software defined networking · everything as a service, cloud computing and tremendous user’s...

Bachelor’s thesis

Information Technology

NINFOS11

Olanrewaju Oladunjoye

SOFTWARE DEFINED NETWORKING –TheEmergingParadigmToComputerNetworking

BACHELOR’S THESIS | ABSTRACT

TURKU UNIVERSITY OF APPLIED SCIENCES

Information Technology

2017 | 39

Olanrewaju Oladunjoye

SOFTWARE DEFINED NETWORKING -AnEmergingParadigmToComputerNetworking

SoftwareDefinedNetworking(SDN)isanemergingparadigminnetworkingtechnologythatenablesinnovationonhownetworksystemsaremanagedanddesigned.SDNplaysahugeroleintheefforttomakecomputernetworksprogrammable.

Thisthesisdiscussesthehistoryandeffortstoprogrammableandactivenetworks,theearlypracticestowardsseparatingthecontrolplaneanddataplane.Highlightingthearchitecturalconceptsinnetworkingthatsoftwaredefinednetworksemanatedaswellasthehistoryandevolutionofsoftwaredefinednetworking.ThethesisfurtherdiscusseshowSDNsimplifiesthecomplexityofmanaginglargeanddistributednetworksystem.ItalsoexaminesthetechnologiesthatsupportsoftwaredefinednetworkingsuchasNetworkVirtualizationandOpenFlow.Thethesisreviewsthecomponentsofsoftwaredefinednetworkarchitecture:thedataplanelayer,thecontrollerplanelayer,andapplicationlayer.Furthermore,itreportsthepracticalimplementationofSDNinnetworkfunctionsvirtualization.Finally,itdepictsthenotionofsoftwaredefinednetworking,whoseApplicationProgrammingInterfacemaybeimplementedbyOpenFlow.

Thepracticalaspectofthisthesisshowsasimpleemulationofsoftware-definednetworkarchitectureusingMininetnetworkemulationtool.Hopefully,thisworkaimstobenefitthosewhointendtolearnaboutthefundamentalprinciplesofSoftwareDefinedNetworking.

KEYWORDS:

SoftwareDefinedNetworking,NetworkFunctionVirtualization,ControllerPlane,DataPlane,ApplicationPlane,ComputerNetworks,mininet

CONTENTS

LIST OF ABBREVIATIONS (OR) SYMBOLS 5

1. INTRODUCTION 6

2. WHAT IS COMPUTER NETWORKING? 7

2.1Architectural theme recognition in computer networking where software defined

networking emanated. 7

3. HISTORY AND EVOLUTION OF SOFTWARE DEFINED NETWORKING 9

3.1Central Network Control. 93.2Network Programmability 10

3.3 Network Virtualization 11

4. COMPONENTS OF SDN ARCHITECTURE 17

4.1The SDN Data Plane 19

4.2The SDN Controller Plane 19

4.3The SDN Application Layer. 20

5. PRACTICAL IMPLEMENTATION OF SOFTWARE DEFINED NETWORKING. 22

5.1Network Functions Virtualization 22

5.2A simple software defined network architecture. 26

6. CONCLUSION 36

REFERENCES 37

FIGURES

Figure 1. Multiple instances of Forwarding Plane Elements (FE) and Control Plane Elements (CE) in FoRCES Network Element (NE). (Doria, et al., 2010). 11Figure 2. Open Signalling in the tempest (Van Der Merwe, Rooney, Leslie, & Crosby, 1998). 13Figure 3. The switch divider (Bavier, Feamster, Huang, Peterson, & Rexford, 2006). 14Figure 4. Shows the internet in a slice architecture running on VINI (Bavier, Feamster, Huang, Peterson, & Rexford, 2006). 15Figure 5. Basic SDN architecture components (Open Networking Foundation, 2012). 18Figure 6. NFV Domains encompassed in the network function virtualization infrastructure (Chiosi, Clarke, Willis , Reid, Feger, & Ruhl , 2012). 23Figure 7. Vision for network function virtualization (Nadeau, 2013). 24Figure 8. Network Functions that could be virtualized (Nadeau, 2013). 25Figure 9. SDN network topology consisting of three hosts with class A IP addressing, an OpenFlow Switch, and OpenFlow refrence controller. 28Figure 10. Starting mininet. 29Figure 11. IP address assigned to all hosts, and switch links are up. 30Figure 12. H1 cannot reach H2 and vice versa. 31Figure 13. Ping failure among all host. 32Figure 14. Manual Installation of flows on open switch flow table. 33Figure 15. Succesful pings between host H1 and H2, while H3 is unrecheable because the switch flow table includes entries for only H1 and H2. 34Figure 16. Starting OVS reference controller. 35Figure 17. All host are now recheable from anywhere on the network. 35

LISTOFABBREVIATIONS(OR)SYMBOLS

AS Autonomous System

API ApplicationProgramInterfaceBGP BorderGatewayProtocolCABO ConcurrentArchitectureareBetterThanOneCPE CustomerPremiseEquipmentDCPI Data-ControllerPlaneInterfaceFIB ForwardingInformationBaseForCES ForwardingandControlElementSeparationIETF InternetEngineeringTaskForceLAN LocalAreaNetworkLIB LabelInformationBaseMAN MetropolitanAreaNetworkNBI NorthBoundInterfaceNCP NetworkControlPointNE NetworkElementsNFV NetworkFunctionVirtualizationNFVI NetworkFunctionVirtualizationInfrastructureOSPF OpenShortestPathFirstPCE PathComputationEngineRCP RoutingControlPlatformRIB RoutingInformationBaseRIP RoutingInformationProtocolSS7 SignallingSystem7VNF VirtualNetworkFunctions

TURKUUNIVERSITYOFAPPLIEDSCIENCESTHESIS|OlanrewajuOladunjoye 6

1.INTRODUCTION

OvertheyearsofComputerNetworkexistenceandgrowth,thedrasticincreaseinnetworkcomplexityhasbroughtaboutdifficultiesincomputernetworkmanagement.Ittendstobedifficultinconfiguringcomputernetworksystemsbypredefinedpolicies,reconfiguringnetworkstorespondtochanges,faults,andloads.Asitappearsthatcurrentnetworksystemsareintegratedvertically,thecontrolplaneanddataplanearealltieduptogether.SoftwareDefinedNetworkingisanemergingstandardthatportrayschangesinthecurrentstateofcomputernetworks,byseparatingthenetworkofequipment'scontrollogicfromfundamentalswitchesandrouters,logicalpromotionofcentralizednetworkcontrol,introducingcomputernetworkprogrammability(Kreutz,Ramos,Verissimo,Tothenberg,Azodolmolky,&Uhlig,2014). WithSoftwareDefinedNetworking,comestheeaseofcreationandintroductionofnewabstractionsincomputernetworking,networkmanagementsimplificationandfacilitationofcomputernetworkevolution. ThisthesiswillshowthearchitecturalthemerecognitionincomputernetworkingwhereSoftwareDefinedNetworking(SDN)emanated.Furthermore,thehistoryonhownetworksstarttobecomeactiveandprogrammabletoshowthedifferencesandimprovementintraditionalcomputernetworkingtechnologiescomparedtoasoftwaredefinednetwork.Andalsoshowingthebenefitsofsoftwaredefinednetworksareimplementedwiththeaidofnetworkvirtualization.(Rostami,2014)

2.WHATISCOMPUTERNETWORKING?

