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2007CiscoSystems,Inc.Allrightsreserved. CiscoPublicITEPCv4.0Chapter1 1
CCNADiscovery4.0DesigningandSupportingComputerNetworks
IdentifyingApplicationImpactsonNetworkDesignChapter4
ITEPCv4.0Chapter1 22007CiscoSystems,Inc.Allrightsreserved. CiscoPublic
Objectives
ITEPCv4.0Chapter1 32007CiscoSystems,Inc.Allrightsreserved. CiscoPublic
Theimportanceofapplicationperformance
Mostpeoplewhousenetworkservicesknowverylittleabouttheunderlyingnetworkornetworkdesign.Theirexperienceasusersisbasedonhowtheyinteractwiththeapplicationsthatrunonthenetwork.
Inthecaseofthesportsstadium,networkbasedapplicationsprovideessentialservicestothefans,theteams,andthemanagement.Theseservices,andthenetworkonwhichtheyreside,areamongthebusinesscriticalelementsensuringthatcustomeranduserdemandsaremet.
ITEPCv4.0Chapter1 42007CiscoSystems,Inc.Allrightsreserved. CiscoPublic
Theimportanceofapplicationperformance
Gatheringstatisticalinformationfromrouters,servers,andothernetworkdeviceshelpsdeterminewhetherasystemisfunctioningtomanufacturerspecifications.However,technicalconsiderationsalonedonotdeterminesuccessinthemarketplace.
Successdependsonhowthecustomer,thesuppliers,andthevendorsviewtheperformanceofthenetwork.
ITEPCv4.0Chapter1 52007CiscoSystems,Inc.Allrightsreserved. CiscoPublic
Theimportanceofapplicationperformance
Forendusers,applicationperformanceisbasedon:
AvailabilityIstheapplicationworkingwhentheyneedit?
ResponsivenessIstheapplicationrespondingasquicklyasexpected?
Forexample,inthestadium,revenuefromticketsales,concessions,andsouvenirssufferswhentransactionprocessesarenotavailableoraretakingtoolongtocomplete.
ITEPCv4.0Chapter1 62007CiscoSystems,Inc.Allrightsreserved. CiscoPublic
Theimportanceofapplicationperformance
Stadiumcustomersratetheconvenienceofanapplicationbythelengthoftimeittakestocompletethetransaction.Theyalsoexpecttheapplicationtobeavailablewhenevertheywanttouseit.
Applicationsforwhichfastresponsetimeisconsideredcriticalfortheuserinclude:
Interactivekioskservices
Pointofsaleticketmachines
Concessionregisters
ITEPCv4.0Chapter1 72007CiscoSystems,Inc.Allrightsreserved. CiscoPublic
Theimportanceofapplicationperformance
Applicationsconsideredcriticalbystadiumpersonnelinclude:
Emergencyservices
Voiceandvideomonitoringandtransmission
Themeasurementofapplicationperformanceshouldcombineusersatisfactionwithnormaltechnicalmetrics,suchasthroughputonthenetwork,orthenumberofsuccessfultransactions.
ITEPCv4.0Chapter1 82007CiscoSystems,Inc.Allrightsreserved. CiscoPublic
Theimportanceofapplicationperformance
ITEPCv4.0Chapter1 92007CiscoSystems,Inc.Allrightsreserved. CiscoPublic
CharacteristicsofDifferentApplicationCategories
Inanexistingnetwork,applicationcharacterizationhelpsthenetworkdesignertoincorporatebusinessgoalsandtechnicalrequirementsintothenetworkdesign.
Theapplicationcharacterizationprocessinvolveslookingatthefollowingaspectsofnetworkapplications:
Howtheapplicationsworkonthenetwork
Thetechnicalrequirementsoftheapplication
Howapplicationsinteractwitheachotheronthenetwork
ITEPCv4.0Chapter1 102007CiscoSystems,Inc.Allrightsreserved. CiscoPublic
CharacteristicsofDifferentApplicationCategories
Fromtheinformationgatheredduringtheearlyphasesofthedesignprocess,thedesignerdetermineswhichapplicationsareconsideredbusinesscritical.
Thecharacterizationprocessprovidesinformationaboutnetworkbandwidthusageandresponsetimesforspecificapplications.Theseparametersinfluencedesigndecisions,including:
Selectionofthetransmissionmedium
Estimatesofrequiredbandwidth
ITEPCv4.0Chapter1 112007CiscoSystems,Inc.Allrightsreserved. CiscoPublic
CharacteristicsofDifferentApplicationCategories
Trafficfromdifferenttypesofapplicationsresultsinvaryingnetworkdemands.Thenetworkdesignerrecognizesfourmaintypesofapplicationcommunication:
Clienttoclient
Clienttodistributedserver
Clienttoserverfarm
Clienttoenterpriseedge
ITEPCv4.0Chapter1 122007CiscoSystems,Inc.Allrightsreserved. CiscoPublic
CharacteristicsofDifferentApplicationCategories
ITEPCv4.0Chapter1 132007CiscoSystems,Inc.Allrightsreserved. CiscoPublic
CharacteristicsofDifferentApplicationCategories
ITEPCv4.0Chapter1 142007CiscoSystems,Inc.Allrightsreserved. CiscoPublic
CharacteristicsofDifferentApplicationCategories
ITEPCv4.0Chapter1 152007CiscoSystems,Inc.Allrightsreserved. CiscoPublic
CharacteristicsofDifferentApplicationCategories
ITEPCv4.0Chapter1 162007CiscoSystems,Inc.Allrightsreserved. CiscoPublic
Onanexistingnetwork,thefirststepincharacterizingapplicationsistogatherasmuchinformationaboutthenetworkaspossible.Thisincludesgatheringinformationfrom:
Organizationalinput
Networkaudit
Trafficanalysis
CharacteristicsofDifferentApplicationCategories
ITEPCv4.0Chapter1 172007CiscoSystems,Inc.Allrightsreserved. CiscoPublic
OrganizationalInput
Organizationalinputconsistsofexistingdocumentationaboutthenetworkandverbalinputfromthestadiumpersonnel.Duringtheearlyphasesofdesign,obtaininginputiseasybutnotalwaysreliable.Forexample,applicationchangessuchasupgradesoruserinstalledsoftwaremaygoundocumentedorunnoticed.
NetworkAudit
Anetworkauditgathersinformationaboutnetworkdevices,monitorstraffic,andrevealsdetailsofthecurrentnetworkconfiguration.
CharacteristicsofDifferentApplicationCategories
ITEPCv4.0Chapter1 182007CiscoSystems,Inc.Allrightsreserved. CiscoPublic
TrafficAnalysis
Trafficanalysisprovidesinformationabouthowtheapplicationsandprotocolsusethenetwork.Itcanrevealshortcomingsinthenetwork.Forexample,severalhighbandwidthapplicationsusingthesamemediumcangeneratelargeamountsoftraffic.Thiscouldbeapotentialweaknessinthecurrentdesign.
CharacteristicsofDifferentApplicationCategories
ITEPCv4.0Chapter1 192007CiscoSystems,Inc.Allrightsreserved. CiscoPublic
CiscoIOSSoftwareEmbeddedTools
NetworkBasedApplicationRecognition(NBAR)isaCiscoutilitythatconductsauditsandtrafficanalysis.NBARisaclassificationenginethatrecognizesawidevarietyofapplications.NBARrecognizeswebbasedandotherdifficulttoclassifyprotocolsthatutilizedynamicTCPandUDPportassignments.
