The OSI Model - Andrew · PDF file · 2016-09-23OSI Model Consider the network...

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The OSI Model Level 3 Unit 9 Computer Networks Level 3 Unit 9 Computer Networks Lecturer: Andrew Blundell

Transcript of The OSI Model - Andrew · PDF file · 2016-09-23OSI Model Consider the network...

Page 1: The OSI Model - Andrew · PDF file · 2016-09-23OSI Model Consider the network models we have already covered Lecturer: Andrew Blundell Level 3 Unit 9 Computer Networks Whenever data

TheOSIModelLevel3Unit9ComputerNetworks

Level3Unit9 ComputerNetworksLecturer:AndrewBlundell

Page 2: The OSI Model - Andrew · PDF file · 2016-09-23OSI Model Consider the network models we have already covered Lecturer: Andrew Blundell Level 3 Unit 9 Computer Networks Whenever data

OSIModelConsiderthenetworkmodelswehavealreadycovered

Level3Unit9 ComputerNetworksLecturer:AndrewBlundell

WheneverdataistransferredfromPCtoPCorPCtoServeritwilltravelthroughtheLayersoftheOSIModel

Page 3: The OSI Model - Andrew · PDF file · 2016-09-23OSI Model Consider the network models we have already covered Lecturer: Andrew Blundell Level 3 Unit 9 Computer Networks Whenever data

OSIModel

Level3Unit9 ComputerNetworksLecturer:AndrewBlundell

Page 4: The OSI Model - Andrew · PDF file · 2016-09-23OSI Model Consider the network models we have already covered Lecturer: Andrew Blundell Level 3 Unit 9 Computer Networks Whenever data

OSIModelWhydoyouneedtoLearnaboutOSI?

• NetworkprofessionalsusetheOSItocommunicatewitheachotherintheworkplace!

OSI=OpenSystemsInterconnection• DevelopedbyComputerNetworkingindustryatISO(InternationalStandardization

Organization)meetingstoallowforequipmentfromdifferentmanufacturerstoworktogether.

Level3Unit9 ComputerNetworksLecturer:AndrewBlundell

Page 5: The OSI Model - Andrew · PDF file · 2016-09-23OSI Model Consider the network models we have already covered Lecturer: Andrew Blundell Level 3 Unit 9 Computer Networks Whenever data

OSILayers

Level3Unit9 ComputerNetworksLecturer:AndrewBlundell

Page 6: The OSI Model - Andrew · PDF file · 2016-09-23OSI Model Consider the network models we have already covered Lecturer: Andrew Blundell Level 3 Unit 9 Computer Networks Whenever data

OSIModelMnemonicLayer7 All A> ApplicationLayer6 People P> PresentationLayer5 Seem S> SessionLayer4 To T> TransportLayer3 Need N> NetworkLayer2 Data D> DataLinkLayer1 Processing P> Physical

Level3Unit9 ComputerNetworksLecturer:AndrewBlundell

Page 7: The OSI Model - Andrew · PDF file · 2016-09-23OSI Model Consider the network models we have already covered Lecturer: Andrew Blundell Level 3 Unit 9 Computer Networks Whenever data

SoftwareEngineersv’sNetworkEngineers

Level3Unit9 ComputerNetworksLecturer:AndrewBlundell

Page 8: The OSI Model - Andrew · PDF file · 2016-09-23OSI Model Consider the network models we have already covered Lecturer: Andrew Blundell Level 3 Unit 9 Computer Networks Whenever data

SoftwareEngineerLayers

Level3Unit9 ComputerNetworksLecturer:AndrewBlundell

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SoftwareEngineeringLayers

Level3Unit9 ComputerNetworksLecturer:AndrewBlundell

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Layer7– ApplicationLayer

Level3Unit9 ComputerNetworksLecturer:AndrewBlundell

Page 11: The OSI Model - Andrew · PDF file · 2016-09-23OSI Model Consider the network models we have already covered Lecturer: Andrew Blundell Level 3 Unit 9 Computer Networks Whenever data

Layer7– ApplicationLayerLayer7=ApplicationLayer– WhatIfwehadnoGUI?

Wewouldneedtowritecode\commands!

