2008.03.18(Tue) 1 Network Simulator 2 - Introduction for Beginners - 2008. 03. 18 CNLAB ns - 2 seminar

2008.03.18(Tue)2008.03.18(Tue) 11

Network Simulator 2Network Simulator 2

- Introduction for Beginners -- Introduction for Beginners -

2008. 03. 182008. 03. 18

CNLABCNLAB

nsns--22 seminar seminar

2008.03.18(Tue)2008.03.18(Tue) 22

Scope

Basic Requirements for Using ns-2

1) C++

2) Tcl & OTcl

3) Object Orientation concepts

4) ns-2 Mechanisms (ns-2 Core & Utilities)

5) Application-specific Implementation Architectures

. Wired ~ to Wireless world

. Lower Layer ~ to Higher Layer

. Variety of architectural specifics

2008.03.18(Tue)2008.03.18(Tue) 33

Scope

Introduction

Some Basic Concepts - Architectural Views- Plumbing & Duality

- Tcl basics

OTcl Linkage Architecture

Object Orientation in OTcl

Elemental Procedures in ns-2 programming- Network creation- Agents & others

2008.03.18(Tue)2008.03.18(Tue) 44

Introduction

Ns has began as a variant of the REAL network simulator in 1989, and has evolved substantially in the past few years.

In 1995 ns development was supported by DARPA through the VINT project at LBL, Xerox PARC, UCB, and USC/ISI.

- VINT : Virtual InterNet Testbed

http://www.isi.edu/nsnam/ns/

The latest version : ns-2.32 [2007] : hundreds * 1000 LOC

http://www.isi.edu/nsnam/ns/

2008.03.18(Tue)2008.03.18(Tue) 55

Introduction

RRelated Research area - functionality & application

- Network Layer . Routing : unicast, multicast, MPLS . QoS : IntServ / DiffServ . Queuing Disciplines

- Transport . TCP . Reliable multicast . Congestion control

- Application . Web Caching . Multimedia . Traffic Sources

- Wireless world . Mobile IP . Ad hoc routing . Sensor MAC

2008.03.18(Tue)2008.03.18(Tue) 66

Introduction

TK8.x OTcl tclclTcl8.x ns-2 nam-1

tcl

ex test lib

. . .

..

.examples validation tests

C++ code

OTcl code

ns-allinone

mcast

NS-2 Directory

2008.03.18(Tue)2008.03.18(Tue) 77

Introduction

What is NS-2 ? - Discrete Event Simulator

- Packet-level

- Link layer and up

- Wired and Wireless worlds

Languages

- Tcl (Tool Command Language)

- OTcl (MIT Object-oriented Tcl)

- C++

- Some others

2008.03.18(Tue)2008.03.18(Tue) 88

Introduction

Tcl Interpreter with Extents - OTcl : Object-oriented support, extending Tcl/Tk

- TclCL : C++ and OTcl Linkage (interface)

- Discrete Event Scheduler (ordered list of events)

- Data Network (the Internet) Components

tcl8.x

Otcl

tclcl

ns-2EventScheduler

Netw

orkC

omp

onen

t

Users

2008.03.18(Tue)2008.03.18(Tue) 99

Basic Concepts – Architectural View

Object-oriented (C++, OTcl) - Reusability

- Maintenance

Scalability + Extensibility- Control / ““Data” separation

. OTcl for control (scenarios)

. C++ for “data”

- Split OTcl / C++ objects Duality Needs Linkage

Modular approach - Fine-grained Object composition

2008.03.18(Tue)2008.03.18(Tue) 1010


OTcl Script

Analysis

NetworkAnimator

NS Simulator Library

. Event Scheduler Objects. Network Component Objects

. Network Setup Help Modules(Plumbing Modules)

OTcl : Tcl Interpreterwith OO extensions

NAM

..................

..................

SimulationProgram

SimulationResults

Simplified User’s View of NS - NS-2 is basically the Tcl & OTcl Interpreter with network simulation object libraries.

2008.03.18(Tue)2008.03.18(Tue) 1111


Layered View of the NS [an example]

- OTcl : Application, Scenario, or Upper Layer - C++ : Lower Layer or Protocol/Packet Layer

Ingress NodeSource Node Egress Node

TransportC++ Layer

OTcl Lib

TransportC++ Layer

Core Node

ApplicationProcedure

TransportC++ Layer

OTcl Lib

TransportC++ Layer

OTcl Lib

2008.03.18(Tue)2008.03.18(Tue) 1212


Components domain Relationship View of the NS

- NS-2 is written in C++ with OTcl Interpreter as the Front-End.