CharacteristicsofDifferentApplicationCategories
ITEPCv4.0Chapter1 202007CiscoSystems,Inc.Allrightsreserved. CiscoPublic
AnothertoolisCiscoIOSNetFlow.NetFlowefficientlyprovidesasetofservicesforIPapplications.Servicesinclude:
Networktrafficaccounting
Usagebasednetworkbilling
Networkplanning
Security
DenialofServicemonitoringcapabilities
Networkmonitoring
CharacteristicsofDifferentApplicationCategories
ITEPCv4.0Chapter1 212007CiscoSystems,Inc.Allrightsreserved. CiscoPublic
CharacteristicsofDifferentApplicationCategories
ITEPCv4.0Chapter1 222007CiscoSystems,Inc.Allrightsreserved. CiscoPublic
Howtrafficflowaffectsnetworkdesign
InternalTraffic
Internaltrafficisgeneratedbylocalhostsandisdestinedforotherhostswithinthecampusnetwork.Diagramminginternaltrafficflowscanshowareaswherehighbandwidthconnectionsareneeded,aswellasidentifypossiblebottleneckswheretrafficmightbecomecongested.Thesediagramsassistthedesignertoselecttheappropriateequipmentandinfrastructuretosupportthetrafficvolumes.
ITEPCv4.0Chapter1 232007CiscoSystems,Inc.Allrightsreserved. CiscoPublic
Howtrafficflowaffectsnetworkdesign
ExternalTraffic
Externaltrafficisdefinedastrafficthatisinitiatedbyusersoutsidethelocalnetworkaswellastrafficsenttodestinationslocatedonremotenetworks.Sometypesofexternaltraffic,suchasemergencyservicesorfinancialservices,requireredundancyandpresentadditionalsecurityconcerns.ThedesignerdiagramsthistrafficinordertodeterminethelocationoffirewallsandDMZnetworks,aswellastheInternetconnectivityrequirements.
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HowtrafficflowaffectsnetworkdesignInternalTrafficFlow
ITEPCv4.0Chapter1 252007CiscoSystems,Inc.Allrightsreserved. CiscoPublic
HowtrafficflowaffectsnetworkdesignExternalTrafficFlow
ITEPCv4.0Chapter1 262007CiscoSystems,Inc.Allrightsreserved. CiscoPublic
Howapplicationcharacteristicsaffectnetworkdesign
Thetypesofhardwareinstalledonanetworkaffecttheperformanceofanapplication.Acomplexnetwork,suchasthesportsstadiumnetwork,containsmanydifferenttypesofhardware.Eachofthesedevicetypescanintroducedelayinapplicationresponsespeedtouserrequests.Delayaffectscustomersatisfactionwiththeapplicationperformance.Hardwaredelayscanbecausedby:
Processingtimethataroutertakestoforwardtraffic
Olderswitchesthatarenotabletohandletrafficloadsgeneratedbymodernapplications
ITEPCv4.0Chapter1 272007CiscoSystems,Inc.Allrightsreserved. CiscoPublic
Howapplicationcharacteristicsaffectnetworkdesign
Onewaytoensurehighperformanceistousethetopdownapproach.Thetopdownapproachadaptsthedesignofthephysicalinfrastructuretotheneedsofthenetworkapplications.Networkdevicesarechosenonlyafterathoroughtechnicalrequirementsanalysis.
Networkapplicationsonamodernnetworkproducearangeofpackets.Thesepacketsareofvarioussizes,withdistinctsetsofprotocols,differenttolerancestodelay,andothercharacteristics.Whentheservicerequirementsofthesedifferentapplicationsconflictwithoneanother,performanceproblemscanresult.
ITEPCv4.0Chapter1 282007CiscoSystems,Inc.Allrightsreserved. CiscoPublic
Howapplicationcharacteristicsaffectnetworkdesign
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Howapplicationcharacteristicsaffectnetworkdesign
ITEPCv4.0Chapter1 302007CiscoSystems,Inc.Allrightsreserved. CiscoPublic
TransactionProcessing
Networkedapplicationsarenowthebackboneofbusinessactivity.Tomeetthebusinessgoalsoftheclient,thenetworkdesignermustensureapplicationperformance.
Someofthemorecommonapplicationtypesinclude:
Transactionprocessingapplications
Realtimestreamingapplications
Filetransferandemailapplications
HTTPandwebapplications
Microsoftdomainservices
ITEPCv4.0Chapter1 312007CiscoSystems,Inc.Allrightsreserved. CiscoPublic
TransactionProcessing
TransactionProcessingApplications
Transactionprocessingisatypeofprocessinginwhichthecomputerrespondsimmediatelytouserrequests.Eachrequestgeneratedbytheuserisatransaction.Thesetransactionscanrequireadditionaloperationstotakeplaceinresponsetotheoriginalrequest.Forthisreason,applicationtransactionsareauniqueconsiderationinnetworkdesign.
Asanexampleofatransactionprocess,considerwhathappenswhenacustomerpurchasesticketsonlineforaneventatthesportsstadium.
ITEPCv4.0Chapter1 322007CiscoSystems,Inc.Allrightsreserved. CiscoPublic
TransactionProcessing
Thissingletransactiongeneratesallthefollowingoperationsonthenetwork:
Webtrafficfromtheclienttothenetwork
Databasetransactions
Customerordertransaction
Orderprocessingtransaction
Shipping/deliverytransaction
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TransactionProcessing
ITEPCv4.0Chapter1 342007CiscoSystems,Inc.Allrightsreserved. CiscoPublic
TransactionProcessing
Notalltrafficthatentersorexitsanetworkisconsideredatransactionprocess.Avalidtransactionmustmeetthefollowingcriteria:
Itmustbeatomic.
Itmustbeconsistent.
Itmustbeisolated.
Itmustbedurable.
ITEPCv4.0Chapter1 352007CiscoSystems,Inc.Allrightsreserved. CiscoPublic
TransactionProcessing
AtomicTransaction
Anatomictransactionguaranteesthateitherallthetasksofatransactionareperformedornoneofthemare.Ifthetransactionisnotfullyprocessed,thentheentiretransactionisvoid.
ConsistentTransaction
Aconsistenttransactionensuresthatincompletetransactionsarenotallowed.Ifanincompletetransactionoccurs,thesystemreturnstothestatethatitwasinbeforethetransactionbegan.
ITEPCv4.0Chapter1 362007CiscoSystems,Inc.Allrightsreserved. CiscoPublic
TransactionProcessing
IsolatedTransaction
Anisolatedtransactioniskeptsecurefromalltheothertransactionsonthenetwork.Securityisamajornetworkdesignconsideration.Securityoptionsincludetheadditionofaccesscontrollists(ACLs),encryption,andfirewallstothenetworktopology.
ITEPCv4.0Chapter1 372007CiscoSystems,Inc.Allrightsreserved. CiscoPublic
TransactionProcessing
DurableTransaction
Adurabletransactionguaranteesthatoncethetransactioniscompleted,thetransactionwillnotbeundoneevenafterasystemfailure.Adurabledesignfortransactionprocessesrequiresredundancyatmultiplelevels.TheselevelsincludethePhysicalLayerconnections,servers,switchingdevices,androuters.
