39. Rc1 Simulazione-ns3

8/9/2019 39. Rc1 Simulazione-ns3

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Simulation of computer networks 1

Corso di Reti di Calcolatori I

Network simulation with ns-3


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Outline of presentation

• Breve introduzione al concetto disimulazione di computer networks

•Tutorial su ns-3 – ntroduzione – !rchitettura

– "ettura di codice


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To evaluate protocols and distri#uted al$orithms forcomputer networks the followin$ alternatives are

possi#le%

1& Small scale e'perimental test#eds (in the la#orator)&

2& Test#ed sperimentali su media scala (wide area&* +lanet"a#

3& Sistemi di network emulation

,& !m#ienti di simulazione $enerali per reti di calcolatori

• ns-3* "./.S/* .+N0T* NTns*

1& Strumenti di simulazione sviluppati ad hoc

2& /odelli matematici del sistema

Simulation of computer networks


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What is simulation?

system under study(has deterministic rulesgoverning its behavior)

exogenous inputsto system

(the environment)

system boundary

observer

“real” life

computer program

simulates deterministicrules governing behavior

pseudo random inputs

to system(models environment)

program boundary

observer

“simulated” life


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Why Simulation?

goal: stud) s)stem performance, operation real-s)stem not available, is complex/costly or

dangerous ( e$% space simulations* fli$ht simulations& 6uickl) evaluate desi$n alternatives (e$% different

s)stem confi$urations& evaluate complex functions for which closed form

formulas or numerical techni6ues not availa#le Need of complete control over the inputs of the s)stem


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!strazione enerazione di scenari (topolo$ie* pattern di

traffico* 888&

+ro$ramma#ilit9

0stendi#ilit9 :isponi#ilit9 di un;ampia $amma di moduli

di protocolli riutilizza#ili* affida#ili e validati

+ossi#ilit9 di modificare protocolli esistenti


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Simulation of computer networks =

Prorammin a simulation

>hat ?s in a simulation pro$ram@ simulated time: internal (to simulation pro$ram& varia#le thatkeeps track of simulated time

system “state”: varia#les maintained #) simulation pro$ramdefine s)stem Astate

e8$8* ma) track num#er (possi#l) order& of packets in 6ueue* currentvalue of retransmission timer

events: points in time when s)stem chan$es state each event has associated event time

e8$8* arrival of packet to 6ueue* departure from 6ueue

precisel) at these points in time that simulation musttake action (chan$e state and ma) cause new futureevents&

model for time #etween events (pro#a#ilistic& caused #) e'ternalenvironment


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Simulation of computer networks C

!iscrete "vent Simulation

simulation pro$ram maintains and updates list of futureevents% event list

simulator structure%

initialize event list

$et ne't (nearest future&event from event list

time D event time

process event(chan$e state values* addEdelete

future events from event list

update statistics

done@no

Need%

well defined set ofevents

for each event%simulated s)stemaction* updatin$ ofevent list

yes


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Simulation of computer networks 1F

Thins to remem#er a#out !iscrete "vent Simulation

The pro$rammin$ model revolves around Aevents(e$% packet arrivals&% 0vents tri$$er particular su#-routines

Gu$e Aswitch statement to classif) events and call appropriatesu#routine

The su#routine ma) schedule new eventsH (cannot scheduleevents for past* 8e8* events are causal&

Iarel) )ou mi$ht introduce new event types

0vents have associated with them% 0vent t)pe* event data structures (e$% packet&

Simulation time when the event is scheduled Je) event operations% Enqueue (8e8 schedule a event&

:e6ueue is handled #) the simulation en$ine


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!iscrete "vent Simulation$ Scheduler

+urpose% maintain a notion of simulation time* scheduleevents8 !8k8a% Asimulation en$ine Simulation time ≠ Ieal time

! simulation for 4 sec of video transmission might take 1 hourH

0vents are sorted #) simulation time (not #) t)peH&%priorit) 6ueue or heap data structure !fter all su#routines for an event have #een e'ecuted* control is

transferred to the simulation en$ine The simulation en$ine schedules the ne't event availa#le at the same

time (if an)& .nce all the events for current time have #een e'ecuted* simulation time

is advanced and nearest future event is e'ecuted8 Simulation time D time of currentl) e'ecutin$ event


