COMPUTER NETWORK

(LAB FILE)

SUBMITTED BY:
Pawan Kumar Prajapati (1875110043)

Submitted to the department of Computer Science & Engineering

in partial fulfillment of requirement of the degree of
Bachelor of Technology
In

COMPUTER SCIENCE &ENGINEERING

Submitted To

Mr. Ranjeet Rai Sir

KIPM COLLEGE OF ENGINEERING AND TECHNOLOGY

GIDA, GORAKHPUR (273209)

Table of Content
1|Page
 S. No List of the Practical’s

Implementation of stop and wait protocol and sliding window

1
protocol.
2 Study of Socket Programming and client – Server model.

3 Write a code simulating ARP/RARP protocol.

4 Write a code simulating PING and TRACEROUTE commands.

5 Create a socket for HTTP foe Web Pages upload and download.

6 Write a program to implement RPC (Remote Procedure Call).

7 Implementation of Subnetting.

8 Application using TCP Sockets like: -

a) Echo client and echo server b) Chat c) File Transfer

9 Application using TCP and UDP Sockets like d. DNS e. SNMP f.

File Transfer
10 Study of Network simulator (NS) and Simulation of Congestion
Control Algorithm using NS

EX.NO:1(a) Implementation of Sliding Window Protocol

AIM: To write a java program to perform sliding window protocol

2|Page
ALGORITHM:

1.Start the program.

2.Get the frame size from the user
3.To create the frame based on the user request. 4.To send frames to server
from the client side.
5.If your frames reach the server it will send ACK signal to client otherwise it will send NACK
signal to
client.
6.Stop the program

Program:
import java.net. *; import java.io. *; import
java.rmi.*;
public class slidsender
{
public static void main(String a[])throws Exception
{
ServerSocket ser=new ServerSocket(10); Socket s=ser.accept();
DataInputStream in=new DataInputStream(System.in); DataInputStream in1=new
DataInputStream(s.getInputStream()); String sbuff[]=new String[8];
PrintStream p;
int sptr=0,sws=8,nf,ano,i; String ch;
do
{
p=new PrintStream(s.getOutputStream()); System.out.print("Enter the
no. of frames : "); nf=Integer.parseInt(in.readLine()); p.println(nf);
if(nf<=sws-1)
{
System.out.println("Enter "+nf+" Messages to be send\n"); for(i=1;i<=nf;i++)
{
sbuff[sptr]=in.readLine();
p.println(sbuff[sptr]);
sptr=++sptr%8;
}
sws-=nf;
System.out.print("Acknowledgment received"); ano=Integer.parseInt(in1.readLine());
System.out.println(" for "+ano+" frames"); sws+=nf;
}
else
{
System.out.println("The no. of frames exceeds window size"); break;
}
System.out.print("\nDo you wants to send some more frames : "); ch=in.readLine(); p.println(ch);
}
while(ch.equals("yes"));
s.close();
}
}

3|Page
RECEIVER PROGRAM

import java.net.*; import java.io.*; class slidreceiver

{
public static void main(String a[])throws Exception
{
Socket s=new Socket(InetAddress.getLocalHost(),10); DataInputStream in=new
DataInputStream(s.getInputStream()); PrintStream p=new PrintStream(s.getOutputStream());
int i=0,rptr=-1,nf,rws=8; String rbuf[]=new String[8]; String ch;
System.out.println(); do
{
nf=Integer.parseInt(in.readLine()); if(nf<=rws-1)
{
for(i=1;i<=nf;i++)
{
rptr=++rptr%8;
rbuf[rptr]=in.readLine();
System.out.println("The received Frame " +rptr+" is : "+rbuf[rptr]);
}
rws-=nf;
System.out.println("\nAcknowledgment
sent\n"); p.println(rptr+1); rws+=nf; }
else
break;
ch=in.readLine();
}
while(ch.equals("yes"));
}
}

OUTPUT:
//SENDER OUTPUT
Enter the no. of frames : 4
Enter 4 Messages to be send
hiii
how r u
i am fine
how is evryone
Acknowledgment received for 4 frames
Do you wants to send some more frames : no
//RECEIVER OUTPUT
The received Frame 0 is : hiii
The received Frame 1 is : how r u
The received Frame 2 is : i am fine
The received Frame 3 is : how is everyone
EX.NO:1(b) Implementation of Stop and Wait Protocol
AIM To write a java program to perform sliding window protocol

4|Page
ALGORITHM:
1.Start the program.
2.Get the frame size from the user
3.To create the frame based on the user request. 4.To send frames
to server from the client side.
5.If your frames reach the server it will send ACK signal to client otherwise it will send NACK
signal to client.
6.Stop the program

PROGRAM

/SENDER PROGRAM
import java.io.*;
import java.net.*;
public class Sender{
Socket sender;
ObjectOutputStream out;
ObjectInputStream in;
String packet,ack,str, msg;
int n,i=0,sequence=0;
Sender(){}
public void run(){
try{
BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
System.out.println("Waiting for Connection....");
sender = new Socket("localhost",2004);
sequence=0;
out=new ObjectOutputStream(sender.getOutputStream());
out.flush();
in=new ObjectInputStream(sender.getInputStream());
str=(String)in.readObject();
System.out.println("reciver > "+str);
System.out.println("Enter the data to send....");
packet=br.readLine();
n=packet.length();

do{
try{
if(i<n){
msg=String.valueOf(sequence);
msg=msg.concat(packet.substring(i,i+1));
}
else if(i==n){
msg="end";out.writeObject(msg);break;
}
out.writeObject(msg);
sequence=(sequence==0)?1:0;
out.flush();
System.out.println("data sent>"+msg);
ack=(String)in.readObject();
5|Page
 System.out.println("waiting for ack.....\n\n");
if(ack.equals(String.valueOf(sequence))){
i++;
System.out.println("receiver > "+" packet recieved\n\n");
}
else{
System.out.println("Time out resending data....\n\n");
sequence=(sequence==0)?1:0;
}
}catch(Exception e){}
}while(i<n+1);
System.out.println("All data sent. exiting.");
}catch(Exception e){}
finally{
try{
in.close();
out.close();
sender.close();
}
catch(Exception e){}
}
}
public static void main(String args[]){
Sender s=new Sender();
s.run();
}
}