ITEPCv4.0Chapter1 382007CiscoSystems,Inc.Allrightsreserved. CiscoPublic
TransactionProcessing
ITEPCv4.0Chapter1 392007CiscoSystems,Inc.Allrightsreserved. CiscoPublic
TransactionProcessing
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TransactionProcessing
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TransactionProcessing
ITEPCv4.0Chapter1 422007CiscoSystems,Inc.Allrightsreserved. CiscoPublic
TransactionProcessing
Thenetworkdesignerevaluatesredundancyandsecuritytoolsthatsupporttransactionprocessingapplications.
Redundancy
Incorporatingtransactionapplicationsrequiresthedesignertoconsidertheimpactofeachtransactiononthenetwork.Thisprocessiscrucial,becauseadditionalcablingordevicesmaybeneededtoprovidetheredundancyoravailablethroughputthatthesetransactionsrequire.Addingredundancytoanetworkbringsthefollowingadvantages:
Reductionoreliminationofnetworkdowntime
Increasedavailabilityofapplications
ITEPCv4.0Chapter1 432007CiscoSystems,Inc.Allrightsreserved. CiscoPublic
TransactionProcessing
Networkswithredundancyeliminatetheproblemofsinglepointsoffailure.Ifapathordevicefails,theredundantpathordevicecancompletetheprocessortransaction.Serversthathandletransactionprocesseshaveanalternatepathtoreceiveordelivertraffic.Thishelpsensurethattheapplicationisavailablewhenthecustomerrequestsit.
Networkdevicescanalsobeconfiguredforredundancy.Twocommonprotocolsare:
RapidSpanningTreeProtocol(RSTP)
HotStandbyRoutingProtocol(HSRP)
ITEPCv4.0Chapter1 442007CiscoSystems,Inc.Allrightsreserved. CiscoPublic
TransactionProcessing
RSTPpreventsLayer2switchingloopsthatcanoccurwithredundantswitches.
HSRPcanprovideLayer3redundancyinthenetwork.HSRPprovidesimmediateorlinkspecificfailoverandarecoverymechanism.
RedundantlinksanddevicescanbeimplementedintheproposedstadiumnetworkdesignatboththeDistributionandCoreLayers.
ITEPCv4.0Chapter1 452007CiscoSystems,Inc.Allrightsreserved. CiscoPublic
TransactionProcessing
Security
Securityisalwaysamajorconsideration.Itaffectsnotonlythetransactionprocesses,butallapplicationsandtrafficwithinaninternalnetworkandanexternalnetwork.Protectingtheprivacyandintegrityoftransactioninformationandthetransactiondatabaseshouldbethefocusofsecurityconsiderations.Thenetworkdesigneranalyzesthepotentialforthetransactiondatatobeaccessedinappropriatelyoraltered.
ITEPCv4.0Chapter1 462007CiscoSystems,Inc.Allrightsreserved. CiscoPublic
TransactionProcessing
VPNsuseaprocesscalledtunneling.Tunnelingisoftenreferredtoas"portforwarding".Itisthetransmissionofdatathroughapublicnetworkthatisintendedforaprivatenetwork.Tunnelingisaccomplishedbyencapsulatingtheprivatenetworkdataandprotocolinformationwithinthepublicnetworktransmissionunits.
Intrusiondetectionsystems(IDS)areusedtomonitornetworktrafficforsuspiciousactivity.Ifsuspiciousactivityisdetected,anIDSalertsthesystemoradministrator.AnIDScanbeconfiguredtoblocktheusersourceIPaddressfromaccessingthenetwork.
ITEPCv4.0Chapter1 472007CiscoSystems,Inc.Allrightsreserved. CiscoPublic
TransactionProcessing
Firewallsfiltertrafficbasedonasetofcriteria.Thecomplexityofthefirewallconfigurationcancausedelays.Thepotentialimpactofdelaysshouldbeconsideredinthedesignofanetwork.
ACLscanfilterpotentiallyharmfultrafficthatistryingtoenterthenetworkandblockspecifictrafficfromexitingthenetwork.Theseaccesscontrolscanslowthetransactionprocess.ThetimesensitivenatureofsometransactionsshouldbeconsideredwhenconfiguringACLs.
ITEPCv4.0Chapter1 482007CiscoSystems,Inc.Allrightsreserved. CiscoPublic
TransactionProcessing
ITEPCv4.0Chapter1 492007CiscoSystems,Inc.Allrightsreserved. CiscoPublic
RealtimeStreamingandVoice
RealtimeApplications
Whendesigningthenetworktoaccommodaterealtimeapplications,thenetworkdesignermustconsiderhowthenetworkinfrastructurewillaffectapplicationperformance.
Theseconsiderationsincludethephysicalelementsoftheinfrastructure:
Hardwaredevicesandconnections
Networktopology
Physicalredundancy
ITEPCv4.0Chapter1 502007CiscoSystems,Inc.Allrightsreserved. CiscoPublic
RealtimeStreamingandVoice
LogicalconsiderationsincludehowtheconfigurationofQoSandsecuritysolutionsaffecttraffic.Alloftheseconsiderationsaffecthowthedesignerwillimplementnetworksolutions,suchasIPtelephonyservices.
Realtimestreamingapplicationspresentuniquerequirementsforthenetworkdesign.Theonlyrealtimeapplicationcurrentlyinuseinthestadiumisvideosurveillance.IPtelephonyisincludedintheproposednetworkupgrade.Trafficfromtheseapplicationsmustbeforwardedwiththeleastlatencyandjitterpossible.
ITEPCv4.0Chapter1 512007CiscoSystems,Inc.Allrightsreserved. CiscoPublic
RealtimeStreamingandVoice
Whendeterminingthebusinessgoalsandtechnicalrequirementsforthecustomer,allaspectsofthenetworkshouldbeanalyzedtoensureproperimplementationandsupportoftherealtimeapplications.
ITEPCv4.0Chapter1 522007CiscoSystems,Inc.Allrightsreserved. CiscoPublic
RealtimeStreamingandVoice
Infrastructure
Tosupporttheexistingandproposedrealtimeapplications,theinfrastructuremustaccommodatethecharacteristicsofeachtypeoftraffic.
Thenetworkdesignermustdeterminewhethertheexistingswitchesandcablingcansupportthetrafficthatwillbeaddedtothenetwork.Cablingthatcansupportgigabittransmissionsshouldbeabletocarrythetrafficgeneratedandnotrequireanychangestotheinfrastructure.
ITEPCv4.0Chapter1 532007CiscoSystems,Inc.Allrightsreserved. CiscoPublic
RealtimeStreamingandVoice
VoIP
WhenintroducingVoIPtoanetworkthatusestraditionaltelephones,itisimportanttorememberthatVoIPusesvoiceenabledrouters.TheseroutersconvertanalogvoicefromtraditionaltelephonesignalsintoIPpackets.
OnceconvertedintoIPpackets,theroutersendsthosepacketsbetweencorrespondinglocations.Voiceenabledroutersmustbeaddedtothedesign.
ITEPCv4.0Chapter1 542007CiscoSystems,Inc.Allrightsreserved. CiscoPublic
RealtimeStreamingandVoice
IPTelephony
InIPtelephony,theIPphoneitselfperformsvoicetoIPconversion.Voiceenabledroutersarenotrequiredwithintheenterprisenetwork.IPphonescanuseCiscoUnifiedCommunicationsManagerasaserverforcallcontrolandsignaling.ThestadiumnetworkrequirementsincludeIPtelephony.
