ETSINEW INTERNET FORUM
12 October 2018
TowardsIntent-basedNetworking:AHigh-levelNorthboundInterfaceforSDN
Marinos Charalambides (UniversityCollegeLondon)
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BACKGROUNDANDMOTIVATION
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NetworkResourceConfiguration(1/2)
3
• Resourceconfigurationobjectives• Meetrequirementsofofferedservices,e.g.delayguarantees• Meet(internal)operatorrequirements,e.g.security,energyconsumption• Effectiveandefficientuseofinfrastructureresources
• Configurationcomplexity• Widerangeofserviceswithvaryingrequirements• Richsetofresourcesinnumbersandtypes(connectivity,storage,processing)• Largesetofconfigurationparameters• Fluidityofvirtualisedinfrastructures
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NetworkResourceConfiguration(2/2)
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• BusinessobjectivesHigh-levelrequirementsNetworkconfiguration• Manualprocessesmostly• Networkmanagementsolutions• NetConf,SNMP,proprietaryCLIs,OpenFlow• Low-levelconfigurationscriptsneeded
• Limitations• Timeconsuming – lackofautomation• Errorprone – configurationinconsistencies
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Intent-Based Networking
5
• “Don’ttellmewhattodo;tellmewhatyouwant”• Connectivityserviceexample:forwardtrafficfromnodeAtonodeBwithdelay<20ms• Translationofrequirementstoconfigurationcommands
• ManagementofSoftware-definedinfrastructures• Welldefinedsouth-boundinterface,e.g.OpenFlow• Notmuchprogressonnorth-boundinterface(NBI)
• State-of-the-art• ONFandvendors:basicpropertiesandstructureofNBI• Rootsinpolicy-basedmanagement
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High-level requirements
Management / Control Functionality
Network Elements
NB interface
SB interface
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Benefits andChallenges
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• AutomatingrequirementsdecompositionthroughaNBIcan:• Simplifyconfigurationprocessandavoidconfigurationinconsistencies• Allowfrequentchangestohigh-levelrequirements• Facilitatefasterservicedeployment
• Mainchallenge:rightabstractionstoassociaterequirementstomanagementfunctions,resources andcommodities
• Connectivityserviceexample• Resources:end-pointswitches• Commodity:traffic• Managementfunctions:pathcomputation,pathselection
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AN4
10ms 20ms
10ms
10ms 10msB
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DECOMPOSINGHIGH-LEVELREQUIREMENTS
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FutureNetworkRequirements
8
• Commonabstractionsto:• Exposeproperties/attributesofmanagementfunctionsandservices• Representresourcesandcommodities• Specifyandparsehigh-levelrequirements
• Definition/implementationofnorth-boundinterface• Maphigh-levelrequirementstonetworkmanagementfunctions• Currentlyinimmaturestate
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SystemArchitecture
9
Mapstoavailableservicesandappropriatemanagementfunctions(commonabstr.model)
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Enforcesconfigurations
Computesnewresourceconfigurations
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High-levelRequirementsStructure
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• Expressedinageneralformat• Predicate:actionstoexecute,e.g.forward,store,process• Commodity:commodityregulatedbyactions,e.g.traffic,videocontent• Target:networkresourcesinvolved,e.g.switch,server• Constraint:constraintsonactions,e.g.delay• Condition:conditionsonactionapplicability,e.g.valueofcommodity
• ConnectivityserviceexamplePredicate ForwardCommodity TrafficTarget ResourceA->ResourceBConstraint Delaylowerthan20msCondition Trafficfromclient1
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ServiceMapping(1/2)
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• High-levelrequirements<-->attributesofavailableservices• Serviceattributescapturedintemplates(servicedescriptors):• Operation(OP):basicfunctionalityrequiredtoprovidetheservice• InfrastructureRequirements(IR):whatisneededintheinfrastructureforthe
servicetooperate
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Servicename Connectivity
OP Forward
IR CORS
TrafficSwitch;Link
TS CORSCST
AlltrafficResourceA->ResourceBDelay<20ms
PAF delay_connectivity
• TechnicalSpecifications(TS):specificationsonwhichtheservicemustbeoperated
• PerformanceAffectingFactors(PAF):dominatingfactorsaffectingtheperformance
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ServiceMapping(2/2)
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• Resolver:determinesdescriptormatchingtherequirementpredicate==operation
• Instantiator:updatesTechnicalSpecificationsfields(CO,RS,CST)
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ManagementFunctionMapping(1/2)
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• Managementfunctiondescriptors:• Commodities(CO):typeofcommoditiesregulatedbythefunction• Resources(RS):typeofresourcesconfiguredbythefunction• Function(FCT):operationsperformedbythefunctiononresourcesandcommodities
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Functionname PathSelection
CO Traffic
RS Switch;Link
FCT Allocate(end_points,delay_constraint)
OPE delay_connectivity
• OperationEffects(OPE):performancefactorsaffectedbythefunctiondecisions
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ManagementFunctionMapping(2/2)
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• Resolver:determinesfunctiondescriptormatchingtheselectedservicefunctionCO==serviceCO& functionRS==serviceRS& OPE==PAF
• Selector:selectsbestsetoffunctionsaccordingtoknowledgebase
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USECASESANDEVALUATIONRESULTS
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Implementation
16
• Mininetfortopology,hostsandswitches• RESTAPItointerfacenetworkmanagementsystemtomininet• SmallsetofPOXcontrollerAPIsforthesouth-boundinterface• JSONforhigh-levelrequirementsanddescriptors• Iperftoemulatefixed-rateUDPclienttraffic
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UseCase1:ConnectivityServicewithDelayConstraints
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UseCase2:TrafficRedirectionthroughSecurityVNF
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Conclusions
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• North-boundinterfaceforSDNofparamountimportance• Needforrightabstractionlevelandinterfaceimplementation• Solutiondevelopedislightweightandfast• Time-complexityconstantwiththenumberofservicesandfunctions• Futurework• Experimentwithrealistictopologies• Competingrequirements• Feedbackfromnetworkmanagementsystemtomappingmechanism
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Acknowledgement
DaphneTuncer,Gioacchino Tangari,GeorgePavlou
Thankyou
Questions?
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