//RECEIVER PROGRAM
import java.io.*;
import java.net.*;
public class Reciever{
ServerSocket reciever;
Socket connection=null;
ObjectOutputStream out;
ObjectInputStream in;
String packet,ack,data="";
int i=0,sequence=0;
Reciever(){}
public void run(){
try{
BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
reciever = new ServerSocket(2004,10);
System.out.println("waiting for connection...");
connection=reciever.accept();
sequence=0;
System.out.println("Connection established :");
out=new ObjectOutputStream(connection.getOutputStream());
out.flush();

6|Page
 in=new ObjectInputStream(connection.getInputStream());
out.writeObject("connected .");
do{
try{
packet=(String)in.readObject();
if(Integer.valueOf(packet.substring(0,1))==sequence){
data+=packet.substring(1);
sequence=(sequence==0)?1:0;
System.out.println("\n\nreceiver >"+packet);
}
else
{
System.out.println("\n\nreceiver >"+packet +" duplicate data");
}
if(i<3){
out.writeObject(String.valueOf(sequence));i++;
}
else{
out.writeObject(String.valueOf((sequence+1)%2));
i=0;
}
}
catch(Exception e){}
}while(!packet.equals("end"));

System.out.println("Data recived="+data);
out.writeObject("connection ended .");
}
catch(Exception e){}
finally{
try{
in.close();
out.close();
reciever.close();
}
catch(Exception e){}
}
}
public static void main(String args[]){
Reciever s=new Reciever();
while(true){
s.run();
}
}
}
OUTPUT:

//SENDER OUTPUT
Waiting for Connection....

7|Page
 reciver > connected .
Enter the data to send....
myname
data sent>0m
waiting for ack.....
receiver > packet recieved
data sent>1y
waiting for ack.....
receiver > packet recieved
data sent>0n
waiting for ack.....
receiver > packet recieved
data sent>1a
waiting for ack.....
Time out resending data....
data sent>1a
waiting for ack.....
receiver > packet recieved
data sent>0m
waiting for ack.....
receiver > packet recieved
data sent>1e
waiting for ack.....
receiver > packet recieved
All data sent. exiting.

//RECEIVER OUTPUT
waiting for connection...
Connection established :
receiver >0m
receiver >1y
receiver >0n
receiver >1a
receiver >1a duplicate data
receiver >0m
receiver >1e
Data recived=myname
waiting for connection...

EX.NO:2 Study of Socket Programming and Client – Server mode

AIM:
To implement socket programming date and ti me display from client to server using TCP Sockets

ALGORITHM:
8|Page
 Server
1. Create a server socket and bind it to port.
2. Listen for new connection and when a connection arrives, accept it.
3 . Send server‟s date and time to the client.
4. Read client‟s IP address sent by the client.
5. Display the client details.
6. Repeat steps 2-5 until the server is terminated.
7. Close all streams.
8. Close the server socket.
9. Stop.
Client
1 . Create a client socket and connect it to the server‟s port number.
2. Retrieve its own IP address using built-in function.
3. Send its address to the server.
4. Display the date & time sent by the server.
5. Close the input and output streams.
6. Close the client socket.
7. Stop.

PROGRAM:

DateClient.java:
import java.net.*;
import java.io.*;
class dateclient
{
public static void main (String args[])
{
Socket soc;
DataInputStream dis;
String sdate;
PrintStream ps;
try
{
InetAddress ia=InetAddress.getLocalHost();
soc=new Socket(ia,8020);
dis=new DataInputStream(soc.getInputStream());
sdate=dis.readLine();
System.out.println("THE date in the server is:"+sdate);
ps=new PrintStream(soc.getOutputStream());
ps.println(ia);
}
catch(IOException e)
{
System.out.println("THE EXCEPTION is :"+e);
}}}
DateServer.java:
import java.net.*;
import java.io.*;

9|Page
 import java.util.*;
class dateserver
{
public static void main(String args[])
{
ServerSocket ss;
Socket s;
PrintStream ps;
DataInputStream dis;
String inet;
try
{
ss=new ServerSocket(8020);
while(true)
{
s=ss.accept();
ps=new PrintStream(s.getOutputStream());
Date d=new Date();
ps.println(d);
dis=new DataInputStream(s.getInputStream());
inet=dis.readLine();
System.out.println("THE CLIENT SYSTEM ADDRESS IS :"+inet);
ps.close();
}}
catch(IOException e)
{
System.out.println("The exception is :"+e);
}}}
OUTPUT:
CLIENTSIDE:
C:\Program Files\Java\jdk1.5.0\bin>javac dateclient.java
Note: dateclient.java uses or overrides a deprecated API.
Note: Recompile with -deprecation for details.
C:\Program Files\Java\jdk1.5.0\bin>java dateclient
THE date in the server is:Sat Mar 19 13:01:16 GMT+05:30 2008
C:\Program Files\Java\jdk1.5.0\bin>
SERVERSIDE:
C:\Program Files\Java\jdk1.5.0\bin>javac dateserver.java
Note: dateserver.java uses or overrides a deprecated API.
Note: Recompile with -deprecation for details.
C:\Program Files\Java\jdk1.5.0\bin>java dateserver
THE CLIENT SYSTEM ADDRESS IS :com17/192.168.21.17

EX.NO:3 Write a code simulating ARP /RARP protocols.