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RealtimeStreamingandVoice
ITEPCv4.0Chapter1 562007CiscoSystems,Inc.Allrightsreserved. CiscoPublic
RealtimeStreamingandVoice
RealtimeVideoProtocols
Totransportstreamingmediaeffectively,thenetworkmustbeabletosupportapplicationsthatrequiredelaysensitivedelivery.RealTimeTransportProtocol(RTP)andRealTimeTransportControlProtocol(RTCP)aretwoprotocolsthatsupportthisrequirement.
ITEPCv4.0Chapter1 572007CiscoSystems,Inc.Allrightsreserved. CiscoPublic
RealtimeStreamingandVoice
RTPandRTCPenablecontrolandscalabilityofthenetworkresourcesbyallowingQoSmechanismstobeincorporated.TheseQoSmechanismsprovidevaluabletoolsforminimizinglatencyissuesforrealtimestreamingapplications.Thesetoolsincludepriorityqueuing,customqueuing,lowlatencyqueuing,andclassbasedweightedfairqueuing.
ITEPCv4.0Chapter1 582007CiscoSystems,Inc.Allrightsreserved. CiscoPublic
FileTransferandEmail
Filetransfersputhighvolumetrafficontothenetwork.Thistrafficcanhaveagreatereffectonthroughputthaninteractiveendtoendconnections.Althoughfiletransfersarethroughputintensive,theytypicallyhavelowresponsetimerequirements.
ITEPCv4.0Chapter1 592007CiscoSystems,Inc.Allrightsreserved. CiscoPublic
FileTransferandEmail
Someofthecharacteristicsoffiletransfertrafficinclude:
Unpredictablebandwidthusagethistypeoftrafficisusuallyuserinitiatedandthereforecannotbereliablypredicted.
LargepacketsizeFTPandotherfiletransfertrafficuseslargepacketsizesforefficienttransfer.Theselargepacketscancausedelayforothertypesoftrafficwhenthenetworkbecomescongested.
ITEPCv4.0Chapter1 602007CiscoSystems,Inc.Allrightsreserved. CiscoPublic
FileTransferandEmail
Aspartoftheinitialcharacterizationofthenetwork,itisimportanttoidentifythenumberofusersthatusefiletransfersonaregularbasis.FTPisnottheonlytypeoffiletransfertrafficusuallypresentonaLAN.CopyingfilesfromsharednetworkdrivesanddownloadinglargefilesusinghttphavesimilarcharacteristicstoFTP.
Fromthisinformation,thenetworkdesignercananticipatethethroughputrequirements.
ITEPCv4.0Chapter1 612007CiscoSystems,Inc.Allrightsreserved. CiscoPublic
FileTransferandEmail
ITEPCv4.0Chapter1 622007CiscoSystems,Inc.Allrightsreserved. CiscoPublic
FileTransferandEmail
Emailisoneofthemostpopularnetworkservices.Withitssimplicityandspeed,emailhasrevolutionizedhowpeoplecommunicate.Yet,torunonacomputerorotherenddevice,emailrequiresseveralapplicationsandservices.TwocommonApplicationLayerprotocolsarePostOfficeProtocol(POP)andSimpleMailTransferProtocol(SMTP).
ITEPCv4.0Chapter1 632007CiscoSystems,Inc.Allrightsreserved. CiscoPublic
FileTransferandEmail
EmailClientProcesses
Emailuserstypicallyaccesstheiremailserviceusinganapplicationcalledanemailclient.Theemailclientenablesuserstocomposeandsendmessages,thenplacesreceivedmessagesintotheuser'smailbox.
EmailServerProcesses
Theemailserveralsotransfersanddeliversmailtotheemailclient.
Althoughasingleemaildoesnotgeneratesignificanttraffic,itispossibleformassemailstobetransmittedthatinundatethenetworkorserverswithtraffic.
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FileTransferandEmail
ITEPCv4.0Chapter1 652007CiscoSystems,Inc.Allrightsreserved. CiscoPublic
FileTransferandEmail
SupportingFileTransferandEmailApplications
Customersexpectimmediateaccesstotheiremailsandtothefilesthattheyaresharingorupdating.
Tohelpensurethisavailability,thenetworkdesignertakesthefollowingsteps:
Securingfileandmailserversinacentralizedlocation,suchasaserverfarm.
Protectingthelocationfromunauthorizedaccessbyphysicalandlogicalsecuritymeasures.
Creatingredundancyintheserverfarmthatensuresthatifonedevicefails,allfilesarenotlost.
Configuringredundantpathstotheservers.
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FileTransferandEmail
ITEPCv4.0Chapter1 672007CiscoSystems,Inc.Allrightsreserved. CiscoPublic
HTTPandWebTraffic
HTTPandWebTraffic
HypertextTransferProtocol(HTTP)isoneoftheprotocolsintheTCP/IPsuitethatwasoriginallydevelopedtopublishandretrievewebpages.Itisnowusedfordistributedcollaborativeinformationsystems.HTTPisusedacrosstheWorldWideWebfordatatransfer.Itisoneofthemostwidelyusedapplicationprotocols.
HTTPspecifiesarequest/responseprotocolbetweenaclient,typicallyawebbrowser,andaserver.
ITEPCv4.0Chapter1 682007CiscoSystems,Inc.Allrightsreserved. CiscoPublic
HTTPandWebTraffic
Whenaclientsendsarequestmessagetoaserver,theHTTPprotocoldefinesthemessagetypesusedbytheclient.Theprotocolalsospecifiesthemessagetypesthattheserverusestorespond.
Thisprocesswouldappeartobeaminorconsiderationinthedesignprocess.However,iftheserverthatisbeingaccessedisusedforecommerceortostorecustomerinformation,thesecurityandredundancyissuesbecomeevenmoreimportant.
ITEPCv4.0Chapter1 692007CiscoSystems,Inc.Allrightsreserved. CiscoPublic
HTTPandWebTraffic
NetworkMedia
TosupportHTTPandwebtraffic,itisnecessarytohaveLayer3devicesthatcancontroltheinternalandexternaltrafficflows.Inanetworkaudit,theinboundtrafficshouldbeconsideredpartofthenetworkbaselinetesting.
Redundancy
Serversusuallyhaveredundantcomponentsandpowersources.TheymaybeequippedwithtwoormoreNICsconnectedtoseparateswitches.
ITEPCv4.0Chapter1 702007CiscoSystems,Inc.Allrightsreserved. CiscoPublic
HTTPandWebTraffic
Security
SecurityfeaturessuchasACLs,firewalls,andIDS,arealsousedtopreventunauthorizedtrafficfrombeingsentintooroutoftheprotectednetworks.Aswiththeotherapplicationservers,theHTTPservershouldbelocatedattheISPorinthecentralizedserverfarmforaddedphysicalsecurityandredundancy.
ITEPCv4.0Chapter1 712007CiscoSystems,Inc.Allrightsreserved. CiscoPublic
MicrosoftDomainServices
ThestadiumusesMicrosoftActiveDirectoryServices.Therefore,thenetworkdesignermustconsiderbothservertoserverandservertoclientcommunications.Microsoftserverssupportmanydifferenttypesofservicesthatrelyonhighspeedcommunicationsbetweentheserversthemselves.Theseservices,suchasActiveDirectoryreplication,mustbeconsideredwhenrelocatingserversduringanetworkredesign.
