webtp meeting (10/18/1999) link sharing principles class based queueing (cbq) s. floyd and v....
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![Page 1: WebTP Meeting (10/18/1999) Link Sharing Principles Class Based Queueing (CBQ) S. Floyd and V. Jacobson - ToN 1995](https://reader038.vdocument.in/reader038/viewer/2022110207/56649d265503460f949fd8dd/html5/thumbnails/1.jpg)
WebTP Meeting (10/18/1999)
Link Sharing Principles
Class Based Queueing (CBQ)
S. Floyd and V. Jacobson - ToN 1995
![Page 2: WebTP Meeting (10/18/1999) Link Sharing Principles Class Based Queueing (CBQ) S. Floyd and V. Jacobson - ToN 1995](https://reader038.vdocument.in/reader038/viewer/2022110207/56649d265503460f949fd8dd/html5/thumbnails/2.jpg)
Goals
• Link Sharing:– Distribute bandwidth according to some
hierarchy
![Page 3: WebTP Meeting (10/18/1999) Link Sharing Principles Class Based Queueing (CBQ) S. Floyd and V. Jacobson - ToN 1995](https://reader038.vdocument.in/reader038/viewer/2022110207/56649d265503460f949fd8dd/html5/thumbnails/3.jpg)
Goals
• Link Sharing:– Distribute bandwidth according to some
hierarchy
• CBQ: A unified framework for supporting– Link Sharing– Real-time (delay sensitive) services
![Page 4: WebTP Meeting (10/18/1999) Link Sharing Principles Class Based Queueing (CBQ) S. Floyd and V. Jacobson - ToN 1995](https://reader038.vdocument.in/reader038/viewer/2022110207/56649d265503460f949fd8dd/html5/thumbnails/4.jpg)
Link Sharing between Traffic Classes
C onn . 150%
R T - V ideo50%
C onn . 215%
C onn . 310%
T ext, C G I25%
C onn . 412 .5%
C onn . 512 .5%
G IF , JP EG25%
L ink (P ipe)
![Page 5: WebTP Meeting (10/18/1999) Link Sharing Principles Class Based Queueing (CBQ) S. Floyd and V. Jacobson - ToN 1995](https://reader038.vdocument.in/reader038/viewer/2022110207/56649d265503460f949fd8dd/html5/thumbnails/5.jpg)
Link Sharing
C onn . 150%
R T - V ideo50%
C onn . 215%
C onn . 310%
T ext, C G I25%
C onn . 412 .5%
C onn . 512 .5%
G IF , JP EG25%
L ink (P ipe)
Leaf Class
Interior Class
![Page 6: WebTP Meeting (10/18/1999) Link Sharing Principles Class Based Queueing (CBQ) S. Floyd and V. Jacobson - ToN 1995](https://reader038.vdocument.in/reader038/viewer/2022110207/56649d265503460f949fd8dd/html5/thumbnails/6.jpg)
Link Sharing
C onn . 150%
R T - V ideo50%
C onn . 215%
C onn . 310%
T ext, C G I25%
C onn . 412 .5%
C onn . 512 .5%
G IF , JP EG25%
L ink (P ipe)
Level 1
Level 2
Level 3
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Link Sharing between Users
U ser 150%
U ser 250%
L ink (P ipe)
![Page 8: WebTP Meeting (10/18/1999) Link Sharing Principles Class Based Queueing (CBQ) S. Floyd and V. Jacobson - ToN 1995](https://reader038.vdocument.in/reader038/viewer/2022110207/56649d265503460f949fd8dd/html5/thumbnails/8.jpg)
Link Sharing between Users
V ideo10%
F T P40%
U ser 150%
V ideo40%
F T P10%
U ser 250%
L ink (P ipe)
![Page 9: WebTP Meeting (10/18/1999) Link Sharing Principles Class Based Queueing (CBQ) S. Floyd and V. Jacobson - ToN 1995](https://reader038.vdocument.in/reader038/viewer/2022110207/56649d265503460f949fd8dd/html5/thumbnails/9.jpg)
Link Weights Allocation
• Static
• Dynamic– network condition– user preferences– adding/removing connections
![Page 10: WebTP Meeting (10/18/1999) Link Sharing Principles Class Based Queueing (CBQ) S. Floyd and V. Jacobson - ToN 1995](https://reader038.vdocument.in/reader038/viewer/2022110207/56649d265503460f949fd8dd/html5/thumbnails/10.jpg)
Link Sharing Goal
Over appropriate time-intervals, each interior or leaf class should receive its allocated bandwidth
(given sufficient demand)
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Link Sharing between Users
110%
240%
U ser 150%
140%
210%
U ser 250%
L ink (P ipe)
![Page 12: WebTP Meeting (10/18/1999) Link Sharing Principles Class Based Queueing (CBQ) S. Floyd and V. Jacobson - ToN 1995](https://reader038.vdocument.in/reader038/viewer/2022110207/56649d265503460f949fd8dd/html5/thumbnails/12.jpg)
Link Sharing between Traffic Classes
C onn . 150%
R T - V ideo50%
C onn . 215%
C onn . 310%
T ext, C G I25%
C onn . 412 .5%
C onn . 512 .5%