Aim: To write a java program for simulating ARP protocols using TCP

ALGORITHM:
Client
10 | P a g e
 1. Start the program
2. Using socket connection is established between client and server.
3. Get the IP address to be converted into MAC address.
4. Send this IP address to server.
5. Server returns the MAC address to client.
Server
1. Start the program
2. Accept the socket which is created by the client.
3. Server maintains the table in which IP and corresponding MAC addresses are stored.
4. Read the IP address which is send by the client.
5. Map the IP address with its MAC address and return the MAC address to client.
Program

Client:
import java.io.*;
import java.net.*;
import java.util.*;
class Clientarp
{
public static void main(String args[])
{
try
{
BufferedReader in=new BufferedReader(new InputStreamReader(System.in));
Socket clsct=new Socket("127.0.0.1",139);

DataInputStream din=new DataInputStream(clsct.getInputStream());

DataOutputStream dout=new DataOutputStream(clsct.getOutputStream());
System.out.println("Enter the Logical address(IP):");
String str1=in.readLine();
dout.writeBytes(str1+'\n');
String str=din.readLine();
System.out.println("The Physical Address is: "+str);
clsct.close();
}
catch (Exception e)
{
System.out.println(e);
}
}
}

Server:
import java.io.*;
import java.net.*;
import java.util.*;
c lass Serverarp
{
public static void main(String args[])
11 | P a g e
 {
try
{
ServerSocket obj=new ServerSocket(139);
Socket obj1=obj.accept();
while(true)
{
DataInputStream din=new DataInputStream(obj1.getInputStream());
DataOutputStream dout=new DataOutputStream(obj1.getOutputStream());
String str=din.readLine();
String ip[]={"165.165.80.80","165.165.79.1"};
String mac[]={"6A:08:AA:C2","8A:BC:E3:FA"};
for(int i=0;i<ip.length;i++)
{
if(str.equals(ip[i]))
{
dout.writeBytes(mac[i]+'\n');
break;
}
}
obj.close();
}
}
catch(Exception e)
{
System.out.println(e);
}
}
}

Output:
E:\networks>java Serverarp
E:\networks>java Clientarp
Enter the Logical address(IP):
165.165.80.80
The Physical Address is: 6A:08:AA:C2

EX.NO (3(b) Program for Reverse Address Resolution Protocol

(RARP) using UDP
Aim: To write a java program for simulating RARP protocols using UDP

ALGORITHM:
Client
12 | P a g e
 1.Start the program
2. using datagram sockets UDP function is established.
2.Get the MAC address to be converted into IP address.
3.Send this MAC address to server.
4.Server returns the IP address to client.
Server
1. Start the program.
2. Server maintains the table in which IP and corresponding MAC addresses are stored.
3. Read the MAC address which is send by the client.
4. Map the IP address with its MAC address and return the IP address to client.
Program :-
Client:
import java.io.*;
import java.net.*;
import java.util.*;
class Clientrarp12
{
public static void main(String args[])
{
try
{
DatagramSocket client=new DatagramSocket();
InetAddress addr=InetAddress.getByName("127.0.0.1");
byte[] sendbyte=new byte[1024];
byte[] receivebyte=new byte[1024];
BufferedReader in=new BufferedReader(new InputStreamReader(System.in));
System.out.println("Enter the Physical address (MAC):")
String str=in.readLine(); sendbyte=str.getBytes();
DatagramPacket sender=newDatagramPacket(sendbyte,sendbyte.length,addr,1309);
client.send(sender);
DatagramPacket receiver=new DatagramPacket(receivebyte,receivebyte.length);
client.receive(receiver);
String s=new String(receiver.getData());
System.out.println("The Logical Address is(IP): "+s.trim());
client.close();
}
catch(Exception e)
{
System.out.println(e);
}
}
}
Server:
import java.io.*;
import java.net.*;
import java.util.*;
class Serverrarp12
{
public static void main(String args[])
{
try
13 | P a g e
 {
DatagramSocket server=new DatagramSocket(1309);
while(true)
{
byte[] sendbyte=new byte[1024];
byte[] receivebyte=new byte[1024];
DatagramPacket receiver=new DatagramPacket(receivebyte,receivebyte.length);
server.receive(receiver);
String str=new String(receiver.getData());
String s=str.trim();
InetAddress addr=receiver.getAddress();
int port=receiver.getPort();
String
ip[]={"165.165.80.80","165.165.79.1"};
String
mac[]={"6A:08:AA:C2","8A:BC:E3:FA"};
for(int i=0;i<ip.length;i++)
{
if(s.equals(mac[i]))
{
sendbyte=ip[i].getBytes();
DatagramPacket sender=newDatagramPacket(sendbyte,sendbyte.length,addr,port);
server.send(sender);
break;
}
}
break;
}
}
catch(Exception e)
{
System.out.println(e);
}
}
}
Output:
I:\ex>java Serverrarp12
I:\ex>java Clientrarp12
Enter the Physical address
(MAC): 6A:08:AA:C2
The Logical Address is(IP): 165.165.80.80
EX-NO. 4(a). Write a code simulating PING command
Aim: To Write the java program for simulating ping command

Algorithm
Step 1: start the program.
Step 2: Include necessary package in java.
Step 3: To create a process object p to implement the ping command.
Step 4: declare one BufferedReader stream class object.
14 | P a g e
 Step 5: Get thedetails of the server
5.1: length of the IP address.
5.2: time required to get the details.
5.3: send packets , receive packets and lost packets.
5.4: minimum ,maximum and average times.
Step 6: print the results.
Step 7:Stop the program.

Program:
import java.io.*;
import java.net.*;
class pingserver
{
public static void main(String args[])
{
try
{
String str;
System.out.print(" Enter the IP Address to be Ping : ");
BufferedReader buf1=new BufferedReader(new
InputStreamReader(System.in));
String ip=buf1.readLine();
Runtime H=Runtime.getRuntime();
Process p=H.exec("ping " + ip);
InputStream in=p.getInputStream();
BufferedReader buf2=new BufferedReader(new
InputStreamReader(in));
while((str=buf2.readLine())!=null)
{
System.out.println(" " + str);
}
}
catch(Exception e)
{

System.out.println(e.getMessage());
}
}
}

Output:
Enter the IP address to the ping:192.168.0.1
Pinging 192.168.0.1: with bytes of data =32
Reply from 192.168.0.11:bytes=32 time<1ms TTL =128
Reply from 192.168.0.11:bytes=32 time<1ms TTL =128
Reply from 192.168.0.11:bytes=32 time<1ms TTL =128
Reply from 192.168.0.11:bytes=32 time<1ms TTL =128
Ping statistics for 192.168.0.1
Packets: sent=4,received=4,lost=0(0% loss),approximate round trip time in milli seconds:

15 | P a g e
Minimum=1
ms,maximum=4ms,average=2ms

EX-NO. 4(b). Write a code simulating TRACEROUTE command

Aim: To Write the java program for simulating Traceroute command

Program
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

16 | P a g e
 import java.util.ArrayList;
import traceroute.TracerouteItem;
public abstract class Traceroute
{
private Runtime run;
public Traceroute()
{
run = Runtime.getRuntime();
}
public ArrayList<TracerouteItem> traceroute(String destination)
{
ArrayList<TracerouteItem> result = new ArrayList<TracerouteItem>();
Process pr = null;
String cmd = getTracerouteCommand(destination);
try
{
pr = run.exec(cmd);
}
catch(IOException e)
{
e.printStackTrace();
}
BufferedReader buf = new BufferedReader(new InputStreamReader(
pr.getInputStream()));
String line = "";
try
{
while((line = buf.readLine()) != null)
{
TracerouteItem item = parse(line);
result.add(item);
}
}
catch(IOException e)
{ return null;
}
return result;
}
public abstract TracerouteItem parse(String line);
public abstract String getTracerouteCommand(String destination);
}
EX.NO 5. Create a socket for HTTP for web page upload and
download.
Aim: To write a java program for socket for HTTP for web page upload and download .

Algorithm
1.Start the program.
2.Get the frame size from the user
17 | P a g e
 3.To create the frame based on the user request.
4.To send frames to server from the client side.
5.If your frames reach the server it will send ACK signal to client otherwise it will
send NACK signal to client.
6.Stop the program
Program :
Client
import javax.swing.*;
import java.net.*;
import java.awt.image.*;
import javax.imageio.*;
import java.io.*;
import java.awt.image.BufferedImage;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.IOException; import
javax.imageio.ImageIO;
public class Client{
public static void main(String args[]) throws Exception{
Socket soc;
BufferedImage img = null;
soc=new Socket("localhost",4000);
System.out.println("Client is running. ");
try {
System.out.println("Reading image from disk. ");
img = ImageIO.read(new File("digital_image_processing.jpg"));
ByteArrayOutputStream baos = new ByteArrayOutputStream();
ImageIO.write(img, "jpg", baos);
baos.flush();
byte[] bytes = baos.toByteArray();
baos.close();
System.out.println("Sending image to server. ");
OutputStream out = soc.getOutputStream();
DataOutputStream dos = new DataOutputStream(out);
dos.writeInt(bytes.length);
dos.write(bytes, 0, bytes.length);
System.out.println("Image sent to server. ");
dos.close();
out.close();
}catch (Exception e) { System.out.println("Exception: " + e.getMessage());
soc.close();
}
soc.close();
}
}
Server
import java.net.*;
import java.io.*;
import java.awt.image.*;
import javax.imageio.*;
import javax.swing.*;
18 | P a g e
 class Server {
public static void main(String args[]) throws Exception{
ServerSocket server=null;
Socket socket;
server=new ServerSocket(4000);
System.out.println("Server Waiting for image");
socket=server.accept(); System.out.println("Client connected.");
InputStream in = socket.getInputStream();
DataInputStream dis = new DataInputStream(in);
int len = dis.readInt();
System.out.println("Image Size: " + len/1024 + "KB"); byte[] data = new byte[len];
dis.readFully(data);
dis.close();
in.close();
InputStream ian = new ByteArrayInputStream(data);
BufferedImage bImage = ImageIO.read(ian);
JFrame f = new JFrame("Server");
ImageIcon icon = new ImageIcon(bImage);
JLabel l = new JLabel();
l.setIcon(icon);
f.add(l);
f.pack();
f.setVisible(true);
}
}

Output
When you run the client code, following output screen would appear on client side.

EX-NO 6. Write a program to implement RPC (Remote Procedure

Call)
Aim: To write a java program to implement RPC (remote procedure call)

Algorithm:
Step 1: start the program.
Step 2: include the necessary packages in java.
Step 3: create an interface as ucet and extends the predefined interface remote into it.
Step 4: declare the remote methods inside the interface used.
Step 5: declare the class rpc and extends the predefined class.
19 | P a g e
 Step 6: unicast remote object an implement the interface ucet into it.
Step 7: declare the class server &create an object ob for the class rpc.
Step 8: declare the class client
Step 9: call the remote methods using the object ob which is the object of the
interface ucet.
Step 10: the remote method contains the methods such as
functions(a,b),power(a,b)and log(a).
Step 11:Stop the program.
Program:
Client:
import java.rmi.*;
import java.io.*;
import java.rmi.server.*;
public class clientrpc
{
public static void main(String arg[])
{
try
{
String serverurl="rmi://localhost/serverrpc";
ucet ob=(ucet) Naming.lookup(serverurl);
int r=ob.function(10,5);
System.out.println("the answer of(a+b)^2 is:"+r);
int t =ob.power(10,5);
System.out.println("the answer of(a)^(b) is:"+t);
double d=ob.log(10);
System.out.println("the log value of the given number "+10+" is :"+d);
}
catch(Exception e)
{
System.out.println("error.."+e.getMessage());
}
}
}
Server:
import java.rmi.*;
import java.rmi.server.*;
public class serverrpc
{
public static void main(String arg[])
{
try
{
rpc ob=new rpc();
Naming.rebind("serverrpc",ob);
}
catch(Exception e)
{
}
}}

20 | P a g e
 RPC:
import java.rmi.*;
import java.lang.Math.*;
import java.rmi.server.*;
public class rpc extends UnicastRemoteObject implements ucet
{
public rpc()throws Exception
{
}
public int function(int a,int b)throws RemoteException
{
int m;
m=(a*a)+(b*b)+(2*a*b);
return m;
}
public int power(int a,int b)throws RemoteException
{
int m=(int)Math.pow(a,b);
return m;
}
public double log(int a)throws RemoteException
{
return(Math.log(a));
}
}
Ucet:
import java.rmi.*;
public interface ucet extends Remote
{
public int function(int a,int b)throws RemoteException;
public int power(int a,int b)throws RemoteException;

public double log(int a)throws RemoteException;

}

Output:
Javac ucet.java
Start rmiregistry
Javac rpc.java
rmi rpc
javac clientrpc.java
javac serverrpc.java
javac rpc.java
javac ucet.java
javac serverrpc.java
java serverrpc
javac clientrpc.java

21 | P a g e
 java clientrpc
the ans of (a+b)^2 is:225
the ans of (a)^(b) is :100000
the log value of the given number 10 is 2.30258

EX-NO 7. Implementation of Subnetting

Aim: Write a program to implement subnetting and find the subnet masks.