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Simulation$ e%ample

packets arrive (av$8 interrarrival time% 1E λ& to router (av$8e'ecution time 1Eµ& with two out$oin$ links arrivin$ packet Koins link i with pro#a#ilit) φi

µ1

µ2

state of s)stem% size of each 6ueue

s)stem events% packet arrivals

service time completions

λ


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Simulation$ e%ample

µ1

µ2

λSimulator actions on arrival event choose a link

if link idle Lplace pkt in service* determine service time(random num#er drawn from service time distri#ution& add

future event onto event list for pkt transfer completion* setnum#er of pkts in 6ueue to 1M

if #uffer full Lincrement dropped packets* i$nore arrivalM else increment num#er in 6ueue where 6ueued

create event for ne't arrival ($enerate interarrivaltime& stick event on event list


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Simulation of computer networks 1,

Simulation$ e%ample

µ1

µ2

λSimulator actions on departure event

remove event* update simulation time* updateperformance statistics

decrement counter of num#er of pkts in 6ueue f (num#er of Ko#s in 6ueue O F& put ne't pkt into

service – schedule completion event ($enerateservice time for put&


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&s'( tutorial$ assumptions

• Some familiarit) with PP pro$rammin$lan$ua$e

• Some familiarit) with ni' Network+ro$rammin$ (e8$8* sockets&

• Some familiarit) with discrete-eventsimulators


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Resources

>e# site%http%EEwww8nsnam8or$

/ailin$ list%

http%EEmailman8isi8eduEmailmanElistinfoEns-developers

Tutorial%

http%EEwww8nsnam8or$EdocsEtutorialEtutorial8html

ode server%

http%EEcode8nsnam8or$

>iki%

http%EEwww8nsnam8or$EwikiEinde'8phpE/ainQ+a$e

http://www.nsnam.org/http://mailman.isi.edu/mailman/listinfo/ns-developershttp://www.nsnam.org/docs/tutorial/tutorial.htmlhttp://code.nsnam.org/http://www.nsnam.org/wiki/index.php/Main_Pagehttp://www.nsnam.org/wiki/index.php/Main_Pagehttp://www.nsnam.org/wiki/index.php/Main_Pagehttp://code.nsnam.org/http://code.nsnam.org/http://www.nsnam.org/docs/tutorial/tutorial.htmlhttp://www.nsnam.org/docs/tutorial/tutorial.htmlhttp://mailman.isi.edu/mailman/listinfo/ns-developershttp://www.nsnam.org/http://www.nsnam.org/


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Simulation of computer networks 1=

Resources )*+

• /ost of the ns-3 !+ is documented with:o')$en

http%EEwww8nsnam8or$Edo')$enEinde'8html


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Simulation of computer networks 1C

Outline of the tutorial

• ntroduction to ns-3

• !rchitecture of ns-3

• Ns-3 lo$$in$ and tracin$• Ns-3 e'amples


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Introduction to ns'(

• ns-3 is written in PP

• Bindin$s in +)thon

• ns-3 uses the waf #uild s)stem• simulation pro$rams are either PP

e'ecuta#les or p)thon scripts


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the waf #uild system

• >af is a +)thon-#ased framework forconfi$urin$* compilin$ and installin$ applications8

– t is a replacement for other tools such as !utotools* Scons* /ake or !nt

– http%EEcode8$oo$le8comEpEwafE

• To download the simulator

– h$ clone http%EEcode8nsnam8or$Ens-3-allinone

•Steps to #uild the simulator – cd ns-3-dev

– 8Ewaf R-d optimizedde#u$ confi$ure R--ena#le-modulesDnetanim

– make -O 8Ewaf

– make test -O 8Ewaf check (run unit tests&

http://code.google.com/p/waf/http://code.google.com/p/waf/


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waf key concepts

• an run pro$rams throu$h a special wafshellU e8$8 – ./waf --run simple-point-to-point