ITEPCv4.0Chapter1 722007CiscoSystems,Inc.Allrightsreserved. CiscoPublic
MicrosoftDomainServices
PortsusedbyMicrosoftDomainServices
MicrosoftserversandclientscommunicatewitheachotherusingasetofTCPandUDPports.TheseportsareusedforvariousMicrosoftservices,includingauthenticationandauthorization.ManyMicrosoftspecificservicesgeneratelocalbroadcastpacketsontheseports,aswellasunicastrequests.CommonTCPandUDPportsthatmustbeopenforMicrosoftDomainServicestooperatecorrectlyinclude:
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MicrosoftDomainServices
UDP53DNSServices
UDP67DHCP
UDP123WindowsTimeService
TCP135RemoteProcedureCall(RPC)
UDP137NetBIOSNameResolution
UDP138NetBIOSDatagramService
TCP139NetBIOSSessionService
TCP389andUDP389LDAPService
TCP445ServerMessageBlocks(SMB)
TCP1433MicrosoftSQLoverTCP
ActiveDirectoryandDNS
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MicrosoftDomainServices
ActiveDirectoryandDNS
WhenaMicrosoftWindows2003Serverisinstalledinanetwork,thereisverytightintegrationbetweenActiveDirectoryServicesandDNS.ActiveDirectoryrequiresDNStolocatedomaincontrollers,whichprovideauthenticationandauthorizationservices.Windows2003DomainControllersmustbeDNSserversaswell.ThisDNSservicecanprovidethemainDNSforanorganization,ormaybeinadditiontoInternetDNSserviceslocatedonnonWindowsservers
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MicrosoftDomainServices
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WhatisQualityofServiceandwhyisitneeded?
QualityofService(QoS)referstothecapabilityofanetworktoprovidepreferentialservicetoselectednetworktraffic.TheprimarygoalofQoSistoprovidepriority,includingdedicatedbandwidth,controlledjitterandlatency,andreducedpacketloss.
WhencreatingQoSpoliciesforanorganization,itisimportanttofocusonwhichtrafficneedspreferentialtreatment.
ITEPCv4.0Chapter1 772007CiscoSystems,Inc.Allrightsreserved. CiscoPublic
WhatisQualityofServiceandwhyisitneeded?
Usersperceiveservicequalitybasedontwocriteria:
Thespeedwithwhichthenetworkreactstotheirrequests
Theavailabilityoftheapplicationstheywanttouse
QoShelpstomanagetheseissuesfortrafficflowswithinthenetworkinfrastructureandfortheapplicationsthatusethenetwork.
SomeCiscodevices,suchasrouters,havebuiltinQoSmechanisms.
ITEPCv4.0Chapter1 782007CiscoSystems,Inc.Allrightsreserved. CiscoPublic
WhatisQualityofServiceandwhyisitneeded?
PlayflashfromChapter4.3.1(1)
file:///C:/CISCO_CCNA/Discovery4_English/index.html
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WhatisQualityofServiceandwhyisitneeded?
Someapplicationsareextremelysensitivetobandwidthrequirements,packetdelays,networkjitter,andpossiblepacketloss.TheseapplicationsincluderealtimeIPtelephonyandstreamingvideo.
IPTelephonyRequirements
TherequirementsofIPtelephonyillustratemanyoftheproblemsofrealtimeapplicationsinaconvergednetwork.Voicetrafficrequiresmorethanasimpleconnectionbetweenusers.Thequalityofthetransmissionsisextremelyimportant.Whendelaysoccur,voicesbreakupandwordsbecomedistorted.
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Toavoidsubstandardtransmissionquality,IPtelephonyrequiresthatQoSmechanismsbeinplace.Voicepacketsmustnothaveaonewaydelaygreaterthan150ms.ItiscriticalinthedeploymentofIPtelephonysolutionsthatvoicepacketshavelowlatencyandlowjitterateachhopalongagivenpath.
WhatisQualityofServiceandwhyisitneeded?
ITEPCv4.0Chapter1 812007CiscoSystems,Inc.Allrightsreserved. CiscoPublic
StreamingVideoRequirements
Streamingvideoisavideofeedthatisusuallysentfromprerecordedfiles.Itcanbedistributedinalivebroadcastconvertingthevideointoacompresseddigitalsignalandthentransmittedbyaspecialwebserver.Thismediastreamissentasamulticastsomultipleuserscanviewthestreamatthesametime.
WhatisQualityofServiceandwhyisitneeded?
ITEPCv4.0Chapter1 822007CiscoSystems,Inc.Allrightsreserved. CiscoPublic
WhatisQualityofServiceandwhyisitneeded?
InanetworkwithoutQoS,allpacketsreceivethesametreatment,andrealtimeapplicationssuffer
QoSdoesnotactuallycreatemorebandwidth.Instead,itprioritizesbandwidthusetosupporttheapplications,suchasIPtelephony,thatneeditmost.Todothis,QoSusestrafficqueuestohelpmanageprioritytrafficonconvergednetworks.
ITEPCv4.0Chapter1 832007CiscoSystems,Inc.Allrightsreserved. CiscoPublic
WhatisQualityofServiceandwhyisitneeded?
Playflashfromchapter4.3.1(2)
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TrafficQueuing
VoiceandDataTraffic
Inaconvergednetwork,constant,smallpacketvoicetrafficcompeteswithlarger,irregulardataflowsfromserverupdatesandfiletransfers.Althoughtypicallythepacketscarryingvoicetrafficonaconvergednetworkaresmall,delaysthatoccurwhiletheytraversethenetworkwillcausepoorvoicequality.
Datafromrealtimeapplications,suchasIPtelephony,mustbeprocessedatthesamerateasitissent,andthereisnotimetoretransmitpacketswitherrors.Therefore,VoIPusesUDPasabestefforttransportprotocol.
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TrafficQueuing
Conversely,packetscarryingfiletransferdatatypicallyarelarge.ThesepacketsusetheerrorcheckingandretransmissionfeaturesofTCPtosurvivedelaysandpacketdrops.
Itispossibletoretransmitpartofadroppeddatafile,butitisnotfeasibletoretransmitpartofavoiceconversation.Forthisreason,critical,timesensitive,voiceandvideotrafficmusthavepriorityoverdatatraffic.
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TrafficQueuing
QoSMechanisms
MechanismsmustbeinplacetoprovideQoSpriority.Theprioritiesfortrafficcanbehigh,medium,normal,andlow.TrafficqueuesareonlyoneoftheQoSmechanismsavailableforprioritizingtrafficonthenetwork.Trafficqueuesassistinprovidingsecure,predictable,andguaranteedservices.Evenabriefnetworkoutageonaconvergednetworkcanseriouslydisruptbusinessoperations.
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TrafficQueuing
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TrafficQueuing
HardwareandSoftwareQueues
QueuesareusedtomanagetrafficflowwithQoS.Hardwarequeuesstoretrafficasitisreceivedandsendpacketsoutintheorderreceived,onafirstcomefirstservedbasis.Thehardwarequeueissometimesreferredtoasthetransmitqueue,orTxQ.Thisisthephysicalqueuewherepacketswaitforforwardingbasedontheirpriority.