- Simulator objects are implemented in the Compiled hierarchy (C++ domain), but instantiated through the Interpreter.

2008.03.18(Tue)2008.03.18(Tue) 1313

Basic Concepts - Architecture

Nodes

Node

Link

Nodeentry

entry_

LinkLink

PortClassifier

AddrClassifier

classifier_

dmux_

Agent

Agent

Agent

App

2008.03.18(Tue)2008.03.18(Tue) 1414

n0 n1

Addr Classifier

Port Classifier

classifier_

dmux_

entry_

Node entry

Unicast Node

Multicast Classifier

classifier_

dmux_

entry_

Node entry

Multicast Node

multiclassifier_

Classifier : Address, Multicast, Multipath

Nodes


2008.03.18(Tue)2008.03.18(Tue) 1515


Links

n0 n1

enqT_ queue_ deqT_

drophead_ drpT_

link_ ttl_

n1 entry_

head_

tracing simplex link

duplex link

2008.03.18(Tue)2008.03.18(Tue) 1616


n0 n1

Addr Classifier

Port Classifier

classifier_

dmux_

entry_

Node entry

0

1 enqT_ queue_ deqT_

drophead_ drpT_

link_ ttl_n1 entry_head_

Nodes & Links

2008.03.18(Tue)2008.03.18(Tue) 1717

n0 n1

Addr Classifier

Port Classifier

classifier_

dmux_

entry_

0

1

Addr Classifier

Port Classifier

classifier_

dmux_

entry_

1

0Link n0-n1

Link n1-n0


Routing

2008.03.18(Tue)2008.03.18(Tue) 1818

0

1

n0 n1

Addr Classifier

Port Classifier

classifier_

dmux_

entry_

0 Agent/TCP

agents_

Addr Classifier

Port Classifier

classifier_

dmux_

entry_

1

0Link n0-n1

Link n1-n0

0 Agent/TCPSinkagents_

dst_=1.0 dst_=0.0


Transport

2008.03.18(Tue)2008.03.18(Tue) 1919

0

1

n0 n1

Addr Classifier

Port Classifier

classifier_

dmux_

entry_

0 Agent/TCP

agents_

Addr Classifier

Port Classifier

classifier_

dmux_

entry_

1

0Link n0-n1

Link n1-n0

0 Agent/TCPSink

agents_

dst_=1.0 dst_=0.0Application/FTP

Application : Traffic Generator


2008.03.18(Tue)2008.03.18(Tue) 2020


TclObject

NsObject

Connector Classifier

Delay AddrClassifierAgent McastClasifierQueue Trace

DropTail RED TCP Enq Deq Drop

Reno SACK ...

Object Hierarchy

other objects

2008.03.18(Tue)2008.03.18(Tue) 2121


Some differences between NS-2 & Real network

- Node : no queue, above network layer, no lower layer on the basic Node (not in mobile node)

- Link : Compound object with Queues

- No physical media, but simulated environment

- No real data or payload transmissions, except in special applications (web), which uses special transport.

- Normally, the ultimate Packet Transmissions are done by calling the next object’s method (recv( )).

2008.03.18(Tue)2008.03.18(Tue) 2222

Basic Concepts - Plumbing

Network Topology Setup using- Network Objects : Nodes & Links *cf) NsObject

- Plumbing Library functions

Plumbing : for Network Setup

- Plumbing Data Paths among the Network Objects by setting the “Neighbor” pointers of an Object to the Address of an appropriate object.

- Plumbing modules are implemented as member functions of the base Simulator object.