– (this $ets the li#rar) paths ri$ht for )ou&


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Outline of the tutorial



• Ns-3 lo$$in$ and tracin$• Ns-3 e'amples


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!pplication

,rchitecture$ the #asic model

!pplication

+rotocolstack

Node

Net:eviceNet:evice

!pplication !pplication

+rotocolstack

Node

Net:eviceNet:evice

Sockets-like !+

hannel

hannel

+acket(s&


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-undamentals

Je) o#Kects in the simulator are Nodes*+ackets* and hannels

Nodes ma) contain !pplications* Astacks*and Net:evices


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&ode #asics

! Node is a husk of a computer to whichapplications* stacks* and Ns are added

!pplication !pplication !pplication

Astacks


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&et!evices and Channels

Net:evices are stron$l) #ound to hannelsof a matchin$ t)pe

Nodes are architected for multiple interfaces

Wifi&et!evice

WifiChannel


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&ode #asics

Two ke) a#stractions are maintained%1& applications use an (as)nchrounous for

the moment& sockets !+

– Based on the BS: Socket !+2& the #oundar) #etween + and la)er 2

mimics the #oundar) at the device-

independent su#la)er in "inu'i8e8* "inu' +acket Sockets


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&s'( packets

• each network packet contains a #)te #uffer*a list of ta$s* and metadata – #uffer$ #it-#)-#it (serialized& representation of

headers and trailers

– tas$ set of ar#itrar)* user-provided datastructures (e8$8* per-packet cross-la)ermessa$es* or flow identifiers&

– metadata$ descri#es t)pes of headers andand trailers that have #een serialized

• optional-- disa#led #) default


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&s'( packets )*+

• 0ach t)pe of header is represented #) asu#class of ns3%%Geader

• to add a new header* su#class fromGeader* and write )our Serialize(& and:eserialize(& methods – how #its $et written toEfrom the Buffer

• Similar for +acket Ta$s


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Simulation #asics

• Simulation time moves discretel) fromevent to event

• ! simulation scheduler orders the event

e'ecution• Simulation%%Iun(& $ets it all started

• Simulation stops at specific time or when

events end (Simulation%%Stop(&&


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&s'( o#.ect metadata system

• ns-3 is* at heart* a PP o#Kect s)stem

• ns-3 o#Kects that inherit from #ase classns3%%.#Kect $et several additional features

– d)namic run-time o#Kect a$$re$ation

– an attri#ute s)stem

– smart-pointer memor) mana$ement


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O#.ect areation

• Vou can a$$re$ate o#Kects to one anotherat run-time

– !voids the need to modif) a #ase class to

provide pointers to all possi#le connectedo#Kects

• .#Kect a$$re$ation is planned to #e the

main wa) to create new Node t)pes(rather than su#classin$ Node&


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O#.ect areation e%ample

• Gow a$$re$ation works

• Gow to access on a$$re$ated o#Kect


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,ttri#utes

• !n !ttri#ute represents a value in ours)stem

• !n !ttri#ute can #e connected to anunderl)in$ varia#le or function

– e8$8 TcpSocket%%mQcwndU

– or a trace source


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,ttri#utes )*+

• >hat would users like to do@ – Set a default initial value for a varia#le

– Set or $et the current value of a varia#le

– Jnow what are all the attri#utes that affect thesimulation at run time

– nitialize the value of a varia#le when a

constructor is called• The attri#ute s)stem is a unified wa) of

handlin$ these functions


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/ow to handle attri#utes?

• The traditional PP wa)%

– e'port attri#utes as part of a classWs pu#lic !+

– walk pointer chains (and iterators* when

needed& to find what )ou need

– use static varia#les for defaults

• The attri#ute s)stem provides a more

convenient !+ to the user to do thesethin$s


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The traditional C00 way

class Foo {

public: void SetVar1 (uint32t value!"

uint32t #etVar1 (void!"

static void Set$nitialVar1(uint32t value!"

void SetVar2 (uint32t value!"

uint32t #etVar2 (void!"

static void Set$nitialVar2(uint32t value!"