ComputerNetworkingisthepracticeoflinkingoneormorecomputersystemstogetherinothertosharedata.Computersystemscompriseofcomputerhardwaredevicesandsoftware.Computernetworkisagroupofoneormorecomputerdeviceslinkedtoeachother.computernetworkscanbecategorizedintodifferenttypes,including: LocalAreaNetworking(LANs):Computersystemslinkedtogetherinonegeographicalarea.Forinstance,inthesamebuildingorroom. WideAreaNetworks(WANs):Connectingcomputersystemswhicharedistanced,farapart,i.e.,differentgeographicalarea. MetropolitanAreaNetworks(MANs):Anetworkimplementedordesignedforacityortown,forexample,Sparknet.Additionally,computernetworkscanalsobecategorizedbasedonthefollowingcharacteristics: Topologies:Thelogicalorphysicalarrangementofcomputersystems.Typesoftopologiesinclude:bustopology,startopology,ringtopology,andmeshtopologyProtocol:Aprotocolisthedefinitionofthesetsofrulesandsignalsthatnetworkcomputersuseforcommunication.Forexample,EthernetisapopularnetworkforLANs.Architecture:Itistheclassificationofnetworkbasedonthemodelofconnection,thatis,eitherpeertopeerorclient/serverarchitecture.Computersonanetworkareoftenreferredtoasnodesandhosts.Also,acomputerwhichprovidesresourcesinanetworkenvironmentisreferredtoasservers.Inconclusion,twoormorecomputersconnectedtoeachotherwiththeabilitytocommunicateissimplyknownasacomputernetwork.(FloridaCenterforInstructionalTechnology,2013)

2.1 Architecturalthemerecognitionincomputernetworkingwheresoftwaredefinednetworkingemanated.

SoftwareDefinedNetworking(SDN):Anewcomputernetworkingparadigmwherenetworkbehavioriscontrolledbyasinglehigh-levelsoftwareprogram.ASoftware-DefinedNetworkisanetworkarchitectureinwhichthecontrol-plane(softwareprogramswhichcontrolthenetworksystembehavior)anddataplane(devicesthatforwardnetworktraffic)areseparated.Anemergingnetworkparadigmwherenetworkcontrolisbeingdecoupledfromhardwaresuchthatthebehavioralogicallycentralizedsoftwareprogramcontrolstheoverallnetworkbehavior(Kreutz,Ramos,Verissimo,Tothenberg,Azodolmolky,&Uhlig,2014).

ControlPlane

Inatypicalnetwork,thecontrolplaneisasoftwarefunctionthatchecksandmanagesthenetworkbehaviorsuchasnetworkpathsandforwardingbehavior.Also,Itisknownasahigh-levelsoftwarecontroller.

DataPlane

Networkfunctionsresponsibleformakingdecisionsonforwardingtraffic.Thedataplaneistypicallyinstantiatedasforwardingtablesonrouters,firewalls,switches,andmiddleboxes.

ActiveNetworks

Inthe1990s,ActiveNetworksareacollectionofnetworkarchitecturesthatsharedthesamegoalsassoftwaredefinednetworkingandmotivatedbythewidespreaduseoftheinternet(applications)andcomplexityintestingnewideasinreal(Rostami,2014).Inactivenetworks,communicationpatternsallowpacketstoflowthroughthenetworkinfrastructuretodynamicallymodifythenetworksystemsoperation.Activenetworkingisanattempttomakenetworksprogrammable.Forinstance,theprogrammableswitchesinanactivenetworkperformcustomcomputationorprocessingfunctionsonpacketsasittravelsthroughthoseswitches.NetworkVirtualizationRepresentingmanydistinctlogicalnetworksonasinglesharedphysicalnetworkinfrastructure.Forexample,VirtualNetworkasimplementedinTheTempest-practicalframeworkfornetworkprogrammability(VanDerMerwe,Rooney,Leslie,&Crosby,1998).Intoday’stechnology,outburstofsmartmobiledevices,Internetofthings(IOT),everythingasaservice,cloudcomputingandtremendoususer’sneedforcontent,mobilebroadbandwhichallresultstoincreasingnecessityfordatatransferoverthetrillionsofconnectednetworkswhicharepracticallyhard-wirednetworks,bringsaboutdifficultiesinnetworkscalabilityandcomplexityinnetworkmanagement(Benson,Akella,&Maltz,2009).

3.HISTORYANDEVOLUTIONOFSOFTWAREDEFINEDNETWORKING

TheevolutionofSoftwareDefinedNetworkingportraysthetimelineofSDNfromthe1980stillpresent,putsforwardtheprinciplesbehindSDN,andgainawarenessaboutSDNideas.However,SDNprinciplesarenotentirelynew,thisevolutionrecognizesthearchitecturalthemesasseeninapacketswitchednetwork,initiativesonseparationofthedataandcontrolplanesignaling,forexample,AT&TintroducedtheNetworkControlPointtowardsimprovingmanagementandmonitoringofitstelephonenetwork(Kreutz,Ramos,Verissimo,Tothenberg,Azodolmolky,&Uhlig,2014).ThisthesiswilltakealookattheconceptsunderlyingtheevolutionofSDN-TheCentralControl(logicalcentralizationofnetworkcontrol),ProgrammingNetworks(theabilitytomanagethecomputernetworksystemsviasoftwarecontrollerprograms),NetworkVirtualization(possibleformsofnetworkvirtualizationthatemergetothisparadigmshiftinnetworking).

3.1 CentralNetworkControl.

Theoriginsofcentralnetworkcontroldatebacktothe1980sintheformofAT&T'sNetworkcontrolpoint.Intheearlydays,controlanddataplanesoperatedtogetherinthesamechannel,aparadigmknownasin-bandsignalingwheredataandcontrolplanesaresentoverthesamechannel,atcertainfrequenciesinthischannel,anexampleistheBLUEBOXwhichusesthein-bandsignalingmechanismtodothingslikeresettingthephonetrunklines,pulsesonthelinecouldbeusedtoroutecallsandsetupsocketsforcalls.Theresultingnetworkhappenstoturnouttobebrittle,insecure,etc.(Wikipedia,2009).Theearliestinitiativesinanattempttodecouplecontrolanddataplanesignaling,AT&TintroducedtheNetworkControlPoint,toimprovethemonitoringandmanagementofitsTelephoneNetwork.Thisattemptbroughtaboutafasterinnovationpaceinthenetworkandofferedmeansforefficiencyimprovement(Sheinbein&Weber,1982).Inexploringasolutiontocentralizethenetworkcontrol,otherconceptsandinitiativesaretracedbacktotheRoutingControlPlatform(RCP)(Feamster,Balakrishnan,Rexford,Shaikh,&VanderMerwe,2004),whichisasolutionforinterdomainroutingcontrolinIP-networks.RCPcalculatesBorderGatewayProtocol(BGP)routes,forAutonomousSystem(AS),atacentralizedservertogivetransitnetworkoperatorsgreatercontroloverBGProutingdecisionmaking(Caesar,Caldwell,Feamster,Rexford,Shaikh,&VanderMerwe,2005).TheRCPeffectivelyusedBGPasacontrolchannelsothattheforwardingelementsthoughtthattheyweretalkingtoanotherrouterbutthenetworkusesasinglepointcentralization.Otherconceptsofcentralizednetworkcontrolcanbetracedinthetraditionaltelecommunicationsnetworks,whichincludesSignallingSystem7(SS7)andIntelligentNetwork.