Algorithm :
1.Start the program.
2.Get the frame size from the user
3.To create the frame based on the user request.
4.To send frames to server from the client side.
5.If your frames reach the server it will send ACK signal to client otherwise it will
send NACK signal to client.
6.Stop the program
22 | P a g e
Program
import java.util.Scanner;
class Subnet
{
public static void main(String args[])
{
Scanner sc = new Scanner(System.in);
System.out.print(“Enter the ip address”);
String ip = sc.nextLine();
String split_ip[]=ip.split(“\\.”);
//SPlit the string after every .
String split_bip[] = new String[4];
//split binary ip
String bip = “”;
for(int i=0;i<4;i++){
split_bip[i] = appendZeros(Integer.toBinaryString(Integer.parseInt(split_ip[i])));
// “18” => 18 => 10010=>00010010
bip += split_bip[i];
}
System.out.println(“IP in binary is “+bip);
System.out.print(“Enter the number of addresses: “);
int n = sc.nextInt();

//Calculation of mask
int bits = (int)Math.ceil(Math.log(n)/Math.log(2));
/*eg if address = 120, log 120/log 2 gives log to the base 2 => 6.9068, ceil gives us upper
integer */
System.out.println(“Number of bits required for address = “+bits); int mask = 32-bits;
System.out.println(“The subnet mask is = “ +mask);
//Calculation of first address and last
address int fbip[] = new int[32];
for(int i=0; i<32;i++) fbip[i] = (int)bip.charAt(i)-48;
//convert cahracter 0,1 to integer 0,1 for(int i=31;i>31-bits;i–)
//Get first address by ANDing last n bits with 0
fbip[i] &= 0;
String fip[] = {“”,””,””,””};
for(int i=0;i<32;i++)
fip[i/8] = new String(fip[i/8]+fbip[i]);
System.out.print(“First address is = “);
for(int i=0;i<4;i++){
System.out.print(Integer.parseInt(fip[i],2));
if(i!=3) System.out.print(“.”);
}
System.out.println();
int lbip[] = new int[32];
for(int i=0; i<32;i++) lbip[i] = (int)bip.charAt(i)-48; //convert cahracter 0,1 to integer 0,1
for(int i=31;i>31-bits;i–) //Get last address by ORing last n bits with 1
lbip[i] |= 1;
String lip[] ={“”,””,””,””};
for(int i=0;i<32;i++)
23 | P a g e
 lip[i/8] = new String(lip[i/8]+lbip[i]);
System.out.print(“Last address is =”);
for(int i=0;i<4;i++){
System.out.print(Integer.parseInt(lip[i],2));
if(i!=3) System.out.print(“.”);
}
System.out.println();
}
static String appendZeros(String s){
String temp = new String(“00000000″);
return temp.substring(s.length())+ s;
}
}

Output
Enter the ip address: 100.110.150.10
IP in binary is 01100100011011101001011000001010
Enter the number of addresses: 7
Number of bits required for address = 3
The subnet mask is = 29
First address is = 100.110.150.8
Last address is = 100.110.150.15

EX-NO 8. Applications usingTCP Sockets

A. Echo client and Echo server
Aim :- To write a java program for application using TCPSockets Links

Algorithm
1.Start the program.
2.Get the frame size from the user
3.To create the framebased on the user request.
4.To send frames to server from the client side.
5.If your frames reach the server it will send ACK signal to client otherwise it
will send NACK signal to client.
6.Stop the program
EchoServer.java
import java.net.*;
import java.io.*;
public class EServer
{
public static void main(String args[])
{
ServerSocket s=null;

24 | P a g e
 String line;
DataInputStream is;
PrintStream ps;
Socket c=null;
try
{
s=new ServerSocket(9000);
}
catch(IOException e)
{
System.out.println(e);
}
try
{
c=s.accept();
is=new DataInputStream(c.getInputStream());
ps=new PrintStream(c.getOutputStream());
while(true)
{
line=is.readLine();

ps.println(line);
}
}
catch(IOException e)
{
System.out.println(e);
}
}
}

EClient.java

import java.net.*;
import java.io.*;
public class EClient
{
public static void main(String arg[])
{
Socket c=null;
String line;
DataInputStream is,is1;
PrintStream os;
try
{
InetAddress ia = InetAddress.getLocalHost();
c=new Socket(ia,9000);
}
catch(IOException e)
25 | P a g e
 {
System.out.println(e);
}
try
{
os=new PrintStream(c.getOutputStream());
is=new DataInputStream(System.in);
is1=new DataInputStream(c.getInputStream());
while(true)
{
System.out.println("Client:");
line=is.readLine();
os.println(line);
System.out.println("Server:" + is1.readLine());
}}
catch(IOException e)
{
System.out.println("Socket Closed!");
}
}
}

Output
Server
C:\Program Files\Java\jdk1.5.0\bin>javac EServer.java
Note: EServer.java uses or overrides a deprecated API.
Note: Recompile with -deprecation for details.
C:\Program Files\Java\jdk1.5.0\bin>java EServer
C:\Program Files\Java\jdk1.5.0\bin>
Client
C:\Program Files\Java\jdk1.5.0\bin>javac EClient.java
Note: EClient.java uses or overrides a deprecated API.
Note: Recompile with -deprecation for details.
C:\Program Files\Java\jdk1.5.0\bin>java EClient
Client:
Hai Server
Server:Hai Server
Client:
Hello
Server:Hello
Client:
end
Server:end
Client:
26 | P a g e
 ds
Socket Closed!