...

private: uint32t mvar1" // document var1

uint32t mvar2" // document var2

static uint32t minitialvar1"

static uint32t minitialvar2"

%

Foo::Foo(! : mvar1(Foo::minitialvar1!& mvar2(Foo::minitialvar2!{

%

To modif) an instance of Xoo* $et the pointer somehow* and use the pu#lic accessor functions

To modif) the default values* modif) the statics

:efault values ma) #e availa#le in a separate framework (e8$8 ns-2 Bind(&&


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&aviatin the attri#utes

• !ttri#utes are e'ported into a strin$-#asednamespace* with files)stem-like paths

– namespace supports re$ular e'pressions

• 0'amples% – Nodes with identifiers 1* 3* ,* 4* =* C* 1F* 11%

AENode"istER3-4R=-11

– dp",+rotocol o#Kect instance a$$re$ated to matchin$ nodes%

AENode"istER3-4R=-11EYdp",+rotocol – dp",+rotocol o#Kect instances of all nodes%

AENode"istEZEYdp",+rotocol

– 0nd+oints which match the Src+ortD1F24 specification%

AE0nd+ointsEZ%Src+ortD1F24


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Simulation of computer networks ,F

Creatin references in the namespace

• Names%%!dd ([server[* serverNode&U• Names%%!dd ([serverEethF[* server:evice&U

• 888

• onfi$%%Set([ENamesEserverEethFET'\ueueE/a'+ackets[* inte$er


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Simulation of computer networks ,1

,ttri#utes$ details

• !ttri#utes also can #e referred to withoutthe paths – e8$8 'ans)ifi*+,::#ain

• ! onfi$ class allows users to manipulatethe attri#utes – e8$8% Set a default initial value for a varia#le

– (Note% this replaces :efault


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,ttri#utes$ details

• Set or $et the current value of a varia#le• Gere* one needs the path in the namespace to the

ri$ht instance of the o#Kect0onfi::Set4ttribute('/5ode6ist/7/evice6ist/

3/ans)ifi*+,/#ain& ouble(1.!!"ouble d 80onfi::#et4ttribute('/5ode6ist/7/5etevice/3/ans)ifi*+,/#ain!"

• sers can $et +trs to instances also* and+trs to trace sources* in the same wa)


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/ow is all this implemented )overview+

class Foo: public 9bect

{public:

static ,pe$d #et,pe$d (void!"

private:



%

Foo::Foo(! {%

,pe$d Foo::#et,pe$d (void!

{

static ,pe$d tid 8 ,pe$d('Foo!

.4dd0onstructor;Foo< (!"

.4dd4ttribute ('mvar1& 'document var1&

=$nteer(3!& >a?e=$nteer4ccessor (@Foo::mvar1!&

>a?e=$nteer0+ec?er;uint32t< (!!

return tid"

%


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Simulation of computer networks ,,

, real TypeId e%ample

,pe$d

Aandom)al?2d>obilit,>odel::#et,pe$d (void!{

static ,pe$d tid 8 ,pe$d (BAandom)al?>obilit,>odelB!

.Set*arent;>obilit,>odel< (!

.Set#roup5ame (B>obilit,B!

.4dd0onstructor;Aandom)al?2d>obilit,>odel< (!

.4dd4ttribute (BboundsB&

BCounds of t+e area to cruise.B&

Aectanle (.& .& 1.& 1.!& >a?eAectanle4ccessor (@Aandom)al?2d>obilit,>odel::mbounds!&

>a?eAectanle0+ec?er (!!

.4dd4ttribute (BtimeB&

B0+ane current direction and speed after movin for t+is dela,.B&

Seconds (1.!&

>a?eime4ccessor (@Aandom)al?2d>obilit,>odel::mmodeime!&

>a?eime0+ec?er (!!

.4dd4ttribute (BdistanceB& B0+ane current direction and speed after movin for t+is distance.B&

Seconds (1.!&

>a?eime4ccessor (@Aandom)al?2d>obilit,>odel::mmodeime!&

>a?eime0+ec?er (!!


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O#.ect system$ smart pointers

• ns-3 uses reference-countin$ smartpointers at its !+s to limit memor) leaks

– .r Apass #) value or Apass #) reference toconst where appropriate

• ! Asmart pointer #ehaves like a normalpointer (s)nta'& #ut does not lose memor)when reference count $oes to zero

• se them like #uilt-in pointers% *tr;>,0lass< p 8 0reate9bect;>,0lass< (!"

p-


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CreateO#.ect12 )+3

• reate.#Kect]O is a wrapper for operator new8

• >h) not Kust* e8$8* Node Z node D new Node(&@ – Vou have to mana$e the memor) allocation and

deallocation• ns3%%.#Kect are created on the heap usin$

reate.#Kect]O (&* which returns a smartpointerU e8$8

*tr;5ode< r5ode 8 0reate9bect;5ode< (!"


