3 - Computer Network - Basic Concepts.ppt
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Transcript of 3 - Computer Network - Basic Concepts.ppt
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Introduction to Computer Administration
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Computer Network - Basic ConceptsComputer NetworksCommunication ModelTransmission ModesCommunication TypesClassification Of Computer Networks By ScaleBy StructureBy TopologyNetwork MediaInternetworking
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Computer NetworkA computer network is a group of interconnected computers.
It allows computers to communicate with each other and to share resources and information.
First Network : The Advanced Research Projects Agency (ARPA) funded the design of the "Advanced Research Projects Agency Network" (ARPANET) for the United States Department of Defense
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Communication Model
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Communication ModelSourcegenerates data to be transmittedTransmitterConverts data into transmittable signalsTransmission SystemCarries dataReceiverConverts received signal into dataDestinationTakes incoming data
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Communication Model
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Transmission ModesSimplexOne directione.g. Television
Half duplexEither direction, but only one way at a timee.g. police radio
Full duplexBoth directions at the same timee.g. telephone
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Communication TypesUnicasting (one-to-one)
Multicasting (one-to-many)
Broadcasting (one-to-all)
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Network ClassificationBy Size or ScaleLANWANMANCANPAN
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Local Area Network (LAN)Contains printers, servers and computersSystems are close to each otherContained in one office or buildingOrganizations often have several LANS
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Wide Area Networks (WAN)Two or more LANs connectedOver a large geographic areaTypically use public or leased linesPhone linesSatelliteThe Internet is a WAN
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Metropolitan Area Network (MAN)Large network that connects different organizationsShares regional resourcesA network provider sells time
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Campus Area Networks (CAN)A LAN in one large geographic areaResources related to the same organizationEach department shares the LAN
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Personal Area Network (PAN)Very small scale networkRange is less than 2 metersCell phones, PDAs, MP3 players
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Network ClassificationBy Structure / Functional RelationshipClient / ServerPeer to Peer (P2PN)
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Client/Server networkNodes and servers share data rolesNodes are called clientsServers are used to control accessDatabase softwareAccess to data controlled by serverServer is the most important computer
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Peer to peer networks (P2PN)All nodes are equalNodes access resources on other nodesEach node controls its own resourcesMost modern OS allow P2PNDistributed computing is a formKazaa
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Network ClassificationBy Topology / Physical ConnectivityBUSSTARRINGMESHTREE
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Network TopologyLogical layout of wires and equipmentChoice affects Network performanceNetwork sizeNetwork collision detection
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BUSAlso called linear bus
One wire connects all nodes
Terminator ends the wires
AdvantagesEasy to setupSmall amount of wire
DisadvantagesSlowEasy to crash
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STARAll nodes connect to a hubPackets sent to hubHub sends packet to destination
AdvantagesEasy to setupOne cable can not crash network
DisadvantagesOne hub crashing downs entire networkUses lots of cable
Most common topology
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RINGNodes connected in a circle
Tokens used to transmit dataNodes must wait for token to send
AdvantagesTime to send data is knownNo data collisions
DisadvantagesSlowLots of cable
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MESHAll computers connected together
Internet is a mesh network
AdvantageData will always be delivered
DisadvantagesLots of cableHard to setup
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TREEHierarchal Model
AdvantagesScaleableEasy ImplementationEasy Troubleshooting
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Network MediaLinks that connect nodesChoice impactsSpeedSecuritySize
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Twisted-pair cablingMost common LAN cable
Called Cat5 or 100BaseT
Four pairs of copper cable twisted
May be shielded from interference
Speeds range from 1 Mbps to 1,000 Mbps
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Coaxial cableSimilar to cable TV wire
One wire runs through cable
Shielded from interference
Speeds up to 10 Mbps
Nearly obsolete
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Fiber-optic cableData is transmitted with light pulses
Glass strand instead of cable
Immune to interference
Very secure
Hard to work with
Speeds up to 100 Gbps
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Wireless MediaData transmitted through the air
LANs use radio waves
WANs use microwave signals
Easy to setup
Difficult to secure
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InternetworkAn Internetwork is the connection of two or more distinct computer networks or network segments via a common routing technology.
Any interconnection among or between public, private, commercial, industrial, or governmental networks may also be defined as an internetwork.
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InternetworkIntranetAn intranet is a set of networks, using the Internet Protocol and IP-based tools such as web browsers and file transfer applications, that is under the control of a single administrative entity. Most commonly, an intranet is the internal network of an organization ExtranetAn extranet is a network or internetwork that is limited in scope to a single organization or entity but which also has limited connections to the networks of one or more other usually, but not necessarily, trusted organizations or entities by definition, an extranet cannot consist of a single LAN; it must have at least one connection with an external network. InternetThe Internet consists of a worldwide interconnection of governmental, academic, public, and private networks based upon the networking technologies of the Internet Protocol Suite. It is the successor of the Advanced Research Projects Agency Network (ARPANET) developed by DARPA of the U.S. Department of Defense. The Internet is also the communications backbone underlying the World Wide Web (WWW).
Teaching tipUse a real world example to describe an organization with interconnected LANs. Teaching tipUse a real world example to describe an organization with interconnected LANs.