- neighbor_, target_ variables are key to plumbing transmission : target_recv( )

2008.03.18(Tue)2008.03.18(Tue) 2323

Basic Concepts - Duality

C++ OTcl

Pure C++objects

Pure OTclobjects

C++ / OTcl split objects

ns

TclCL linkage

OTcl & C++ Share Class Hierarchy

2008.03.18(Tue)2008.03.18(Tue) 2424


C++ / OTcl Separation - C++ for “Data” . Per Packet action : Packet Headers accessed

- OTcl for Control

. Periodic or Triggered action (~ Scenario scheduling)

. Network(Topology) Creation : Application procedure

- Tradeoff between Composability and Speed (+)

- Learning/debugging are more difficult (-)

Separation on Dual planes need Linkage to compose

2008.03.18(Tue)2008.03.18(Tue) 2525


OTcl : Interpreted hierarchy - Create Network

- Create Connection (wired)

- Create Traffic

C++ : Compiled hierarchy - Packet processing methods

- OTcl command Interpreter

. object::command( ) method : one of the linkage

2008.03.18(Tue)2008.03.18(Tue) 2626


Otcl domainset tcp [new Agent/TCP]

$tcp advance 10

C++ domainint TcpAgent::command(int argc, const char*const* argv)

{if (argc == 3) {

if (strcmp(argv[1], “advance”) == 0) { int newseq = atoi(argv[2]);

…… return(TCL_OK);

}}

return (Agent::command(argc, argv);}

2008.03.18(Tue)2008.03.18(Tue) 2727

Basic Concepts – Tcl/OTcl

Tcl / OTcl Basics - proc command : define a global procedure . proc create_topology {

- set command : assign a value to a variable . set count 10 . $self set count 10

- Substitutions

. Command substitution : brackets as command - set cnt [ $self set count ] cnt = 10

- set cnt [ expr $cnt + $cnt ] set cnt to 20

. Variable substitution : ex) $count 10

$ns at [ $ns now ] “$self send $class $rate"

2008.03.18(Tue)2008.03.18(Tue) 2828

C++ / OTcl Linkage - snapshot view

Export C++ class to Otcl [Create C++ object from OTcl] • Creating a new network object class in C++, & also an instance of this object in Otcl, needs a Linkage object derived from the TclClass (C++ domain).

Export C++ class variables to OTcl • The new network object class in C++ may have some parameter variables, also to be configured from Otcl.

Export C++ Object Control Commands to OTcl • Giving the control of new C++ object to Otcl, via the Otcl command interpreter: command() function.

Execute an OTcl command from C++

• Execute an OTcl command from the new C++ object.

2008.03.18(Tue)2008.03.18(Tue) 2929

C++ / OTcl Linkage

Root Class of ns-2 object hierarchy

bind(): Link variable values between C++ and OTcl TclObject

command() : Link OTcl methods to C++ implementations

TclClass Create and initialize TclObject’s

Tcl C++ methods to access Tcl interpreter

TclCommand Standalone global commands

EmbeddedTcl ns script initialization

2008.03.18(Tue)2008.03.18(Tue) 3030

C++ / OTcl Linkage - TclObject

TclObject : base class - Basic hierarchy in ns-2 for split objects

- Mirrored in both C++ & OTcl

- NsObject : the superclass of all network component objects that handle packets

Connector, Classifier subclasses

- Connector : having only one output data path

- Classifier : having multiple output data path (Router)

- Node : Compound object ~ Node Entry, Classifier objects

- Link : ’’ ~ Queue, Delay, TTL objects..

2008.03.18(Tue)2008.03.18(Tue) 3131

C++ / OTcl Linkage - TclObject

TclObject

Agent

Agent/TCP

Agent/TCP OTcl shadow object

_o123

Agent/TCP C++ object

*tcp

TclObject

Agent

TcpAgent

OTcl classhierarchy

C++ classhierarchy

TclObject : Hierarchy and Shadowing

static TcpClass : public TclClass {public: TcpClass():TclClass(“Agent/Tcp"){} TclObject* create(int,const char*const*) { return (new TcpAgent());}};

2008.03.18(Tue)2008.03.18(Tue) 3232

C++/OTcl Linkage - TclObject

TclObject Creation & Deletion

- Global Procedures : new{ }, delete{ }

- Example :

set tcp [ set tcp [ newnew Agent/TCP ] Agent/TCP ] … …

deletedelete $tcp $tcp

2008.03.18(Tue)2008.03.18(Tue) 3333

C++ / OTcl Linkage – TclObject

C++

OTcl

invoke parentconstructor

Agent/TCPconstructor

parentconstructor


TclObjectconstructor

create C++object

AgentTCPconstructor



parent (Agent)constructor

do nothing,return

TclObject (C++)constructor

bind variablesand return

bind variablesand return

create OTclshadow object

complete initialization

complete initialization

which C++ objto create? – TclClass

set tcp [ new Agent/TCP ]

2008.03.18(Tue)2008.03.18(Tue) 3434

C++/OTcl Linkage - TclObject::bind()

Linking C++ member variable to OTcl object variable • Bound variables can be configured from Both C++/OTcl.