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Create12 )+3

• >hat is reate]O (&@

• reate]O provides some smart pointerhelp for o#Kects that use ns3%%+tr]O #utthat do not inherit from .#Kect8

• +rincipall)* class ns3%%+acket*tr;*ac?et< p 8 0reate;*ac?et<

(data&siDe!"


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Simulation of computer networks ,=

&on'default constructors

• The attri#ute s)stem allows )ou to alsopass them throu$h the reate.#Kect]Oconstructor8

• This provides a generic non-defaultconstructor for users (an) com#ination ofparameters&* e8$8%

*tr;ans)ifi*+,< p+, 8 0reate9bect;ans)ifi*+,<('#ain& ouble (1.!!"


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Simulation of computer networks ,C

/ow to parse command line aruments

• To confiure the from the command line ns'(provides the Command facility

• int main (int ar$c* char Zar$vR&

L

888

ommand"ine cmdU cmd8+arse (ar$c* ar$v&U

888

M

• The snippet of code a#ove ena#les the settin of all

the attri#utes in the ns'( attri#utes namespace

• 8Ewaf --run [scratchEfirst --ns3%%+ointTo+ointNet:evice%%:ataIateD4/#ps[


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/ow to parse command line aruments )*+

• ustom $lo#al properties can #e set fromthe command line as well – int main(int ar$c* char Z ar$vR&L

888

uint32Qt n+ackets D 1U

ommand"ine cmdUcmd8!dd


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/elpers o#.ects

• +rovide simple Ws)ntactical su$arW to makesimulation scripts look nicer and easier to read fornetwork researchers

• Gelpers make it easier to repeat the sameoperations on a set of resources (e8$8 nodes*interfaces&

• The settin$s are applied to the helper and used to

perform the operations on the resources• 0ach function applies a sin$le operation on a WWset

of same o#Kects


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/elper O#.ects )*+

• nternetStackGelper • /o#ilit)Gelper

• .lsrGelper

• 888 0ach model provides a helper class• >hat does this appl) to@

– Nodeontainer% vector of +tr]NodeO

– Net:eviceontainer% vector of +tr]Net:eviceO

T t i l tli


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Tutorial outline

• ntroduction to ns-3• !rchitecture of ns-3

• Ns-3 lo$$in$ and tracin$

• Ns-3 e'amples


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&s'( loin

• ns-3 has a #uilt-in lo$$in$ facilit) to stderr

• Xeatures% – /ultiple lo$ levels like s)slo$

– can #e driven from shell environmentvaria#les

– Xunction and call ar$ument tracin$

• ntended for de#u$$in$* #ut can #e

a#used to provide tracin$ – t is not $uaranteed that format is unchan$in$


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&s'( loin e%ample

• 4oin facilities

– NSQ".Q0II.I -- "o$ error messa$esU – NSQ".Q>!IN -- "o$ warnin$ messa$esU

– NSQ".Q:0B -- "o$ relativel) rare* ad-hoc de#u$$in$ messa$esU

– NSQ".QNX. -- "o$ informational messa$es a#out pro$ram pro$ressU

– NSQ".QXNT.N -- "o$ a messa$e descri#in$ each function calledU

– NSQ".Q". -- "o$ messa$es descri#in$ lo$ical flow within a functionU

– NSQ".Q!"" -- "o$ ever)thin$8 – NSQ".QN.N:(& – "o$ unconditionall) (irrespective to the de#u$ settin$s&U

