面向SLA的NGN业务管理质量模糊评价

(TheQualityofServiceManagement)inNGNYanDanfengScienceStateKeyLaboratoryofNetworkingandSwitchingTechnology,BeijingUniversityofPostsandTelecommunications,Beijing,China(100876)E-mail：[e-mail]rvicemanagement-QoSMisanimportantevaluationfactorforservicemanagementinNGN.ToevaluateQoSMefficiently,itisnecessaryandelementarytodefineanevaluationmetricsandfindanevaluationmethod.First,theevaluationmetricsforQoSMbasedonSLA’sservicemanagementcontentsisproposed.Fuzzyevaluatingisamethodbasedonfuzzymathematics.Itissuitabletoevaluateanobjectwithmanyfactorswhichhavedifferentinfectionstotheobjectandinteractionstoeachother.AfuzzyevaluatingmethodtoevaluateQoSMbasedonaboveevaluationmetricsisdesigned.Atlast,anexampleofevaluatingisdescribedtoilluminatethatthefuzzyevaluatingmethodfortheQoSMofNGNisusefulandcorrect.Keywords:NGN,QualityofServicemanagement,ServiceLevelAgreement,FuzzyEvaluating1.IntroductionThequickdevelopmentofNextGenerationNetwork-NGNchallengesthequalityofservice.Servicemanagementworksasanimportantroletoguaranteethequalityofservices.Atpresent,theresearchworkaboutservicemanagementhasbecomeoneofimportantresearchpointinNGNfield.Butoneproblemcomesout-howtocomparethoseservicemanagementsystemsimplementedbymultipletechnologiesandmethods,whichhavehigherorlowerquality.Theelementaryworkistodefineanevaluationmetricsandanevaluatingmethodofthequalityofservicemanagement-QoSM.Untilnow,theevaluationofQoSMisarealnewandcomplexproblemurgenttofindaresolution.TheresearchaboutgeneralsoftwarequalitymodelhasbeendonebysomeinternationalorganizationssuchasISO/IEC9126[2][3],butsomecharacteristicsarenotappropriatetoevaluateQoSMdirectly.Thespecialfeaturesofservicemanagementcan’tbeignoredbecausecustomers’satisfactionstoservicesareaffectedbymostofthesespecialfeatures.ServiceLevelAgreement-SLAisanewmethodtoresolveservicemanagementbetweentheserviceprovidersandthecustomers.Itusescontractstoregulatetheservicesprovisionandsubscriptiondetails.SLAfocusesontherelativeactionsbetweenthecustomersandtheserviceproviders,soitisrealizabletoimproveservicequalitytoincreasecustomers’satisfactionsbySLA’sspecifications.ThispaperproposesanevaluationmetricsofSLA-orientedQoSMandanevaluatingmethodbasedonfuzzyevaluationcomingfromfuzzymathematics.Theremainderofthispaperisorganizedasfollows.Section2presentstheevaluationmetricsofQoSMbasedonSLAwithanewconceptiondefinitionofQoSMandtheanalysisofSLAefficientcontents.ThenSection3describestheproposedfuzzyevaluatingmethodandanexampletoillustratethatthemethodisvaluable.Finally,section4isourconclusions.2.EvaluationMetricsofSLA-orientedQoSM2.1ConceptionofQoSMQoSMisanewconceptionthathasnodirectreference.Basedontheconceptionsofservicemanagement,:Overallcharacteristicsofservicemanagementthatworktogethercoordinatelytosatisfytheuser’sexplicitandimpliedrequirements.Inotherwords,QoSMisanexactdescriptionabouthowmuchservicemanagementcapabilityis.QoSMofNGNexpressestheservicemanagementcapabilitycompletedbytheNGNservicemanagementsystems.Forexample,inNGN,afteracustomerhaveappliedaservicefromaserviceprovider,theproblemsofwhethertheservicesisprovidedontime,whetherservicebillingisreasonable,whethertheserviceisprovidedefficientlyandcorrectlyareallaboutQoSM.Thecharacteristicsaffectcustomers’satisfactionsandserviceproviders’evaluationtothequalityofservices.[6][8]2.2TheAnalysisofSLAServiceManagementQoSMisacomplexproblembecauseofitsmulti-fieldfeatures.Anall-embracingevaluationmetricswillbeexceedingcomplexandisdifficulttogettheidealevaluationresult.SoitisappliedtochoosesomeappropriateandnecessarycharacteristicstoevaluateNGNservicemanagementquality.SLA-basedservicemanagementcontentistheprocessofnegotiation,customizationandsubscriptionbetweentheserviceprovidersandthecustomers[1].ReferringtoTMF-SLA[1]standards,thereisthreelayersofSLAmetrics:1）“Customerlayer”includesthecharacteristicsthatmeasuretheserviceusabilitysuchasserviceusabilityrate,serviceprovisiontime,servicerecoverytimeandserviceinvalidationfrequency.2）“Servicelayer”includesthecharacteristicsthatrelatetoserviceexecutionandrunningsuchasservicesupportcapability,serviceexecutioncapability,servingabilityandsecuritycapability.3）“Networklayer”includesthecharacteristicsthatrelatetonetworktechnologysuchastransmissiondelay,bandwidthanddithering.IntheNGN,theseparationofservicefromcontrol,ofcallcontrolfrombearer,providesthelayeringanalysischanceofservicemanagement.Infact,whatthenetworkdetailsaffectsservicelayermanagementislessthanwehaveimaged.Forexample,whenaserviceerroroccurs,thereasonmaybeanyoneofthefollowing:faultofnetworkconnection,thefaultofnetworkequipmentorsoftwaresystemerror.Forservicelayer,thenetworkusabilityisenoughtoguidethefollowingservicemanagementactions.Thesimplificationofnetworkdetaildoesn’taffectservicelayermanagement.So,inthispaper,wefocusontheSLAcontentsincustomerlayerandservicelayerprimarily.[6]2.3Evaluati