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I T C K Information Technology Center Of Kabul University
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I T C K Information Technology Center Of Kabul University

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  1. ITCK Information Technology Center Of Kabul University Networking BasicsIntroducing Basic Network Concepts“In the beginning, there wereno networks. Life was bad.”—MIKE MEYERS Date: 17/ Oct / 2016

  2. Objectives In this Lecture, you will learn : Defining OSI Model Layers • • • • Identifynetworkaddressing DescribeIP addressesandtheirclasses Describeand distinguishbetweenprivate andpublicaddresses DescribeIPv6 • • • • Identifythedatalinklayer. Describedata linksublayers. Identifywhataframeis. Identifytheroleof thephysical layer. Date: 17/ Oct / 2016

  3. NetworkAddressing • • Addressing is away touniquelyidentify eachnodeona network. Thereare two typesof addressing schemes: • Physical (MACAddress) 12Hixadecemal • Logical(IP Address) 32bit We will coveredthe physicaladdressing schemeinComing Slides. Henceourfocus onlogicaladdressing. • • Date: 15/ Oct / 2016

  4. IP Address • Internet Protocol Address(orIP Address) is an uniqueaddress that computingdevices suchaspersonalcomputers,tablets,and smartphones useto identify itself and communicatewithother devicesintheIPnetwork. Any deviceconnectedto the IPnetworkmust havean uniqueIP addresswithinthe network. Thereare two versions of IP Address: • • • • IPv4 IPV6 • Each versiondefinesanIP addressdifferently. Date: 15/ Oct / 2016

  5. IP version4 • In IPv4 an address consistsof32 bits whichlimitsthe address space to 4294967296 (232)possible uniqueaddresses. IPv4 addressesarerepresentedindotted-decimalnotation,whichconsistsoffour decimalnumbers,each rangingfrom 0 to 255,separatedbydots. Each partrepresentsa groupof 8bits (octet)ofthe address. • • Date: 15/ Oct / 2016

  6. IPv4 AddressPortions • An IP address is intendedto determinetwothings: • • Network address Hostaddress • So anIP addresshastwo portions: • The networkportion • The hostportion Thehighestorderoctet(most significanteight bits)inanaddressisdesignatedas thenetworknumberandthe remainingbitsarecalledthehost identifierandare usedfor hostnumberingwithina network. • Date: 15/ Oct / 2016

  7. IPv4 Classes • Baseonthe value ofthe firstoctetthere arefive classesof IPv4: Class First octetvalue Networkbits Hostbits range A 1-126 8 24 B 128-191 16 16 C 192-223 24 8 D 224-239 NA NA E 240-255 NA NA Date: 15/ Oct / 2016

  8. IPv4

  9. ReservedAddresses • • • • OnlyIP addresseswithinclassesA,BandC areusedto identify hosts. 127 NetworkAddressreserved for loopbacktest. ClassD(224-239)addressesareusedfor multicastcommunications. ClassE(240-255)addressesare used for experimentalpurposes. Date: 15/ Oct / 2016

  10. A CloserLook • Bynowweknowthere canbemultiplenetworks withineachclassand multiplehostswithineachnetwork. The numberofaddressesusablefor addressing specific hosts ineach • 2N networkis always - 2 (whereN is thenumberof rest fieldbits,andthe subtractionof2 adjustsforthe useof theall-bits-zero hostportionfor networkaddressandthe all-bits-onehost portionasabroadcast address.) Date: 15/ Oct / 2016

  11. Public and Private IP Addresses • Devicesthat needto bepubliclyidentifiedsuchas webormailservers must havea globallyuniqueIP address, andthey are assigneda publicIP address. Devicesthat donotrequirepublicaccess may beassigneda privateIP address, andmake ituniquelyidentifiablewithinoneorganization. For example,a networkprintermay beassigneda privateIP addressto prevent theworldfromprintingfromit. The followingIP blocks are reservedfor privateIP addresses. • • • Date: 15/ Oct / 2016

  12. Subnet Mask • • • A wayto determinethenetworkportionandhost portionofan IP address. Allnetwork bits takethe value‘1’ andallhost bits takethe value ‘0’. For examplefor a class B addressthe subnetmask wouldbe: 11111111.11111111.00000000.00000000 =255.255.0.0 Another schemeusedfor this purposeis the prefix: 172.16.0.0/16 • Date: 15/ Oct / 2016

  13. Networkand BroadcastAddresses • • Asmentionedbefore twoaddresseswithineachnetworkcan notbeassignedto hosts. Firstone is thefirstaddress inrange knownas thenetworkaddress intendedto uniquely identify anetwork. The secondoneis the lastaddress inrange knownas the broadcastaddress intendedto broadcast messageswithinthat network. Consider172.16.0.0 • • • • Networkaddress: 172.16.0.0 Broadcastaddress: 172.16.255.255 Date: 15/ Oct / 2016

  14. IP version6 • • IPv4’sprimaryaddresspoolwas exhaustedon 3February2011. The permanentsolutionwas deemedto be a redesignof theInternet Protocol itself. This new generationof theInternet Protocol was eventually namedInternet Protocol Version6 (IPv6)in 1995. The address size was increasedfrom 32 to 128bits (16octets),thus providing • • 2128 (approximately3.403×1038)addresses. upto Date: 15/ Oct / 2016