B.Chat

Aim :- Write a Program client –server application for chat using UDP Sockets

Program

UDPserver.java
import java.io.*;
import java.net.*;
class UDPserver
{
public static DatagramSocket ds;
public static byte buffer[]=new byte[1024];
public static int clientport=789,serverport=790;
public static void main(String args[])throws Exception
{
ds=new DatagramSocket(clientport);
System.out.println("press ctrl+c to quit the program");
BufferedReader dis=new BufferedReader(new InputStreamReader(System.in));
InetAddress ia=InetAddress.geyLocalHost();
while(true)
{
DatagramPacket p=new DatagramPacket(buffer,buffer.length);
ds.receive(p);
String psx=new String(p.getData(),0,p.getLength());
System.out.println("Client:" + psx);
System.out.println("Server:");
String str=dis.readLine();
if(str.equals("end"))
break;
buffer=str.getBytes();
ds.send(new
DatagramPacket(buffer,str.length(),ia,serverport));
}
}
}
UDPclient.java
import java .io.*;
import java.net.*;
class UDPclient
{
public static DatagramSocket ds;
public static int clientport=789,serverport=790;

27 | P a g e
 public static void main(String args[])throws Exception
{
byte buffer[]=new byte[1024];
ds=new DatagramSocket(serverport);
BufferedReader dis=new BufferedReader(new InputStreamReader(System.in));
System.out.println("server waiting");
InetAddress ia=InetAddress.getLocalHost();
while(true)
{
System.out.println("Client:");
String str=dis.readLine();
if(str.equals("end"))
break;
buffer=str.getBytes();
ds.send(new DatagramPacket(buffer,str.length(),ia,clientport));
DatagramPacket p=new DatagramPacket(buffer,buffer.length);
ds.receive(p);
String psx=new String(p.getData(),0,p.getLength());
System.out.println("Server:" + psx);
}
}
}
OUTPUT:
Server
C:\Program Files\Java\jdk1.5.0\bin>javac UDPserver.java
C:\Program Files\Java\jdk1.5.0\bin>java UDPserver
press ctrl+c to quit the program
Client:Hai Server

Server:
Hello Client
Client:How are You
Server:
I am Fine
Client
C:\Program Files\Java\jdk1.5.0\bin>javac UDPclient.java
C:\Program Files\Java\jdk1.5.0\bin>java UDPclient
server waiting
Client:
Hai Server
Server:Hello Clie
Client:
How are You
Server:I am Fine
Client:
end

C. File Transfer
28 | P a g e
Program

File Client
import java.io.*;
import java.net.*;
import java.util.*;

class Clientfile
{ public static void main(String args[])
{
Try
{
BufferedReader in=new BufferedReader(new
InputStreamReader(System.in)); Socket clsct=new Socket("127.0.0.1",139);
DataInputStream din=new DataInputStream(clsct.getInputStream());
DataOutputStream dout=new DataOutputStream(clsct.getOutputStream());
System.out.println("Enter the file name:");
String str=in.readLine();
dout.writeBytes(str+'\n');
System.out.println("Enter the new file name:");
String str2=in.readLine();
String str1,ss;
FileWriter f=new
FileWriter(str2); char buffer[];
while(true)
{ str1=din.readLine();
if(str1.equals("-1")) break;
System.out.println(str1);
buffer=new char[str1.length()];
str1.getChars(0,str1.length(),buffer,0);
f.write(buffer);
}
f.close();
clsct.close();
}
catch (Exception e)
{
System.out.println(e);
}}}

Server
import java.io.*;
import java.net.*;
import java.util.*;
class Serverfile
{ public static void main(String args[])
{
Try
29 | P a g e
 {
ServerSocket obj=new ServerSocket(139);
while(true)
{
Socket obj1=obj.accept();
DataInputStream din=new DataInputStream(obj1.getInputStream());
DataOutputStream dout=new DataOutputStream(obj1.getOutputStream());
String str=din.readLine();
FileReader f=new FileReader(str);
BufferedReader b=new BufferedReader(f);
String s;
while((s=b.readLine())!=null) {
System.out.println(s);
dout.writeBytes(s+'\n');
}
f.close();
dout.writeBytes("-1\n");
}}
catch(Exception e)
{ System.out.println(e);}
}
}

Output
File content
Computer networks
jhfcgsauf
jbsdava
jbvuesagv
client
Enter the file name:
sample.txt
server
Computer networks
jhfcgsauf
jbsdava
jbvuesagv
client
Enter the new file name:
net.txt
Computer networks
jhfcgsauf
jbsdava
jbvuesagv
Destination file
Computer networks
30 | P a g e
 jhfcgsauf
jbsdava
jbvuesagv

EX-NO 9. Applications using TCP and UDP Sockets like DNS, SNMP
and FileTransfer
Aim :- To write a java program for DNS application

Algorithm
1.Start the program.
2.Get the frame size from the user
3.To create the frame based on the user request.
4.To send frames to server from the client side.
5.If your frames reach the server it will send ACK signal to client otherwise it will
send NACK signal to client.
6.Stop the program

Program
/ UDP DNS Server
Udpdnsserver
.java import java.io.*;
import java.net.*;
public class udpdnsserver
{
private static int indexOf(String[] array, String str)

31 | P a g e
 {
str = str.trim();
for (int i=0; i < array.length; i++)
{
if (array[i].equals(str)) return i;
}
return -1;
}
public static void main(String arg[])throws IOException
{
String[] hosts = {"yahoo.com", "gmail.com","cricinfo.com", "facebook.com"};
String[] ip = {"68.180.206.184", "209.85.148.19","80.168.92.140", "69.63.189.16"};
System.out.println("Press Ctrl + C to Quit");
while (true)

