set ns [new Simulator]

#Open trace file set nt [open lab1.tr w] $ns trace-all $nt

#Open namtrace file set nf [open lab1.nam w] $ns namtrace-all $nf

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

#Assign color to the packet $ns color 1 Blue $ns color 2 Red

#label nodes $n0 label "Source/udp0" $n1 label "Source/udp1" $n2 label "Router" $n3 label "Destination/null"

#create links, specify the type, nodes, bandwidth, delay and ARQ algorithm for it $ns duplex-link $n0 $n2 10Mb 300ms DropTail $ns duplex-link $n1 $n2 10Mb 300ms DropTail Computer Network Laboratory (BCS502) V SEM Dept. of CS&E, BIT, 2024 – 25 2

$ns duplex-link $n2 $n3 100Kb 300ms DropTail

#set queue size between the nodes $ns queue-limit $n0 $n2 10 $ns queue-limit $n1 $n2 10 $ns queue-limit $n2 $n3 5

       #create and attach UDP agent to n0, n1 and Null agent to n3  
       set udp0 [new Agent/UDP] 
       $ns attach-agent $n0 $udp0 

set udp1 [new Agent/UDP] $ns attach-agent $n1 $udp1

set null3 [new Agent/Null] $ns attach-agent $n3 $null3

#attach Application cbr to udp set cbr0 [new Application/Traffic/CBR] $cbr0 attach-agent $udp0

set cbr1 [new Application/Traffic/CBR] $cbr1 attach-agent $udp1

#set udp0 packet to red color and udp1 packet to blue color $udp0 set class_ 1 $udp1 set class_ 2

#connect the agents $ns connect $udp0 $null3 $ns connect $udp1 $null3

#set packet size and interval for cbr1 $cbr1 set packetSize_ 500Mb $cbr1 set interval_ 0.005

       #finish procedure  

proc finish { } { global ns nf nt $ns flush-trace exec nam lab1.nam & close $nt close $nf exit 0 }

$ns at 0.1 "$cbr0 start" $ns at 0.1 "$cbr1 start" $ns at 10.0 "finish" $ns run Computer Network Laboratory (BCS502) V SEM Awk file- BEGIN { count=0; } { } if($1=="d") count++ END{ printf("Number of packets dropped is = %d\n",count); }

#create Simulator object set ns [new Simulator] #open trace file set nt [open prac2.tr w] $ns trace-all $nt #open namtrace file set nf [open prac2.nam w]

$ns namtrace-all $nf #create nodes set n0 [$ns node] set n1 [$ns node] set n2 [$ns node] set n3 [$ns node] set n4 [$ns node] set n5 [$ns node]

#label nodes $n0 label "ping0" $n1 label "ping1" $n2 label "ping2" $n3 label "ping3" $n4 label "ping4" $n5 label "router”

#create links, specify the type, nodes, bandwidth, delay and ARQ algorithm for it $ns duplex-link $n0 $n5 1Mb 10ms DropTail $ns duplex-link $n1 $n5 1Mb 10ms DropTail $ns duplex-link $n2 $n5 1Mb 10ms DropTail $ns duplex-link $n3 $n5 1Mb 10ms DropTail $ns duplex-link $n4 $n5 1Mb 10ms DropTail

#set queue length $ns queue-limit $n0 $n5 5 $ns queue-limit $n1 $n5 5 $ns queue-limit $n2 $n5 2 $ns queue-limit $n3 $n5 5 $ns queue-limit $n4 $n5 2

$ns color 2 Red $ns color 3 Blue $ns color 4 Green $ns color 5 Yellow

#define ‘recv’ function for class Agent/Ping Agent/Ping instproc recv {from rtt} { $self instvar node_ puts "node [$node_ id] received ping answer from $from with round-trip time $rtt ms" } #create ping agent and attach them to node set p0 [new Agent/Ping] $ns attach-agent $n0 $p0 $p0 set class_ 1

set p1 [new Agent/Ping] $ns attach-agent $n1 $p1 $p1 set class_ 2 set p2 [new Agent/Ping] $ns attach-agent $n2 $p2 $p2 set class_ 3 set p3 [new Agent/Ping] $ns attach-agent $n3 $p3 $p3 set class_ 4 set p4 [new Agent/Ping] $ns attach-agent $n4 $p4 $p4 set class_ 5 #connect 2 agents $ns connect $p2 $p4 $ns connect $p3 $p4 #procedure proc sendPingPacket { } { global ns p2 p3

set intervalTime 0.001 set now [$ns now] $ns at [expr $now + $intervalTime] "$p2 send" $ns at [expr $now + $intervalTime] "$p3 send" $ns at [expr $now + $intervalTime] "sendPingPacket" } proc finish { } { global ns nt nf $ns flush-trace close $nt close $nf exec nam prac2.nam & exit 0 }

