Description:

    This network consists of 6 nodes. The duplex links between nodes are configured with the specific bandwidth and delay. Each link uses a DropTail queue. A "TCP" agent is attached to n0 and a connection is established to a tcp "sink" agent attached to n4. As default, the maximum size of a packet that a "TCP" agent can generate is 1KByte. A "TCPSink" agent generates and sends ACK packets to the sender (tcp agent) and frees the received packets. An "UDP" agent is attached to n1 and a connection is established to udp "Null" agent attached to n5. "TCP" agent is attached with "FTP" application and "UDP" agent is attached with "CBR" traffic for packet generation. The ftp is set to start at 1.0 sec and stop at 10.5 sec. The cbr is set to start at 0.1 sec and stop at 10.0 sec.

File name: “tcpred4.tcl”

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

set ns [new Simulator]

#---Open the Trace files---#

set file1 [open Tcpred4.tr w]
$ns trace-all $file1

#--Open the NAM trace file----#

set file2 [open Tcpred4.nam w]
$ns namtrace-all $file2

#Define different colors for data flows (for NAM)

$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"
$ns at 10.0 "$ftp stop"
$ns at 10.5 "$cbr stop"

#Define a 'finish' procedure

proc finish {} {
        global ns file1 file2
        $ns flush-trace
        close $file1
        close $file2
        exec nam Tcpred4.nam &
        exit 0
}

$ns at 12.0 "finish"
$ns run

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

$ns tcpred4.tcl

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