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Ex. No: 10STUDY OF NS-2 SIMULATOR

Date:

A simulator is a device, software or system which behaves or operates like a given system when provided with a set of controlled inputs. The need for simulators is:

Provide users with practical feedback such as accuracy, efficiency, cost, etc., when designing real world systems.

Permit system designers to study at several different levels of abstraction

Simulation can give results that are not experimentally measurable with our current level of technology.

Simulations take the building/rebuilding phase out of the loop by using the model already created in the design phase.

Effective means for teaching or demonstrating concepts to students.

A few popular network simulators are NS-2, OPNET, GLOMOSIM, etc.

Network Simulator NS2

NS2 is an object-oriented, discrete event driven network simulator developed at UC Berkley written in C++ and OTcl (Object-oriented Tool Command Language). NS is useful for simulating local and wide area networks. NS2 is an open-source simulation tool that primarily runs on Linux (cygwin for Windows). The features of NS2 are:

Is a discrete event simulator for networking research Works at packet level.

Provide support to simulate bunch of protocols like TCP, UDP, FTP, etc. Simulate wired and wireless network.

Is a standard experiment environment in research community.

Class Hierarchy

Network Animator (NAM)

NS together with NAM forms a very powerful set of tools for teaching networking concepts. With NAM protocols can be visualized as animations. The NAM graphical editor is the latest addition to NAM. With this editor, one can create their network topology and simulate various protocols and traffic sources by dragging the mouse.

NS2 Execution

The overall simulation procedure in NS is shown below. NS is composed of OTcl Script and Interpreter. NS simulation results can be observed through graphs by analyzing the trace file or viewing animations with NAM.

$ ns filename.tcl

NS2 Program Elements

Event Scheduler

a Creating event scheduler

set ns [new Simulator]

b Schedule events

$ns at time"event"

c Start scheduler

$ns run

Creating Network

a Create set of Nodes

set n0 [$ns node]

set n1 [$ns node]

b Create links and queuing

$ns duplex-link $n0 $n1 bandwidth delay queue_typeBandwidth is generally in MB

Delay is generally in ms

Queue type is either DropTail, RED, CBQ, FQ, SFQ, etc

$ns duplex-link $n0 $n2 1Mb 10ms DropTail

c Layout

$ns duplex-link-op $n0 $n2 orient position

where position is either right,right-up,right-down,left,left-up, left-down, up, down

d Marking flows

$ns color 1 Blue

$ns color 2 Red

$udp0 set class_ 1

$udp1 set class_2

Tracing

a NAM Trace all links (must succeed scheduler creation)

set nf [open out.nam w]

$ns namtrace-all $nf

b Trace all links (must succeed scheduler creation)

set tf [open out.tr w]

$ns trace-all $tf

Trace file ouput format

event, time, from_node, to_node, pkt type, pkt size, flags, fid, src_addr, dst_addr, seq_num, pkt_id

where events are r received, + enqueued, - dequeued, d dropped

c Tracing specific links

$ns trace-queue $n0 $n1

$ns namtrace-queue $n0 $n1

Connection

a UDP

set udp [new Agent/UDP]

set null [new Agent/Null]

$ns attach-agent $n0 $udp0

$ns attach-agent $n1 $null

$ns connect $udp0 $null

b TCP

set tcp0 [new Agent/TCP/FullTcp]

$tcp0 set window_ 30

$tcp0 set segsize_ 536

$ns attach-agent $n0 $tcp0

set sink0 [new Agent/TCP/FullTcp]

$ns attach-agent $n5 $sink0

$sink0 listen

$ns connect $tcp0 $sink0

Traffic Generation

a UDP

set src [new Application/Traffic/type]

$src attach-agent $udp0

where type is either CBR,Exponential,Pareto

b TCP

set ftp [new Application/FTP]

$ftp attach-agent $tcp

set telnet [new Application/Telnet]

$telnet attach-agent $tcp

Finish procedure

a Flush NS tracing, Close tracing files and execute any post-analysis programs (display results, run NAM, etc)

proc finish {} {

global ns nf

$ns flush-trace

close $nf

exec nam out.nam &

exit

RESULT:

Thus the study of NS-2 simulator is done

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Ex. No:11SIMULATION OF DV ROUTING PROTOCOL

Date:

AIM:

To simulate the Distance Vector (DV) routing protocol.