C++ domainTcpAgent::TcpAgent( ) { // Constructor

bind(“window_”, &wnd);… …

} // other type : bind_time(), bind_bool(), bind_bw()

OTcl domain set tcp [new Agent/TCP]set tcp [new Agent/TCP]

$tcp set $tcp set window_window_ 200 200

2008.03.18(Tue)2008.03.18(Tue) 3535

C++ / OTcl Linkage - TclObject::command()

Export C++ Object Control Commands to OTcl

int MyAgent::command(int argc, const char*const* argv ) { if (argc == 2) {

if (strcmp(argv[1], “call-my-func”) == 0) {MyPrivFunc( ));

return (TCL_OK);}

}return (Agent::command(argc, argv));

}

- Effect : Implement OTcl methods in C++

- Trap point : OTcl method cmd{ }

2008.03.18(Tue)2008.03.18(Tue) 3636

C++ / OTcl Linkage - TclObject::command()

$tcp send TclObject::unknown{} $tcp cmd sendno suchprocedure

TcpAgent::command()

match “send”?

Invoke parent: return Agent::command()

process and return

Yes No

OTcl space

C++ space

2008.03.18(Tue)2008.03.18(Tue) 3737

C++ / OTcl Linkage – TclClass

TclObject

Agent

Agent/TCP

TclObject

Agent

TcpAgent

NsObject ??

OTclC++ mirroringStatic class TcpClass : public TclClass {public:

TcpClass() : TclClass(“Agent/TCP”) { }

TclObject* create(int, const char*const*) {return (new TcpAgent( ) );

}} class_tcp;

Static class TcpClass : public TclClass {public:

TcpClass() : TclClass(“Agent/TCP”) { }

TclObject* create(int, const char*const*) {return (new TcpAgent( ) );

}} class_tcp;

2008.03.18(Tue)2008.03.18(Tue) 3838


Class TclClass ( in C++ )

- This compiled class is pure virtual class : only 2 functions

• Construct the interpreted class hierarchy to mirror the compiled class hierarchy.

• Method to Create instances of the associated TclObject.

- For the static variable class_tcp, ns-2 will execute the constructor of TcpClass. The constructor specifies the interpreted class explicitly as “Agent/TCP”.

- This sets up the related methods and the interpreted class hierarchy in the Otcl space. Next slide

- This class is associated with the class TcpAgent, and when the user issues “new …”, TcpClass::create( ) is invoked. TcpAgent is created.

2008.03.18(Tue)2008.03.18(Tue) 3939


Interpreted Class Hierarchy construction (more)

- When the object constructor is executed, the TclClass constructor stores the name of the class, and inserts this object into Linked List of TclClass objects.

- During initialization, TclClass::bind() is invoked.

- For each object in the List, bind() invokes register{… } with the class name as its argument.

- register{ } establishes the class hierarchy, creating the class required.

class TcpAgent : public Agent { public: TcpAgent( ); // Constructor protected: int command(int argc, const char* const* argv); int xxx_;};

2008.03.18(Tue)2008.03.18(Tue) 4040

C++ / OTcl Linkage – Tcl

Singleton class with a handle to Tcl interpreter

Usage - Invoke OTcl procedure from C++ : 4 methods

- Obtain OTcl evaluation results : tcl.result( )

- Pass a result string to OTcl : tcl.result(*s), tcl.resultf(*s)

2008.03.18(Tue)2008.03.18(Tue) 4141

C++ / OTcl Linkage – Tcl

Execute an OTcl command from C++

Tcl& tcl = Tcl::instance();

tcl.eval (“puts \ “Message from MyPrivFunc\””);

or char wrk[128]; sprintf(wrk, “$s recv %d”, name(), result); tcl.eval (wrk);

tcl.evalc (“puts \ “Message from MyPrivFunc\””);

tcl.evalf (“puts \ “ my_var1 = %d\””, my_var1);

tcl.evalf (“puts \ “ my_var2 = %d\””, my_var2);

