the translator).translator). Network TermsNetwork Terms
  • Copyright Protected 2005: Hi Tech Criminal Justice, Raymo Data CompressionData Compression  Techniques to reduceTechniques to reduce the size of data inthe size of data in order to improveorder to improve storage andstorage and bandwidthbandwidth (transmission)(transmission) capacity.capacity.
  • Copyright Protected 2005: Hi Tech Criminal Justice, Raymo BandwidthBandwidth  Refers to theRefers to the capacitycapacity ofof the medium that carriesthe medium that carries the signal.the signal.  Analog bandwidth isAnalog bandwidth is measured in Hz.measured in Hz.  Digital bandwidth isDigital bandwidth is measured in the numbermeasured in the number of bits per second theof bits per second the medium can carry.medium can carry.  Determines the speed atDetermines the speed at which data can be movedwhich data can be moved through a networkthrough a network More bandwidth = more data, faster
  • Copyright Protected 2005: Hi Tech Criminal Justice, Raymo ProtocolsProtocols An agreement between people on howAn agreement between people on how a transaction should take place.a transaction should take place. Many networks use theMany networks use the TransmissionTransmission Control Protocol/Internet ProtocolControl Protocol/Internet Protocol (TCP/IP).(TCP/IP). Your computer must useYour computer must use TCP/IP to go on the Internet.TCP/IP to go on the Internet.
  • Copyright Protected 2005: Hi Tech Criminal Justice, Raymo Basic Network TypesBasic Network Types  HierarchicalHierarchical - vertical- vertical or tree structureor tree structure  Local Area NetworkLocal Area Network (LAN(LAN) - horizontal) - horizontal network. Allows eachnetwork. Allows each device on the networkdevice on the network to receive everyto receive every network transmission.network transmission.  Star ConfigurationStar Configuration –– All transmissionsAll transmissions
  • Copyright Protected 2005: Hi Tech Criminal Justice, Raymo  LANLAN is a network that operates inis a network that operates in oneone specific location.specific location.  Wide Area Network (WAN)Wide Area Network (WAN) is used tois used to connect geographically separatedconnect geographically separated networks together.networks together. Basic Network TypesBasic Network Types
  • Copyright Protected 2005: Hi Tech Criminal Justice, Raymo Basic Network TypesBasic Network Types  Wireless LocalWireless Local Area NetworkArea Network (WLAN)(WLAN) uses radiouses radio waves to connectwaves to connect among the mobileamong the mobile node, mobilenode, mobile computer, and thecomputer, and the hardwired network.hardwired network.
  • Copyright Protected 2005: Hi Tech Criminal Justice, Raymo Data SecurityData Security  Could be called Network security orCould be called Network security or Computer security.Computer security.  What we are most trying toWhat we are most trying to protect isprotect is the informationthe information contained in thecontained in the various systems.various systems.
  • Copyright Protected 2005: Hi Tech Criminal Justice, Raymo Physical Security is . . .Physical Security is . . . Anything we do to physically protectAnything we do to physically protect our systems and information:our systems and information:  Placing servers, routers andPlacing servers, routers and switching equipment behind lockedswitching equipment behind locked doorsdoors  Backing up data in one or moreBacking up data in one or more locationlocation
  • Copyright Protected 2005: Hi Tech Criminal Justice, Raymo  FirewallFirewall - operates by controlling- operates by controlling access to the network based upon theaccess to the network based upon the contents of the data packets beingcontents of the data packets being transmitted on the network.transmitted on the network.  EncryptionEncryption - changing text or data- changing text or data into a form that is unreadable withoutinto a form that is unreadable without a key (secret code)a key (secret code) Virtual Security is…..Virtual Security is…..
  • Copyright Protected 2005: Hi Tech Criminal Justice, Raymo Virtual Security is…..Virtual Security is…..  Intrusion DetectionIntrusion Detection –– security managementsecurity management system that gatherssystem that gathers and analyses infoand analyses info from different part offrom different part of the network. Scansthe network. Scans network looking fornetwork looking for user and systemuser and system activity and anyactivity and any pattern of abnormalpattern of abnormal behavior.behavior.
  • Copyright Protected 2005: Hi Tech Criminal Justice, Raymond E. Foster Police TechnologyPolice Technology Go to theGo to the Student ResourcesStudent Resources page atpage at www.hitechcj.comwww.hitechcj.com