SignallingSystem7(SS7)

Anout-of-bandsignalingsystemthatisolatesthecommunicationchannelformanagementinformationfromtheuserdata'spath,andacleavagebetweenuserdataandcontrolintoseparatechannelorlinks(Russell,1998).

IntelligentNetwork(IN)architecture

Ontheotherhand,isanetworkfunctionalitysupportwhichenablescallplacementstoinvokeaquerytotheDetectionPointsthatescapeoutofnormalcallhandlingandthatcitesper-servicecode(InternationalTelecommunicationUnion,1993).

3.2 NetworkProgrammability

NetworkProgrammabilityhasalonghistorywhichprovidesasolutiontotheneedforadaptationandflexibilityinthenetworksystems.Thisthesiswilladdresstheapproachesandinitiativestowardsprogrammablenetworkefforts,whichlaidafoundationtomanyoftheSDNconceptsthatemerged.Activenetworks,whichisanearlyefforttowardsbuildingnewnetworkarchitecturesbasedonnetworkprogrammabilityconcepts.Insuchnetworkarchitectures,switchesperformcustomcomputationsonpacketsasittravelsthroughthenetwork,ormodifythepacketcontentifnecessary.ActiveNetworksportraystwomethods:ProgrammableSwitchesapproachandcapsulesapproach.Theprogrammableswitchapproachdoesnotmakeanychangestotheexistingpacketformatbutusesadifferentmechanismbyassumingthatswitchingdevicesdownloadandexecuteactivenetworkingprogramswithspecificinstructionsonhowpacketsareprocessed.Thecapsuleapproachaddssmallprogramstothepresentpacketformat,thepacketsareencapsulatedintransmissionsframes,andcodeembeddedinthepacketsarepreparedandexecutedateachactivenetworknodealongthepacket's'path.Examplesofanactivenetworkareroutersonanetworkperformingtracingprogramonapacketasthepacketstravelthroughtherouters.MiddleBoxesarealsoexamplesofactivenetworks,boxesinthenetworkthatdeliversfirewalling,proxying,applicationservices.Thesearecustomcomputationontrafficthatisperformedinthenetworkorastheytravelthroughthenetwork.Theactivenetworkwhichproposesasimilarmotivationofacceleratinginnovationinexistingnetworksystemssothattechnologycouldbeintroducedmorerapidlywithoutconsensusstandardization.Itisobservedthatactivenodesallowrouterstodownloadnewservicesintothenetworkinfrastructurewhichmotivatesuser-driveninnovation.ActiveNetworksposesalegacyforSDNwiththeideaofprovidingprogrammablefunctionsinthenetworktoenableinnovation.Oneofthemotivationsforactivenetworkswastheproliferationofdifferentkindofmiddleboxesandavisionofunified

architecture,thesekindsofarchitecturecanalsobeseeninvariousSDNprojects(Tennenhouse,Smith,Wetherall,&Minden,1997).TheapproachtoNetworkprogrammabilityhasnotonlybelimitedtoActiveNetworking,buttheInternetEngineeringTaskForce(IETF)alsoinitiatedForwardingandControlElementSeparation(ForCES)(Yang,Dantu,Anderson,&Gopal,2004),intheearly2000swhichproposedanapproachtonetworkprogrammabilityinadifferentmannerfromActiveNetworking.ForCESdefineanarchitecturalframeworkandassociatedprotocolstostandardizeinformationexchangeandseparatescontrolplaneandforwardingplaneinaForCESNetworkElements.

Figure1.MultipleinstancesofForwardingPlaneElements(FE)andControlPlaneElements(CE)inFoRCESNetworkElement(NE).(Doria,etal.,2010).

Thestandardessentiallydefinesprotocolsthatwillallowmultiplecontrolelementstocontrolforwardingelementswhichwillessentiallyberesponsibleforforwardingpackets,metering,shaping,performingtrafficclassificationandsoforth.TheideawasthattheswitchesandforwardingelementcouldbecontrolledoverastandardcontrolchannelcalledtheForCESinterfaceandtheremightbemultiplesuchcontrollerscontrollingtheforwardingbehavioroftheseforwardingelements.ForCESfacedproblemssuchastherequirementofstandardization,adoptionbyvendorsanddeploymentofnewhardware(Doria,etal.,2010),(Yang,Dantu,Anderson,&Gopal,2004).

3.3NetworkVirtualization

WhatisNetworkVirtualization?

NetworkVirtualizationistherepresentationofoneormorelogicalnetworktopologiesonthesameunderlyingphysicalinfrastructure.TherehavebeendifferentinstantiationsofnetworkvirtualizationsuchasvirtualLANs(VLANs).Thisthesiswilllookintovarioustechnologiesanddifferentnetworktestbedsthatuseanddevelopnetworkvirtualizationthathasmostlyledtomaturevirtualnetworktechnologyseen

intheformofcompaniesandcommercialproductstoday.Oneofthebenefitsofnetworkvirtualizationissharing,onecaninstantiatemultiplelogicalroutersontopofasinglephysicalnodeorasingleplatform,andonecaninstantiatemultiplevirtualnetworksontopofthesamephysicalnetworkinfrastructure.Thissharingrequirestheabilitytoisolateresourcesintermsofmemory,CPU,bandwidth,forwardingtablesandsoforth.Also,Networkvirtualizationoffersaprospectofcustomizabilityinadditiontosharing,usersofavirtualnetworkcangetaviewoftheirlogicalnetworkandlogicalnetworktopologythatisseparatefromotherlogicalnetworktopologythatmayberunningonthesameunderlyingphysicalnetworkinfrastructure.Theabilitytoseeanindependentlogicalnetworkalsoallowscapacitytoruncustomroutingandforwardingsoftwareonthatparticularsliceofthevirtualnetwork(MosharafKabirChowdhury&Raouf,2010).ThisthesiswillexplorethreedifferentexamplesofVirtualnetworks;

TheTempestarchitecture

Switchlets,separationofthecontrolframeworksfromtheunderlyingswitchesitselfandthecapabilitytovirtualizetheunderlyingswitchhardwaretoprovidetheappearanceofmultiplevirtualswitches(VanDerMerwe,Rooney,Leslie,&Crosby,1998).

