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Quality of Service in the Internet

Dr. Vasil Y. Hnatyshin. Quality of Service in the Internet. Outline. Introduction QoS via traffic differentiation QoS Building Blocks Integrated Services Differentiated Services Bandwidth Distribution Scheme Summary and Conclusions. Outline. Introduction

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Quality of Service in the Internet

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  1. Dr. Vasil Y. Hnatyshin Quality of Service in the Internet Rowan University Vasil Y. Hnatyshin

  2. Outline • Introduction • QoS via traffic differentiation • QoS Building Blocks • Integrated Services • Differentiated Services • Bandwidth Distribution Scheme • Summary and Conclusions Rowan University Vasil Y. Hnatyshin

  3. Outline • Introduction • QoS via traffic differentiation • QoS Building Blocks • Integrated Services • Differentiated Services • Bandwidth Distribution Scheme • Summary and Conclusions Rowan University Vasil Y. Hnatyshin

  4. What is QoS? • What is Quality of Service? • What parameters influences perceived network QoS? • Why do we need QoS in the Internet? Rowan University Vasil Y. Hnatyshin

  5. Internet Architecture APPLICATION What architectural model is being used in today’s Internet? TCP/UDP IP What are IP, TCP, and UDP and how do they work? MAC TCP/IP Internet Architecture Rowan University Vasil Y. Hnatyshin

  6. Widener Rowan APPLICATION APPLICATION APPLICATION APPLICATION INTERNET TCP/UDP TCP/UDP TCP/UDP TCP/UDP IP IP IP IP MAC MAC MAC MAC How does Internet work? ISP ISP Rowan University Vasil Y. Hnatyshin

  7. How to achieve QoS? • Provisioning • Traffic differentiation • In ISP routers (and the end nodes) • In the Internet core routers • Combination of the above Rowan University Vasil Y. Hnatyshin

  8. Outline • Introduction • QoS via traffic differentiation • QoS Building Blocks • Integrated Services • Differentiated Services • Bandwidth Distribution Scheme • Summary and Conclusions Rowan University Vasil Y. Hnatyshin

  9. Incoming Packet Outgoing Packet QoS Building Blocks Classifier Admission Control Rate Controller Scheduler Rowan University Vasil Y. Hnatyshin

  10. Version Header Length Type of Service Total Packet Length … TTL Protocol Header Checksum Source Address Destination Address Options (Variable Size) Classifiers • Application block • Source/Destination IP addresses • Source/Destination ports • Transport protocol • Type of Service Field (Differentiated Services) Rowan University Vasil Y. Hnatyshin

  11. Class #1 Class #2 Classifiers Classifier Rowan University Vasil Y. Hnatyshin

  12. Link utilization is 60 % Link utilization is 90 % Admission control • Ensures that the load on a particular link is manageable by determining if the new flow can be admitted into the network. Admission Control Rowan University Vasil Y. Hnatyshin

  13. Rate Controllers • What are rate controllers and how rate control is achieved? • Shapers • Droppers • Common rate control mechanisms • Token bucket • Timestamp driven Rowan University Vasil Y. Hnatyshin

  14. Processing Queue Rate Controller Delay Queue Dropper Rate Controllers Rowan University Vasil Y. Hnatyshin

  15. Schedulers • What are schedulers? • Scheduling mechanisms: • FIFO • Priority Queuing • Potential problem? • Preemptive vs. non-preemptive • Weighted-Fair Queuing Rowan University Vasil Y. Hnatyshin

  16. Priority Queue #1 Priority Queue #2 Priority Queue #3 Outgoing Link Priority Scheduler Rowan University Vasil Y. Hnatyshin

  17. Incoming Packet Outgoing Packet QoS Blocks Revisited Classifier Admission Control SLA Rate Controller Scheduler Rowan University Vasil Y. Hnatyshin

  18. Outline • Introduction • QoS via traffic differentiation • QoS Building Blocks • Integrated Services • Differentiated Services • Bandwidth Distribution Scheme • Summary and Conclusions Rowan University Vasil Y. Hnatyshin

  19. Integrated Services • Simplified Idea: for each newly admitted flow reserve network resources at each node on the flow’s path from source to destination. • Uses per-flow resource reservation protocol called resource reservation protocol (RSVP). Rowan University Vasil Y. Hnatyshin

