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Session 1Session Name: Traffic Management

Author Name: Anilkumar Vishwanath Brahmane

Department: Computer Engineering

Subject/Course: Design and Analysis of Computer

Network

Cell Number: 9922827812

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Page 2 Ver : 1.01 Topic NameHere

Author Name: College Name:

Session Objectives

At the end of this session, the learner will be able to:

Identify the need of Traffic Management.

Dramatize the various Traffic Models.

Explain the various Traffic Classes.

Outline the pros and cons of different Traffic Management model and

classes.

Teaching Learning Material

White Board and Markers

Presentation Slides

LCD Projector

Placards and props for the role play


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Topic Name Here Page 3Author Name: College Name:

Session Plan

Time(in min)

ContentLearning Aid

andMethodology

FacultyApproach

Typical StudentActivity

LearningOutcomes(Blooms +Gardeners)

10Need of TrafficManagement

AnalogiesFacilitatesExplain

ParticipatesAnalyzesAnswers

AnalyzingIntrapersonalInterpersonalLogicalVerbal-Linguistic

15

Traffic Model :Telephone TrafficModel, InternetTraffic Model

Role Pay

FacilitatesGuidesMonitorsDebriefs

ParticipatesObservesComprehendsListens

ApplyingIntrapersonalInterpersonalKinestheticVerbal-Linguistic

20Traffic Classes :CBR, VBR, ABR, UBRetc

PresentationSlides (PPT)

ExplainFacilitates

ListensObserversComprehendsAnalyzes

AnalyzingIntrapersonalVisual- SpatialLinguistic

10Pros and ConsAnalysis

Board ActivityFacilitatesVerifiesTabulates

DiscussesIdentifies

UnderstandingIntrapersonalInterpersonalVisualVerbal

05 Conclusion

l

Questions andAnswers

Questions Recall Answers

Remembering

IntrapersonalVerbal


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Session Inputs

Need of Traffic Management

Traffic Management is an important activity in Computer network.

We can begin the session with an activity which will help the

learners understand the need of Traffic Management.

Suggested Activity: Analogies

We can narrate some analogies for problems that can occur in the absence

of scheduling, and invite the learners response on what major problems can

occur due to its absence or due to poor design

Some sample analogies could be as follows:

Highway Traffic Management: On highway many vehicles aremoving from both directions. How n numbers of cars and other

vehicles are managed so that all can travel smoothly without

accident and any type of deadlock or collision.

Traffic Signals and Traffic Police plays important role in highway

traffic management so that deadlock avoid.

Some of the problems faced without traffic management are:

Analogy (Highway Traffic Management):

Road accident can take places, collisions of vehicles can occur. As a result of accident human life can face serious problems Deadlock situation can occur.


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Incomputer networks,network traffic measurementis the process of

measuring the amount and type of traffic on a particular network.

Traffic Management is set of policies and mechanisms that allow a

network to efficientlysatisfy a diverse range of service requests

Traffic Models: TelephoneTraffic Model, Internet TrafficModelHaving explained the need of Traffic Management, it would now

be appropriate to discuss about the different models of Traffic

Management with help of role-play.

The learners have to be made very clear about the four main

scheduling methods so as to proceed smoothly with the session.Therefore, maximum time is dedicated for this segment.

The two main traffic management models are Telephone Traffic Model,Internet Traffic Model.

Suggested Activity: Role -Play

We can select a few learners (minimum 13) to volunteer for the role-play.

Role- play participants have the roles of the following;

Call Sender (Caller) (Anil is sender who calls to his friend, Sunil) Call Receiver ( Sunil who is receiver, called by Anil) Telephone Device (Analog to Digital and vice versa convertor) Intermediate Telephone exchange( Router, gateways etc) Group of PCs Clients One Server
http://en.wikipedia.org/wiki/Computer_networkshttp://en.wikipedia.org/wiki/Computer_networkshttp://en.wikipedia.org/wiki/Computer_networkshttp://en.wikipedia.org/wiki/Computer_networks


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Model 1 : Telephone Traffic Model

Caller (Anil) dials the number.

Telephone Ring is sounded at receiver end.