• /ow to activate loin messaes$

– Xrom the shell

• e'port NSQ".D>ifiNet:evice%Vans>ifihannel (ni'&

• e'port NSQ".DZ (ni'&

• e'port NSQ".Ddp0cholient!pplicationDlevelQall

– n the code

• "o$omponent0na#le([lass[* ".NQ"0


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Tracin model

• Tracin$ is a structured form of simulation output

– tracin$ format should #e relativel) static across simulatorreleases

• 0'ample (from ns-2&%

E 1.G3H7 2 cbr 21 ------- . 3.1 227 I1

- 1.G3H7 2 cbr 21 ------- . 3.1 227 I1

r 1.GGH1 2 1 cbr 21 ------- 1 3. 1. 1J7 I

r 1.G7II 2 ac? G ------- 2 3.2 .1 2 I2

E 1.G7II 2 tcp 1 ------- 2 .1 3.2 12 I11

• Needs var) widel)


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Crude tracin

Kinclude ;iostream<

...

int main (!

{ ...

std::cout ;; B+e value of is B ;; ;;

std::endl"

...

%


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Slihtly less crude

Kinclude ;iostream<

...

int main (!

{ ...

5S69#=5095 (B+e value of is B ;; !"

...

%


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Simple ns'( tracin

• these are wrapper functionsEclasses

• see e'amplesEmi'ed-wireless8cc Kinclude Bns3/ascii-trace.+B

4sciirace asciitrace (Bmied-wireless.trB!"

asciitrace.race4llLueues (!"

asciitrace.race4ll5eteviceA (!"


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Simple ns'( tracin )pcap version+

• these are wrapper functionsEclasses

• see e'amplesEmi'ed-wireless8cc Kinclude Bns3/pcap-trace.+B

*caprace pcaptrace (Bmied-wireless.pcapB!"

pcaptrace.race4ll$p (!"


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&s'( tracin model

• Xundamental 1% decouple trace sourcesfrom trace sinks

• Xundamental 2% prefer standard trace

outputs for #uilt-in traces

Trace source

Trace source

Trace source

Trace sink

unchaninconfiura#le #yuser


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Tracin overview

• Simulator provides a set of pre-confi$uredtrace sources

– sers ma) edit the core to add their own

• sers provide trace sinks and attach to thetrace source

– Simulator core provides a few e'amples for

common cases• /ultiple trace sources can connect to a

trace sink


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5ultiple levels of tracin

• Gi$hest-level% se #uilt-in trace sourcesand sinks and hook a trace file to them

• /id-level% ustomize trace sourceEsink

#ehavior usin$ the tracin$ namespace

• "ow-level% !dd trace sources to thetracin$ namespace

– .r e'pose trace source e'plicitl)


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/ih'level of tracin

• Gi$h-level% se #uilt-in trace sources andsinks and hook a trace file to them

// 4lso confiure some tcpdump traces" eac+ interface will be traced

// +e output files will be named

// simple-point-to-point.pcap-;node$d


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/ih level of tracin )*+

//Su Helper di interfaccia

...

void EnablePcap (std::string prefix, Ptr


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Readin pcap files

• pcap files can #e read #) means of – >ireshark – Tcpdump

// Nample of tcpdump usae

tcpdump -nn -tt -r simple-point-to-point.pcap

readin from file m,first--.pcap& lin?-t,pe *** (***!

2. $* 1.1.1.1.GJ173 < 1.1.1.2.J: =*& lent+ 12G

2.71GIG $* 1.1.1.2.J < 1.1.1.1.GJ173: =*& lent+ 12G


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5id'level of tracin

• /id-level% ustomize trace sourceEsink#ehavior usin$ the tracin$ namespace

static void &+ndracer (uint')t oldval, uint')t ne+val$

-

NS)0)1N# (23oving c+nd fro! 2


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4ow'level of tracin

• :efine )our own trace sources• Xor specific advanced needs

• Need to modif) the core of ns-3

–an #e defined in custom-elements –0as) to appl) to an) e'istin$ o#Kect

attri#ute


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,n additional trace method$ statistics

• !void lar$e trace files

• ollect statistics of the simulation

• Ieuse tracin$ framework

• .ne similar approach% ns-2-measure proKect – http%EEinfo8iet8unipi8itE^cn$Ens2measureE

– Static AStat o#Kect that collects samples of varia#les #ased on e'plicitfunction calls inserted into the code