VirtualNetworkInfrastructure(VINI)

AVirtualNetworkInfrastructureprovidesavirtualnetworkinfrastructuresothatexperimenterscouldrunexperimentsontheirpersonallogicalnetworksystemsharedonthesameunderlyingphysicalnetworktopology(Bavier,Feamster,Huang,Peterson,&Rexford,2006).

ConcurrentArchitecturearebetterthanone(CABO)

Anetworkarchitecturewhichusesomeofthevisionoftheemergingvirtualnetworktechnologiestorealizethatvirtualnetworkcouldallowserviceproviderstooperateindependentlyoftheprovidersthatmaketheunderlyingphysicalnetworkinfrastructureavailable(Feamster,Gao,&Rexford,Howtoleasetheinternetinyoursparetime,2007).

TheTempest

Datedbackin1998,AninitiativethatintroducesnetworkvirtualizationbyproposingtheconceptsofswitchletsinATMnetworks.TempestaddstheabilitytocontrolagivenATMswitchwithmultiplecontrollersbypartitioningtheresourcesofthatswitchbetweenthosecontrollers,Switchletisthatpartition,whichisasmall,butacompleteswitchtothecontroller(VanDerMerwe,Rooney,Leslie,&Crosby,1998).

Figure2.OpenSignallinginthetempest(VanDerMerwe,Rooney,Leslie,&Crosby,1998).

SwitchletscameoutoftheTempestarchitecturewhereithasasingleunderlyingswitchwithitsresourcesandanopenswitchcontrolinterfacethatexposesthoseresourcestotheircontrollers.SwitchletsallowsmultiplecontrolarchitecturestooperateoverasingleATMnetwork.Theopencontrolinterfaceseparatedtheswitchcontrollerandthefabricviaanopensignallingprotocol,andthedividerpartitionedtheswitchresourcestoalloweachmultiplecontrollerstohavetheirpersonalviewofalogicalswitch(VanDerMerwe,Rooney,Leslie,&Crosby,1998).

Figure3.Theswitchdivider(Bavier,Feamster,Huang,Peterson,&Rexford,2006).

Theswitchdivider,partitionportspace,bandwidth,andbuffers,allowdifferentcontrollerstocontroleachswitchlet.Thetempestframeworkconcludedthat:byallowingmultiplearchitecturestocoexist,addressestheissuesofmigrationandupgrading,thatallnetworkoperatorsarefamiliarwith(VanDerMerwe,Rooney,Leslie,&Crosby,1998).VirtualNetworkInfrastructure(VINI):Virtualnetworkinfrastructurescanallownetworkexperimentersandresearcherstobridgethegapbetweensmall-scalesimulationsorexperimentsandreallivedeploymentswhichwerethemotivationbehindVINI.VINIrunsrealroutingsoftwareandexposesrealisticnetworkconditionstotheapplicationsrunningonit.Itgivescontroltotheexperimenteroverdifferentnetworkevents,suchasfailures,andalsocarriestrafficonbehalfofrealusers,itcanalsobesharedamongmanydifferentexperimenters.However,VINIalsousestheseparationofthecontrolanddataplanetoachievesomeofitsgoalsofnetworkvirtualization.

Figure4.ShowstheinternetinaslicearchitecturerunningonVINI(Bavier,Feamster,Huang,Peterson,&Rexford,2006).

TheVINIcontrolplaneissoftwareroutercalledXORP,whichrunsavarietyofdifferentroutingprotocolswiththegoalofallowingexperimenterstorunrealroutingprotocolsontopofvirtualnetworktopologies.VINI’sdataplaneprovidestheappearanceofthesevirtualnetworktopologiestoexperimenters,thedataplaneisimplementedusingasoftwareroutercalledClick,andthevirtualinterfaceswereimplementedusingTunnelling.Tunnellinghasalsobeenusedinmanyothervirtualnetworktechnologiestocreatetheappearanceofvirtuallinks.InVINI,experimenterscouldalsodeployfiltersinfrontofthesetunnelstocreatetheillusionorappearanceofafailinglink.Thesefiltersessentiallyblockpacketsonindividualtunnels(MosharafKabirChowdhury&Raouf,2010)(Bavier,Feamster,Huang,Peterson,&Rexford,2006).

ConcurrentArchitecturearebetterthanone(CABO)

CABOproposesanexploitinnetworkvirtualizationwhichallowsaserviceprovidertosimultaneouslyrunmultipleendtoendservicesoverinfrastructureprovider’sownequipmentbydecouplinginfrastructureprovider(thosepartiesthatmaintaindatacenters,linksrouters,andotherphysicalinfrastructure)fromservicesprovider(thatoffersendtoendservicesontopofthatinfrastructure)(Feamster,Gao,&Rexford,Howtoleasetheinternetinyoursparetime,2007).

4.COMPONENTSOFSDNARCHITECTURE

SeparatingDataPlaneandControlPlane

Theconceptofseparatingthecontrolplanefromthedataplaneisnotnewinnetworking,forinstance,thecontrolplaneorthebrainofamulti-slotrouterorswitch,builtwithinthelasttenyears,executesonadedicatedprocessororoftentwoprocessorsforredundancy.Whiletheswitchingfunctionsofthedataplaneperformindependentlyononeormorelinecards,whicheachofthesecardshasitsindividualdedicatedprocessor(Stalling,2016).Separationofthedataorforwardingplaneandcontrolplaneisthefundamentalcharacteristicofasoftwaredefinednetwork.Thecouplinginconventionalroutersandswitcheswhichembodiesatightintegrationbetweenthedataplaneandcontrolplaneportrayschallengesinvariousmanagementtaskssuchasmonitoringorpredictingroutingbehavioranddebuggingconfigurationproblems.SoftwaredefinedNetworkingaddressesthesechallengesaseffortstoseparatethedataplane,andthecontrolplaneemergesinthisparadigm.ThetrendinSeparatingthecontrolplaneanddataplanecatalyzedinnovationssuchas; Anopeninterfacebetweentheforwardingordataplaneandthecontrolplane.Forinstance,ForCES(ForwardingandControlElementSeparation)interface,anIETFstandardization(Doria,etal.,2010).Logicallycentralizedprogrammaticcontrolofthenetwork,Forexample,RoutingControlPlatform(RCP)architecture(Feamster,Balakrishnan,Rexford,Shaikh,&VanderMerwe,2004).Bydefinition,networkmanagementisanetworksystem-wideactivity,anditshowsthatsegregatingthecontrolfunctionalitiesoffofnetworkequipmentintodifferentserversmakesalotofsense.Theemergenceofopensourceroutingsoftware,whichreducedthebarriertodesigningprototypeimplementationsandbroughtaboutpossibilitiesforlogicallycentralizedroutingcontrollers(Stalling,2016).Theseparationofthecontrolplanefromthedataplaneoffersnetworkoperatorsadvantagesofcentralizedprogrammaticcontrolandeconomicbenefitssuchastheabilitytoconsolidatecomplicatedsoftwaretomanageandconfigurecommodityhardware.SoftwareDefinedNetworkingaimstowardstheprovisionofopeninterfacesenablingsoftwaredevelopmentthatcontrolsconnectivityprovidedbyanunderlyingsetofnetworkinfrastructureorresourcesandnetworktrafficthatflowthroughthem,aswellaspossiblemodificationandinspectionoftrafficperformedinthenetwork(Chiosi,Clarke,Willis,Reid,Feger,&Ruhl,2012).ThearchitectureoftheSDNisbasedonLayer2/Layer3(L2/L3)switchesarchitecture,whichhasthecentralizedcontrollersystemthatcontrolstheforwardingbehaviorforsetsofdistributedswitches.AccordingtothedefinitionofSDN,itsframeworkistreatedasabstractandcontrolledbyaprogrammablepartwithminimalinteractionwiththemainnetworkcomponents(Nadeau,2013).