Router, Switches, Gateways find the appropriate destination and connect

with respect their functionalitiesReceiver (Sunil) Pick up the receiver and say Hello.

Caller says Hello Sunil.

Model 2 : Internet Traffic Model

LAN ,WAN

One students acts like SERVER

Four to five students can acts like CLIENTS.

CLIENTS can send the request to SERVER.

SERVER can send the response to CLIENTS.Here we can show that students who act like a client can send request in

the form of any message. Also student who act like a server can send

response in the from of message.

The role-play depicted various situations, each analogous to the

different CPU scheduling algorithms. As we saw, each algorithmworks well in certain situations but must be replaced if at times the

outcome is not satisfactory.


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Traffic Classes: CBR, VBR, UBR, ABR, etc

Suggested Activity: Presentation Slides

Traffic classes

Networks should match offered service to source requirementsNetworks should match offered service to source requirements(corresponds to utility functions)(corresponds to utility functions)

Example: telnet requires low bandwidth and low delayExample: telnet requires low bandwidth and low delay

utility increases with decrease in delayutility increases with decrease in delay

network should provide a lownetwork should provide a low--delay servicedelay service

or, telnet belongs to the lowor, telnet belongs to the low--delaydelay traffic classtraffic class

Traffic classes encompass bothTraffic classes encompass both user requirementsuser requirementsandand networknetwork

service offeringsservice offerings


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Traffic classes - details

A basic division:A basic division: guaranteed serviceguaranteed service andand best effortbest effort

like flying with reservation or standbylike flying with reservation or standby

GuaranteedGuaranteed--serviceservice

utility is zero unless app gets a minimum level of service qualiutility is zero unless app gets a minimum level of service qualityty

bandwidth, delay, lossbandwidth, delay, loss

openopen--loop flow control with admission controlloop flow control with admission control

e.g. telephony, remote sensing, interactivee.g. telephony, remote sensing, interactive multiplayermultiplayer gamesgames

BestBest--efforteffort

send and praysend and pray

closedclosed--loop flow controlloop flow control

e.g. email, net newse.g. email, net news

GS vs. BE (cont.)

Degree of synchronyDegree of synchrony

time scale at which peer endpoints interacttime scale at which peer endpoints interact

GS are typicallyGS are typically synchronoussynchronousoror interactiveinteractive

interact on theinteract on the timescaletimescale of a round trip timeof a round trip time

e.g. telephone conversation or telnete.g. telephone conversation or telnet

BE are typicallyBE are typically asynchronousasynchronousoror nonnon--interactiveinteractive

interact on longer time scalesinteract on longer time scales

e.g. Emaile.g. Email

Sensitivity to time and delaySensitivity to time and delay

GS apps areGS apps are realreal--timetime

performance depends on wall clockperformance depends on wall clock

BE apps are typically indifferent to real timeBE apps are typically indifferent to real time

automatically scale back during overloadautomatically scale back during overload


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Traffic subclasses (roadmap)

ATM Forum

based on sensitivity tobased on sensitivity to

bandwidthbandwidth

GSGS

CBR, VBRCBR, VBR

BEBE

ABR, UBRABR, UBR

IETFIETF

based on sensitivity to delaybased on sensitivity to delay

GSGS

intolerantintolerant

toleranttolerant

BEBE

interactive burstinteractive burst

interactive bulkinteractive bulk

asynchronous bulkasynchronous bulk

ATM Forum GS subclasses

Constant Bit Rate (CBR)Constant Bit Rate (CBR)

constant, cellconstant, cell--smooth trafficsmooth traffic

mean and peak rate are the samemean and peak rate are the same

e.g. telephone call evenly sampled and uncompressede.g. telephone call evenly sampled and uncompressed

constant bandwidth, variable qualityconstant bandwidth, variable quality

Variable Bit Rate (VBR)Variable Bit Rate (VBR)

long term average with occasional burstslong term average with occasional bursts

try to minimize delaytry to minimize delay

can tolerate loss and higher delays than CBRcan tolerate loss and higher delays than CBR

e.g. compressed video or audio with constant quality, variablee.g. compressed video or audio with constant quality, variablebandwidthbandwidth


