Improving Individual Flow Performance with Multiple Queue Fair Queuing

Author: Manfred Georg, Christoph Jechlitschek, Sergey Gorinsky

Publisher: Quality of Service, 2007 Fifteenth IEEE International Workshop on

Presenter: Chun-Yi Li

Date: 2008/10/29

2

Overview Previous Work

Protecting Flow Performance Fair Queuing Stochastic Fair Queuing (SFQ)

Multiple Queue Fair Queuing Introduction Deficit Round Robin Avoid Reordering

Performance

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Protecting Flow Performance

Per-Flow Fair Queuing Poor scalability

Aggregate Fair Queuing (SFQ, SFB) No protection within aggregate

Identify and Limit (CHOKe, AFD) Delayed reaction Difficult to detect some flows

Multiple Queue Fair Queuing (MQFQ) Per-aggregate fair queuing with backup queue for

each flow

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Fair Queuing Each Flow Has Different Queue

Serve queues independently

IncomingPackets

OutgoingPackets

Flow 1

Flow 3

Flow 2

5

1

Stochastic Fair Queuing Fixed Number of Queues

Hash function maps flow to queueBlue

Orange

Gray

GreenHash

Function

1

2

4

2

3

1 122 33 22 44 11

Flow 1 and 3 Interfere

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Multiple Queue Fair Queuing (MQFQ) Fixed Number of Queues Two Hash Functions Protection of Individual Flows in

Aggregate Queuing Surrender Some Capacity to

Misbehavers No Packet Reordering Within Flow

7

1

1

2

3

1

1

1

1

2

Multiple Queue Fair Queuing (MQFQ) Two Hash Functions

Place packet in queue with fastest service Avoid misbehavior

Blue

Orange

Gray

Green

HashFunction 1

HashFunction 2

1

1

1

1

1

1

2

2

2

QuantumPartial InterferenceBetween Flows 1 and 2

3

3

31

1

1

1

1

1

4

4

4

Complete InterferenceBetween Flows 1 and 4

8

Deficit Round Robin Each Queue Maintains a Deficit

Quantum added to deficit and then spent

Outgoing Link

QuantumBlue

Orange

Gray

Green

1

2

4

2

3 3

12 42

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Probability of Flow Interference

MQFQ Partial

MQFQ Complete

SFQ Complete

(k)

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Avoid Reordering MQFQ Can Reorder Different Length Packets

by at Most One Round

Split Packets Into Constant Sized Cells All packets have same possibilities Cells generally used in multi-stage switches

1

1 1 111

11

50 TCP Flows

12

49 TCP flows + Misbehaving CBR

13

50 CBR Flows

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Many Hash Functions (TCP Flows)