NS2 SIMULATOR TUTORIAL

NS2 Simulator Tutorial offers you brief and compact information about NS2 to equip you with some basics of NS2. Our Simulator Tutorial service is a collaborative effort of top professionals and technocrats from all over the world. To be precise, we can say that our service is started in a motive, to share our valuable information with the budding students to make their career enlighten with our knowledge. NS2 is an open source simulator used to simulate wide range of networks and networking protocols. To work with NS2, one must be well aware of C++ and TCL. Students can approach our online tutoring service to learn the basics of NS2 along with complete NS2 programming fundamentals.

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LEARN THE BASICS OF NS-2:

Languages Used:

C++[Used to define the mechanism of each block like scheduling events, packet forwarding, collecting statistics etc ]
OTCL[Object oriented Extension of TCL(Tool Command language)]

Major Components:

NAM[Network Animator]:

Used to view the Network simulation traces
Supports packet transmission, topology, data inspection etc
During the execution of simulation, it supports animation

Trace File:

Used to store the coverage information or overall network information
To generate a trace file, we have to first create a trace file using OTCL Script.

X-Graph:

Used to visualize the resulting graph

AWK Script:

Used to process the data from the log[i.e. trace file]

Ns2 Simulation:

Define the Simulation Object
Connect the object with each other through links
Start the Source applications.
Packets are creates and transmitted through the network
Exit the simulation at fixed time

Programming with NS2:

Create an Event Scheduler:

Set ns [ new simulator ]//create a new simulator

$ ns at < time > < event >//Schedules the event

$ns run// Start the scheduler

Tracing in NS2:

General syntax: $ns traceall[open filename.tr w]

………………………………………………….

Trace file format[12 fields]:

Event[packet dropped, added to queue , received]

+ = Add to queue

-= To remove from queue

D= drop the packet

R = received the packed

Time[Second field used to indicate the time at which the event occurs]
From and to Node[Used to specify the sender and receiver of current package]
Packet type[5^th field-represent the packet type(FTP,CBR, HTTP)]
- -Tcp[TCP packet]
- -Aodv[AODV packet]
- -Cbr[CBR traffic packet]
Packet Size[sixth field used to show the packet size(bytes)]
Flags[seven flags are used- disabled, ECN echo(C), priority in IP header is enabled(P), TCP fast start(F), Congestion action(A), Congestion experienced(E), explicit congestion notification is on(N)]
Flow ID[provides IP flow id as per IPv6]
Source and destination address[specified as addr.port-port is also specified]
Sequence number[agents attach sequence number with packets]
Packet ID[Unique identifier for each packet]

Sample trace file

+ 0.52 0 1 cbr 100—— 0 0.0 5.0 0 2

– 0.52 0 1 cbr 100—– 0 0.0 5.0 0 2

r 0.524 0 1 cbr 100 ——0 0.0 5.0 0 0

To create Network topology:

Link creation between two nodes:

First create nodes using

set n1 [ $ns node ]

setn2 [ $ns node ]

Now, create link using the command:

$ns < link_type(Simplex/duplex)> $n1 $n2 <bandwidth> <delay> <queue-type>

For ex. – $ns duplex-link $n1 $n2 5Mb 100ms Drop Tail

To create transport connection and generate traffic:

Traffic generation[FTP, telnet]

set ftp new Application / FTP ]

set telnet [new Application / Telnet ]

For data sending

//create UDP agent

set udp1 [ new Agent/ UDP ]

$ns attach – agent $n1 $udp1

//Create CBR traffic source

set cbr1 [ new Application / Traffic / CBR ]

$cbr1 set packetSize_ 100

$ cbr1 set interval_ 0.05

$cbr1 attach – agent $udp1

// to create a traffic Sink

set null1 [ new Agent/Null ]

$ns attach – agent$n2 $null1

// To connect the agents

$ns connect $udp1 $null1

// to start and stop

$ns at 0.1 “$cbr0 start”

$ ns at 1.0 “$cbr0 stop”

We have provided an overview about NS2, for students to get an insight about NS2 basics and syntax. Beginners can get comprehensive knowledge about NS2 through our NS2 Simulator Tutorial service. If you feel to have further guidance on NS2, approach us through our online tutoring service or you can also refer our other articles available in this site. You can also approach us for any kind of support regarding your NS2 based projects/research, assignments or lab cycles. We are there for you at 24/7, approach us anytime, through anyway

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