Final networks lab manual

DEPARTMENT OF INFORMATION TECHNOLOGY
LAB MANUAL
IT6511 - NETWORKS LABORATORY
Program : B.Tech Semester : V
Batch : 2013-17 Subject code : IT6511
Subject name : Networks Laboratory Credits : 2
Faculty : M.C.Jayaprasanna
Anjalai Ammal Mahalingam Engineering College
Kovilvenni-614 403
Department of Information Technology

SYLLABUS FOR THE COURSE
IT6511 NETWORKS LABORATORY L T P C 0 0 3 2
LIST OF EXPERIMENTS
1. Implementation of Stop and Wait Protocol and Sliding Window Protocol.
2. Study of Socket Programming and Client – Server model
3. Write a code simulating ARP /RARP protocols.
4. Write a code simulating PING and TRACEROUTE commands
5. Create a socket for HTTP for web page upload and download.
6. Write a program to implement RPC (Remote Procedure Call)
7. Implementation of Sub netting.
8. Applications using TCP Sockets like
a. Echo client and echo server
b. Chat
c. File Transfer
9. Applications using TCP and UDP Sockets like
d. DNS
e. SNMP
f. File Transfer
10. Study of Network simulator (NS).and Simulation of Congestion Control Algorithms using
NS
11. Perform a case study about the different routing algorithms to select the network path with its
optimum and economical during data transfer.
i. Link State routing
ii. Flooding
iii. Distance vector
TOTAL: 45 PERIODS

OBJECTIVE OF THE COURSE
The student should be made to:
1. Learn socket programming.
2. Be familiar with simulation tools.
3. Have hands on experience on various networking protocols.
OUTCOME OF THE COURSE
At the end of the course, the student should be able to
1. Use simulation tools
2. Implement the various protocols.
3. Analyze the performance of the protocols in different layers.
4. Analyze various routing algorithms

LIST OF FIRST CYCLE EXPERIMENTS
1. Implementation of Stop and Wait Protocol and Sliding Window Protocol.
2. Study of Socket Programming and Client – Server model
3. Write a code simulating ARP /RARP protocols.
4. Write a code simulating PING and TRACEROUTE commands
5. Create a socket for HTTP for web page upload and download.
6. Write a program to implement RPC (Remote Procedure Call)
LIST OF SECOND CYCLE EXPERIMENTS
7. Implementation of Sub netting.
8. Applications using TCP Sockets like
a. Echo client and echo server
b. Chat
c. File Transfer
9. Applications using TCP and UDP Sockets like
d. DNS
e. SNMP
f. File Transfer
10. Study of Network simulator (NS).and Simulation of Congestion Control Algorithms using
NS
11. Perform a case study about the different routing algorithms to select the network path with its
optimum and economical during data transfer.
ii. Flooding
iii. Distance vector

PREREQUISITES OF THE SUBJECT
1. BUILDING A NETWORK
To build a computer network, that has the potential to grow to global proportions and to support
applications as diverse as teleconferencing, video-on-demand, electronic commerce, distributed
computing, and digital libraries.
What is network?
1. Network meant the set of serial lines used to attach dumb terminals to mainframe computers.
2. Other important networks include the voice telephone network and the cable TV network used to
disseminate video signals.
3. The main thing these networks have in common is that they are specialized to handle one
particular kind of data (keystrokes, voice, or video) and they typically connect to special-purpose
devices (terminals, hand receivers, and television sets).
What distinguishes a computer network from these other types of networks?
1. Probably the most important characteristic of a computer network is its generality.
2. Computer networks are built primarily from general-purpose programmable hardware, and they
are not optimized for a particular application like making phone calls or delivering television
signals.
Links and Nodes
1. A network consists of two or more computers directly connected by some physical medium,
such as a coaxial cable or an optical fiber. Such a physical medium is called as links.
2. The links are connected to the computers named as nodes.
Basics
Most network application can be divided into two programs: client and server with the
communication link between them as shown in figure.
Fig. Network application: client and server
1. Client- initiates the request, Server – response to the request
Examples: A web browser communicates with a web server.
A FTP client fetches a file from a FTP server, etc.
2. A client normally communicates with a server at a time. However, a server is likely to communicate
with multiple clients is shown in figure
3. If the client and server are on the same Ethernet, we would have the arrangement as shown in below
figure
4. In the below shown figure the client and server on different LANs, with both LANs connected to a
wide area network (WAN) using routers.
Fig. Server handling multiple clients at the same time
Client Server
Client
Client
Client
Server