Anetworkarchitecturewherenetworkcontrol(controlplane)islogicallycentralizedanddecoupledfromforwarding(dataplane),anditisdirectlyprogrammable.Withsoftwaredefinednetworking,theapplicationscanbenetworkaware,theSDNcontrollerprovidesaviewofthenetworkstateforapplicationsandalsotranslatesapplicationrequirementstolow-levelrules(Feamster,Rexford,&Zegura,TheRoadtoSDN:Anintellectualhistoryofprogrammablenetworks,2014).

Figure5.BasicSDNarchitecturecomponents(OpenNetworkingFoundation,2012).

Figure5assimilarlyintroducedintheONFwhitepaper,(OpenNetworkingFoundation,2012),depictsthebasicSDNarchitecturecomponents,whichcomprisesoftheinfrastructurelayerordataplane,controllayerorcontrollerplaneandapplicationlayerorapplicationplane.FortheinteractionofthethreelayersoftheSDN,anopenapplicationprograminterface(API)ispresentandallowscommunicationbetweenthem.Thedataplanecomprisesofnetworkelements,exposingtheircapabilitiestowardthecontrollerplanethroughinterfacessouthboundfromthecontroller,SouthBoundInterface,alsoreferredtoasthedata-controlplaneinterface.Theapplicationplane,wheretheSDNapplicationsexist,communicatestheirnetworkrequirementtothecontrolplanethroughnorthboundinterfaces(NBIs)(OpenNetworkingFoundation,2014).TheSDNarchitectureoffersasimplifiedandunifiedconfigurationforresourcesset,anditssuccesscanbesignificantlyrecognizedifdeployedwithinapreexisting,largeandmultilayerenvironment.WhileforthefunctionalityoftheSDNinasmallerenvironment,propersubsetscanbeprofiledfromitsarchitecture(Nadeau,2013).

4.1 TheSDNDataPlane

TheSDNdataplanewhichisalsoreferredintheONFpaper(OpenNetworkingFoundation,2014)astheinfrastructurelayercomprisesofsetsofnetworkelementsandorentities.Atthislayer,networkelementsperformthetransportandprocessingofdatapacketsbythedecisionmadebytheSDNcontrollerplane;thesedecisionsareforwardedtothedataplanebythecontrollerplaneviatheData-controllerplaneinterface(DCPI).Thedata-controllerplaneinterface(DCPI)isanapplicationinterfacewhichdefinesthewaythecontrolplaneinteractsortakeexclusivecontroloverasetofresourcesexposedbynetworkelementsinthedataorforwardingplanetomakethenecessaryadjustmenttomeetbusinessornetworkingneeds.Forinstance,informationexchangedthroughthisinteractionaresuchthatincludecontrollinginformationprovidedbytheSDNcontrollerplanetothedataplane(e.g.,policyprovisioningornetworkresourcesconfiguration)(OpenNetworkingFoundation,2012).Thedataplaneresourcesareabstractionsoftheunderlyingphysicalnetworkentitiesorcapabilities,thedataplaneofanSDNissimplyasystem,asetofnodeswithcharacteristicssuchasperformingtrafficforwardingandmayalsoconsume,produce,storeorprocesstraffic.Thesessetsofnodesarenetworkelements(NEs)andareinterconnectedbylinks.TheNetworkElements(NEs)provideexternaldataplaneportstoclientequipmentandothernetworks.AspartoftheSDNbenefitsarebasedoncentralizedcontrol,anSDNcontrollerwillcontrolmorethanoneNE(OpenNetworkingFoundation,2012).Accordingto(Shin,Nam,&Kim,2012),Thedataplaneincludevariousabstractionmodelssuchas

- Packetforwardingabstractionmodels(IPv4,IPv6,Ethernet,etc.).- CircuitSwitchingabstractionModels(Optical,MPLS,etc.)- WirelessIntegration,characterizationofwirelessinterfaces,flows,handover

support- Evolvedpacketcore,LTEsupport.

4.2 TheSDNControllerPlane

Inatraditionalnetwork,i.e.,anonsoftwaredefinednetworkinwhichthedataplaneandthecontrolplanearenotdecoupled.Thecontrollerplaneisaroutercomponentthatdetermineshowthatparticularindividualboxinteractswithitsneighborswithastateexchange.TheNetworkOSintherouterprocessestheRoutingInformationBase(RIB)andLabelInformationBase(LIB),whichisusedtopopulatetheForwardingInformationBase(FIB)andLabelForwardingInformationBase(LFIB).Routerproprietorsimplementvariouswaysofpartitioningthosetablesbetweenmultipleroutinginstances.