$ns at 0.1 "sendPingPacket" $ns at 2.0 "finish" $ns run

#set ns Simulator set ns [new Simulator]

#define color for data flow $ns color 1 Blue $ns color 2 Red

#open trace file set tracefile1 [open lab3.tr w] set winfile [open winfile w] $ns trace-all $tracefile1

#open namtrace file set namfile [open lab3.nam w] $ns namtrace-all $namfile

#define finish procedure proc finish { } { global ns tracefile1 namfile $ns flush-trace close $tracefile1 close $namfile exec nam lab3.nam & exit 0

}

#create 6 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]

$n1 shape box #create link between 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

set lan [$ns newLan "$n3 $n4 $n5" 0.5Mb 40ms LL Queue/DropTail MAC/802_3]

#give node position $ns duplex-link-op $n0 $n2 orient right-down $ns duplex-link-op $n1 $n2 orient right-up $ns simplex-link-op $n3 $n2 orient left $ns simplex-link-op $n2 $n3 orient right

#set queue size of link(n2-n3) $ns queue-limit $n2 $n3 20

#setup tcp connection set tcp [new Agent/TCP] $ns attach-agent $n0 $tcp set sink [new Agent/TCPSink] $ns attach-agent $n4 $sink $ns connect $tcp $sink $tcp set fid_ 1 $tcp set packetSize_ 552

#set ftp over tcp connection set ftp [new Application/FTP] $ftp attach-agent $tcp

#setup a TCP1 connection set tcp1 [new Agent/TCP] $ns attach-agent $n1 $tcp1 set sink1 [new Agent/TCPSink] $ns attach-agent $n5 $sink1 $ns connect $tcp1 $sink1 $tcp1 set fid_ 2 $tcp1 set packetSize_ 552

set telnet0 [new Application/Telnet] $telnet0 attach-agent $tcp1

#title congestion window1 set outfile1 [open congestion1.xg w] puts $outfile1 "TitleText: Congestion Window-- Source _tcp" puts $outfile1 "xUnitText: Simulation Time(Secs)"

puts $outfile1 "yUnitText: Congestion WindowSize"

#title congestion window2 set outfile2 [open congestion2.xg w] puts $outfile2 "TitleText: Congestion Window-- Source _tcp1" puts $outfile2 "xUnitText: Simulation Time(Secs)" puts $outfile2 "yUnitText: Congestion WindowSize"

proc plotWindow {tcpSource outfile} { global ns set time 0.1 set now [$ns now] set cwnd [$tcpSource set cwnd_] puts $outfile "$now $cwnd" $ns at [expr $now+$time] "plotWindow $tcpSource $outfile" }

$ns at 0.1 "plotWindow $tcp $winfile" $ns at 0.0 "plotWindow $tcp $outfile1" $ns at 0.1 "plotWindow $tcp1 $outfile2" $ns at 0.3 "$ftp start" $ns at 0.5 "$telnet0 start" $ns at 49.0 "$ftp stop"

$ns at 49.1 "$telnet0 stop" $ns at 50.0 "finish"

$ns run

import java.util.Scanner; public class CRC { public static int n; public static void main(String[] args) { Scanner sc=new Scanner(System.in); CRC crc=new CRC(); String copy,rec,code,zero="0000000000000000"; System.out.println("enter the dataword to be sent"); code=sc.nextLine(); n=code.length(); copy=code; code+=zero; code=crc.divide(code); System.out.println("dataword="+copy); copy=copy.substring(0,n)+code.substring(n); System.out.print("CRC="); System.out.println(code.substring(n));

System.out.println("transmitted frame is="+copy); System.out.println("enter received data:"); rec=sc.nextLine(); if(zero.equals(crc.divide(rec).substring(n))) System.out.println("correct bits received"); else System.out.println("received frame contains one or more error"); sc.close(); }

public String divide(String s) { String div="10001000000100001"; int i,j; char x; for(i=0;i<n;i++) { x=s.charAt(i); for(j=0;j<17;j++) { if(x=='1') { if(s.charAt(i+j)!=div.charAt(j)) s=s.substring(0,i+j)+"1"+s.substring(i+j+1); else s=s.substring(0,i+j)+"0"+s.substring(i+j+1); } } } return s; } }