ForExample:TheHTTPGetRequest:

GET /index.html HTTP/1.1 Host: www.google.co.uk

Level3Unit9 ComputerNetworksLecturer:AndrewBlundell

Page 12: The OSI Model - Andrew · PDF file · 2016-09-23OSI Model Consider the network models we have already covered Lecturer: Andrew Blundell Level 3 Unit 9 Computer Networks Whenever data

Layer6– PresentationLayerFormattheDataCorrectly!EnsureitisReadable:

Compression- LZ(Lossless)MP3(Lossy)Encryption- SSL,IPSecFileFormats– ASCII,MIME,XML,RTF(Text)

JPEG,GIF,PNG(Picture)MPEG,MP4(Video)MP3(Audio)

Level3Unit9 ComputerNetworksLecturer:AndrewBlundell

Page 13: The OSI Model - Andrew · PDF file · 2016-09-23OSI Model Consider the network models we have already covered Lecturer: Andrew Blundell Level 3 Unit 9 Computer Networks Whenever data

Layer5– SessionLayerLayer5=SessionLayer– StartaSession!

TCP3WayHandshaking>

1/.Client1Q:WouldYouLiketoHaveaConversation?2/.Client2A:Yes!3/.Client1A:OKLetsStartTalking!

Level3Unit9 ComputerNetworksLecturer:AndrewBlundell

Page 14: The OSI Model - Andrew · PDF file · 2016-09-23OSI Model Consider the network models we have already covered Lecturer: Andrew Blundell Level 3 Unit 9 Computer Networks Whenever data

Layer5– SessionLayerLayer5=SessionLayer– MultipleSessions

SessionAuthentication–

e.g.LoggingInToOnlineBankingoreStudy

Level3Unit9 ComputerNetworksLecturer:AndrewBlundell

• ConsiderBrowser“Tabs”• 1xApplications,3xSessionsOpen!

Page 15: The OSI Model - Andrew · PDF file · 2016-09-23OSI Model Consider the network models we have already covered Lecturer: Andrew Blundell Level 3 Unit 9 Computer Networks Whenever data

DayinthelifeofaPacketPt.1

Level3Unit9 ComputerNetworksLecturer:AndrewBlundell

Page 16: The OSI Model - Andrew · PDF file · 2016-09-23OSI Model Consider the network models we have already covered Lecturer: Andrew Blundell Level 3 Unit 9 Computer Networks Whenever data

NetworkEngineerLayers

Level3Unit9 ComputerNetworksLecturer:AndrewBlundell

Page 17: The OSI Model - Andrew · PDF file · 2016-09-23OSI Model Consider the network models we have already covered Lecturer: Andrew Blundell Level 3 Unit 9 Computer Networks Whenever data

Layer4- TransportADayintheLifeofaPacket!– EmailExamplePart2

Layer4=TransportLayer– LogicalPortNumbers

Encapsulation=SplittheDataintoSegments

Encapsulation =LabelLogicalPortNumbersGettheDatatotheCorrectApplication

From:SMTPPort#25 (SendorReceive?)To:POP3Port#110

Level3Unit9 ComputerNetworksLecturer:AndrewBlundell

Page 18: The OSI Model - Andrew · PDF file · 2016-09-23OSI Model Consider the network models we have already covered Lecturer: Andrew Blundell Level 3 Unit 9 Computer Networks Whenever data

Layer3– NetworkLayerADayintheLifeofaPacket!– EmailExamplePart3

Encapsulation=Packets

Remember:TheIPAddressislookedupusingDNS

LabelFrom:SourceIPAddresse.g.192.168.1.10LabelTo:DestinationIPAddresse.g.192.168.2.10

UsingaMaskof255.255.255.0AretheseClientsintheSameNetwork?

Level3Unit9 ComputerNetworksLecturer:AndrewBlundell

Page 19: The OSI Model - Andrew · PDF file · 2016-09-23OSI Model Consider the network models we have already covered Lecturer: Andrew Blundell Level 3 Unit 9 Computer Networks Whenever data

Layer2– DataLinkLayerLayer2=DataLinkLayer– MediaIndependence

DifferentTypeofFramesforDifferentMediae.g.CopperorFibreopticCabling

ADayintheLifeofaPacket!– EmailExamplePart4

Encapsulation=Frames

LabelFrom:SourceMACAddresse.g.00-11-22-33-44-55LabelTo:DestinationMACAddresse.g.66-77-88-99-AA-BB(Note:MACisaGloballyUniqueIdentifieronallNICsitismadeupofHexadecimaldigits0-9andA-F)