Thefunctionofthecontrolplaneinaconventionalnetworkingdeviceinclude;management,thesystemconfiguration,andexchangeofroutingtableinformationandareinfrequentlyperformed.Theroutecontrollerexchangesthetopologyinformationwithotherroutersandconstructsaroutingtablebasedonaroutingprotocol,forexample,RoutingInformationProtocol(RIP),OpenShortestPathFirst(OSPF),orBorderGatewayProtocol(BGP).Itcanalsocreateaforwardingtablefortheforwardingplane.Sincethecontrolfunctionsarenotperformedoneacharrivingpacket,theydonothaveastrictspeedconstraintandareimplementedinsoftware(Chao&Liu,2007).Ontheotherhand,SoftwareDefinedNetworking(SDN)isasetofvarioustechniqueandapproachthatallowsuserstoprogram,orchestratedirectly,controlandmanagenetworkresources,whichfacilitatesthedesign,delivery,andoperationofnetworkservicesinadynamicandscalableway.TheSDNcontrollerplaneisadedicatednetworkentity.Itcomprisesofcontrollersthatarelogicallycentralized,eachofwhichhascontrolovertheresourcesexposedbythedataplaneTheSDNcontrollerplane,alsoreferredtoasSDNcontrollayer,providesmeanstodynamicallycontrolthebehaviorofnetworkresources(dataplane),asrequiredbytheapplicationplaneorlayer.TheSDNapplicationsdefinenetworksystemresourcescontrolandallocationbyinteractingwiththeSDNcontrollayerviaApplication-ControlPlaneInterface(ACPI),thisinterfaceisalsoreferredtoastheNorthBoundInterface(NBI).ThenorthboundinterfaceallowsSDNapplicationstoprogramapplication-specificnetworkbehaviorandaccessnetworkinformation.Thishelpsforapplicationstobeabletooperateonanabstractionofthenetworkandleveragenetworkservicesandpotentialitieswithoutbeingtiedtothedetailsoftheirimplementations.Theorchestrationfunctionalityofthecontrolplaneprovidesautomatedcontrolandmanagementofthenetworkresourcesonthedataplane,requestscoordinationfromapplicationlayerfornetworkresourcesordataplanebasedonpolicyprovisionbytheapplicationlayerormulti-layermanagementfunction.Forinstance,interactingwiththemulti-layermanagementservicestoprovidemanagementofSDNapplication-relatedoperationssuchasservicecreationandprovisioning,usermanagement(OpenNetworkingFoundation,2012).

4.3 TheSDNApplicationLayer.

TheSDNapplicationsareprogramsintheapplicationlayerorplane,whichspecifiesbusinessapplicationsornetworkservicesanddefinesaservice-awarebehaviorofnetworkresourcesinaprogrammaticmanner.TheseprogramscommunicatetheirnetworkrequirementsandresponsebyinteractingwiththeSDNcontrollerplaneviatheNorthboundInterface(NBI)sothatcontrollerplanecanautomaticallycustomizethebehaviorofthenetworkresources.Theseprogramsattheapplicationplane(SDNapplications)makesuseoftheglobalabstractnetworkviewofthenetworkresources,fortheirinternaldecision-makingpurposes,providedbytheSDNcontrollerplaneby

usinginformationanddatamodelsexposedviatheNorthboundInterface(TelecommunicationStandardizationSectorofITU,2014).SDNapplicationsvaryaccordingtodifferentkindsofservicestoachieveitsobjectives;itmayinvokeotherexternalservices,andorchestrateanynumberofSDNcontrollers.Thisapplicationrequiresacertainamountofknowledgeoftheirenvironmentandroles.TheONFwhitepaper(OpenNetworkingFoundation,2012)statesthat:Anapplicationplaneentitymayactasaninformationmodelserverbyexposinganinformationmodelinstancesforusebyotherapplications.Formally,theotherapplicationsareclientsthatcommunicatetotheSDNapplicationserveragent.Anapplicationplaneentitymayalsoactasaninformationmodelclientbyoperatingonaninformationmodelinstanceexposedbyaserverentity.ThisserverentitymaybeeitheranSDNcontrollerorasecondaryapplication.Anapplicationplaneentitymayactinbothrolessimultaneously.Forexample,apathcomputationengine(PCE)mayrelyonanSDNcontrollerforvirtualnetworktopologyinformation(maintainedinatrafficengineeringdatabase),whileofferingtheSDNcontrollerapathcomputationservice(OpenNetworkingFoundation,2012).

5.PRACTICALIMPLEMENTATIONOFSOFTWAREDEFINEDNETWORKING.

SincetheevolutionofSDN,anetworkarchitecturethatdecouplesthedataplanefromthecontrolplane,andturningthecontrolplaneintoasoftware-basedcentralizedcontroller.ManyvendorsseevaluesinSDNnetworkarchitectureasenablingnetworkprogrammability.Networkprogrammability,ontheotherhand,iscapableofharvestinginformationfromnetworkdevices,evolvingfromthetechnologypushandusepullwhichencouragedActiveNetworkingasitgrowsintonetworkprogrammability,andmotivatedpushingoutnewconfigurations,policies,profiledefinitionsinresponsetodynamicnetworkconditionsorserviceprovisioningrequests(Shin,Nam,&Kim,2012).Overtheevolvingyears,SDNhasgainedpracticalimplementationinvariousaspectsofnetworkingtechnologies.ThisthesiswilllookintohowSDNmakesiteasytoimplementandmanageNetworkFunctionVirtualization,ApplicationsofNetworkFunctionVirtualization,NetworkFunctionVirtualizationusingMininet,emulatorforquickprototypingofSoftwareDefinedNetwork.

5.1 NetworkFunctionsVirtualization

Networkvirtualizationenvironmentsupportsthecoexistenceofmultiplevirtualnetworksonthesameunderlyingphysicalsubstrate,whereeachofthesevirtualnetworksisacollectionofvirtuallinksandvirtualnodes.However,thesevirtualnetworkscanalsoberegardedasasubsetoftheunderlyingphysicalnetworkinfrastructure(Stalling,2016).NetworkFunctionVirtualizationInfrastructureisacollectionofresourcesandfunctionswhichencompassthreemaindomain;thecomputedomain,hypervisordomain,Infrastructurenetworkdomain.Intotality,NFVIconsistsofallsoftwareandhardwarecomponentswhichbuildupanenvironmentwherevirtualnetworkfunctionsaredeployed(Chiosi,Clarke,Willis,Reid,Feger,&Ruhl,2012).

Figure6.NFVDomainsencompassedinthenetworkfunctionvirtualizationinfrastructure(Chiosi,Clarke,Willis,Reid,Feger,&Ruhl,2012).

Thecomputedomainwithinthenetworkfunctionsvirtualizationinfrastructure(NFVI)includestheserversandstoragehardwarewhichenableprovisionforcommercialoff-the-shelf(COTS)high-volumestorageandservers.TheHypervisordomainwithinNFVIprovidesabstractionlayerofthehardwarebymediatingthecomputedomainresourcestothevirtualmachinesofthesoftwareappliances. TheInfrastructurenetworkdomain,thisdomainwithintheNFVIcomprisesofallgenericandhighvolumeswitcheswhichareinterconnectedtogetherbyanetwork,enablingconfigurationforinfrastructurenetworkservicessupply.NFVimplementationaimstotransformhownetworkoperatorsandarchitectsdesignnetworksystemsbyevolvingvirtualizationtechnologiestointegratevariousnetworkequipmenttypesontoindustrystandardhighvolumeEthernetswitches,serversandstorage,locatedintheenduserpremises,datacenters,andNetworkNodes.NFVinvolvessoftwareimplementationofnetworkfunctions,whichcanrunonvariousindustrystandardhardware,andmovedtoorinstantiatedindifferentnetworklocationsasrequired,withoutanyneedofnewequipmentinstallation(Chiosi,Clarke,Willis,Reid,Feger,&Ruhl,2012).

Figure7.Visionfornetworkfunctionvirtualization(Nadeau,2013).

