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IntServ & DiffServ


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IntServ & DiffServ

  1. 1. 1
  2. 2. Attention Question Why we classify hotels for  Three stars  Four stars  Five stars Base on Quality of Service !! ?? 2
  3. 3. Outline Introduction  QoS requirements  Internet QoS  Differentiated Services  Integrated Services  Comparison Diffserv VS Intserv  Conclusions  References  3
  4. 4. Introduction  QoS (Quality of Service) refers to a broad collection of networking technologies and techniques. The goal of QoS is to provide guarantees on the ability of a network to deliver predictable results. Elements of network performance within the scope of QoS often include availability (uptime), bandwidth (throughput), latency (delay), and error rate. QoS involves prioritization of network traffic. QoS can be targeted at a network interface, toward a given server or router's performance, or in terms of specific applications. A network monitoring system must typically be deployed as part of QoS, to insure that networks are performing at the desired level. 4
  5. 5. Introduction Con.   QoS is especially important for the new generation of Internet applications such as VoIP, video-on-demand and other consumer services. Some core networking technologies like Ethernet were not designed to support prioritized traffic or guaranteed performance levels, making it much more difficult to implement QoS solutions across the Internet. Quality of Service is “The collective effect of service performances which determine the degree of satisfaction of a user of the service”, According to the definition of ITU (International Telecommunication Union). 5
  6. 6. Introduction Con. 6
  7. 7. QoS requirements The main QoS requirements are:  Bandwidth :represents a data stream bandwidth.  Reliability : represents the tolerance for losses in a data stream.  Delay :The relative delay between packets and the round Trip Delay. The actual QoS assigned to a stream depends on many parameters: • • • • the server scheduling algorithm, the server priority settings, the server load, the scheduling cost. 7
  8. 8. Internet QoS I. II. Internet supports best-effort service only. The existing applications are time-sensitive, delay-sensitive, jittersensitive or have other importance requirements which are not supported by best-effort Internet. Differentiated services which aims to:  Classify the traffic into groups  Handles different traffic groups differently. Integrated services  Collective service to put the traffic demands in domain, and to Limit the demand & the reserve 8 resources.
  9. 9. I. Differentiated Services Definition:  Differentiated Services (DiffServ ) means a multiple service model that can satisfy the most requirements.  DiffServ is used for several mission-critical applications and to provide end-to-end QoS.  DiffServ reduces the burden on network devices and easily scales as the network grows. 9
  10. 10. Differentiated Services Components • • • • • Traffic conditioning: (or traffic policing and traffic shaping)to ensure that traffic entering the DiffServ domain. Packet classification: It uses a traffic descriptor to categorize a packet within a specific group. Packet marking: to classify a packet based on a specific traffic descriptor. Congestion management: achieve scheduling and traffic queuing. Congestion avoidance to monitor network traffic loads to avoid congestion at common network bottlenecks. It may be achieved through packet dropping. 10
  11. 11. . The main components of a DiffServ network: The Differentiated Model goal is to Divide the Traffic into Classes Differentiated Services Platinum Class Low Latency Gold . Voice Guaranteed: Latency and Delivery Silver Guaranteed Delivery Bronze Best Effort Delivery E-Commerce Application Traffic E-mail, Web Browsing Traffic Classification Voice 11
  12. 12. Differentiated Services     Services: Differentiated Services ( DiffServ or DS) represents a computer networking architecture that specifies a simple, scalable and coarse-grained mechanism for classifying, managing network traffic and providing Quality of Service A Differentiated Model is a model that is appropriate for aggregate flows. It alleviates the bottlenecks through efficient management of current corporate network resources 12
  13. 13. II. Integrated Services Integrated services (IntServ) is an architecture to specify the elements to guarantee QoS.  IntServ can be used to delete the receiver interruption for the video and sound.  The IntServ idea is to let every router in the system implements IntServ, and let every application requires some kind of guarantees to make an individual reservation. The integrated services structure can be implemented through the following components: • the signaling protocol. • the admission control routine. 13
  14. 14. II. Integrated Services con. • •   the classifier . the packet scheduler. This model requires explicit signaling mechanism to convey information to routers so that they can provide the requested resources. RSVP is one of the most widely known example of such a signaling mechanism. 14
  15. 15. Integrated Services Example: Data Path  Per-flow classification Receiver Sender 15 15
  16. 16. Integrated Services Example: Data Path  Per-flow buffer management Receiver Sender 16 16
  17. 17. Integrated Services Example: Data Path  Per-flow scheduling Receiver Sender 17 17
  18. 18. Comparison Diffserv VS Intserv Differentiated services aims to mark the packets with priority and send it to the network. No prior reservation of resources are involved in diffserv. Integrated services involves prior reservation of resources before sending to achieve the required Quality of Service. 18
  19. 19. Comparison Best-Effort Diffserv • Per aggregation isolation • Per aggregation guarantee Intserv • Per flow isolation • Per flow guarantee Service • Connectivity • No isolation • No guarantees Service Scope •End-to-end •Domain •End-to-end Complexity •No set-up •Long term setup • Per flow setup Scalability • Highly scalable • (nodes maintain only routing state) • Scalable (edge routers maintains per aggregate state; core routers per class state) • Not scalable (each router maintains per flow state) 19
  20. 20. Conclusions The main two traffic management frameworks are:  Differentiated Services (DS, DiffServ): helps to classify the traffic into a number of traffic groups and handle it based on the traffic group.  Integrated Services (IS, ISA, IntServ): based mainly on reserving resources per session and limit total demand to the capacity that can be handled by the network. 20
  21. 21. References     Technical, Commercial and Regulatory Challenges of QoS: An Internet Service Model Perspective by Xipeng Xiao (Morgan Kaufmann, 2008, ISBN 0-12-373693-5) Deploying IP and MPLS QoS for Multiservice Networks: Theory and Practice by John Evans, Clarence Filsfils (Morgan Kaufmann, 2007, ISBN 0-12-370549-5) QoS Over Heterogeneous Networks by Mario Marchese (Wiley, 2007, ISBN 978-0-470-01752-4) Teletraffic Engineering Handbook ITU-T Study Group 2 (350 pages, 4·48MiB)(It uses abbreviation GoS instead of QoS) 21