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TrafficQueuing
Softwarequeuesallowthepacketstobesentoutbasedontheprioritysetbythenetworkdesigneroradministrator.ThequeuesarebasedontheQoSrequirements.Priorityqueuing(PQ)andCustomQueuing(CQ)areexamplesofsoftwarequeues.
ImplementingQoSinTrafficQueues
ToimplementQoSonanetwork,thedesignerfollowsthreebasicstepstoensurethattrafficisproperlyprioritized:
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TrafficQueuing
Step1:IdentifyTrafficRequirements
DeterminetheQoSrequirementsneededforthedifferenttypesoftrafficsuchasvoice,missioncriticalapplications,andwhichlowprioritytrafficcanbemarkedasbesteffort.
Step2:DefineTrafficClasses
Aftertraffichasbeenidentified,itcanbeplacedinappropriateclasses,suchasvoicetraffic,whichhasthehighestpriority,followedbymissioncriticalapplications.Allothertrafficcanbeprioritizedasnormalorlowdependingonthepurposeofthedata.
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TrafficQueuing
Step3:DefineQoSPolicies
ThelaststepistodefinetheQoSpoliciestobeappliedtoeachclass.Thesepoliciesincludeschedulingtrafficqueuesandrulesformanagingcongestion.
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Prioritiesandtrafficmanagement
Manymethodsareavailableformanagingtrafficonanetwork.OnemethodisPriorityQueuing(PQ).AspartofimplementingQoSonanetwork,PriorityQueuingclassifiestrafficashigh,medium,normal,orlowpriority.PriorityQueuingcanthenbeappliedtotheseQoSclasses.
PriorityQueuingisusefulfortimesensitive,missioncriticalprotocols.PQworksbyestablishingfouroutputinterfacequeueshigh,medium,normal,andloweachservingadifferentlevelofpriority.Thesequeuesareconfigurableforthefollowingcharacteristics:
Queuetype
Trafficassignment
Size
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Prioritiesandtrafficmanagement
Incomingtrafficisclassified,markedtoindicateitsclass,andforwarded.
TrafficisassignedtothevariousqueuesbasedonQoSpoliciesdefinedinaprioritylist.Thesepoliciescanbebasedonprotocol,portnumber,orothercriteriaestablishedforthedesignatedtraffictype.Theyrepresentasetoffiltersthatseparatedifferenttraffictypesintothefourclassbasedqueues.
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Prioritiesandtrafficmanagement
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Prioritiesandtrafficmanagement
CiscoisincorporatingtoolstoassistwiththeconfigurationofQoS.OneofthosetoolsisAutoQoS,whichisavailableaspartoftheCiscoIOSsoftware.
CiscoAutoQoSprovidesasimple,intelligentCommandLineInterface(CLI).ThisCLIenablesLANandWANQoSforVoIPonCiscoswitchesandrouters.
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Prioritiesandtrafficmanagement
AutoQoSincorporatestheCiscobestpracticesforimplementingqualityofserviceandmakesiteasyforcustomerstoconfiguretheirnetworkstosupporthighprioritytraffic,suchasvoiceorvideo.
CiscoAutoQoScanreducethedeploymentcostandtimeframebyasmuchastwothirds,whencomparedtoamanualapproach.
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Prioritiesandtrafficmanagement
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WherecanQoSbeimplemented?
WhenconfiguringQoSfeatures,thenetworkadministratorcanselectthespecificnetworktraffic,prioritizeitaccordingtoitsrelativeimportance,andusecongestionmanagementtechniquestoprovidepreferentialtreatment.QoScanbeimplementedattheAccess,Distribution,andCoreLayersofanetwork.
Layer2Devices
Layer2switchesattheAccessLayercansupportQoSbasedonIEEE802.1pClassofService(CoS).TheLayer2switchQoSusesclassificationandschedulingtoprioritizesendingframesfromtheswitchintothenetwork.
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WherecanQoSbeimplemented?
Layer3Devices
Layer3devicescansupportQoSbasedonphysicalinterface,IPaddresses,logicalportnumbers,andQoSbitsintheIPpacket.QoSinDistributionandCoreLayerdevicesmustbesupportedinbothdirectionsoftrafficflow.
ClassificationandMarking
Classificationistheprocessbywhichtrafficisgrouped.Classificationsaremadebasedonhowtrafficismarkedorbyprotocol.
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WherecanQoSbeimplemented?
TrafficcanbemarkedbyLayer2classofservice,anIPprecedence,oraDifferentiatedServicesCodePoint(DSCP)value:
Classofservice(CoS)isthefirst3bitsofan802.1qVLANtag.
IPprecedenceisthefirst3bitsoftheTypeofService(ToS)byteintheIPheader.
DSCPcanbeassignedbytherouterorswitch.Itisthefirst6bitsintheToSbyteintheheader.
Classificationandmarkingallowthepartitioningoftrafficintomultipleprioritylevels,orclassesofservice.
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WherecanQoSbeimplemented?
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ConvergedNetworkConsideration
Modernnetworkscansupportconvergedserviceswherevideoandvoicetrafficaremergedwithdatatraffic.Thenetworkinthestadiumisatypicalexample.
ManagingConvergedNetworks
Controlmethodsforvoiceandvideotrafficonconvergednetworksaredifferentfromcontrolmethodsforothertraffic,suchaswebbased(HTTP)traffic.
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ConvergedNetworkConsideration
QualityofService(QoS)onConvergedNetworks
AllnetworksperformbetterwhenQoScontrols:
Delayandjitter
Bandwidthprovisioning
Packetlossparameters
Convergednetworksrequirestrongperformanceandsecurityfeaturestomanagetheconflictingrequirementsoftheirtraffic.Forthisreason,QoSmechanismsaremandatory.
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ConvergedNetworkConsideration
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RequirementsofanIPtelephonysolution
OneofthetechnicalrequirementsofthestadiumnetworkistoupgradetoanIPtelephonysolution.
IPTelephonyDesignConsiderations
Theproposednetworkdesignmustinclude:
Powerandcapacityplanning
Identifyingcontendingtrafficflows
SelectingthecomponentsfortheIPtelephonysolution
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RequirementsofanIPtelephonysolution
ThecomponentsofanIPtelephonysolutioncaninclude:
IPphones
Gateway
Multipointcontrolunit(MCU)
Callagent
Applicationservers
Videoendpoint
Softwaretelephone
Othercomponents,suchassoftwarevoiceapplicationsandinteractivevoiceresponse(IVR)systems,provideadditionalservicestomeettheneedsofenterprisesites.
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RequirementsofanIPtelephonysolution
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RequirementsofanIPtelephonysolution
IsolatingTraffic
IfboththeclientPCandtheIPphoneareonthesameVLAN,eachwilltrytousetheavailablebandwidthwithoutconsideringtheotherdevice.ThesimplestmethodtoavoidaconflictistouseseparateVLANsforIPtelephonytrafficanddatatraffic.
BenefitsofSeparateVLANs
UsingseparateVLANsprovidesthesebenefits:
QoScanprioritizetheIPtelephonytrafficasitcrossesthenetwork.
NetworkadministratorscanidentifyandtroubleshootnetworkproblemsmoreeasilywhenphonesareonseparateIPsubnetsandVLANs.
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RequirementsofanIPtelephonysolution
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RequirementsofanIPtelephonysolution
ThestadiummanagementwantstoreplacetheirdigitaltelephonesystemwithIPtelephony.