{
DatagramSocket serversocket=new DatagramSocket(1362);
byte[] senddata = new byte[1021];
byte[] receivedata = new byte[1021];
DatagramPacket recvpack = new DatagramPacket(receivedata, receivedata.length);
serversocket.receive(recvpack);
String sen = new String(recvpack.getData());
InetAddress ipaddress = recvpack.getAddress();
int port = recvpack.getPort();
String capsent;
System.out.println("Request for host " + sen);
if(indexOf (hosts, sen) != -1)
capsent = ip[indexOf (hosts, sen)];
else capsent = "Host Not Found";
senddata = capsent.getBytes();
DatagramPacket pack = new DatagramPacket (senddata, senddata.length,ipaddress,port);
serversocket.send(pack);
serversocket.close();
}
}
}
/ /UDP DNS Client –
Udpdnsclient
.java import java.io.*;
import java.net.*;
public class udpdnsclient
{
public static void main(String args[])throws IOException
{
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
DatagramSocket clientsocket = new DatagramSocket();
InetAddress ipaddress;
if (args.length == 0)
ipaddress =
InetAddress.getLocalHost(); else
32 | P a g e
 ipaddress = InetAddress.getByName(args[0]);
byte[] senddata = new byte[1024];

byte[] receivedata = new byte[1024];

int portaddr = 1362;
System.out.print("Enter the hostname : ");
String sentence = br.readLine();
Senddata = sentence.getBytes();
DatagramPacket pack = new DatagramPacket(senddata,senddata.length, ipaddress,portaddr);
clientsocket.send(pack);
DatagramPacket recvpack =new DatagramPacket(receivedata,receivedata.length);
clientsocket.receive(recvpack);
String modified = new String(recvpack.getData());
System.out.println("IP Address: " + modified);
clientsocket.close();
}
}
OUTPUT
Server
javac udpdnsserver.java
java udpdnsserver
Press Ctrl + C to Quit Request for host yahoo.com
Request for host cricinfo.com
Request for host youtube.com

Client
javac udpdnsclient.java
java udpdnsclient
Enter the hostname : yahoo.com
IP Address: 68.180.206.184
java udpdnsclient
Enter the hostname : cricinfo.com
IP Address: 80.168.92.140
java udpdnsclient
Enter the hostname : youtube.com
IP Address: Host Not Found

B.SNMP
Aim :- To write a java program for SNMP application program

Algorithm
1.Start the program.
2.Get the frame size from the user
3.To create the frame based on the user request.
4.To send frames to server from the client side.

33 | P a g e
 5.If your frames reach the server it will send ACK signal to client otherwise it will
send NACK signal to client.
6.Stop the program
Program
import java.io.IOException;
import org.snmp4j.CommunityTarget;
import org.snmp4j.PDU;
import org.snmp4j.Snmp;
import org.snmp4j.Target;
import org.snmp4j.TransportMapping;
import org.snmp4j.event.ResponseEvent;
import org.snmp4j.mp.SnmpConstants;
import org.snmp4j.smi.Address;
import org.snmp4j.smi.GenericAddress;
import org.snmp4j.smi.OID;
import org.snmp4j.smi.OctetString;
import org.snmp4j.smi.VariableBinding;
import org.snmp4j.transport.DefaultUdpTransportMapping;
public class SNMPManager {
Snmp snmp = null;
String address = null;
* Constructor
* @param
add
*/
public SNMPManager(String add)
{
address = add;
public static void main(String[] args) throws IOException {
/**
* Port 161 is used for Read and Other operations
* Port 162 is used for the trap
generation */
SNMPManager client = new SNMPManager("udp:127.0.0.1/161");
client.start();
/**
* OID - .1.3.6.1.2.1.1.1.0 => SysDec
* OID - .1.3.6.1.2.1.1.5.0 => SysName
* => MIB explorer will be usefull here, as discussed in previous
article */
String sysDescr = client.getAsString(new OID(".1.3.6.1.2.1.1.1.0"));
System.out.println(sysDescr);
}
/**
* get any answers because the communication is asynchronous
* and the listen() method listens for answers.
* @throws IOException
*/
private void start() throws IOException {
TransportMapping transport = new DefaultUdpTransportMapping();
snmp = new
34 | P a g e
Snmp(transport);
// Do not forget this line!
transport.listen();
}
/**
* Method which takes a single OID and returns the response from the agent as a String.
* @param oid
* @return
* @throws IOException
*/

public String getAsString(OID oid) throws IOException {

ResponseEvent event = get(new OID[] { oid });
return event.getResponse().get(0).getVariable().toString();
}
/**
* This method is capable of handling multiple OIDs
* @param oids
* @return
* @throws IOException
*/
public ResponseEvent get(OID oids[]) throws IOException {
PDU pdu = new PDU();
for (OID oid : oids) {
pdu.add(new VariableBinding(oid));
}
pdu.setType(PDU.GET);
ResponseEvent event = snmp.send(pdu, getTarget(), null);
if(event != null) {
return event;
}
throw new RuntimeException("GET timed out");
}
/**
* This method returns a Target, which contains information about
* where the data should be fetched and how.
* @return
*/
private Target getTarget() {
Address targetAddress = GenericAddress.parse(address);
CommunityTarget target = new CommunityTarget();
target.setCommunity(new OctetString("public"));
target.setAddress(targetAddress);
target.setRetries(2);
target.setTimeout(1500);
target.setVersion(SnmpConstants.version2c);
return target;
}}

35 | P a g e
OUT PUT
Hardware: x86 Family 6 Model 23 Stepping 10 AT/AT COMPATIBLE – Software:
Windows 2000 Version 5.1 (Build 2600 Multiprocessor Free)

C. File Transfer
AIM :- To write a java program for applaction using TCP and UDP Sockets Links

Program
File Client import
java.io.*; import
java.net.*; import
java.util.*; class
Clientfile
{ public static void main(String args[])
{
Try
{
BufferedReader in=new BufferedReader(new
InputStreamReader(System.in)); Socket clsct=new Socket("127.0.0.1",139);
DataInputStream din=new DataInputStream(clsct.getInputStream());
DataOutputStream dout=new DataOutputStream(clsct.getOutputStream());
System.out.println("Enter the file name:");
String str=in.readLine();
dout.writeBytes(str+'\n');
System.out.println("Enter the new file name:");
String str2=in.readLine();
String str1,ss;
FileWriter f=new
FileWriter(str2); char buffer[];
while(true)
{ str1=din.readLine();
if(str1.equals("-1")) break;
System.out.println(str1);
buffer=new char[str1.length()];
str1.getChars(0,str1.length(),buffer,0);
f.write(buffer);
}
f.close();
clsct.close();
}
catch (Exception e)
{
System.out.println(e);
}}}