G IF , JP EG25%
L ink (P ipe)
![Page 13: WebTP Meeting (10/18/1999) Link Sharing Principles Class Based Queueing (CBQ) S. Floyd and V. Jacobson - ToN 1995](https://reader038.vdocument.in/reader038/viewer/2022110207/56649d265503460f949fd8dd/html5/thumbnails/13.jpg)
CBQ Fundamentals
• Scheduling– General scheduler– Link sharing scheduler
![Page 14: WebTP Meeting (10/18/1999) Link Sharing Principles Class Based Queueing (CBQ) S. Floyd and V. Jacobson - ToN 1995](https://reader038.vdocument.in/reader038/viewer/2022110207/56649d265503460f949fd8dd/html5/thumbnails/14.jpg)
CBQ Fundamentals
• Scheduling– General scheduler– Link sharing scheduler
• Classes– Unregulated– Regulated
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CBQ Fundamentals
• Scheduling– General scheduler– Link sharing scheduler
• Classes– Unregulated– Regulated
• Bandwidth Estimator– Exponential weighted moving average
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Classes - Definitions
• Bandwidth Utilization– Overlimit– Underlimit– At-limit
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Classes - Definitions
• Bandwidth Utilization– Overlimit– Underlimit– At-limit
• Satisfaction– Unsatisfied: Underlimit + persistent backlog– Satisfied
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Link Sharing - Guidelines
• A class stays unregulated if1. It is not overlimit
![Page 19: WebTP Meeting (10/18/1999) Link Sharing Principles Class Based Queueing (CBQ) S. Floyd and V. Jacobson - ToN 1995](https://reader038.vdocument.in/reader038/viewer/2022110207/56649d265503460f949fd8dd/html5/thumbnails/19.jpg)
Link Sharing - Guidelines
• A class stays unregulated if1. It is not overlimit, OR
2. It has a not-overlimit ancestor at level j, and there are no unsatisfied classes in the link-sharing structure at levels lower than j.
![Page 20: WebTP Meeting (10/18/1999) Link Sharing Principles Class Based Queueing (CBQ) S. Floyd and V. Jacobson - ToN 1995](https://reader038.vdocument.in/reader038/viewer/2022110207/56649d265503460f949fd8dd/html5/thumbnails/20.jpg)
Link Sharing - Guidelines
• A class stays unregulated if1. It is not overlimit, OR
2. It has a not-overlimit ancestor at level j, and there are no unsatisfied classes in the link-sharing structure at levels lower than j.
• Otherwise it should be regulated
![Page 21: WebTP Meeting (10/18/1999) Link Sharing Principles Class Based Queueing (CBQ) S. Floyd and V. Jacobson - ToN 1995](https://reader038.vdocument.in/reader038/viewer/2022110207/56649d265503460f949fd8dd/html5/thumbnails/21.jpg)
Link Sharing - Guidelines
• A class stays unregulated if1. It is not overlimit, OR
2. It has a not-overlimit ancestor at level j, and there 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
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Examples
1 2
A
1 2
B
L ink
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Example 1
1 2
A
1 2
B
L ink
Under
Over
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Example 2
1 2
A
1 2
B
L ink
Under
Over
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Example 2
1 2
A
1 2
B
L ink
Backlog
![Page 26: WebTP Meeting (10/18/1999) Link Sharing Principles Class Based Queueing (CBQ) S. Floyd and V. Jacobson - ToN 1995](https://reader038.vdocument.in/reader038/viewer/2022110207/56649d265503460f949fd8dd/html5/thumbnails/26.jpg)
Example 2
1 2
A
1 2
B
L ink
Unsatisfied
Unsatisfied
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Example 2
1 2
A
1 2
B
L ink
Regulated
Unsatisfied
Unsatisfied
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Example 3
1 2
A
1 2
B
L ink
Unsatisfied
Overlimit +Backlog
Regulated
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CBQ - Pros
• Bandwidth protection
• Hierarchy
• Support of priorities for delay-sensitive services
• flexibility
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CBQ - Cons
• No deterministic/statistical guarantees on performance measure (delay, throughput)
• Many tunable parameters with unknown effects
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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