TraditionalTelephony
Traditionalbusinesstelephonesystemsaretypicallybuiltaroundacentralcontrolunit,calledaPrivateBranchExchange(PBX).ThePBXroutesvoicecallsviaanalogordigitallines,dependingonthetypeofdevice.Forexample,ananalogfaxmachineoranalogphoneusesananalogline,andadigitaldesktopphoneusesadigitalline.
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RequirementsofanIPtelephonysolution
VoIP
CiscousesthetermVoIPwhenusingvoiceenabledrouterstoconvertanalogvoicefromtraditionaltelephonesintoIPpacketsandroutethosepacketsbetweenlocations.WithintheITindustry,VoIPisusedinterchangeablywithIPtelephony.WithVoIP,thePBXconnectstoavoiceenabledrouter.ItdoesnotconnecttoaPSTNortoanotherPBX.BusinessesuseVoIPtoreducecostsbyconsolidatingWANlinks,decreasinglongdistancecallingchargesandreducingthenumberofsupportstaff.
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RequirementsofanIPtelephonysolution
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RequirementsofanIPtelephonysolution
IPTelephony
IPtelephonyreplacestraditionalphoneswithIPphonesandusesCiscoUnifiedCommunicationsManager,whichisaserverforcallcontrolandsignaling.IPtelephonyhasthefollowingfeatures:
IntegratesvoiceandvoicemessagingapplicationsthatconnectviatheIPnetworkratherthanviatheanalogordigitalsystems.
UsesanIPphonetoperformvoicetoIPconversion.
CreatespeertopeerrelationshipsbetweenthephonesinvolvedinaconversationratherthancentrallyroutingcallsasaPBXdoes.
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RequirementsofanIPtelephonysolution
ThenetworkdesignerandcustomercanincorporateVoIPorIPtelephonyontotheexistingdatanetwork,creatingaconvergednetwork.
ThestadiumcompanyexpectstogainthefollowingbenefitsofIPtelephony:
Simplifiedadministrationofofficemoves,additions,andchanges
Additionalapplications,suchasdirectoriesandwebpages,tothetelephonysystem
Reducedcosttomanagetheseparateinfrastructures
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RequirementsofanIPtelephonysolution
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RequirementsofanIPtelephonysolution
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RequirementsofanIPtelephonysolution
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Videoliveandondemand
LiveVideo
Livevideo,orstreamingvideo,enablesuserstoseecontentbeforeallthemediapacketsareinsidetheircomputersystem.Streamingmediafilesdonothaveawaitingperiodforviewing;theyareavailableimmediatelyasacontinuousstreamofdatapackets.Streamingvideoeliminatestheneedtostorelargemediafilesortoallocatestoragespaceforthefilesbeforeplayingthem.Alivevideofeedisoftensentusingmulticastpacketstomanyusersatthesametime.
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Videoliveandondemand
VoD
WithVoD,userscaneitherstreamordownloadallofthecontenttotheircomputercachebeforetheyviewit.Downloadingthecompletevideofilebeforeviewingisalsocalledstoreandforward.Thismethodminimizestheloadonsystemresources.Installingaservertodirectstreamingmediaintoacomputercacheallowsuserstoretainthecontentandviewitatalatertime.VoDissentusingunicastpacketstothespecificuserrequestingthevideo..
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Videoliveandondemand
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Videoliveandondemand
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SupportingRemoteuserswithvoiceandvideo
Technologydevelopmentsallowgreaterflexibilitytoworkersintermsofhowandwheretowork.Atthestadium,forexample,workersconnecttothecentralsitefromseveralremotesites.
Totakeadvantageofcentralsiteresourcesandcommunications,ateleworker,branchoffice,ormobileusertypicallyhasatleastoneWANconnectiontothecentralsite.ThebandwidthrequirementsfortheWANconnectiondependonthetypeofnetworkresourcesthattheusersneedtofunctionintheirjob.IfremoteworkersarepartoftheIPtelephonynetwork,acallmanagersystemmayneedtobelocatedremotely.
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Thisaccessimpactsbandwidth.Forexample,streamingvideomaybeusedforacorporatemeeting.ThesedesigndecisionsrequireassessingthebandwidthatthecentralsiteWANconnectionaswell.
PermanentLinkorOnDemand?
Thenetworkdesignerdecideswhetheritisbettertousepermanentorondemandlinkstothecentralsite.Thedesignerworkswiththecustomertoconsidercost,security,andavailabilityrequirements.
SupportingRemoteuserswithvoiceandvideo
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SupportingRemoteuserswithvoiceandvideo
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SupportingRemoteuserswithvoiceandvideo
AhighspeedInternetconnectionisagoodsolutionforteleworkers.Itiseasytosetupinremoteofficesandisalsoavailableinmanyhotels.ThestadiummanagementplanstoprovideanInternetconnectionusingwirelessAPsintheluxuryboxesandthestadiumrestaurant.
Sometimes,asynchronousdialupconnectionsaretheonlyremoteaccesssolutionavailabletotravelers.EmployeeswhotravelcanuseaPCwithamodemandtheexistingtelephonenetworktoconnecttothecompany.
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SupportingRemoteuserswithvoiceandvideo
WANconnectionsattelecommutersitescanhavethefollowingfeatures:
Asynchronousdialup
ISDNBRI
Cablemodems
DSL
Wirelessandsatellite
VPN
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Whatisatrafficflow
TrafficFlow
Trafficflowonanetworkissimilartothetrafficflowoncitystreets.Justascarsmovefromonelocationtoanotherthroughoutthecity,trafficgeneratedfromapplicationsmovesfromonelocationinthenetworktoanother.
Acaronthestreettravelsfromastartingpointtoadestination.Similarly,atrafficflowcreatedbyanapplicationtravelsasaunidirectionalstreamofpacketsbetweenasourceandadestination.
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Whatisatrafficflow
ThepathistypicallydefinedbyaNetworkLayerIPaddress.DependingontheQoSandpoliciesconfiguredinthenetwork,thepathcanbeinfluencedbyotherinformationsuchasTransportLayersourceanddestinationportnumbers.
ThepathistypicallydefinedbyaNetworkLayerIPaddress.DependingontheQoSandpoliciesconfiguredinthenetwork,thepathcanbeinfluencedbyotherinformationsuchasTransportLayersourceanddestinationportnumbers.
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Whatisatrafficflow
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Whatisatrafficflow
ApplicationTrafficFlows
Theflowofapplicationtrafficinandoutofaportionofthenetworkcanbeminimalattimesandsignificantlyhigheratothers.Forinstance,inthesportsstadium,earlymorningtrafficmayincludeemailrequests,Internetaccess,andfileuploadstothestadiumservers.AfternoontrafficmightincludeVoIP,email,filetransfers,andtransactionprocessesfromticketsales.
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Whatisatrafficflow
Ifthenetworkdesignerdoesnotcorrectlyestimatethevolumeofapplicationtrafficduringtheinitialdesignofthestadiumnetwork,allapplicationscouldexperiencenetworkcongestionanddegradedperformance.Customersatconcessionstandsandticketpurchasingkiosksmightencountersignificantdelaysorevenaninabilitytoaccesstheapplications.Customersatisfactionwoulddiminish.
