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COMPUTERNETWORKINGATOPDOWNAPPROACHFEATURINGTHEINTERNET,3RDEDITIONSOLUTIONSTOREVIEWQUESTIONSANDPROBLEMSVERSIONDATEAPRIL26,2005THISDOCUMENTCONTAINSTHESOLUTIONSTOREVIEWQUESTIONSANDPROBLEMSFORTHE3RDEDITIONOFCOMPUTERNETWORKINGATOPDOWNAPPROACHFEATURINGTHEINTERNETBYJIMKUROSEANDKEITHROSSTHESESOLUTIONSAREBEINGMADEAVAILABLETOINSTRUCTORSONLYPLEASEDONOTCOPYORDISTRIBUTETHISDOCUMENTTOOTHERSEVENOTHERINSTRUCTORSPLEASEDONOTPOSTANYSOLUTIONSONAPUBLICLYAVAILABLEWEBSITEWELLBEHAPPYTOPROVIDEACOPYUPTODATEOFTHISSOLUTIONMANUALOURSELVESTOANYONEWHOASKSALLMATERIALCOPYRIGHT19962005BYJFKUROSEANDKWROSSALLRIGHTSRESERVEDCHAPTER1REVIEWQUESTIONS1THEREISNODIFFERENCETHROUGHOUTTHISTEXT,THEWORDS“HOST”AND“ENDSYSTEM”AREUSEDINTERCHANGEABLYENDSYSTEMSINCLUDEPCS,WORKSTATIONS,WEBSERVERS,MAILSERVERS,INTERNETCONNECTEDPDAS,WEBTVS,ETC2SUPPOSEALICE,ANAMBASSADOROFCOUNTRYAWANTSTOINVITEBOB,ANAMBASSADOROFCOUNTRYB,OVERFORDINNERALICEDOESNTSIMPLYJUSTCALLBOBONTHEPHONEANDSAY,“COMETOOURDINNERTABLENOW”INSTEAD,SHECALLSBOBANDSUGGESTSADATEANDTIMEBOBMAYRESPONDBYSAYINGHESNOTAVAILABLETHATPARTICULARDATE,BUTHEISAVAILABLEANOTHERDATEALICEANDBOBCONTINUETOSEND“MESSAGES”BACKANDFORTHUNTILTHEYAGREEONADATEANDTIMEBOBTHENSHOWSUPATTHEEMBASSYONTHEAGREEDDATE,HOPEFULLYNOTMORETHAN15MINUTESBEFOREORAFTERTHEAGREEDTIMEDIPLOMATICPROTOCOLSALSOALLOWFOREITHERALICEORBOBTOPOLITELYCANCELTHEENGAGEMENTIFTHEYHAVEREASONABLEEXCUSES3ANETWORKINGPROGRAMUSUALLYHASTWOPROGRAMS,EACHRUNNINGONADIFFERENTHOST,COMMUNICATINGWITHEACHOTHERTHEPROGRAMTHATINITIATESTHECOMMUNICATIONISTHECLIENTTYPICALLY,THECLIENTPROGRAMREQUESTSANDRECEIVESSERVICESFROMTHESERVERPROGRAM4THEINTERNETPROVIDESITSAPPLICATIONSACONNECTIONORIENTEDSERVICETCPANDACONNECTIONLESSSERVICEUDPEACHINTERNETAPPLICATIONMAKESUSEOFONETHESETWOSERVICESTHETWOSERVICESWILLBEDISCUSSEDINDETAILINCHAPTER3SOMEOFTHEPRINCIPLECHARACTERISTICSOFTHECONNECTIONORIENTEDSERVICEARETWOENDSYSTEMSFIRST“HANDSHAKE”BEFOREEITHERSTARTSTOSENDAPPLICATIONDATATOTHEOTHERPROVIDESRELIABLEDATATRANSFER,IE,ALLAPPLICATIONDATASENTBYONESIDEOFTHECONNECTIONARRIVESATTHEOTHERSIDEOFTHECONNECTIONINORDERANDWITHOUTANYGAPSPROVIDESFLOWCONTROL,IE,ITMAKESSURETHATNEITHERENDOFACONNECTIONOVERWHELMSTHEBUFFERSINTHEOTHERENDOFTHECONNECTIONBYSENDINGTOMANYPACKETSTOFASTPROVIDESCONGESTIONCONTROL,IE,REGULATESTHEAMOUNTOFDATATHATANAPPLICATIONCANSENDINTOTHENETWORK,HELPINGTOPREVENTTHEINTERNETFROMENTERINGASTATEOFGRIDLOCKTHEPRINCIPLECHARACTERISTICSOFCONNECTIONLESSSERVICEARENOHANDSHAKINGNOGUARANTEESOFRELIABLEDATATRANSFERNOFLOWCONTROLORCONGESTIONCONTROL5FLOWCONTROLANDCONGESTIONCONTROLARETWODISTINCTCONTROLMECHANISMSWITHDISTINCTOBJECTIVESFLOWCONTROLMAKESSURETHATNEITHERENDOFACONNECTIONOVERWHELMSTHEBUFFERSINTHEOTHERENDOFTHECONNECTIONBYSENDINGTOMANYPACKETSTOFASTCONGESTIONCONTROLREGULATESTHEAMOUNTOFDATATHATANAPPLICATIONCANSENDINTOTHENETWORK,HELPINGTOPREVENTCONGESTIONINTHENETWORKCOREIE,INTHEBUFFERSINTHENETWORKROUTERS6THEINTERNETSCONNECTIONORIENTEDSERVICEPROVIDESRELIABLEDATATRANSFERBYUSINGACKNOWLEDGEMENTSANDRETRANSMISSIONSWHENONESIDEOFTHECONNECTIONDOESNTRECEIVEANACKNOWLEDGEMENTFROMTHEOTHERSIDEOFTHECONNECTIONFORAPACKETITTRANSMITTED,ITRETRANSMITSTHEPACKET7ACIRCUITSWITCHEDNETWORKCANGUARANTEEACERTAINAMOUNTOFENDTOENDBANDWIDTHFORTHEDURATIONOFACALLMOSTPACKETSWITCHEDNETWORKSTODAYINCLUDINGTHEINTERNETCANNOTMAKEANYENDTOENDGUARANTEESFORBANDWIDTH8INAPACKETSWITCHEDNETWORK,THEPACKETSFROMDIFFERENTSOURCESFLOWINGONALINKDONOTFOLLOWANYFIXED,PREDEFINEDPATTERNINTDMCIRCUITSWITCHING,EACHHOSTGETSTHESAMESLOTINAREVOLVINGTDMFRAME9ATTIMET0THESENDINGHOSTBEGINSTOTRANSMITATTIMET1L/R1,THESENDINGHOSTCOMPLETESTRANSMISSIONANDTHEENTIREPACKETISRECEIVEDATTHEROUTERNOPROPAGATIONDELAYBECAUSETHEROUTERHASTHEENTIREPACKETATTIMET1,ITCANBEGINTOTRANSMITTHEPACKETTOTHERECEIVINGHOSTATTIMET1ATTIMET2T1L/R2,THEROUTERCOMPLETESTRANSMISSIONANDTHEENTIREPACKETISRECEIVEDATTHERECEIVINGHOSTAGAIN,NOPROPAGATIONDELAYTHUS,THEENDTOENDDELAYISL/R1L/R210INAVCNETWORK,EACHPACKETSWITCHINTHENETWORKCOREMAINTAINSCONNECTIONSTATEINFORMATIONFOREACHVCPASSINGTHROUGHITSOMEOFTHISCONNECTIONSTATEINFORMATIONISMAINTAINEDTOAVCNUMBERTRANSLATIONTABLESEEPAGE2511THECONSOFVCSINCLUDEITHENEEDTOHAVEASIGNALINGPROTOCOLTOSETUPANDTEARDOWNTHEVCSIITHENEEDTOMAINTAINCONNECTIONSTATEINTHEPACKETSWITCHESFORTHEPROS,SOMERESEARCHERSANDENGINEERSARGUETHATITISEASIERTOPROVIDEQOSSERVICESSUCHASSERVICESTHATGUARANTEEAMINIMUMTRANSMISSIONRATEORSERVICESTHATGUARANTEEMAXIMUMENDTOENDPACKETDELAYWHENVCSAREUSED121DIALUPMODEMOVERTELEPHONELINERESIDENTIAL2DSLOVERTELEPHONELINERESIDENTIALORSMALLOFFICE3CABLETOHFCRESIDENTIAL4100MBPSSWITCHEDETHERENTCOMPANY5WIRELESSLANMOBILE6CELLULARMOBILEACCESSFOREXAMPLE,WAPMOBILE13ATIER1ISPCONNECTSTOALLOTHERTIER1ISPSATIER2ISPCONNECTSTOONLYAFEWOFTHETIER1ISPSALSO,ATIER2ISPISACUSTOMEROFONEORMORETIER114APOPISAGROUPOFONEORMOREROUTERSINANISPSNETWORKATWHICHROUTERSINOTHERISPSCANCONNECTNAPSARELOCALIZEDNETWORKSATWHICHMANYISPSTIER1,TIER2ANDLOWERTIERISPSCANINTERCONNECT15HFCBANDWIDTHISSHAREDAMONGTHEUSERSONTHEDOWNSTREAMCHANNEL,ALLPACKETSEMANATEFROMASINGLESOURCE,NAMELY,THEHEADENDTHUS,THEREARENOCOLLISIONSINTHEDOWNSTREAMCHANNEL16ETHERNETLANSHAVETRANSMISSIONRATESOF10MB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