Layer2vsLayer3AddressingLocalLAN(MAC)vsRemoteWAN(IP)AddressingIPAddressStaystheSame!MACChangesEveryStep

Level3Unit9 ComputerNetworksLecturer:AndrewBlundell

Page 20: The OSI Model - Andrew · PDF file · 2016-09-23OSI Model Consider the network models we have already covered Lecturer: Andrew Blundell Level 3 Unit 9 Computer Networks Whenever data

Layer2– DataLinkLayerQ:Layer2=DataLinkLayer– HowDoestheClientKnowtheMACAddress?A:ARP(AddressResolutionProtocol)(CoverLater!)

Level3Unit9 ComputerNetworksLecturer:AndrewBlundell

Page 21: The OSI Model - Andrew · PDF file · 2016-09-23OSI Model Consider the network models we have already covered Lecturer: Andrew Blundell Level 3 Unit 9 Computer Networks Whenever data

Layer2– DataLinkLayer• ARPisusedtoperformIPaddressresolutionwhichisthelinkingofaLayer3IPaddressestoaLayer2

MAC(MediaAccessControl)hardwareaddresses.

• ARPusesabroadcasttodothisbyaskingthehostthathasthegivenIPaddresstorespondtothebroadcast(ARPREQUEST=WHOHASXX.XX.XX.XX.XX.XXTELL172.19.13.1)withitsMACaddress([email protected]).

• BroadcasttrafficgoestoallhostsintheLAN,soallhostswillreceivetheARPrequestandthespecifichostwillbetheonlyonetoreply.

• EntriesinARPcachearekeptforamaximumof10minutes.Anentrythatisnotusedwithin2minutesisdeleted.

• ThisallowsforfaultyhardwarebeingremovedfromthenetworkandtheIPaddressbeingassignedtodifferentphysicalhardware.

Level3Unit9 ComputerNetworksLecturer:AndrewBlundell

Page 22: The OSI Model - Andrew · PDF file · 2016-09-23OSI Model Consider the network models we have already covered Lecturer: Andrew Blundell Level 3 Unit 9 Computer Networks Whenever data

Layer1– PhysicalLayer

Level3Unit9 ComputerNetworksLecturer:AndrewBlundell

Page 23: The OSI Model - Andrew · PDF file · 2016-09-23OSI Model Consider the network models we have already covered Lecturer: Andrew Blundell Level 3 Unit 9 Computer Networks Whenever data

Layer1– PhysicalLayer

Level3Unit9 ComputerNetworksLecturer:AndrewBlundell

RepresenttheDataasElectricalorLightPulses

Page 24: The OSI Model - Andrew · PDF file · 2016-09-23OSI Model Consider the network models we have already covered Lecturer: Andrew Blundell Level 3 Unit 9 Computer Networks Whenever data

OSIModel

Level3Unit9 ComputerNetworksLecturer:AndrewBlundell

Page 25: The OSI Model - Andrew · PDF file · 2016-09-23OSI Model Consider the network models we have already covered Lecturer: Andrew Blundell Level 3 Unit 9 Computer Networks Whenever data

Level3Unit9 ComputerNetworksLecturer:AndrewBlundell

Page 26: The OSI Model - Andrew · PDF file · 2016-09-23OSI Model Consider the network models we have already covered Lecturer: Andrew Blundell Level 3 Unit 9 Computer Networks Whenever data

Level3Unit9 ComputerNetworksLecturer:AndrewBlundell

Page 27: The OSI Model - Andrew · PDF file · 2016-09-23OSI Model Consider the network models we have already covered Lecturer: Andrew Blundell Level 3 Unit 9 Computer Networks Whenever data

Level3Unit9 ComputerNetworksLecturer:AndrewBlundell

Page 28: The OSI Model - Andrew · PDF file · 2016-09-23OSI Model Consider the network models we have already covered Lecturer: Andrew Blundell Level 3 Unit 9 Computer Networks Whenever data

Level3Unit9 ComputerNetworksLecturer:AndrewBlundell

Page 29: The OSI Model - Andrew · PDF file · 2016-09-23OSI Model Consider the network models we have already covered Lecturer: Andrew Blundell Level 3 Unit 9 Computer Networks Whenever data