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ATM Forum BE subclasses

Available Bit Rate (ABR)Available Bit Rate (ABR)

users get whatever is availableusers get whatever is available

zero loss if network signals (in RM cells) are obeyedzero loss if network signals (in RM cells) are obeyed

no guarantee on delay or bandwidthno guarantee on delay or bandwidth

Unspecified Bit Rate (UBR)Unspecified Bit Rate (UBR)

like ABR, but no feedbacklike ABR, but no feedback

no guarantee on lossno guarantee on loss

presumably cheaperpresumably cheaper

IETF GS subclasses

Tolerant GSTolerant GS

nominal mean delay, but can toleratenominal mean delay, but can tolerate occasionaloccasional variationvariation

not specified what this means exactlynot specified what this means exactly

usesuses controlledcontrolled--loadloadserviceservice

book uses older terminology (predictive)book uses older terminology (predictive)

even ateven at high loadshigh loads, admission control assures a source that its, admission control assures a source that itsserviceservice does not sufferdoes not suffer

it really is this imprecise!it really is this imprecise!

Intolerant GSIntolerant GS

need a worst case delay boundneed a worst case delay bound

equivalent to CBR+VBR in ATM Forum modelequivalent to CBR+VBR in ATM Forum model


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IETF BE subclasses

Interactive burstInteractive burst

bounded asynchronous service, where bound is qualitative, butbounded asynchronous service, where bound is qualitative, but

pretty tightpretty tight

e.g. paging, messaging, emaile.g. paging, messaging, email

Interactive bulkInteractive bulk

bulk, but a human is waiting for the resultbulk, but a human is waiting for the result

e.g. FTPe.g. FTP

Asynchronous bulkAsynchronous bulk

junk trafficjunk traffic

e.ge.g netnewsnetnews


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Pros and Cons Analysis

Having completed the discussion on Traffic Classes, it is necessary

to structure the summary of Pros and Cons for all the Traffic Classes.

This can be done with the help of an activity.

Suggested Activity: Board Activity

We can divide the learners into four groups namely, A, B, C and D. The following

table can be drawn on the board. Each group can be assigned one Traffic

Class. The groups can be asked to discuss and populate the cells

corresponding to the assigned class. Inputs can be taken from all the groupsand the table can be filled so that it will be easy for the learners to grasp and

memorize the key points.

ATM Forum IETF

GS BE GS BE

Basic entity of

measurement

Bandwidth Bandwidth Delay Delay

CBR

VBR

ABR

UBR

Intolerant

Tolerant

Interactive

burst

Interactive

bulk

Asynchronous

bulk

Example Telephone

call,

Compresses

video or

audio with

constant

quality

Compresses

video or

audio with

constant

quality

FTP,

Netnews

Paging,

Messaging,

Email


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Conclusion

We can conclude the session by revising the key concepts discussed by during

the session through q question and answer activity.

Suggested Activity: Questions and Answers

The following questions can be asked to ensure that the learners hav

gained a good understanding of the concepts discussed so far.

What are the advantages of traffic management? What are the basic principles of traffic models? How the traffic in guaranteed services and best effort service

managed.

What are the traffic classes? Give their classification. Explain the CBR, VBR, ABR, UBR, Intolerant, tolerant, Interactive bulk,

Interactive burst, asynchronous bulk with examples.


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Summary

In this session, we learnt to:

1. Identify the need of Traffic management.2. Dramatize the various Traffic management models;

Telephone traffic model; Internet Traffic model.

3. Presentation of the various Traffic classes;

Constant bit rate Variable bit rate Available bit rate Universal bit rate Intolerant Tolerant Interactive burst Interactive bulk Asynchronous bulk

4. Outline the pros and cons of different traffic classes.


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Assignment

1.Explain with examples the guaranteed services and best effort services.2.How we can manage the traffic of guaranteed services and best

effort services? Give example.3.What are the advantages and disadvantages of various traffic

classes?


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4.ReferencesAn Engineering Approach to Computer Network by S.Keshavhttp://www.cs.cornell.edu/skeshav/book/slides/

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