  20. IntServ Example Internet Widener Core1 Core 3 ISP 3 ISP 1 ISP 2 ISP 4 Core 2 FTP connection from Rowan to CNN Rowan Video conference call from Rowan to CNN Allocated resources for corresponding connections FTP connection from Widener to CNN Video conference call from Widener to CNN Rowan University Vasil Y. Hnatyshin

  21. Main Advantage Main Disadvantage IntServ Summary • Support for fine-grained per-flow QoS • Resource hogging • Not Scalable Rowan University Vasil Y. Hnatyshin

  22. Outline • Introduction • QoS via traffic differentiation • QoS Building Blocks • Integrated Services • Differentiated Services • Bandwidth Distribution Scheme • Summary and Conclusions Rowan University Vasil Y. Hnatyshin

  23. Differentiated Services Goal: Provide scalable QoS. DiffServ Implementation: • Establishes a few classes/aggregates • Classifies arriving traffic into one of pre-defined classes. • Packets are differentiated based on the DSCP marking set in the IP header. • Core routers treat arriving traffic based on the packet’s class. Rowan University Vasil Y. Hnatyshin

  24. DiffServ Example Internet Widener Core1 Core 3 ISP 3 ISP 1 ISP 2 ISP 4 Core 2 DS Class A FTP connection from Rowan to CNN Rowan DS Class B Video conference call from Rowan to CNN FTP connection from Widener to CNN Video conference call from Widener to CNN Rowan University Vasil Y. Hnatyshin

  25. Main Advantage Main Disadvantage DiffServ Summary • Scalability • Providing only coarse-grained per-aggregated QoS Rowan University Vasil Y. Hnatyshin

  26. Outline • Introduction • QoS via traffic differentiation • QoS Building Blocks • Integrated Services • Differentiated Services • Bandwidth Distribution Scheme (BDS) • Summary and Conclusions Rowan University Vasil Y. Hnatyshin

  27. Idea of the BDS • Flow request certain amounts of bandwidth upon activation. • Bandwidth flow requirements are aggregated and distributed in the network via Resource Distribution and Feedback Protocol (RDF Protocol). • Based on the aggregate flow requirements individual edge routers control the rate of the traffic. Rowan University Vasil Y. Hnatyshin

  28. BDS Example Internet Widener Core1 Core 3 ISP 3 ISP 1 ISP 2 ISP 4 Core 2 Aggregate Flow Requirements FTP connection from Rowan to CNN Rowan Video conference call from Rowan to CNN FTP connection from Widener to CNN Video conference call from Widener to CNN Rowan University Vasil Y. Hnatyshin

  29. Outline • Introduction • QoS via traffic differentiation • QoS Building Blocks • Integrated Services • Differentiated Services • Bandwidth Distribution Scheme • Summary and Conclusions Rowan University Vasil Y. Hnatyshin

  30. Summary and Conclusions The BDS approach has potential to become superior to current IntServ and DiffServ approaches. BDS Advantages: • Scalability • Per-flow QoS • Fairness • Congestion control BDS Disadvantages: • Not tested under real-life scenarios • Overhead of the RDF protocol Rowan University Vasil Y. Hnatyshin

  31. Ongoing BDS Research • Evaluation of the BDS approach under more realistic scenarios. • Dealing with the inter-domain traffic. • Extending the BDS framework to mobile environment. • Influence of the BDS model on TCP traffic. Rowan University Vasil Y. Hnatyshin

  32. The BDS Publications • V. Hnatyshin and A.S. Sethi, “Reducing load distribution overhead with message aggregation,” Proc of IPCCC’03, Phoenix, AZ (April 2003) • V. Hnatyshin and A.S. Sethi, “Fair and Scalable Load Distribution in the Internet,” Proc. 3rd International Conference on Internet Computing, Las Vegas, NV (June 2002). • V. Hnatyshin and A.S. Sethi, “Achieving Fair and Predictable Service Differentiation Through Traffic Degradation Policies,” Proc. SPIE QoS 2001, Conference on Quality of Service over Next-Generation Data Networks, Denver, CO (Aug. 2001). • V. Hnatyshin and A.S. Sethi, “Avoiding Congestion Through Dynamic Load Control,” Proc. ITCom-2001, SPIE's International Symposium on The Convergence of Information Technologies and Communications, Denver, CO (Aug. 2001). Rowan University Vasil Y. Hnatyshin