2008.03.18(Tue)2008.03.18(Tue) 4242

C++ / OTcl Linkage - summary

TclObject

- Unifies Interpreted (OTcl) and Compiled (C++) class hierarchies

- Seamless access (Method call and Variable access) between OTcl and C++

TclClass

- The mechanism that makes TclObject work

- Interpreted hierarchy & shadowing methods

Tcl

- Primitives ( in C++ ) to access Tcl interpreter

2008.03.18(Tue)2008.03.18(Tue) 4343


Some Differences between C++ & OTcl

- OTcl Class vs. C++ Class architecture

. OTcl attaches methods to Object or Class (evolving)

. C++ has single Class Declaration

- C++/OTcl Split Objects

. Implement methods in either language

. Define instance variables in either C++ or Otcl

Through in different Syntax & Forms

2008.03.18(Tue)2008.03.18(Tue) 4444


class PingAgent : public Agent { public: PingAgent( ); int command(int argc, const char* const* argv); void recv (Packet*, Handler*); protected: int off_ping_;};

Class Link

Link instproc init { src dst } { $self next $self instvar fromNode_ toNode_ … set fromNode_ $src set toNode_ $dst …………}

Link instproc head { } { $self instvar head_ return $head_}

Class structures comparison

2008.03.18(Tue)2008.03.18(Tue) 4545


Some Differences between C++ / OTcl

- instvar : to define/access member variable

- instproc : to define member function (procedure)

- OTcl init{ } vs. C++ Constructor( )

- $self this

- Syntax checking in Tcl/OTcl

. No new line from “{” + body, but only after “{”

. if {, } elseif {, …

2008.03.18(Tue)2008.03.18(Tue) 4646

OTcl Basics

Class Mom

Mom instproc greet {} {

$self instvar age_

puts “$age_ years old mom: How are you doing?”

}

Class Kid -superclass Mom

Kid instproc greet {} {

$self instvar age_

puts “$age_ years old kid: What’s up, dude?”

}

set mom [new Mom]$mom set age_ 45

set kid [new Kid]$kid set age_ 15

$mom greet

$kid greet

45 years old mom: How are you doing?

15 years old kid: What's up, dude?

2008.03.18(Tue)2008.03.18(Tue) 4747

Elemental Tcl Procedures in ns-2 programming

- Creating the Event Scheduler

- [Turn on tracing]

- Creating network

- Setup routing

- Insert errors

- Creating connection(Agents)

- Creating traffic

- Configuring Algorithmic Scenario specific to this App ….

- Start ns simulation

2008.03.18(Tue)2008.03.18(Tue) 4848

Example Procedures

# Application code Tcl/OTcl Script.

set end 200.0set warmup 20.0 # For Stable data timingset linkrate 5Mb # May be Adjusted.

set ns [new Simulator] # ns Created : First line of App

create_topology # Creating topology...

create_agents # Creating agents...

create_sources # Creating traffic sources...

create_conditioners # Creating conditioners...

configure_scheduler # Configuring Queue Scheduler...

$ns at $end "end"

$ns run # Starting simulation...

2008.03.18(Tue)2008.03.18(Tue) 4949

Creating Event Scheduler

Create event scheduler

set ns [new Simulator]

Scheduling Events$ns at <time> “<event>”

<event> : any legitimate ns/tcl commands

Start scheduler

$ns run

2008.03.18(Tue)2008.03.18(Tue) 5050

Event Scheduling

Scheduler

Event QueueTarget objectEvent (Packet)Time

Object BObject A

Deque

Dispatch Dispatch

Register Event

2008.03.18(Tue)2008.03.18(Tue) 5151

Creating Network

Nodes

set n0 [$ns node]

set n1 [$ns node]

. . .