36 | P a g e
Server
import java.io.*;
import java.net.*;
import java.util.*;
class Serverfile
{ public static void main(String args[])
{
Try
{
ServerSocket obj=new ServerSocket(139); while(true)
{
Socket obj1=obj.accept();
DataInputStream din=new DataInputStream(obj1.getInputStream());
DataOutputStream dout=new DataOutputStream(obj1.getOutputStream());
String str=din.readLine();
FileReader f=new FileReader(str);
BufferedReader b=new
BufferedReader(f); String s;
while((s=b.readLine())!=null) {
System.out.println(s);
dout.writeBytes(s+'\n');
}
f.close();
dout.writeBytes("-1\n");
}}
catch(Exception e)
{ System.out.println(e);}
}
}

Output
File content Computer networks jhfcgsauf
jbsdava jbvuesagv client
Enter the file name: sample.txt
server
Computer networks jhfcgsauf
jbsdava jbvuesagv client
Enter the new file name: net.txt
Computer networks jhfcgsauf
jbsdava jbvuesagv Destination file
Computer networks jhfcgsauf
jbsdava jbvuesagv

37 | P a g e
 EX-NO 10. Study of Network simulator (NS).and Simulation of
Congestion Control Algorithms using NS
Aim:

To Study of Network simulator (NS).and Simulation of Congestion Control Algorithms using

NS

NET WORK SIMULATOR (NS2)

Ns overview

􀂾 Ns programming: A Quick start 􀀃

􀀃
Case study I: A simple Wireless network 􀀃 􀀃
􀂾
Case study II: Create a new agent in Ns 􀀃 􀀃
􀂾
Ns overview 􀀃
Ns Status 􀀃 􀀃
􀂾
Periodical release (ns-2.26, Feb 2003) 􀀃 􀀃
􀂾
􀂾 Platform support 􀀃 􀀃
􀂾 FreeBSD, Linux, Solaris, Windows and Mac 􀀃
Ns unctionalities

Routing, Transportation, Traffic sources,Queuing

38 | P a g e
 disciplines, QoS
Wireless

Ad hoc routing, mobile IP, sensor-MAC

Tracing, visualization and various utilitie
NS(Network Simulators)
Most of the commercial simulators are GUI driven, while some network simulators are
CLI driven. The network model / configuration describes the state of the network (nodes,routers,
switches, links) and the events (data transmissions, packet error etc.). An important output of
simulations are the trace files. Trace files log every packet, every event that occurred in the
simulation and are used for analysis. Network simulators can also provide other tools to facilitate
visual analysis of trends and potential trouble spots.
Most network simulators use discrete event simulation, in which a list of pending "events"
is stored, and those events are processed in order, with some events triggering future events—
such as the event of the arrival of a packet at one node triggering the event of the arrival of that
packet at a downstream node.
Simulation of networks is a very complex task. For example, if congestion is high, then
estimation of the average occupancy is challenging because of high variance. To estimate the
likelihood of a buffer overflow in a network, the time required for an accurate answer can be
extremely large. Specialized techniques such as "control variates" and "importance sampling"
have been developed to speed simulation.

Examples of network simulators

There are many both free/open-source and proprietary network simulators. Examples of
notable network simulation software are, ordered after how often they are mentioned in research
papers:
1. ns (open source)
2. OPNET (proprietary software)
3. NetSim (proprietary software)

Uses of network simulators

Network simulators serve a variety of needs. Compared to the cost and time involved in setting
up an entire test bed containing multiple networked computers, routers and data links, network
simulators are relatively fast and inexpensive. They allow engineers, researchers to test scenarios
that might be particularly difficult or expensive to emulate using real hardware - for instance,
simulating a scenario with several nodes or experimenting with a new protocol in the network.
Network simulators are particularly useful in allowing researchers to test new networking
protocols or changes to existing protocols in a controlled and reproducible environment. A
typical network simulator encompasses a wide range of networking technologies and can help the
users to build complex networks from basic building blocks such as a variety of nodes and links.
With the help of simulators, one can design hierarchical networks using various types of nodes
like computers, hubs, bridges, routers, switches, links, mobile units etc.
Various types of Wide Area Network (WAN) technologies like TCP, ATM, IP etc. and Local
Area Network (LAN) technologies like Ethernet, token rings etc., can all be simulated with a
typical simulator and the user can test, analyze various standard results apart from devising some
novel protocol or strategy for routing etc. Network simulators are also widely used to simulate
battlefield networks in Network-centric warfare

39 | P a g e
 There are a wide variety of network simulators, ranging from the very simple to the very
complex. Minimally, a network simulator must enable a user to represent a network topology,
specifying the nodes on the network, the links between those nodes and the traffic between the
nodes. More complicated systems may allow the user to specify everything about the protocols
used to handle traffic in a network. Graphical applications allow users to easily visualize the
workings of their simulated environment. Text-based applications may provide a less intuitive
interface, but may permit more advanced forms of customization.

Packet loss

occurs when one or morepacketsof data travelling across a computer networkfail to reachtheir
destination. Packet loss is distinguished as one of the three main error types encountered in
digital communications; the other two being bit errorand spurious packets caused due to noise.
Packets can be lost in a network because they may be dropped when a queue in the network node
overflows. The amount of packet loss during the steady state is another important property of a
congestion control scheme. The larger the value of packet loss, the more difficult it is for
transportlayer protocols to maintain high bandwidths, the sensitivity to loss of individual packets,
as well as to frequency and patterns of loss among longer packet sequences is strongly dependent
on the application itself.

Throughput

This is the main performance measure characteristic, and most widely used.
Incommunicationnetworks, such asEthernetorpacket radio, throughputor network throughputis
the average rate of successfulmessage delivery over a communication channel. The throughput is
usually measured inbitsper second (bit/s orbps), andsometimes indata packetsper second or data
packets pertime slotThis measure how soon the receiver is able to get a certain amount of data
send by the sender. It is determined as the ratio of the total data received to the end to end delay.
Throughput is an important factor which directly impacts the network performance
Delay

Delay is the time elapsed while a packet travels from one point e.g., source premise or network
ingress to destination premise or network degrees. The larger the valueof delay, the more difficult
it is for transport layer protocols to maintain highbandwidths. We will calculate end to end delay

Queue Length

A queuing system in networks can be described as packets arriving for service, waiting for
service if it is not immediate, and if having waited for service, leaving thesystem after being
served. Thus queue length is very important characteristic to determine that how well the active
queue management of the congestion control
algorithm has been working.

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