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Internet QoS : Pieces of the puzzle. 2010. Március 22. Topics:. Introduction Definitions and Terminology Internet Service Regulation QoS Architectural Issues Conclusions: Joining the Pieces Together. Sources:. - PowerPoint PPT Presentation

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  • 2010. Mrcius 22.Internet QoS: Pieces of the puzzle

  • Introduction

    Definitions and Terminology

    Internet Service Regulation

    QoS Architectural Issues

    Conclusions: Joining the Pieces TogetherTopics:*

  • Internet QoS: Pieces of the Puzzle: IEEE Comm. Magazine, 2010. 01. p. 86-94QoS: is QoS? Components:*

  • Introduction

  • Quality of Serviceresource reservation control mechanismsability to provide different priority to different applicationsguarantees a certain level of performance to a data flow, eg: real-time streamingimportant if the network capacity is insufficient

    What is QoS?*

  • The Internet isunregulatedconnectionlessdesigned without QoS!

    Routers and switches cannot provide QoS cheap, fastBest effort: default QoS level


  • IP QoS is not Internet QoSneeded:more architectures scalability

    IP was designed without QoSBig growth rateDriven by market demandsMany autonomous systemsneeded:simplepragmaticWhy QoS is not widely used? (1):*

  • No consensus on the exact meaning of Internet serviceneeded:Understand the benefits of QoSGood business models including QoS

    Free mentality and internet neutralityInvestment in QoS cost for the end-usersneeded:flexiblerigid

    Why QoS is not widely used? (2):*

  • Definitions and Terminology

  • Packet lossLatency: end-to-end delayJitter: delay variationUptime: availabilityThroughput: data trasfer rate

    QoS parameters:*

    parametervoice serviceaverage Internetmaximum InternetPacket loss1%2%27%Latency200 ms65 ms85 msJitter30 ms--

  • IntServ:Reserving network resourcesRSVP protocolNot scalable, not supported

    DiffServ:Marked packets by typeQueuing strategies in routers and switchesNot widely used: the costs of premium are too high relative to the perceived benefits

    BE (= Best Effort):Not really QoS, just FIFO queuing strategy

    QoS categories, mechanisms:*

  • CoS (= Class of Service):*Applying a set of priority levelsImplementation: IntServDiffServ: PHB (= Per Hop Behavior): a service classEF (= Expedicted Forwarding)AF (= Assured Forwarding)BE (= Best Effort)

  • Business orientedTechnical specifications:SLS (= Service Level Specification): guideline for impelentationSLO (= Service Level Objetive): subset of SLS, describes the goals

    Main drivers: voice and video applicationsEg:MOS = Mean Opinion ScoreASR = Answer Seizure Ratio, percentage of calls that are successfully completedGuaranteed uptimeSLA (= Service Level Agreement):*

  • Only local agreementNot rigorousPresented as terms of service without CoSLimits the responsibility of ISPsLittle assurance of service quality

    Problems with SLA:*

  • 98% ofE-mail response time does not exceed 20 sConnenction to hosted server does not exceed 1,5 sWebsite download does not exceed 8 s

    Problems with SLA example:*

  • Subsription-based QoS:Fixed bandwidth allocatedPay for the serviceUnusedOn-demand QoS:According to actual needs allocatedPay-per-useNo guarentee

    Types of QoS(1):*

  • Soft QoS:No service quality assured during abnormal network conditionsNot good for applications that need predictable service qualityNot attractive enough to payNot much better as Best EffortHard QoS:Provides predictable service qualityAttractive enough to pay extra feeDifficult for ISPs to provide QoS under abnormal network conditionsTypes of QoS(2):*

  • Explicit QoS:The customer explicitly requires a specific service levelselling QoS as an optionImplicit QoS:The customer does not specifically asks for QoSEmbedded into services, eg: premium serviceNo special fee

    Types of QoS(3):*

  • TE (= Traffic Engineering):Performance evaluationOptimization of networksTM (= Traffic Management):Network operationTC (= Traffic Control):Means and actions

    Usage:By vendors to implement CoSBy ISPs to offer differenciated servicesBy Internet backbone providers to achieve specific network performanceBy IT departments to prioritize traffic

    Other issues:*

  • QoS planning:To be considered together:TopologyCapacityTrafficRouting methodsControl schemes

    Aim:To optimize network performanceTo be QoS not a constraint, but an objective*

  • Reliability:For customers:Availability of end-to-end functionalityFor the network provider:Ability to experience failuresNo impact into the service*