NodeAgent

Link

Node entry

entry_

Agent

Agent

LinkLink

PortClassifier

AddrClassifier

classifier_

dmux_

2008.03.18(Tue)2008.03.18(Tue) 5252

Creating Network

Links and Queuing

$ns duplex-link $n0 $n1 <bandwidth> <delay> <queue_type>

<queue_type> : DropTail, RED, CBQ, FQ, SFQ, DRR, WRR

n0 n1

enqT_ queue_ deqT_

drophead_ drpT_


tracing simplex link

duplex link

2008.03.18(Tue)2008.03.18(Tue) 5353

Creating Network

n0 n1

Addr Classifier

Port Classifier

classifier_

dmux_

entry_

Node entry

0

1 enqT_ queue_ deqT_

drophead_ drpT_


Nodes & Links

2008.03.18(Tue)2008.03.18(Tue) 5454

Packet Format

header

data

ip header

tcp header

rtp header

trace header

cmn header

...

ts_

ptype_

uid_

size_

iface_

Packet Format

2008.03.18(Tue)2008.03.18(Tue) 5555

Packet Format

Packet- Fundamental unit of exchange between objects

- Contain packet headers

Packet Header- Per-protocol information

- New protocols may define their own header or may extend existing headers

New Type Packet added in the Application ?

- “ns-allinone2.xx/ns-2.xx/packet.h”

Add “PT_xxx” Type

2008.03.18(Tue)2008.03.18(Tue) 5656

Agents

Agents - UDP TCP/Reno, TCP/NewReno,

- TCP TCP/Sack, TCP/Fack,

- RTP TCP/FullTcp, TCP/Vegas,

- RTCP TCP/Asym, TCP/Reno/Asym,

- SRM TCPSink, TCPSink/….

- SRM/Adaptive

- CtrMcast/Encap, CtrMcast/Decap

- Message, Message/Prune

- Null

: Endpoint where network-layer packets are constructed or consumed, for protocol implementation at various layers.

2008.03.18(Tue)2008.03.18(Tue) 5757

Agents

Agents

- Normally Transport, Routing Entities . End-to-End pair : not Hop-by-Hop . Hop-by-Hop : Routing Agent

- Implemented partly in C++, and partly in OTcl : ~ns-2.x/common/agent.cc, ~ns-2.x/tcl/lib/ns-agent.tcl

- Basic Member functions . Packet* allocpkt() : not over-ridden . void recv(Packet*, Handler) : main entry point

- OTcl Linkage . Agents are created within OTcl code space . set newtcp [new Agent/TCP]

2008.03.18(Tue)2008.03.18(Tue) 5858

Agents

Creation & Attach-Agent{ } set tcp1 [ new Agent/TCP ] set tcp2 [ new Agent/TCPSink ]

$ns attach-agent $node1 $tcp1 $ns attach-agent $node2 $tcp2 $ns connect tcp1 tcp2

# Internally Calls attach{ } method of Node in ns-node.tcl. Simulator instproc attach-agent { node agent } {

$node attach $agent # Compare with below command}

2008.03.18(Tue)2008.03.18(Tue) 5959

Agents

# Attach an Agent to a Node. Pick a Port and Bind the Agent to the Port number. Simulator's attach-agent{ } internally calls this method : $node attach $agent

Node instproc attach { agent { port "" } } { $self instvar agents_ address_ dmux_ classifier_ $self instvar classifiers_ lappend agents_ $agent # agents_ = port list ??

# Attach Agents to this Node (i.e., the Classifier inside). We call the Entry method on ourself to find the front door. Also, stash the node in the Agent and set the local addr of this Agent.

$agent set node_ $self # $self = Node

if [Simulator set EnableHierRt_] { $agent set agent_addr_ [AddrParams set-hieraddr $address_] } else { $agent set agent_addr_ [expr ($address_ & [AddrParams set NodeMask_(1)]) \ << [AddrParams set NodeShift_(1) ] ] } . . .

2008.03.18(Tue)2008.03.18(Tue) 6060

Agents

# If a Port Demuxer doesn't exist, Create it.

if { $dmux_ == "" } { set dmux_ [new Classifier/Port]

# Point the Node's Routing entry to itself at the Port Demuxer if {[Simulator set EnableHierRt_]} { $self add-hroute $address_ $dmux_ } else { $self add-route $address_ $dmux_ ;# install addr in classifier, } ;# classifier target = dmux } if {$port == ""} { set ns_ [Simulator instance] $ns_ instvar nullAgent_ set port [$self alloc-port $nullAgent_] } $agent set agent_port_ $port $self add-target $agent $port ;# send / recv targets of age

nt}

2008.03.18(Tue)2008.03.18(Tue) 6161

Agents

attach-agent (another for comparison) # In contrast, $App attach-agent $agent is used to attach Application to the Agent in C++ level.

int Application::command(int argc, const char*const* argv) { if (strcmp(argv[1], "attach-agent") == 0) // OTcl command { agent_ = (Agent*) TclObject::lookup(argv[2]); if (agent_ == 0) { tcl.resultf("no such agent %s", argv[2]); return(TCL_ERROR); } agent_->attachApp(this); // agent.cc; this = App return(TCL_OK); } ……..

