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WebTP Meeting (10/18/1999)

WebTP Meeting (10/18/1999). Link Sharing Principles Class Based Queueing (CBQ) S. Floyd and V. Jacobson - ToN 1995. Goals. Link Sharing: Distribute bandwidth according to some hierarchy. Goals. Link Sharing: Distribute bandwidth according to some hierarchy

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WebTP Meeting (10/18/1999)

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  1. WebTP Meeting (10/18/1999) Link Sharing Principles Class Based Queueing (CBQ) S. Floyd and V. Jacobson - ToN 1995

  2. Goals • Link Sharing: • Distribute bandwidth according to some hierarchy

  3. Goals • Link Sharing: • Distribute bandwidth according to some hierarchy • CBQ: A unified framework for supporting • Link Sharing • Real-time (delay sensitive) services

  4. Link Sharing between Traffic Classes

  5. Link Sharing Interior Class Leaf Class

  6. Link Sharing Level 3 Level 2 Level 1

  7. Link Sharing between Users

  8. Link Sharing between Users

  9. Link Weights Allocation • Static • Dynamic • network condition • user preferences • adding/removing connections

  10. Link Sharing Goal Over appropriate time-intervals, each interior or leaf class should receive its allocated bandwidth (given sufficient demand)

  11. Link Sharing between Users

  12. Link Sharing between Traffic Classes

  13. CBQ Fundamentals • Scheduling • General scheduler • Link sharing scheduler

  14. CBQ Fundamentals • Scheduling • General scheduler • Link sharing scheduler • Classes • Unregulated • Regulated

  15. CBQ Fundamentals • Scheduling • General scheduler • Link sharing scheduler • Classes • Unregulated • Regulated • Bandwidth Estimator • Exponential weighted moving average

  16. Classes - Definitions • Bandwidth Utilization • Overlimit • Underlimit • At-limit

  17. Classes - Definitions • Bandwidth Utilization • Overlimit • Underlimit • At-limit • Satisfaction • Unsatisfied: Underlimit + persistent backlog • Satisfied

  18. Link Sharing - Guidelines • A class stays unregulated if 1. It is not overlimit

  19. Link Sharing - Guidelines • A class stays unregulated if 1. It is not overlimit, OR 2. It has a not-overlimit ancestor at level j, andthere are no unsatisfied classes in the link-sharing structure at levels lower than j.

  20. Link Sharing - Guidelines • A class stays unregulated if 1. It is not overlimit, OR 2. It has a not-overlimit ancestor at level j, andthere are no unsatisfied classes in the link-sharing structure at levels lower than j. • Otherwise it should be regulated

  21. Link Sharing - Guidelines • A class stays unregulated if 1. It is not overlimit, OR 2. It has a not-overlimit ancestor at level j, andthere are no unsatisfied classes in the link-sharing structure at levels lower than j. • Otherwise it should be regulated • Remark: The root is always not-overlimit

  22. Examples

  23. Example 1 Under Over

  24. Example 2 Under Over

  25. Example 2 Backlog

  26. Example 2 Unsatisfied Unsatisfied

  27. Example 2 Unsatisfied Unsatisfied Regulated

  28. Example 3 Unsatisfied Regulated Overlimit + Backlog

  29. CBQ - Pros • Bandwidth protection • Hierarchy • Support of priorities for delay-sensitive services • flexibility

  30. CBQ - Cons • No deterministic/statistical guarantees on performance measure (delay, throughput) • Many tunable parameters with unknown effects

  31. CBQ and WebTP • Allow sharing of multiple connections with different requirements within a pipe • Allow sharing between multiple users or protocols (FAT pipes) • Open questions: • Traffic classification, admission control • Variable-rate server • interaction with the ADU scheduler

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