  • Internet Service Regulation

  • Regulation(1):Internet service:Regulate the Internet as a whole serviceRegulate specific servicesEg: Internet telephonyILECs (= Incumbent Local Exchange Carriers): basic serviceISPs: embedded service*

  • Regulation(2):Common standard:DifficultSophisticatedCostly OAM (= Operation, Administration and Maintenance)Regulators:Rather penalties, than incentivesMinimum targetsResponsibility:Service is sold by ISPs and delivered over the ILEC infrastructureDifficult to specify responsibility*

  • Internet neutrality vs Two-tier InternetInternet neutrality: Users control the content they viewgood for data applicationsNew definition: equal treatment among similar applicationsTwo-tier Internet:ISPs discriminate content according to paymentGood for delay-sensitive applications, eg: voice, videoSophisticated

    Hot debate!*

  • Service monitoring and accountingMonitoring:Initiated by the operatorObtains a general view of the network performance

    Accounting:Requested by the customerSophisticated

    Can use the same collection tools*

  • Internet Service Monitoring:ISPs use self-reporting systemsRegulators can audit the ISP logsRAQMON (= Real-time Applications QoS Monitoring Framework): to improve service qualityInternet traffic reports:Internettrafficreport.comwww-iepm.slac.stanford.eduUses pingMeasures packet loss and delayUSA and developed / developing countries37% of the world has poor packet loss ratio*

  • Internet Traffic report:*

  • Internet Service Accounting:No standard model1991: accounting framework (made by OSI)Motivations, pros:Provides feedback for the userVerifies performancePenalizes inefficient / reward efficient usage

    Cons: overheadDetailed information about the user protectionComplex OAM, high costs


  • Internet Service Pricing:Key role for successFlat pricing:SimpleNo overheadLow management costsbut:Over consumingInefficient in congestion situationsTrade-off:ISPs want predictable incomesUsers want flexible pricing and not paying for unused services*

  • Internet Service Marketing:Management processIdentifies customers requirementsLast step: advertisingTrade-off: how to meet customer requirements and satisfy in a profitable manner


  • A feasible business model:Presenting value added services with the Internet service Embedded services, eg: video conference, IPTVPricing relies on usage growthservice providers should price QoS into their services and not sell QoS explicitly*

  • QoS Architectural Issues

  • Issues:QoS supported at application, transport, network, data link layerSome of themWhere, when ,how to perform QoS routing and signaling?*

  • DiffServ (= Differentiated Services):ScalableEfficient for streaming, file transferInefficient for delay-sensitive applicationsFactors:Cost of deploymentImpact on performanceComplexity of provisioningImpact on network planning and monitoringBest performance: premium traffic is a minor proportion of overall traffic


  • Application level QoS:Applications adjust service levelRequires a signaling protocol, eg: RSVPRequires IntServ or DiffServProblems: Scalability (IntServ)No means for negotiating the service level (DffServ)Solution: hybrid model, but not yet demonstrated*

  • Transport Layer QoS:Compatible with DiffServeNo need to involve the applicationProblem: a QoS level provided which is not needed or not enoughTCP:Flow and congestion control: slow start, windowingError control: retransmission, ACK mechanismNot adequate for delay-sensitive applications

    UDP:No delivery guaranteesRequires higher level protocol, eg: RTPAdequate for delay-sensitive applications


  • QoS Routing(1):Assumption: BE (= Best Effort) path is used for BE and distinguished trafficNo path discovery feature routing protocol neededAlready existing: QOSPF (= Quality Of Service Path First)Q-BGP (= QoS-Enhanced Border Gateway Protocol)Problem: critical issues not addressed, eg: processing delay, convergence time, instability, inaccuracy*

  • Solution: scalability: SLA based on the local QoS capabilitiesSingle-domain QoSMultidomain QoSThe whole InternetQ-BGP (= QoS-Enhanced Border Gateway Protocol)Application-layer QoS routingPerformance-based routing: best routes selected by monitoring the network performanceMultiple connections to other ISPsAQR (= Assured Quality Routing): dynamically reroutes traffic

    QoS Routing(2):*

  • IP over QoS-driven lower layer technologiesTransport technologies, eg: Ethernet OBS (= Optical Burst Switching)Traffic classification


  • A viable QoS ArchitectureLayer 7 switching: processing of layer 2 up to layer7 headerWeb switch: can interpret HTML tags and make decisions at layer 2 or 3Load balancingWeb cachingMove content close to the end user

    Popular, good results


  • Conclusion: Joining the Pieces Together

  • Conclusion:Customers willingness to pay depend on the effectiveness of the modelISP: sell QoS implicitly without special feesAdequate trade-off between pe

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