2008.03.18(Tue)2008.03.18(Tue) 6262

End-to-End Transport with Plumbing

0

1

n0 n1

Addr Classifier

Port Classifier

entry_

0 Agent/TCP Addr Classifier

Port Classifier

entry_

1

0Link n0-n1

Link n1-n0

0 Agent/TCPSink

dst_=1.0 dst_=0.0Application/FTP

2008.03.18(Tue)2008.03.18(Tue) 6363

Creating Connection

Connect : Transport level

- $ns connect tcp1 tcp2

- UDP

. set udp [new Agent/UDP]

. set null [new Agent/Null]

. $ns attach-agent $n0 $udp

. $ns attach-agent $n1 $null

. $ns connect $udp $null

2008.03.18(Tue)2008.03.18(Tue) 6464

Creating Connection

# Need to check that Agents are already Attached to Nodes : ns-lib.tcl

# This is an Agent-level Connect.

Simulator instproc connect { src dst } {

$self simplex-connect $src $dst # One-way connection

$self simplex-connect $dst $src # The other way return $src}

Simulator instproc simplex-connect { src dst } {

$src set dst_addr_ [$dst set agent_addr_] # Get agent_addr $src set dst_port_ [$dst set agent_port_] # Get agent_port return $src}

2008.03.18(Tue)2008.03.18(Tue) 6565

Creating Connection

Connect : Application level $UA connect $DM : Application-to-Application connection

Http instproc connect { server } {

Http instvar TRANSPORT_

$self instvar ns_ slist_ node_ fid_ id_

lappend slist_ $server # Client side Server List

set tcp [new Agent/TCP/$TRANSPORT_] # Transport_ = FullTcp

$tcp set fid_ [$self getfid]

$ns_ attach-agent $node_ $tcp # $node attach $tcp

# Make a Wrapper in Server, and associate it with Client.

# Client calls <connect>, meanwhile Server calls <alloc-connection>.

set ret [$server alloc-connection $self $fid_] # Server = Manager

set snk [$ret agent] # ret = server wrapper

$ns_ connect $tcp $snk # $ns connect{} : 2 agents

# $tcp set dst_addr_ [$snk set addr_] See $ns connect{}

$tcp set window_ 100

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Creating Connection

Connect : Application level

# Use a Wrapper(in Client) to implement Application Data Transfer

set wrapper [new Application/TcpApp $tcp] # Agent Wrapper

$self cmd connect $server $wrapper # HttpApp::command( )

# Application(Server) is associated with Client TcpApp Agent wrapper

# TcpApp->target( ) = (Process*) this; tagret( ) : return target_

$wrapper connect $ret # TcpApp connect : private

# dst_ = peer object, with each other

#puts "HttpApp $id_ connected to server [$server id]"

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Configuring Algorithm/Scenario

Algorithm/Scenario : specific to the Application

- Queue Scheduling/Management parameter configuration

. DropTail, CBQ, FQ, SFQ, DRR, WRR

. RED, MRED

- Network Measurement parameter configuration . Admission Control (QoS)

. Network Measurement & Monitoring

……..

- uncountable examples

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Drawing Outputs

Xgraph : exec xgraph out0.tr out1.tr out2.tr -geometry 800x400 &

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Compilation after New Components

xxx.cc : C++ Code Added - “ns-allinone2.xx/ns-2.xx/Makefile.in”

Add “OBJ_CC = xxx.o”

xxx.h : Header Added - Declare New Packet type Data Structure in the header

xxx.tcl : OTcl Library Added - “ns-allinone2.xx/ns-2.xx/Makefile.in”

Add “NS_TCL_LIB=xxx.tcl”

at ns-2.32/: $ make

Documents

2008.03.18(Tue) 1 Network Simulator 2 - Introduction for Beginners - 2008. 03. 18 CNLAB ns - 2 seminar