OSI model for the Internet protocol suite:
1. Internet Protocol Suite is a set of communication Protocols used on the internet. It is
commonly known as TCP/IP, named from two of the most important protocols in it:
the Transmission Control Protocol (TCP) and the Internet Protocol (IP), which were the first
two networking protocols defined in this standard.
2. A common way to describe the layers in a network to use the International Organization for
standardization (ISO) Open System Interconnection (OSI) model for computer
communications.
3. This is a seven layer model which is shown in figure along with the approximate mapping to
the Internet Protocol Suite.
4. The upper three layers of OSI model are combined into a single layer called the application.
This is the Web Client (Browser), Telnet client, Web Server, FTP server or whatever
application we are using.
5. The transport layer comprises of TCP and UDP.
6. There is a gap between TCP and UDP in figure to indicate that it is possible for an
application to bypass the transport layer and use IPv4 and IPv6 directly. This is called raw
socket.
7. The two programming interfaces are sockets and XTI(X/Open Transport Interface). It is
intended to study: how to write applications using either Sockets that use either TCP or UDP.
8. Upper three layers handle all the details of the application (FTP, Telnet or HTTP etc) and
know little about the communication details. Whereas the lower four layers know little about
the application but handle all communication details: sending data, waiting for an
acknowledgements, sequencing data that arrives out of order , calculating and verifying the
checksums and so on.
9. Upper three layers often form what is called a user process while the lower 4 layers are
normally provided as part of the operating system kernel.

Port Number
1. Port is an application-specific or process-specific software construct serving as a
communications endpoint in a computer's host operating system.
2. A port is associated with an IP address of the host, as well as the type of protocol used for
communication.
3. A port is identified for each address and protocol by a 16-bit number, commonly known
as the port number.
4. Port Numbers: At any given time multiple processes can use either UDP or TCP. Both
use 16 bit integer port numbers to differentiate between these processes.
5. TCP and UDP define a group of well-known ports that to identity well known services.
FTP assigns the well-known ports of 21 to the FTP server .Trivial FTP servers are
assigned the UDP port of 69.
6. Clients use ephemeral ports that are short lived ports. These port numbers are manually
assigned by TCP or UDP to the client.
7. The port numbers are divided into three categories
 Well known ports: 0 through 1023 .These port numbers are controlled and
assigned by the IANA. When possible same port number is assigned to a given
service of both TCP and UDP.
 The Registered Ports: 1024 through 49151.These are not controlled by the IANA,
(Internet Assigned Numbers Authority) but the IANA registers and lists the uses
of these ports as a convenience to the community.
 Dynamic private ports: 49152 through 65535. These are what we call as
ephemeral ports. It is also called Short lived transport protocol port that is created
by OS when a program requests any available user ports.
Allocation of Port Numbers
Socket Pair
1. Socket is a method for communication between a client program & a server program in a
network. A socket is defined as “the endpoint in a connection”.
2. The two values that identify each endpoint, an IP address and a port number, are called a
socket.
3. The socket pair for a TCP connection is the 4-tuple that defined the two end points of the
connection:
i) The local IP address ii) local TCP port,
ii) Foreign IP address iv) foreign TCP port.
Types of Sockets
There are 3 types of sockets
1. Stream Socket (designed to be used with a connection-oriented protocol such as TCP)
2. Datagram Socket (designed to be used with a connectionless protocol such as UDP)
3. Raw Socket (provide access to ICMP to move esoteric (secret) facilities of an existing
protocol)