Level3Unit9 ComputerNetworksLecturer:AndrewBlundell

Page 30: The OSI Model - Andrew · PDF file · 2016-09-23OSI Model Consider the network models we have already covered Lecturer: Andrew Blundell Level 3 Unit 9 Computer Networks Whenever data

Level3Unit9 ComputerNetworksLecturer:AndrewBlundell

Page 31: The OSI Model - Andrew · PDF file · 2016-09-23OSI Model Consider the network models we have already covered Lecturer: Andrew Blundell Level 3 Unit 9 Computer Networks Whenever data

Level3Unit9 ComputerNetworksLecturer:AndrewBlundell

Page 32: The OSI Model - Andrew · PDF file · 2016-09-23OSI Model Consider the network models we have already covered Lecturer: Andrew Blundell Level 3 Unit 9 Computer Networks Whenever data

Level3Unit9 ComputerNetworksLecturer:AndrewBlundell

Page 33: The OSI Model - Andrew · PDF file · 2016-09-23OSI Model Consider the network models we have already covered Lecturer: Andrew Blundell Level 3 Unit 9 Computer Networks Whenever data

Level3Unit9 ComputerNetworksLecturer:AndrewBlundell

Page 34: The OSI Model - Andrew · PDF file · 2016-09-23OSI Model Consider the network models we have already covered Lecturer: Andrew Blundell Level 3 Unit 9 Computer Networks Whenever data

Level3Unit9 ComputerNetworksLecturer:AndrewBlundell

Page 35: The OSI Model - Andrew · PDF file · 2016-09-23OSI Model Consider the network models we have already covered Lecturer: Andrew Blundell Level 3 Unit 9 Computer Networks Whenever data

Level3Unit9 ComputerNetworksLecturer:AndrewBlundell

Page 36: The OSI Model - Andrew · PDF file · 2016-09-23OSI Model Consider the network models we have already covered Lecturer: Andrew Blundell Level 3 Unit 9 Computer Networks Whenever data

Level3Unit9 ComputerNetworksLecturer:AndrewBlundell

Page 37: The OSI Model - Andrew · PDF file · 2016-09-23OSI Model Consider the network models we have already covered Lecturer: Andrew Blundell Level 3 Unit 9 Computer Networks Whenever data

Level3Unit9 ComputerNetworksLecturer:AndrewBlundell

Page 38: The OSI Model - Andrew · PDF file · 2016-09-23OSI Model Consider the network models we have already covered Lecturer: Andrew Blundell Level 3 Unit 9 Computer Networks Whenever data

Level3Unit9 ComputerNetworksLecturer:AndrewBlundell

Page 39: The OSI Model - Andrew · PDF file · 2016-09-23OSI Model Consider the network models we have already covered Lecturer: Andrew Blundell Level 3 Unit 9 Computer Networks Whenever data

Level3Unit9 ComputerNetworksLecturer:AndrewBlundell

Page 40: The OSI Model - Andrew · PDF file · 2016-09-23OSI Model Consider the network models we have already covered Lecturer: Andrew Blundell Level 3 Unit 9 Computer Networks Whenever data

Level3Unit9 ComputerNetworksLecturer:AndrewBlundell

Page 41: The OSI Model - Andrew · PDF file · 2016-09-23OSI Model Consider the network models we have already covered Lecturer: Andrew Blundell Level 3 Unit 9 Computer Networks Whenever data

Level3Unit9 ComputerNetworksLecturer:AndrewBlundell

Page 42: The OSI Model - Andrew · PDF file · 2016-09-23OSI Model Consider the network models we have already covered Lecturer: Andrew Blundell Level 3 Unit 9 Computer Networks Whenever data

Level3Unit9 ComputerNetworksLecturer:AndrewBlundell

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Level3Unit9 ComputerNetworksLecturer:AndrewBlundell


Unit 12 IT Technical Support - Andrew Blundell · Unit 12 IT Technical Support Tools ... Collision light (activity) ... PowerPoint Presentation Author: therealblund@gmail.com

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July 2007 Richard Blundell Andrew Shephard …uctp39a/Blundell WPEG Slides 10...2010/07/07  · and more recent reform proposals Structural Model Elasticities Participation elasticity

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Richard Blundell Martin Browning Ian Crawfordcowles.yale.edu/sites/default/files/files/lunch/blundell2-051116.pdf · Richard Blundell Martin Browning Ian Crawford THE INSTITUTE FOR

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