Internet QoSPieces of the Puzzle

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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
                                             2
Sources:
• Internet QoS: Pieces of the Puzzle:
  IEEE Comm. Magazine, 2010. 01. p. 86-94
• QoS: http://en.wikipedia.org/wiki/Quality_of_service
• What is QoS?
  http://www.tomahawkcomputers.com/qos.html
• QoS Components:
  http://www.ciscopress.com/articles/article.asp?p=35299
  1&seqNum=4
                                                           3
Introduction
What is QoS?
• Quality of Service
• resource reservation control mechanisms
• ability to provide different priority to different
  applications
• guarantees a certain level of performance to a data
  flow, eg: real-time streaming
• important if the network capacity is insufficient
                                                        5
Problem:
The Internet is
• unregulated
• connectionless
• designed without QoS!


• Routers and switches cannot provide QoS
  cheap, fast
• Best effort: default QoS level
                                             6
Why QoS is not widely used? (1):
• IP QoS is not Internet QoS
• needed:
   – more architectures
   – scalability


• IP was designed without QoS
   – Big growth rate
   – Driven by market demands
   – Many autonomous systems
• needed:
   – simple
   – pragmatic
                                   7
Why QoS is not widely used? (2):
• No consensus on the exact meaning of Internet service
• needed:
   – Understand the benefits of QoS
   – Good business models including QoS


• Free mentality and internet neutrality
   – Investment in QoS cost for the end-users
• needed:
   – flexible
   – rigid


                                                          8
Definitions and Terminology
QoS parameters:
• Packet loss
• Latency: end-to-end delay
• Jitter: delay variation
• Uptime: availability
• Throughput: data trasfer rate

        parameter     voice service   average Internet   maximum Internet

        Packet loss   1%              2%                 27%

        Latency       200 ms          65 ms              85 ms

        Jitter        30 ms           -                  -
                                                                            10
QoS categories, mechanisms:
IntServ:
• Reserving network resources
• RSVP protocol
• Not scalable, not supported


DiffServ:
• Marked packets by type
• Queuing strategies in routers and switches
• Not widely used: „the costs of premium are too high relative to the
   perceived benefits”


BE (= Best Effort):
• Not really QoS, just FIFO queuing strategy                            11
CoS (= Class of Service):
• Applying a set of priority levels
• Implementation:
   – IntServ
   – DiffServ:
     PHB (= Per Hop Behavior):
     a service class
      • EF (= Expedicted Forwarding)
      • AF (= Assured Forwarding)
      • BE (= Best Effort)
                                       12
SLA (= Service Level Agreement):
              • Business oriented
              • Technical specifications:
                  – SLS (= Service Level Specification): guideline
                      for impelentation
                  – SLO (= Service Level Objetive): subset of SLS,
                      describes the goals


              • Main drivers: voice and video applications
              • Eg:
                  – MOS = Mean Opinion Score
                  – ASR = Answer Seizure Ratio, percentage of calls that
                      are successfully completed
                  – Guaranteed uptime                              13
Problems with SLA:
• Only local agreement
• Not rigorous
• Presented as terms of service
   – without CoS
   – Limits the responsibility of ISPs
   – Little assurance of service quality


                                           14
Problems with SLA – example:




• 98% of
  – E-mail response time does not exceed 20 s
  – Connenction to hosted server does not exceed 1,5 s
                                                         15
  – Website download does not exceed 8 s
Types of QoS(1):
• Subsription-based QoS:
  – Fixed bandwidth allocated
  – Pay for the service
  – Unused

• On-demand QoS:
  – According to actual needs allocated
  – Pay-per-use
  – No guarentee
                                          16
Types of QoS(2):
• Soft QoS:
  – No service quality assured during abnormal network conditions
  – Not good for applications that need predictable service quality
  – Not attractive enough to pay
  – Not much better as Best Effort
• Hard QoS:
  – Provides predictable service quality
  – Attractive enough to pay extra fee
  – Difficult for ISPs to provide QoS under abnormal network
    conditions                                                    17
Types of QoS(3):
• Explicit QoS:
   – The customer explicitly requires a specific service level
   – selling QoS as an option

• Implicit QoS:
   – The customer does not specifically
     asks for QoS
   – Embedded into services, eg: premium service
   – No special fee
                                                                 18
Other issues:
• TE (= Traffic Engineering):
   – Performance evaluation
   – Optimization of networks
• TM (= Traffic Management):
   – Network operation
• TC (= Traffic Control):
   – Means and actions

• Usage:
   – By vendors to implement CoS
   – By ISPs to offer differenciated services
   – By Internet backbone providers to achieve specific
     network performance
   – By IT departments to prioritize traffic              19
QoS planning:
To be considered together:
•      Topology
•      Capacity
•      Traffic
•      Routing methods
•      Control schemes


Aim:
•      To optimize network performance
•      To be QoS not a constraint, but an objective
                                                      20
Reliability:



•       For customers:
    •     Availability of end-to-end functionality

•       For the network provider:
    •     Ability to experience failures
    •     No impact into the service

                                                     21
Internet Service Regulation
Regulation(1):
•   Internet service:
     –   Regulate the Internet as a whole service
     –   Regulate specific services

•   Eg: Internet telephony
     –   ILECs (= Incumbent Local Exchange Carriers):
         basic service
     –   ISPs: embedded service