ApplicationOfNetworkFunctionVirtualization

AvirtualizedimplementationoftraditionalnetworkfunctioncanalsoberegardedasaVirtualNetworkFunction(VNF).VariousnetworkelementscanbevirtualizedasshowninFigure7.

Figure8.NetworkFunctionsthatcouldbevirtualized(Nadeau,2013).

Furthermore,NFVcouldbeapplicableinasetofservicemodelsandhigh-levelusecaseswhichareintendedtodrivethedevelopmentofproductsandstandardsfornetwork-wideimplementation.AsaddressedbyISGNFV,ApplyingNFVcanbecategorizedintoarchitecturalusecasesandService-Orientedusecases.ArchitecturalapplicationofNetworkFunctionVirtualizationfocusesontheprovisionofgeneralpurposeservicesandapplicationswhicharebasedontheNetworkFunctionVirtualizationInfrastructure(NFVI)architecture.NetworkFunctionVirtualizationInfrastructureasaService(NFVIaaS):NFVIisprovidedasaserviceinascenariowhichmapsNetworkasaService(NaaS)andcloudcomputingservicemodel,InfrastructureasaService(IaaS)aselementswithNFVI.AserviceproviderdeploysandimplementsanNFVIthatmaybeusedtosupportVirtualNetworkFunctions(VNFs)bybothNFVIaaSproviderandothernetworkserviceproviders.TheInfrastructureisdesignedtosupportthevendor'srequirementsfordeployingVNFsandmorecapacitythatcanbesoldouttootherproviders(Nadeau,2013).

5.2 Asimplesoftwaredefinednetworkarchitecture.

ThisthesisworkwillshowapracticalimplementationofnecessarysoftwaredefinednetworkarchitecturebysettingupadevelopmentenvironmentonasinglemachineusingvariousSDNtoolsalongwithgeneralnetworkingutilitiesonavirtualizedenvironment.ImplementationwilldeploySDNarchitecture,showinghowthesouthboundAPIandNorthboundAPIinteract.ThedesignfeaturesSDN/OpenFlowarchitecturewherethenetworkwillbedesignedontopofthestandardinterface,OpenFlow,toensureconfigurationandcommunicationcompatibilityandinteroperabilityamongthedataandcontrolplanevirtualdevices.Inthisimplementation,thetwomostimportantelementsarethecontrollerandforwardingdevices.Utilizingavirtualnetworksimulator,mininet,tocreatesoftwaredefinednetworkarchitectureforthreehosts,aswitch,andacontroller.SDNarchitecturewithOpenFlowcontrollerusingmininet.SoftwaredefinedNetworking,anemergingparadigmandevolutionaryapproachtonetworkdesignandfunctionalitybasedonthecapabilitytoprogrammaticallymodifythebehaviorofnetworkdevicesaccordingtobusinessandortrafficneeds.SDNarchitecturemakesiteasiertoprogramconfigurableandcustomizablesoftwareatthecontrollerlayer,whichisindependentoftheunderlyinghardwareontheforwardingplanetoexpanddataflowcontrol.Thisapproachtonetworkingwillmakenetworksmorecost-effective,dynamicandflexible,inthelongrun,simplifyingoperationalcomplexity.Inrecentnetworkingtrends,changeinnetworktrafficpattern,bigdata,informationtechnologyconsumerization,theriseofcloudcomputingandservices,morebandwidthconsumption,allbringsabouttheneedforaflexiblearchitecturalapproachtonetworks(ASoftwareDefinedNetworkArchitecture).ThecontrolplaneinSDNallowstheunderlyingnetworkinfrastructuretobeabstractedandenablingnetworkapplicationstoviewthenetworkasasingle,logicalswitchentity.Theapplication-programminginterface(API)inSDNspecifieshowsoftwarecomponentsshouldinteractwitheachother,makingitpossibletoimplementbasicnetworkfunctionssuchas;routing,securitypathcomputation,andothertasks.ThesouthboundAPIallowsthecontrollertodefinethebehavioroftheswitchesatthebottomofthearchitecture;agoodexampleistheOpenFlowAPIasusedinthisthesisimplementation.Ontheotherhand,NorthboundAPIprovidesanetworkabstractioninterfacetotheapplicationsandmanagementsystemsatthetopofthearchitecture.Thecoreofasoftware-definednetworkisthecontrollersoftwareatthecontrolplane,whichfacilitatesautomatednetworkmanagement,makingapplicationprogramsintegrationandadministrationeasier.ThecontrollersoftwareusesprotocolssuchasOpenFlowtoconfigurenetworkdevicesandmanagesflowcontroltoenableintelligentnetworking.OpenFlow,anapproachasusedinthisthesisimplementation,isaprotocolthatisusedtodefinethecommunicationinterfacebetweenthecontrolandforwardinglayers.OpenFlowallowsformanipulationandprovidesdirectaccesstotheforwardingplaneofthenetworkdevices.Itidentifiesnetworktrafficusingtheconceptofflows.

Thisapproachhelpstocentralizecontrol,increasenetworksecurityandreliability,reducescomplexityviaautomation.WithSDN,staticnetworkscouldbetransformedintoscalable,flexible,programmableplatformsthathavetheintelligencetoallocateresourcesdynamically.MininetisaninstantvirtualnetworkonaPC.Mininetcreatesarealisticvirtualnetwork,runningrealkernel,andswitchandapplicationcode,onasinglemachine.Mininetisanexcellentwaytodevelop,shareandexperimentwithOpenFlowandSoftware-DefinedNetworkingsystems(MininetTeam).OpenFlowisthefirststandardcommunicationinterfacedefinedbetweenthecontrolplaneandthedataplaneofSDNarchitecture.OpenFlowallowsdirectaccessto,andmanipulationoftheforwardingplaneofnetworkdevicessuchasswitchesandrouters,bothphysicalandvirtual(hypervisor-based)(OpenNetworkingFoundation).WewilldemostrateasimplifiedinitialdevelopmentanddeploymentprocesswithmininetsimulationtoolwhichallowsOpenFlownetworktobeemulatedonasinglemachine.Toaccomplishthisdemonstration,wewilluseavirtualenvironmentforSDNdevelopmentbuiltbysdnhub.org,thevirtualmachineisa64-bitubuntu14.04image(3GB)thathasanumberofSDNsoftwareandtoolsinstalled.IwilldemonstrateasimpleSDN/OpenFlownetworkwiththreehosts,anOpenVswitchandanOpenFlowreferencecontroller.Fromubuntuterminal,Mininetwillemulateanetworktopologyconsistingofthreehosts,aswitch,andanopenflowcontrollerandautomaticallyassignClassAprivateIPadresses.

Figure9.SDNnetworktopologyconsistingofthreehostswithclassAIPaddressing,anOpenFlowSwitch,andOpenFlowrefrencecontroller.

