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Network Simulator 2

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This post shows you how to write TCL code for Wireless simulations in ns2. It also explains the various aspects of wireless network.

It is part of a lecture series in network simulator 2.

The following image is shown for explanation

Wireless Networks
Wireless Networks
Download the Source code for Wireless Networks

#Example of Wireless networks
#Step 1 initialize variables
#Step 2 - Create a Simulator object
#step 3 - Create Tracing and animation file
#step 4 - topography
#step 5 - GOD - General Operations Director
#step 6 - Create nodes
#Step 7 - Create Channel (Communication PATH)
#step 8 - Position of the nodes (Wireless nodes needs a location)
#step 9 - Any mobility codes (if the nodes are moving)
#step 10 - TCP, UDP Traffic
#run the simulation

#initialize the variables
set val(chan)           Channel/WirelessChannel    ;#Channel Type
set val(prop)           Propagation/TwoRayGround   ;# radio-propagation model
set val(netif)          Phy/WirelessPhy            ;# network interface type WAVELAN DSSS 2.4GHz
set val(mac)            Mac/802_11                 ;# MAC type
set val(ifq)            Queue/DropTail/PriQueue    ;# interface queue type
set val(ll)             LL                         ;# link layer type
set val(ant)            Antenna/OmniAntenna        ;# antenna model
set val(ifqlen)         50                         ;# max packet in ifq
set val(nn)             6                          ;# number of mobilenodes
set val(rp)             AODV                       ;# routing protocol
set val(x) 500 ;# in metres
set val(y) 500 ;# in metres
#Adhoc OnDemand Distance Vector

#creation of Simulator
set ns [new Simulator]

#creation of Trace and namfile 
set tracefile [open w]
$ns trace-all $tracefile

#Creation of Network Animation file
set namfile [open wireless.nam w]
$ns namtrace-all-wireless $namfile $val(x) $val(y)

#create topography
set topo [new Topography]
$topo load_flatgrid $val(x) $val(y)

#GOD Creation - General Operations Director
create-god $val(nn)

set channel1 [new $val(chan)]
set channel2 [new $val(chan)]
set channel3 [new $val(chan)]

#configure the node
$ns node-config -adhocRouting $val(rp) \
-llType $val(ll) \
-macType $val(mac) \
-ifqType $val(ifq) \
-ifqLen $val(ifqlen) \
-antType $val(ant) \
-propType $val(prop) \
-phyType $val(netif) \
-topoInstance $topo \
-agentTrace ON \
-macTrace ON \
-routerTrace ON \
-movementTrace ON \
-channel $channel1 

set n0 [$ns node]
set n1 [$ns node]
set n2 [$ns node]
set n3 [$ns node]
set n4 [$ns node]
set n5 [$ns node]

$n0 random-motion 0
$n1 random-motion 0
$n2 random-motion 0
$n3 random-motion 0
$n4 random-motion 0
$n5 random-motion 0

$ns initial_node_pos $n0 20
$ns initial_node_pos $n1 20
$ns initial_node_pos $n2 20
$ns initial_node_pos $n3 20
$ns initial_node_pos $n4 20
$ns initial_node_pos $n5 50

#initial coordinates of the nodes 
$n0 set X_ 10.0
$n0 set Y_ 20.0
$n0 set Z_ 0.0

$n1 set X_ 210.0
$n1 set Y_ 230.0
$n1 set Z_ 0.0

$n2 set X_ 100.0
$n2 set Y_ 200.0
$n2 set Z_ 0.0

$n3 set X_ 150.0
$n3 set Y_ 230.0
$n3 set Z_ 0.0

$n4 set X_ 430.0
$n4 set Y_ 320.0
$n4 set Z_ 0.0

$n5 set X_ 270.0
$n5 set Y_ 120.0
$n5 set Z_ 0.0
#Dont mention any values above than 500 because in this example, we use X and Y as 500,500

#mobility of the nodes
#At what Time? Which node? Where to? at What Speed?
$ns at 1.0 "$n1 setdest 490.0 340.0 25.0"
$ns at 1.0 "$n4 setdest 300.0 130.0 5.0"
$ns at 1.0 "$n5 setdest 190.0 440.0 15.0"
#the nodes can move any number of times at any location during the simulation (runtime)
$ns at 20.0 "$n5 setdest 100.0 200.0 30.0"

#creation of agents
set tcp [new Agent/TCP]
set sink [new Agent/TCPSink]
$ns attach-agent $n0 $tcp
$ns attach-agent $n5 $sink
$ns connect $tcp $sink
set ftp [new Application/FTP]
$ftp attach-agent $tcp
$ns at 1.0 "$ftp start"

set udp [new Agent/UDP]
set null [new Agent/Null]
$ns attach-agent $n2 $udp
$ns attach-agent $n3 $null
$ns connect $udp $null
set cbr [new Application/Traffic/CBR]
$cbr attach-agent $udp
$ns at 1.0 "$cbr start"

$ns at 30.0 "finish"

proc finish {} {
global ns tracefile namfile
$ns flush-trace
close $tracefile
close $namfile
exit 0

puts "Starting Simulation"
$ns run

T S Pradeep Kumar


  1. Thank you for sharing. I cannot find node 2 and node 3 in NAM. They are not visible in video tutorial also

  2. Sir,
    nam is not working for this code.
    i am getting the error that your trace filr is empty so cant connect nam.

    plz help

  3. how can we set the data rate for each node in wireless sensor networks?

  4. Enter followings into terminal.
    nam wireless.nam

  5. sir,
    can you provide me source code for adhoc tcp variants like tcp feedback ,tcp bus and calculating their average throughput and simulation in ns2 or ns3. My email id is in advance.

  6. # random motion
    for {set j 0} {$j < $val(n)} {incr j} {
    for {set i 0} {$i < $val(n)} {incr i} {
    set xx_ [expr rand()*$val(x)]
    set yy_ [expr rand()*$val(y)]
    set rng_time [expr rand()*$val(end)]
    $ns at $rng_time "$node_(1) setdest $xx_ $yy_ 10.0";

    I have written this code for random motion but there is an error :can't read "node_(1)": no such variable
    while executing
    "$ns at $rng_time "$node_(1) setdest $xx_ $yy_ 10.0""
    ("for" body line 6)
    invoked from within
    "for {set j 0} {$j < $val(n)} {incr j} {
    for {set i 0} {$i < $val(n)} {incr i} {
    set xx_ [expr rand()*$val(x)]
    set yy_ [expr rand()*$val(y)]..."
    (file "ash.tcl" line 345)


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