JAVA:

You are required to implement a simplied network store-forward simulating program. You are required to set up your system with computers to emulate the sender, receiver and router, which are connected as shown in the following figure:

The sender will send Y packets (changing Y from 10; 20; 40; 60; 80; 100) via the router to the receiver. The receiver will reply with corresponding acknowledge packet as in the following gure. The router in the middle will randomly drop a packet with a probability (10+X) %, where X is 4. We further assume that the router only randomly drop data packets, not acknowledge packets.

You have to:

Implement programs running on the sender, router, and the receiver by using of TCP transmission protocol.

Here are the sample programs:

Reciever.java:

import java.io.IOException;

import java.io.PrintWriter;

import java.net.ServerSocket;

import java.net.Socket;

import java.util.Scanner;

public class TcpReceiver {

private static ServerSocket serverSocket;

private static final int PORT = 1240;

public static void main(String[] args)

{

System.out.println("Opening port ");

try

{

serverSocket = new ServerSocket(PORT);

/* Complete here */

}

catch(IOException ioEx)

{

System.out.println(

"Unable to attach to port for receiver!");

System.exit(1);

}

do

{

handleRouter();

}while (true);

}

private static void handleRouter()

{

Socket link = null;

try

{

link = serverSocket.accept();

/* Complete here */

}

catch(IOException ioEx)

{

ioEx.printStackTrace();

}

finally

{

try

{

System.out.println(

" * Closing connection *");

link.close(); //Step 5.

}

catch(IOException ioEx)

{

System.out.println(

"Unable to disconnect!");

System.exit(1);

}

}

}

}

____________________________________________________________________________________________________

Sender.java

//package org.test;

import java.io.*;

import java.net.*;

import java.util.*;

public class TcpSender {

private static InetAddress host;

private static final int PORT = 1241;

public static void main(String[] args)

{

try

{

host = InetAddress.getLocalHost();

}

catch(UnknownHostException uhEx)

{

System.out.println("Host ID not found!");

System.exit(1);

}

accessServer();

}

private static void accessServer()

{

Socket link = null;

try

{

link = new Socket(host,PORT);

/* Complete here */

}

catch(IOException ioEx)

{

ioEx.printStackTrace();

}

finally

{

try

{

System.out.println(" * Closing connection*");

link.close(); //Step 4.

}

catch(IOException ioEx)

{

System.exit(1);

}

}

}

}

____________________________________________________________________________________________________

Router.java

//package org.test;

import java.io.*;

import java.net.*;

import java.util.*;

public class TcpRouter

{

private static ServerSocket serverSocket;

private static InetAddress host;

private static final int PORT = 1241;

private static final int PORT2 = 1240;

private static Socket link2 = null;

private static int counter = 0;

private static int dropPacketSize = 0;

public static void main(String[] args)

{

System.out.println("Opening port");

{

try

{

Random roundInteger = new Random();

dropPacketSize = (int) Integer.valueOf(args[0])*14/100;

dropPacketSize += roundInteger.nextInt(2);

/* Complete here */

host = InetAddress.getLocalHost();

/* Complete here */

}

catch(UnknownHostException uhEx)

{

System.out.println("Host ID not found!");

System.exit(1);

}

}

try

{

serverSocket = new ServerSocket(PORT); //Step 1.

link2 = new Socket(host,PORT2);

/* Complete here */

}

catch(IOException ioEx)

{

System.out.println(

"Unable to attach to port for router!");

System.exit(1);

}

handleClient();

}

private static String handleClient()

{

Socket link = null;

try

{

link = serverSocket.accept();

/* Complete here */

}

catch(IOException ioEx)

{

ioEx.printStackTrace();

}

finally

{

try

{

System.out.println(

" * Closing connection*");

link.close(); //Step 5.

}

catch(IOException ioEx)

{

System.out.println(

"Unable to disconnect!");

System.exit(1);

}

}

return null;

}

}

Router Sender Receiver Figure 1: Network Transmission Model (Topology)