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DiffServ MIB 02 - 47th IETF

Kwok Ho ChanMarch 2000

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Changes from version 01

Consolidated Classifier TableRemoved ConfigSrc Table and its

usageImproved flexibility in Action and

Queue Tables For defining different Action types For enqueueing, and dequeue

scheduling

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Classifiers

Removed the BA Classifier TableUsing IP Six Tuple Classifier for BA

Classifier functionality

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Actions

Improved the flexibility of the Action Table by usage of Action Type Tables: Mark Action Type Table Count Action Type Table Drop Action Type Table

Allow easy future addition of new Action Types

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Count and Mark Action Type Tables

Count Action Type Table Entry is always performed first when it is one of multiple cascaded actions for always counting all traffic of a flow. 64 bit counters are provided by an augment table, IFMIB style.

Mark Action Type Table for marking and remarking of DSCP.

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Drop Action Type Table

Drop Action Type Table uses the same set of attributes for three kinds of drops: Tail Drop Random Drop Deterministic Drop

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Tail Drop Action Type

Tail Drop Action uses the Qmax attribute to represent the current queue length for the drop probability to step up to 1.

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Tail Drop Curve

P

0

0.2

0.4

0.6

0.8

1

1.2

Qmax

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Random Drop Curve

P

0

0.2

0.4

0.6

0.8

1

1.2

0 Qmin Qmax Qclip

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Random Drop Action Type

Notice: Pmax does not jump to 1 when Qmax is

reached, instead P approaches 1 when Qclip is reached. Please see “A Study of Active Queue Management for

Congestion Control” by Victor Firoiu and Marty Borden.

http://www.ieee-infocom.org/2000/papers/405.pdfA supportive reference:

http://www.aciri.org/floyd/REDfunc.txt

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Deterministic Drop Action

Deterministic Drop is a simple case of Random Drop, with Qmin=Qmax=Qclip, at which point drop probability jumps to 1.

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Queue and Drop Control

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Q Measure TableAdded Q Measure Table to facilitate

implementation of traffic treatment algorithms.

Q Measure contains: Q Average Sampling Interval, allowing usage of

a timer, enqueue, or dequeue as trigger for sampling interval

Q Average Weight Exponent Q Average Weight Mantissa Current Q Average

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Queue Table

A queue is very simple, containing only its weight, used by its Queue Set for scheduling.

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Queue Set

A Queue Set organizes all the queues controlled by the same scheduler.

Attributes: Method, RateUnit, MinRate, MaxRate are for the scheduler.

Attributes: Parent, Weight are for hierarchical queueing structure