Description:

     This network consists of 6 nodes. The duplex links between n0, n1, and n2 have 2 Mbps of bandwidth and 10 ms of delay. The simplex link between n2 and n3 has 0.3Mbps of bandwidth and 100 ms of delay. The duplex link between n3 and n4 has 0.5Mbps of bandwidth and 40ms of delay. Each link uses DropTail queue. A "TCP" agent is attached to n0 and a connection is established to a “TCPSink” agent attached to n4. As default, the maximum size of a packet that a "TCP" agent can generate is 1000bytes. A “TCPSink” agent generates and sends ACK packets to the sender (tcp agent) and frees the received packets. "UDP" agent is attached to n1 and connection is established to udp "Null" agent attached to n5. Here we will generate the trace-annotate file. It will provide the information about the events at each time. The cbr is set to start at 0.1 sec and stop at 7.5 sec. The ftp is set to start at 1.0 sec and stop at 7.0 sec.

File name: “trace.tcl”

#-------Event scheduler object creation--------#

set ns [new Simulator]

#Open the Trace files

set file1 [open trace.tr w]
$ns trace-all $file1

#Open the NAM trace file

set file2 [open trace.nam w]
$ns namtrace-all $file2

$ns color 1 Blue
$ns color 2 Red

#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 $n2 2Mb 10ms DropTail
$ns duplex-link $n1 $n2 2Mb 10ms DropTail
$ns simplex-link $n2 $n3 0.3Mb 100ms DropTail
$ns simplex-link $n3 $n2 0.3Mb 100ms DropTail
$ns duplex-link $n3 $n4 0.5Mb 40ms DropTail
$ns duplex-link $n3 $n5 0.5Mb 30ms DropTail

#Give node position (for NAM)

$ns duplex-link-op $n0 $n2 orient right-down
$ns duplex-link-op $n1 $n2 orient right-up
$ns simplex-link-op $n2 $n3 orient right
$ns simplex-link-op $n3 $n2 orient left
$ns duplex-link-op $n3 $n4 orient right-up
$ns duplex-link-op $n3 $n5 orient right-down

#Set Queue Size of link (n2-n3) to 10

$ns queue-limit $n2 $n3 20

#Setup a TCP connection

set tcp [new Agent/TCP/Newreno]
$ns attach-agent $n0 $tcp
set sink [new Agent/TCPSink/DelAck]
$ns attach-agent $n4 $sink
$ns connect $tcp $sink
$tcp set fid_ 1
$tcp set window_ 8000
$tcp set packetSize_ 552

#Setup a FTP over TCP connection

set ftp [new Application/FTP]
$ftp attach-agent $tcp
$ftp set type_ FTP

#Setup a UDP connection
set udp [new Agent/UDP]
$ns attach-agent $n1 $udp
set null [new Agent/Null]
$ns attach-agent $n5 $null
$ns connect $udp $null
$udp set fid_ 2

#Setup a CBR over UDP connection

set cbr [new Application/Traffic/CBR]
$cbr attach-agent $udp
$cbr set type_ CBR
$cbr set packet_size_ 1000
$cbr set rate_ 0.01mb
$cbr set random_ false

$ns at 0.1 "$cbr start"
$ns at 1.0 "$ftp start"
$ns at 7.0 "$ftp stop"
$ns at 7.5 "$cbr stop"

#-------------Trace file creation---------#

$ns at 1.1025 "$ns trace-annotate \"Time: 1.1025 Pkt Transfer Path thru node_(1)..\""
$ns at 2.1025 "$ns trace-annotate \"Time: 2.1025 Pkt Transfer Path thru node_(1)..\""
$ns at 3.1025 "$ns trace-annotate \"Time: 3.1025 Pkt Transfer Path thru node_(1)..\""

#Define a 'finish' procedure

proc finish {} {
        global ns file1 file2
        $ns flush-trace
        close $file1
        close $file2
        exec nam trace.nam &
        exit 0
}
#Calling finish procedure

$ns at 10.0 "finish"
$ns run

#-----How to run-----#

$ns filename.tcl

#----------Snapshot-----------#