  33. The End!

  34. Network Domain Core 1 Core 2 Network Domain Network Domain Network Domain Network Domain Network Domain The Internet Edge B Edge A Core 3 Edge C Edge D Network Architecture Rowan University Vasil Y. Hnatyshin

  35. Core 1 Core 2 Edge B Edge A Core 3 Edge C Edge D DiffServ Scalability • Edge Routers: • Maintain all per-flow information via SLA • Perform traffic classification • Mark arriving packets Network Domain • Core Routers: • Maintain only class information • Treat arriving traffic based on the DSCP marking Rowan University Vasil Y. Hnatyshin

  36. Flow List SLA Table Source Destination Source Destination Path Table … … … … … Data Data Data Source Destination Egress node … Link Table Complete Path … Link Capacity Arrival Rate IP Address Data Aggregate RBR IP Address Data Path List IP Address Data … … BDS Edge Node Data Structures Rowan University Vasil Y. Hnatyshin

  37. Interfaces Table Link Capacity Arrival Rate IP Address Data Aggregate RBR IP Address Data Edge Nodes List IP Address Data … … BDS Core Node Data Structures Rowan University Vasil Y. Hnatyshin

  38. BDS Objectives • Scalability • Per-flow QoS • Fair distribution of bandwidth • Congestion Control Rowan University Vasil Y. Hnatyshin

  39. Core 1 Core 2 Edge B Edge A Core 3 Edge C Edge D BDS Scalability • Edge Routers: • Maintain all per-flow information via SLA • Perform traffic classification • Adjust transmission rate of the flows based on the network feedback Network Domain • Core Routers: • Maintain only aggregate flow requirements • Provide network feedback to the edge routers Rowan University Vasil Y. Hnatyshin

  40. BDS Per-flow QoS • Admission control • Resource management • Control protocol Note: Fairness and congestion control achieved via same modules Rowan University Vasil Y. Hnatyshin

  41. -- A new flow -- A link -- Capacity of link k -- A path of a flow -- A set of flows that travel through link k -- A flow Admission Control • Flow Requirements: Requested Bandwidth Range (RBR) [Min Rate, Max Rate] = • Aggregate RBR • Admission control test: Rowan University Vasil Y. Hnatyshin

  42. Resource Management • Definitions of Fairness: • Proportional Fairness • Maximizing Utility Fairness • Per-Flow Resource Allocation Rowan University Vasil Y. Hnatyshin

  43. The RDF Protocol • Purpose: • Distribute the Aggregate RBR among the nodes in the network. • Path Probing Phase: • Edge routers periodically probe the network to discover the route changes (e.g. aggregate RBR, excess bandwidth). • RBR Update Phase: • Edge nodes notify the core routers about the change of the aggregate RBR due to flow activation or termination. • Notification Phase: • Core routers notify the edge nodes about congestion. Rowan University Vasil Y. Hnatyshin

  44. Edge 5 Flow F2 requests to enter the network at Edge 2 to travel to Edge 5 Edge 1 Probe Edge 6 C1 CN C2 C3 F1 CN F1 Probe Reply Edge 4 Edge 2 Edge 3 Core Router C1 discovers that link C1-C2 is congested F2 F2 The RDF Protocol Example 1. Initiates the Path Probing Phase 2. Updates Local Data Structures 3. Performs Admission Control Test 4. Computes Allocated Rate of F2 5. Initiates the RBR Update Phase 1. C1 initiates the Notification Phase. 6. Allows F2 to enter the network 2. Edge 1 and Edge 2 adjust allocated rates of F1 and F2 to eliminate congestion. Rowan University Vasil Y. Hnatyshin

  45. Per-Flow Admission Control RBR Distribution and Feedback Protocol Resource Allocation The BDS Framework Network Architecture Flow Requirements Scalability Definitions of Fairness Excess BW Management Per-Flow QoS Congestion Control Specifications and Definitions The BDS Objectives The BDS Architecture The BDS Architecture Rowan University Vasil Y. Hnatyshin

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