– raphical front end* and framework for replicatin$ simulation runs

• Xlow/on is currentl) availa#le

– http%EEtelecom8inescn8ptE^$KcEflowmon-presentation8pdf

& ( i l


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&s'( tutorial



• "o$$in$ and tracin$

• Ns-3 e'amples

l 6 di t


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e%amples6 directory

• e'amplesE contains other scripts with similar themesO lscsma-broadcast.cc simple-point-to-point.cc

csma-multicast.cc tcp-lare-transfer-errors.cc

csma-one-subnet.cc tcp-lare-transfer.cc

csma-pac?et-soc?et.cc tcp-nonlistenin-server.cc

mied-lobal-routin.cc tcp-small-transfer-oneloss.ccsimple-alternate-routin.cc tcp-small-transfer.cc

simple-error-model.cc udp-ec+o.cc

simple-lobal-routin.cc wafsimple-point-to-point-olsr.cc wscript

-irst e%ample )udp'echo+


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-irst e%ample )udp'echo+

• >e simulate a simple network with 2nodes connected throu$h an ethernet link

• .ne node send a (udp& packet to asecond node

• The second node receives the packet andsend a cop) of the packet #ack

udp'echo


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udp'echo

• Xirst step% create nodes – ode!ontainer n

– n"!reate (#$%

• nstall the fundamental T+E+ entitieson the nodes – &nternet'tac)elper internet%

– internet"&nstall (n$%

7dp'echo )*+


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7dp'echo )*+

• reate the local network (i8e8 ethernetnetwork& – !sma)elper csma%

– csma"'et!hannel*ttribute (+ata-ate+,

ata-ate.alue (ata-ate (000000$$$% – csma"'et!hannel*ttribute (+elay+, 1ime.alue

(2illi'econds (3$$$%

– csma"'etevice*ttribute (+2tu+, 4integer.alue

(5#00$$% – etevice!ontainer d 6 csma"&nstall (n$%

7dp'echo )(+


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7dp echo )(+

• !ssi$n the addresses to the nodesWinterfaces – &pv#*ddress)elper ipv#%

– ipv#"'et7ase (+50"5"5"0+, +3"3"3"0+$%

– &pv#&nterface!ontainer i 6 ipv#"*ssign (d$% – server*ddress 6 *ddress(i"8et*ddress (5$$%

udp'echo


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udp echo

• nstall the server application on node 1 – uint59t port 6 ;% // well


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udp echo

• nstall the client application on node F – uint=3t pacet'i>e 6 503#% – uint=3t max?acet!ount 6 5%

– 1ime inter?acet&nterval 6 'econds (5"$%

– 4dpEcho!lient)elper client (server*ddress, port$%

– client"'et*ttribute (+2ax?acets+, 4integer.alue(max?acet!ount$$%

– client"'et*ttribute (+&nterval+, 1ime.alue (inter?acet&nterval$$%

– client"'et*ttribute (+?acet'i>e+, 4integer.alue (pacet'i>e$$%

– apps 6 client"&nstall (n"8et (0$$%

– apps"'tart ('econds (3"0$$%

– apps"'top ('econds (50"0$$%

udp'echo


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udp echo

• 0na#le netanim lo$s – Rinclude [ns3Enetanim-module8h[ – !nimationnterface anim ([udp-echo8'ml[&U

• 0na#le pcap lo$s

– !sciiTraceGelper asciiU – csma80na#le!scii!ll (ascii8reateXileStream ([udp-

echo8tr[&&U

– csma80na#le+cap!ll ([udp-echo[* false&U

• Start the simulation – Simulator%%Iun (&

One more thin ns ( sed for em lation


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One more thin$ ns'( used for emulation

virtualmachine ns-3

virtualmachine realmachine

ns-3

Test#ed Test#ed

realmachine

ns-3

1& ns-3 interconnects virtualmachines

2& test#eds interconnect ns-3stacks

real machine

Summary


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=F

Summary

• ns-3 is an emer$in$ simulator to replace ns-2

• onsider ns-3 if )ou are interested in% – /odular architecture

• 0asil) e'tenda#le

– /ore faithful representations of real computers andthe nternet

– nte$ration with test#eds – ! powerful low-level !+ – +)thon scriptin$

39. Rc1 Simulazione-ns3

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