                                                        23
Regulation(2):
•   Common standard:
     –   Difficult
     –   Sophisticated
     –   Costly OAM (= Operation, Administration and Maintenance)
•   Regulators:
     –   Rather penalties, than incentives
     –   Minimum targets
•   Responsibility:
     –   Service is sold by ISPs and delivered over the ILEC infrastructure
     –   Difficult to specify responsibility
                                                                         24
Internet neutrality vs Two-tier Internet
•   Internet neutrality:
     –   Users control the content they view
     –   good for data applications
     –   New definition: equal treatment among similar applications

•   Two-tier Internet:
     –   ISPs discriminate content according to payment
     –   Good for delay-sensitive applications, eg: voice, video
     –   Sophisticated



•   Hot debate!                                                       25
Service monitoring and accounting
•   Monitoring:
     –   Initiated by the operator
     –   Obtains a general view of
         the network performance


•   Accounting:
     –   Requested by the customer
     –   Sophisticated


•   Can use the same collection tools
                                        26
Internet Service Monitoring:
•   ISPs use self-reporting systems
•   Regulators can audit the ISP logs
•   RAQMON (= Real-time Applications QoS Monitoring
    Framework): to improve service quality
•   Internet traffic reports:
      –   Internettrafficreport.com
      –   www-iepm.slac.stanford.edu
      –   Uses ping
      –   Measures packet loss and delay
      –   USA and developed / developing countries
      –   37% of the world has poor packet loss ratio

                                                        27
Internet Traffic report:




                           28
Internet Service Accounting:
•   No standard model
•   1991: accounting framework (made by OSI)
•   Motivations, pros:
     –      Provides feedback for the user
     –      Verifies performance
     –      Penalizes inefficient / reward efficient usage

•   Cons:
     –      overhead
     –      Detailed information about the user protection
     –      Complex OAM, high costs
                                                              29
Internet Service Pricing:
                   •   Key role for success
                   •   Flat pricing:
                        –      Simple
                        –      No overhead
                        –      Low management costs
                        but:
                        –      Over consuming
                        –      Inefficient in congestion situations
                   •   Trade-off:
                        –      ISPs want predictable incomes
                        –      Users want flexible pricing and not
                               paying for unused services
                                                             30
Internet Service Marketing:
   Management process

   Identifies customers
    requirements

   Last step: advertising

   Trade-off: „how to meet
    customer requirements and
    satisfy in a profitable
    manner”
                                31
A feasible business model:
   Presenting value added services with the Internet
    service

   Embedded services, eg: video conference, IPTV

   Pricing relies on usage growth

   „service providers should price QoS into their
    services and not sell QoS explicitly”
                                                        32
QoS Architectural Issues
Issues:
             QoS supported at application,
              transport, network, data link
              layer

             Some of them

             Where, when ,how to perform
              QoS routing and signaling?


                                        34
DiffServ (= Differentiated Services):
• Scalable

• Efficient for streaming, file transfer

• Inefficient for delay-sensitive applications

• Factors:
    – Cost of deployment
    – Impact on performance
    – Complexity of provisioning
    – Impact on network planning and monitoring
• Best performance: premium traffic is a minor proportion of
   overall traffic
                                                               35
Application level QoS:
   Applications adjust service level

   Requires a signaling protocol, eg: RSVP

   Requires IntServ or DiffServ

   Problems:
      –   Scalability (IntServ)
      –   No means for negotiating the service level (DffServ)

   Solution: hybrid model, but not yet demonstrated

                                                                 36
Transport Layer QoS:
   Compatible with DiffServe

   No need to involve the application

   Problem: a QoS level provided which is not needed or not enough

   TCP:

     – Flow and congestion control: slow start, windowing
     – Error control: retransmission, ACK mechanism
     – Not adequate for delay-sensitive applications



   UDP:

     – No delivery guarantees
     – Requires higher level protocol, eg: RTP
                                                                      37
     – Adequate for delay-sensitive applications
QoS Routing(1):
   Assumption: BE (= Best Effort) path is used for BE
    and distinguished traffic
   No path discovery feature routing protocol needed
   Already 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
                                                         38
QoS Routing(2):
   Solution:
    – scalability: SLA based on the local QoS capabilities
       – Single-domain QoS
       – Multidomain QoS
       – The whole Internet
       – Q-BGP (= QoS-Enhanced Border Gateway Protocol)
    – Application-layer QoS routing
    – Performance-based routing: best routes selected by monitoring the
      network performance
       – Multiple connections to other ISPs
       – AQR (= Assured Quality Routing): dynamically reroutes traffic    39
IP over QoS-driven lower layer technologies
   Transport technologies, eg:

     – Ethernet

     – OBS (= Optical Burst Switching)

   Traffic classification




                                         40
A viable QoS Architecture
   Layer 7 switching: processing of layer 2 up to layer7
    header
       Web switch: can interpret HTML tags and make decisions
        at layer 2 or 3
       Load balancing
   Web caching
       Move content close to the end user


   Popular, good results

                                                             41
                Conclusion:
Joining the Pieces Together
Conclusion:
• Customer’s willingness to pay depend on the effectiveness of the model

• ISP: sell QoS implicitly without special fees

• Adequate trade-off between penalties and incentives

• Goal of QoS: improve overall Internet performance

• QoS should rely on usage growth

• Selling service bundles: Best Effort should be only one bundle

• Not necessarily CoS

• Only effective when a small fraction of the traffic has to be prioritized

• Planning, TE, OAM, accounting, reliability play key roles
                                                                              43
The puzzle:




              44
Internet QoS: Pieces of the Puzzle
• Introduction

• Definitions and Terminology

• Internet Service Regulation

• QoS Architectural Issues

• Conclusions: Joining the Pieces Together

 Köszönöm a figyelmet!                       45

				
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