EX.NO:1 Implementation of Stop and Wait Protocol and Sliding Window Protocol
AIM
To write a java program to perform stop & wait and sliding window protocols.
CONCEPT
1. Stop-and-Wait Protocol means that the sender sends one frame, stops until it receives
confirmation from the receiver (okay to go ahead), and then sends the next frame.
2. If data frames arrive at the receiver site faster than they can be processed, the frames must be
stored until their use.
3. Normally, the receiver does not have enough storage space, especially if it is receiving data
from many sources. This may result in either the discarding of frames or denial of service.
4. To prevent the receiver from becoming over-whelmed with frames, we need to tell the sender
to slow down.
5. A sliding window protocol is a feature of packet-based data transmission protocols.
conceptually, each portion of the transmission is assigned a unique consecutive sequence
number, and the receiver uses the numbers to place received packets in the correct order.
6. Sliding window protocol allows an unlimited number of packets to be communicated using
fixed-size sequence numbers.
7. The term "window" on transmitter side represents the logical boundary of the total number of
packets yet to be acknowledged by the receiver.
ALGORITHM FOR STOP AND WAIT:
1. Start the program.
2. Create the socket by specifying the address and establishes the connection
3. Send and receive information.
4. The sender sends one frame, stops until it receives confirmation from the receiver and
then sends the next frame.
5. Stop the program.
ALGORITHM FOR SLIDING WINDOW:
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
SOURCE CODE
Stop & wait protocol
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();
System.out.println("waiting for ack.....nn");
if(ack.equals(String.valueOf(sequence))){
i++;
System.out.println("receiver > "+" packet recievednn");
}
else{
System.out.println("Time out resending data....nn");
}
}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();
}
}
//ReceiverProgram
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();
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);
System.out.println("nnreceiver >"+packet);
}
else
{

System.out.println("nnreceiver >"+packet +" duplicate data");
}
if(i<3){
out.writeObject(String.valueOf(sequence));i++;
}
else{
out.writeObject(String.valueOf((sequence+1)%2));
i=0;
}
}
}while(!packet.equals("end"));
System.out.println("Data received="+data);
out.writeObject("connection ended .");
}
finally{
try{
in.close();
out.close();
reciever.close();
}
}
}
Reciever s=new Reciever();
while(true){
s.run();
}}}
SAMPLE INPUT& OUTPUT
Sender
C:>javac Sender.java
C:>java Sender
Waiting for Connection....
reciver > connected .
Enter the data to send....
hi
data sent>0h
waiting for ack.....
receiver > packet recieved
data sent>1i
waiting for ack.....
receiver > packet recieved
All data sent. exiting.
Receiver
C:>javac Reciever.java

C:>java Reciever
Waiting for connection …
Connection established:
receiver > 0h
receiver > 1i
Data received=hi
Waiting for connection…
Sliding window protocol
Sender
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 sendn");
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();
}
}
Receiver
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
sentn"); p.println(rptr+1); rws+=nf; }
else break;
ch=in.readLine();
}
while(ch.equals("yes"));
}
}
SAMPLE INPUT& OUTPUT
//SENDER OUTPUT
C:>javac slidsender.java
Note: slidsender.java uses or overrides a deprecated API.
Note: Recompile with -Xlint:deprecation for details.
C:>java slidsender
Enter the no. of frames: 4
Enter 4 Messages to be send
hi

how are u?
fine
thank u
Acknowledgment received for 4 frames
Do you want to send some more frames: y
//RECEIVER OUTPUT
C:>javac slidreceiver.java
Note: slidreceiver.java uses or overrides a deprecated API.
C:>java slidreceiver
The received Frame 0 is : hi
The received Frame 1 is : how are u?
The received Frame 2 is: fine
The received Frame 3 is : thank u
Acknowledgment sent
RESULT
Thus the program for implementing Stop and Wait Protocol and Sliding Window
Protocol was executed successfully and output verified.

EX.NO:2 Study of Socket Programming and Client – Server model
AIM
To implement socket programming date and time display from client to server using TCP
Sockets.
CONCEPT
Socket Programming
1. Sockets provide the communication mechanism between two computers using TCP. A
client program creates a socket on its end of the communication and attempts to connect
that socket to a server.
2. When the connection is made, the server creates a socket object on its end of the
communication. The client and server can now communicate by writing to and reading
from the socket.
Client–server model
1. The client–server model of computing is a distributed application structure that partitions
tasks or workloads between the providers of a resource or service, called servers, and
service requesters, called clients.
2. Often clients and servers communicate over a computer network on separate hardware,
but both client and server may reside in the same system.
3. A server host runs one or more server programs which share their resources with clients.
A client does not share any of its resources, but requests a server's content or service
function.
4. Clients therefore initiate communication sessions with servers which await incoming
requests. Examples of computer applications that use the client–server model are Email,
network printing, and the World Wide Web.
ALGORITHM
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.