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Whatisatrafficflow
Toaidinvisualizingcurrentandfuturetrafficonthenetwork,thedesignercreatesadiagramoftrafficflows.Thefirststepistoidentifytheprojectedapplicationsonthenetwork.Thisinformationisgatheredfromthefollowingsources:
Customerinput
Networkaudit
Trafficanalysis
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Whatisatrafficflow
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Whatisatrafficflow
Itisextremelyimportanttoidentifytrafficflowsbetweenhosts.Thenetworkdesignerusesthecontentsoflogicalorphysicaldiagramstoplanthedesigntoaccommodatebothexistingandnewapplicationstraffic.
Thenetworkdesignergenerallyusesadesignprogram,suchasMSVisio,tocreateadiagramthatshowstheidentifiedapplicationsandthelogicaltopologyofthenetwork.
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Whatisatrafficflow
Fromthelogicaldiagram,thedesigneridentifiespossibleareasofcongestion.Thedesignerthendeterminestheequipmentneededtohandlethetrafficflowingfromhosttohostandfromhosttoserver.
Inthestadium,thelogicaltopologydiagramshowsthetrafficflowsfromhosttohostandfromhosttoservers.Theconnectionofthedevicesalsoshowstheapplicationsthatwillbeused.Thetrafficgeneratedbetweenthehostsisrelativelyminorwhencomparedtothetrafficgeneratedfromthehoststotheservers.
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Whatisatrafficflow
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Whatisatrafficflow
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DiagrammingInternal(Intranet)trafficflow
Thestadiumnetworkservesacomplexorganizationthathasmanyoperationalareas.Themanagementoffices,servers,vendors,andticketofficesareallapartofthelargernetwork.
EachLANwithinthestadiumhandlestrafficbeingsentfromhosttohostandhosttoserver.Generalfiletransfersfromhosttohostandemailtrafficdonotconsumelargeamountsofbandwidth.However,thedailybackupstotheserverconsumelargeamountsofbandwidthandneedtobeanalyzedduringthedesignphase.
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DiagrammingInternal(Intranet)trafficflow
Alltrafficflows,fromboththeinternalandexternalnetworks,mustbecarefullyassessedwhendesigninganewnetworkorproposingupgradesforanexistingnetwork.Thisassessmentposesuniquechallengesforthenetworkdesigner:
Trafficwithintheinternalnetworkiseasytoidentify.Thistrafficcanbeusedtoestimateutilizationofthenetwork.
Trafficfromexternalsourcesisdifficulttocharacterize.Thedesignerneedstoestimatethebandwidthrequirementsforexternaltrafficflows.
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DiagrammingInternal(Intranet)trafficflow
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Diagrammingtrafficflowstoandfromremotesites
AfterallsectionsoftheinternalLANhavebeencharacterizedanddiagrammed,thenetworkdesignerfocusesontheremotesitesandVPNs.
Theamountoftrafficsenttoorreceivedfromaremotesitecanbesmall.Inthestadiumnetwork,thetrafficflowsmaybesmall,buttheyareprimarilytransactionalprocessessentfromtheticketofficetotheserverslocatedatthestadium.Becausetheseapplicationsaremissioncritical,itisimportanttoidentifytheflowsforQoS,redundancy,andsecuritypurposes.
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Diagrammingtrafficflowstoandfromremotesites
AswiththeLANtopology,theremotedevicesthatgeneratetrafficonthenetworkneedtobeidentified.Allswitchesandroutersthatareusedtoconnecttheremotesitestothestadiumarepartofthepaththattheapplicationtraffictakes.
Thenetworkdesignershouldcalculatetheamountoftrafficflowingfromtheremotesitesaspartoftheexternaltrafficflowsintothestadiumnetwork.ThedesignershouldalsodetermineifanyACLsorfirewallswillinterferewiththeflowofappropriatetraffic.
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Diagrammingtrafficflowstoandfromremotesites
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DiagrammingExternalTrafficFlows
Althoughmostofthetrafficintheexistingstadiumnetworkisinternal,thenetworkdesignermustconsidertheexternaltrafficthatisdestinedfortheInternet.
DiagrammingtheInternetisimpossible,consideringthenumberofdevicesthatareconnectedtoit.However,itispossibletodetermine:
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DiagrammingExternalTrafficFlows
TheoutgoingtrafficflowsdestinedfortheInternet.Anexampleofoutgoingtrafficinthestadiumnetworkisusersinthestadiumwhorequireaccesstoexternalresources,suchasonlinesportsnews.
TheincomingtrafficflowsfromtheInternettolocallyprovidedservices.Anexampleofincomingtrafficiscustomerspurchasingticketsonlinewhoneedaccesstotheinternalserverstoprocessthepurchases.
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DiagrammingExternalTrafficFlows
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DiagrammingExtranetTrafficFlows
ThestadiumhasaremotesiteandavendorthatisallowedtoaccesstheinternalnetworkthroughVPNs.TheseVPNspermitaccesstothestadiuminternetworkviasecure,encryptedconnections.Thestadiumalsohasawebbasedecommerceserverthatallowscustomerstobuytickets.ThisserverisprotectedusingSSL.
vendorandcustomersareusingIPSectosecuretrafficflowsintothestadiumnetwork.
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DiagrammingExtranetTrafficFlows
CCNA Discovery 4.0 Designing and Supporting Computer NetworksObjectivesThe importance of application performanceSlide 4Slide 5Slide 6Slide 7Slide 8Characteristics of Different Application CategoriesSlide 10Slide 11Slide 12Slide 13Slide 14Slide 15Slide 16Slide 17Slide 18Slide 19Slide 20Slide 21How traffic flow affects network designSlide 23Slide 24Slide 25How application characteristics affect network designSlide 27Slide 28Slide 29Transaction ProcessingSlide 31Slide 32Slide 33Slide 34Slide 35Slide 36Slide 37Slide 38Slide 39Slide 40Slide 41Slide 42Slide 43Slide 44Slide 45Slide 46Slide 47Slide 48Real-time Streaming and VoiceSlide 50Slide 51Slide 52Slide 53Slide 54Slide 55Slide 56Slide 57File Transfer and E-mailSlide 59Slide 60Slide 61Slide 62Slide 63Slide 64Slide 65Slide 66HTTP and Web TrafficSlide 68Slide 69Slide 70Microsoft Domain ServicesSlide 72Slide 73Slide 74Slide 75What is Quality of Service and why is it needed?Slide 77Slide 78Slide 79Slide 80Slide 81Slide 82Slide 83Traffic QueuingSlide 85Slide 86Slide 87Slide 88Slide 89Slide 90Slide 91Priorities and traffic managementSlide 93Slide 94Slide 95Slide 96Slide 97Where can QoS be implemented?Slide 99Slide 100Slide 101Converged Network ConsiderationSlide 103Slide 104Requirements of an IP telephony solutionSlide 106Slide 107Slide 108Slide 109Slide 110Slide 111Slide 112Slide 113Slide 114Slide 115Slide 116Slide 117Video-live and on-demandSlide 119Slide 120Slide 121Supporting Remote users with voice and videoSlide 123Slide 124Slide 125Slide 126What is a traffic flowSlide 128Slide 129Slide 130Slide 131Slide 132Slide 133Slide 134Slide 135Slide 136Slide 137Slide 138Diagramming Internal (Intranet) traffic flowSlide 140Slide 141Diagramming traffic flows to and from remote sitesSlide 143Slide 144Diagramming External Traffic FlowsSlide 146Slide 147Diagramming Extranet Traffic FlowsSlide 149