  15. Recap • • TheApplicationlayerprovidestheinterfaceto theuser. TheTransportlayerisresponsiblefordividingandmanagingcommunications processes runninginthetwo endsystems. betweenthe • TheNetworklayerprotocolsorganizeourcommunicationdata internetworksfrom theoriginatinghost to adestinationhost. so that it can travel across Date: 15/ Oct / 2016

  16. The DataLinkLayer • For Network layer packets to be transported from source host to destinationhost,they must traversedifferentphysicalnetworks. Thesephysicalnetworkscanconsistofdifferenttypesofphysicalmedia suchascopperwires,microwaves,opticalfibers,andsatellitelinks. Network layer packets do not have a way to directly access these different media. ItistheroleoftheOSIDataLinklayertoprepareNetworklayerpackets fortransmissionandto controlaccessto thephysical media. • • • Date: 15/ Oct / 2016

  17. Continued… • TheDataLinklayerprovidesameansforexchangingdataoveracommonlocal media. TheDataLinklayerperformstwo basicservices: • • • Allowstheupperlayersto accessthemediausingtechniquessuchasframing. Controlshowdataisplacedontothemediaandisreceivedfrom usingtechniquessuchasmediaaccess controland errordetection. the media Date: 15/ Oct / 2016

  18. Terminologies Date: 15/ Oct / 2016

  19. Frame • UnliketheotherPDUsthathavebeendiscussedinthiscourse,theDataLinklayer frameincludes: • • Data-Thepacketfrom theNetwork layer. Header-Containscontrolinformation,suchaddressing,andislocated beginningofthePDU. Trailer- Contains controlinformationaddedto theend ofthePDU. at the • Date: 15/ Oct / 2016

  20. Continued • • Whendatatravelsonthemedia,itisconverted intoa streamof bits,or 1sand0s. Ifanodeisreceivinglongstreamsofbits,howdoesitdeterminewhereaframestartsand stopsorwhichbitsrepresent theaddress? Typicalfieldtypesinclude: • • • • • Start andstop indicatorfields- Thebeginningandendlimits oftheframe. Namingoraddressingfields. Typefield-ThetypeofPDUcontainedintheframe. A datafield-Theframepayload(Network layerpacket). • Fieldsattheendoftheframeformthetrailer.Thesefieldsareusedforerrordetectionand mark the endof theframe. Date: 15/ Oct / 2016

  21. Date: 15/ Oct / 2016

  22. DataLinkSublayers • To support a widevariety ofnetworkfunctions, theData Linklayeris oftendividedintotwo sublayers:an uppersublayerandalowersublayer. • The uppersublayerdefinesthe software processesthat provideservicesto the Network layerprotocols. The lowersublayerdefinesthemedia access processesperformed bythe hardware. • • SeparatingtheData Linklayerintosublayers allowsfor onetypeofframedefinedbythe upper layerto access different typesof mediadefined by thelowerlayer. Date: 15/ Oct / 2016

  23. DataLinkLayerProtocols • • In a TCP/IPnetwork,all OSI Layer 2protocols workwiththe InternetProtocolat OSI Layer3. However,the actualLayer2 protocol used depends onthelogicaltopologyof thenetwork andthe implementationof thePhysical layer. Giventhe widerange of physicalmedia used acrossthe range of topologiesinnetworking,there are acorrespondinglyhighnumberof Layer2protocols inuse. Protocols most used are: • • • • • • • Ethernet Point-to-PointProtocol(PPP) High-LevelData LinkControl (HDLC) FrameRelay Asynchronous TransferMode(ATM) Date: 15/ Oct / 2016

  24. The Physical Layer • UpperOSIlayerprotocolspreparedatafromthehuman networkfor transmissionto its destination. ThePhysicallayercontrolshowdataisplacedonthe communicationmedia. TheroleoftheOSIPhysicallayeristoencodethebinary digitsthatrepresentDataLinklayerframesintosignals and to transmit and receive these signals across the • • physicalmedia-copperwires,optical - that connectnetworkdevices. fiber, and wireless Date: 15/ Oct / 2016

  25. Purpose of thePhysicalLayer • TheOSIPhysicallayerprovidesthemeanstotransportacrossthenetworkmediathebitsthat make upa Data Linklayer frame. ThislayeracceptsacompleteframefromtheDataLinklayerandencodesitasaseriesof signalsthat aretransmittedonto thelocalmedia. Thedeliveryof framesacross thelocalmediarequiresthefollowingPhysicallayerelements: • • • • • • The The physical mediaand associatedconnectors. A representationofbitson themedia. Encodingofdata andcontrol information. Transmitter andreceivercircuitryonthenetworkdevices. purposeofthePhysicallayeristocreatetheelectrical,optical,ormicrowavesignalthat • representsthebitsineachframe. Thesesignals arethensentonthemediaoneatatime. ItisalsothejobofthePhysicallayertoretrievetheseindividualsignalsfromthemedia, restorethemtotheirbitrepresentations,andpassthebitsuptotheDataLinklayerasa completeframe. • • Date: 15/ Oct / 2016

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  29. References : • Lammle,T. (2007).CiscoCertifiedNetworkAssociate.StudyGuide. 6thEd. WileyPublishing:Indianapolis,Indiana. Warner,K.(2003).CiscoNetworkingAcademyProgram. CompanionGuide. • 3rd Ed.Ciscopress:CiscoSystemsInc. • CompTIA Network+ 2009 Training Moreresourcesareavailableat: • CCNA Curriculum:Exploration1 v 4.0 • • Moreresourcesareavailable at:   http://whatismyipaddress.com/ip-address https://www.iplocation.net/ip-address