VirtualEthernetpairs

ControllerC0

Port6633

Loopback(127.0.0.1)

OpenFlowSwitchS1

Ovs-ofctl(administeropenflowdatapaths)

127.0.0.1:6634

h110.0.0.2

h1-eth0

h210.0.0.3

h2-eth0

h310.0.0.4

h3-eth0

s1-eth0S1-eth1

s1-eth2

TorunmininetanddefinenetworktopologyCommand:sudomn–toposingle,3

–mac–switchovsk–controllerremoteTheabovecommandtellsMininettocreatethreevirtualhosts,andassigneachwithaseparateipaddress,createasingleopenFlowsoftwareswitchinthekernelwiththreeports,connecteachvirtualhosttotheswitchwithavirtualEthernetcableandconfiguretheOpenFlowswitchtoconnecttoaremotecontroller

Figure10.Startingmininet.

Mininetsimplycreateanetworktopology,addacontrollerC0,addswitchS1,addhostsh1,h2andh3,addslinksbetweenh1ands1,h2ands2,h3ands1.Furthermoremininetconfiguresthethreehosts,startsthecontrollerandtheswitch.

Figure11.IPaddressassignedtoallhosts,andswitchlinksareup.

Pingtestingamongallhost,tocheckifvirtualethernetpairsarerecheable.Command:h1ping–c3h2

Figure12.H1cannotreachH2andviceversa.

Figure13.Pingfailureamongallhost.

Therewerenopingrepliesamongthehosts,theswitchflowtableisempty,flowscaneitherbemanuallyinstalledtoforwardnecessarypacketsorgetinstructionsfromthecontroller.However,thecontrollerisnotyetconnectedtotheopenVswitch;thereforetheswitchdoesnotknowwhattodowiththeincomingtraffic,andthisleadstopingfailure.Note:Atthispointtheswitchflowtableisempty.Toenablevisibilityandcontrolovertheswitchflowtable,whichwillbeusefulfordebuggingflowcounterandflowstate,weusetheovs-ofctlutilitythatcomeswiththeopenvswitch.Mostopenvswitchstartupwithapassivelisteningport.Usingovs-ofctl,wewillmanuallyinstallthenecessaryflowsontheopenswitchflowtabletoforwardpacketscomingfromport1toport2andvice-versa.Usingthefollowingcommand:Command:#ovs-ofctladd-flows1in_port=1,actions=output:2#ovs-ofctladd-flows1in_port=2,actions=output:1

Figure14.ManualInstallationofflowsonopenswitchflowtable.

ovs-ofctlistalkingtoalocalinstanceofopenvswitchviaunixdomainsocketwhichitislookingupbyname(s1).Nowthatwehaveconfiguredthenecessaryflowonport1andport2oftheopenvswitch,thisallowspacketscominginfromport1tobeforwardedoutonport2andviceversa.Therefore,hosth1andh2connectedtoport1andport2oftheswitchcanonlybereachable,whilehosth3cannotreachanyotherhostonthenetwork.

Figure15.SuccesfulpingsbetweenhostH1andH2,whileH3isunrecheablebecausetheswitchflowtableincludesentriesforonlyH1andH2.

WewillsetupthecontrollertogetallhoststobereacheableWewilluseWiresharktocaptureandwatchOpenFlowprotocolmessages.Havingsetupwiresharktolistentotraffic,Wewillstarttheopenflowreferencecontroller,whichstartsasimplecontrollerthatactsasalearningswitchwithoutinstallinganyflow-entries.Command:#ovs-controllerptcp:

Figure16.StartingOVSreferencecontroller.

Afterthecontrollerisstarted,itactsasalearningswitchandallowsconnectivityamongallhosts,h3willnowbereacheablefromotherhostonthenetworkandviceversa.NowTestforreachabilityamongallhosts.

Figure17.Allhostarenowrecheablefromanywhereonthenetwork.

6.CONCLUSION

TraditionalNetworksystemsbecameverycomplicatedtomanagefornetworkoperators,thenetworksystemsstatechangescontinually,anditremainsdifficulttoconfigurenetworkdevicesacrossabroadnetworksystem.Complexityintoday'snetworkandlackofflexibilitycausesoperatorstomasteravarietyofnetworkprotocols.However,inatraditionaldistributednetwork,operatorscancombinenetworkdevicesfromdifferentvendorsintoasinglelargenetworksystem.ThisworkshowsthatSDNdoesnotonlyaddressestheseproblemsbutalsosimplifiesit,byseparatingthecontrolplanesandthedataplanesofthenetworkandcentralizingthecontrolandmanagementoftheoverallnetworksystemwithauniformAPI.TheSDNarchitecturemakesiteasiertohaveanoverviewofthenetworksuchthat;networkoperatorsandadministratorscantailortheirnetworksystemstomeettheirrequirementsandneeds,asthenetworkchangesstate.Also,itshowsthatthecentralizedcontrolsystemscanhavesufficientcontrolandvisibilityoverthedataplaneresourcestoautomateanddeployavarietyofnetworkservicessuchasmiddleboxes,networktrafficprofiling,loadbalancing,switching,accesscontrol,routing,etc.Asaresult,SDNhasgainedsubstantialinterestandconcerninbothacademicandcommercialinstitutions.ThisworkalsoshowsfundamentalaspectsofSDNarchitecture,suchastheOpenFlowProtocolandOpenFlowAPI,thatemergedandwidelyadopted.ItindicatesthatSDNvendorsandprogrammerscandesignprogramsthattranslatenetworkrequirementsintoOpenFlowtablesandcanmaintaintheflowtablesasnetworksystemchangesoccur.Moreover,thequalityofthecontrollerplaneprogramsisacriticalfactorintheoverallperformanceofthenetworksystem.ThefutureofSoftwareDefinedNetworkisfeasibleandapplicableinavariousnetworkenvironment,andthisparadigmshiftbringsnumerousbenefitscomparedtotraditionalnetworking.ThisthesishasdemonstratedthatSDNispractical,efficientandimplementedinvariousnetworkingdomain.ItappliestousethesimplestSDNprogrammingmodel,wherenetworktopologycanbesimulatedtoimplementvariousSDNtechniques.However,Itencouragesnetworkingstudenttoadoptprogrammingskillsapplicableinsoftwaredefinednetworkingdomain;networkprogrammerscandevelopawidevarietyofSDNapplicationswithafamiliar,general-purposeprogramminglanguage.SDNgivestheflexibilityofintroducingnewideas,withoutlimitationsorrestrictiontoproprietarynetworkdevices,throughasoftwareprogram.Thispracticemakesiteasiertomanipulateandmakechanges,ascomparedtousingasetofcommands,onproprietaryequipment.SDNbenefitstonetworkoperatorsbytacklingthecomplexityofmanaginglargenetworks.Withthecentralizedapproachtonetworkmanagementandconfiguration,operatorsdonothavetoconfigurenetworkdevicesindividuallywhenmakingchangesinnetworkbehavior,butinsteadmaketrafficforwardingdecisionsatalogicallycentralizedlocation,thecontrollerlayer,withaglobalviewoftheoverallnetworkstate.

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