ALGORITHM:

1. Create a new simulator instance.

2. Set the color for data flows in NAM with blue and red color.

3. Open the trace file and NAM file in write mode.

4. In the finish function, flush the trace file and execute the NAM file.

5. Create a node for the corresponding network path.

6. Create the link between the nodes, set the duplex-link and speed, time and droptail techniques.

7. Set the position for the nodes and set the queue limits of nodes.

8. Set up the TCP and UDP connection between the nodes.

9. Set up FTP over TCP connection.

10.Start ns and simulate till 5 minutes are over.

11. Display using xgraph the simulated data.

CODING:

//dv.tcl


#Define different colors for data flows (for NAM)

$ns color 1 Blue

$ns color 2 Red

#Open the Trace file set file1 [open dv.tr w]

$ns trace-all $file1

#Open the NAM trace file set file2 [open dv.nam w]

$ns namtrace-all $file2

#Define a 'finish' procedure proc finish {} {

global ns file1 file2

$ns flush-trace close $file1 close $file2

exec nam dv.nam &

exit 0

}

# Next line should be commented out to have the static routing

$ns rtproto DV

#Create six nodes set n0 [$ns node] set n1 [$ns node] set n2 [$ns node] set n3 [$ns node] set n4 [$ns node] set n5 [$ns node]

#Create links between the nodes

$ns duplex-link $n0 $n1 0.3Mb 10ms DropTail






#Give node position (for NAM)

$ns duplex-link-op $n0 $n1 orient right


$ns duplex-link-op $n2 $n3 orient up

$ns duplex-link-op $n1 $n4 orient up-left

$ns duplex-link-op $n3 $n5 orient left-up

$ns duplex-link-op $n4 $n5 orient right-up

#Setup a TCP connection

set tcp [new Agent/TCP/Newreno]

$ns attach-agent $n0 $tcp

set sink [new Agent/TCPSink/DelAck]

$ns attach-agent $n5 $sink

$ns connect $tcp $sink

$tcp set fid_ 1

#Setup a FTP over TCP connection set ftp [new Application/FTP]


$ftp set type_ FTP

$ns rtmodel-at 1.0 down $n1 $n4

$ns rtmodel-at 4.5 up $n1 $n4

$ns at 0.1 "$ftp start"

$ns at 6.0 "finish"

$ns run

OUTPUT:

[student@localhost ~]$ ns dv.tcl

RESULT: Thus the simulation of the Distance Vector (DV) routing protocol is executed successfully.

Ex. No:12 SIMULATION FOR COMPARISON OF LS AND DV

Date :

AIM:

To compare the performance of Link State (LS) and Distance Vector (DV) routing protocol.

ALGORITHM:

1. Create a new simulator instance.

2. Set the color for data flows in NAM with blue and red color.

3. Open the trace file and NAM file in write mode for both LS and DV.

4. Create six nodes.

5. Create duplex link between the nodes created and with proper orientation.

6. Set up a TCP connection

7. Then set up FTP over TCP.

8. In the finish function, flush the trace file and execute the NAM file.

9. The link from node 1 to node 4 is set to down at time 1.0 and up at time 4.5

10.Start ns and simulate till 5 minutes are over.

11. The comparison of LS and DV is displayed using xgraph tool.

CODING:

//dv.tcl



$ns color 1 Blue

$ns color 2 Red

#Open the Trace file set file1 [open dv.tr w]


#Open the NAM trace file set file2 [open dv.nam w]





exec nam dv.nam &

exit 0

}


$ns rtproto DV






















$tcp set fid_ 1



$ftp set type_ FTP




$ns at 6.0 "finish"

$ns run

//ls.tcl



$ns color 1 Blue

$ns color 2 Red

#Open the Trace file set file1 [open ls.tr w]


#Open the NAM trace file set file2 [open ls.nam w]





exec nam ls.nam &

exit 0

}


$ns rtproto LS






















$tcp set fid_ 1



$ftp set type_ FTP




$ns at 6.0 "finish"

$ns run

OUTPUT:

[student@localhost ~]$ ns dv.tcl

[student@localhost ~]$ ns ls.tcl

[student@localhost ~]$ raw2xg -a ls.tr > ls.xg

[student@localhost~]$ raw2xg -adv.tr>dv.xg

[student@localhost~]$xgraphls.xgdv.xg -tComparisonof LS&DV

RESULT: Thus the performance of Link State (LS) and Distance Vector (DV) routing protocol is compared and studied.

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