Applications plicalica catca - UBC ECEteerawat/publications/NS2/W11-Applications.pdf•Two NS2 A pplication 1. Traffic generator – Conform to a predefined scheduleConform to a predefined

ApplicationsApplicationsApplicationsApplicationsApplicationsApplicationsApplicationsApplications

Textbook: T. Issariyakul and E. Hossain, Introduction to Network Simulator NS2, Springer 2008. 1ed

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Outline• Application Overview

Timer• Timer• Two Derived Classes

– Traffic Generator– Simulated Application– Simulated Application

• Summary


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A Two Node NetworkA Two Node NetworkA li iApplication

Source Agent Sink Agent

packetn0 n1

Link: Connecting Nodes

Buffer ManagementAgent:

Packet Creation andD Node:

A computer host + A router

gDestruction

Application: Demand Indication

Textbook: T. Issariyakul and E. Hossain, Introduction to Network Simulator NS2, Springer 2008. 3

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Applicationd d d• Indicate user demand

• Two NS2 Applicationpp1. Traffic generator

– Conform to a predefined scheduleConform to a predefined schedule– E.G., CBR

2. Simulated applications– Create demand as if the application is– Create demand as if the application is

running– E.G. FTP


E.G., FTP

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NS2 Implementation• C++ Class Application

S ns/ pps/ pp h• See ~ns/apps/app.h,cc• Main variables: agent_g _

Textbook: T. Issariyakul and E. Hossain, Introduction to Network Simulator NS2, Springer 2008. 5PPrepook: T. Iss

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Functions of Class ApplicationFunctions of Class Application• send(nbytes): Tell TL to send out nbytes ofsend(nbytes): Tell TL to send out nbytes of

data ( agent_->sendmsg(nbyte) )

• recv(nbytes): Invoked by an agent; Be ( y ) y ginformed that nbytes are received.

• resume(): Invoked by sending agent when it h s s t t ll its p k tshas sent out all its packets

• start(): start the applicationst p(): st p th ppli ti n


• stop(): stop the applicationdIn

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OTcl Commands of Class Applicationpp

• start{}: start the applicationstart{}: start the application• stop{}: stop the application• attach-agent{$agent}: create a

two way connection to $agenttwo-way connection to $agent


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OTcl Commands A li ti tt h tApplication:: attach-agent

Textbook: T. Issariyakul and E. Hossain, Introduction to Network Simulator NS2, Springer 2008.8

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• Summary


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Timer

• Timer is similar to a Scheduler.I f i h S h d l• In fact, it uses the Scheduler.

• It provides interface toIt provides interface to – Schedule events,– Reschedule events, and

Cancel events– Cancel events.

Textbook: T. Issariyakul and E. Hossain, Introduction to Network Simulator NS2, Springer 2008. 10edev

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Sche

Timer Life Cycle

Active

• Active or Idle• Public functions

– sched(delay) or resched(delay)• start the timer• Wait till the timer expires• Take expiration action by invoking exire(e)


Take expiration action by invoking exire(e)– cancel() go back to Idle.

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Expiration ActionD fi d i f ti i ( )• Defined in function expire(e)

• E G Timer� MyTimerE.G., Timer � MyTimer

• Print out “MyTimer has just y jexpired!!”


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• Summary


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T ffi G n tTrafficGenerator

• Generate traffic based on a predefined schedule p f

• E.G., CBRC Cl T ffi G• C++ Class TrafficGenerator


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TrafficGeneratorff• Class declaration

Used to create packet arrival time

Packet size


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Traffic Timer• Class TrafficTimer derives from

class Timerclass Timer– Key variable: tgen_– Key function: expire(e)


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Traffic GeneratorTraffic GeneratorTrafficGenerator

• Relationship to trafficRelationship to traffic timerE l f k tgen_

timer_• Example of packet

generatorTrafficGenerator::timeout()

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Textbook: T. Issariyakul and E. Hossain, Introduction to Network Simulator NS2, Springer 2008. 17nextPkttime_

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Traffic Timer Life CycleTraffic Timer Life Cycle


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Class CBR TrafficClass CBR_Traffic

• C++: CBR Traffic� OTcl:C++: CBR_Traffic � OTcl: Application/Traffic/CBRF l / l/ b ff h• File: ~ns/tool/cbr_traffic.h,cc

• Key variables:Key variables:


Q: Where do we set the default values? ( ~ns/tcl/lib/ns-default.tcl )

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Si l t d A li tiSimulated Application

• Run as if the application is running• Interact with agent (function resume())• Interact with agent (function resume())• E.G. FTP,

– Instprocs/OTcl commands• attach-agent{agent}: Associate with an agent

t t{} St t t f i fil ith i fi it i• start{}: Start transferring a file with infinite size • stop{}: Stop the FTP

– Note: the connecting agent will send data onlyNote: the connecting agent will send data only when its congestion window allows


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• Summary


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SSummaryA li ti Th i• Applications: The main purpose =

( Indicate user demand )( )• Timer

h d l h d l l– schedule, reschedule, cancel– Timeout ( expiration action )

• Two derived classes– Traffic generator (e g CBR )– Traffic generator (e.g., CBR )– Simulated application (e.g., FTP )

Textbook: T. Issariyakul and E. Hossain, Introduction to Network Simulator NS2, Springer 2008. 22dgen

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Related Files• ~ns/apps/app.h,cc• ~ns/tool/trafgen.h,ccfg ,• ~ns/tool/cbr_traffic.h,cc


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Documents

Applications plicalica catca - UBC ECEteerawat/publications/NS2/W11-Applications.pdf•Two NS2 A pplication 1. Traffic generator – Conform to a predefined scheduleConform to a predefined