SOURCE CODE
//TCP Date Server--tcpdateserver.java
import java.net.*;
import java.io.*;
import java.util.*;
class tcpdateserver
{
public static void main(String arg[])
{
ServerSocket ss = null; Socket cs;
PrintStream ps; BufferedReader
dis; String inet; try
{
ss = new ServerSocket(4444); System.out.println("Press
Ctrl+C to quit"); while(true)
{
cs = ss.accept();
ps = new PrintStream(cs.getOutputStream());
Date d = new Date();
ps.println(d);
dis = new BufferedReader(new InputStreamReader(cs.getInputStream())); inet =
dis.readLine(); System.out.println("Client System/IP address is :"+ inet); ps.close();
dis.close();
}
}
catch(IOException e)
{
System.out.println("The exception is :" + e);
}
}
}
// TCP Date Client--tcpdateclient.java
import java.net.*;
import java.io.*;
class tcpdateclient
{
public static void main (String args[]) {
Socket soc; BufferedReader dis;
String sdate; PrintStream ps;
try { InetAddress ia = InetAddress.getLocalHost();
if (args.length == 0)
soc = new Socket(InetAddress.getLocalHost(),4444);
else soc = new Socket(InetAddress.getByName(args[0]),4444);
dis = new BufferedReader(new InputStreamReader(soc.getInputStream()));
sdate=dis.readLine(); System.out.println("The date/time on server is : " +sdate); ps =
new PrintStream(soc.getOutputStream());
ps.println(ia);

ps.close();
}
{
System.out.println("THE EXCEPTION is :" + e);
}
}
}
SAMPLE INPUT & OUTPUT
Server:
C:>javac tcpdateserver.java
C:>java tcpdateserver
Press Ctrl+C to quit
Client System/IP address is :welcome-PC/192.168.1.102
Client:
C:>javac tcpdateclient.java
C:>java tcpdateclient
THE EXCEPTION is: java.net.ConnectException: Connection refused: connect
C:>java tcpdateclient
The date/time on server is: Tue May 19 20:19:23 IST 2015
RESULT
Thus the program for implementing to display date and time from client to server using
TCP Sockets was executed successfully and output verified using various samples.

EX.NO:3 Simulation of ARP /RARP protocols
AIM
To write a java program for simulating arp/rarp protocols
CONCEPT
ARP (Address Resolution Protocol)
 The logical (IP) address is obtained from the DNS if the sender is the host or it is found
in a routing table if the sender is a router. But the IP datagram must be encapsulated in a
frame to be able to pass through the physical network.
 The host or the router sends an ARP query packet. The packet includes the physical and
IP addresses of the sender and the IP address of the receiver.
 Because the sender does not know the physical address of the receiver, the query is
broadcast over the network.
 Every host or router on the network receives and processes the ARP query packet, but
only the intended recipient recognizes its IP address and sends back an ARP response
packet.
 The response packet contains the recipient's IP and physical addresses.
RARP (Reverse Address Resolution Protocol
 RARP finds the logical address for a machine that knows only its physical address.
 Each host or router is assigned one or more logical (IP) addresses, which are unique and
independent of the physical (hardware) address of the machine.
 To create an IP datagram, a host or a router needs to know its own IP address or
addresses.
ALGORITHM
SERVER
Step1: Create a server socket and client socket.
Step2: Create a process.
Step3: Get request from client.
Step4: Send the physical address to the client.
Step5: Close server socket and client socket connection.
CLIENT
Step1: Create a client socket connection with specified port.
Step2: Read the message from the client.
Step3: Send the System name to the server.
Step4: Read the message from the server. Print the message.
Step5: Close the client connection.
SOURCE CODE (ARP)
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.*;
class Serverarp
{
{
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 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)
{
}
}
}
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
SOURCE CODE (RARP)
Client:
import java.io.*;
import java.net.*;
import java.util.*;
class Clientrarp12
{
{
try
{
DatagramSocket client=new DatagramSocket();
InetAddress addr=InetAddress.getByName("127.0.0.1");
byte[] sendbyte=new byte[1024];
byte[] receivebyte=new byte[1024];
System.out.println("Enter the Physical address (MAC):");
String str=in.readLine();
sendbyte=str.getBytes();
DatagramPacket sender=new
DatagramPacket(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)
{
}
}
}
Server:
import java.io.*;
import java.net.*;
import java.util.*;
class Serverrarp12
{
{
try
{
DatagramSocket server=new DatagramSocket(1309);
while(true)
{
byte[] sendbyte=new byte[1024];
byte[] receivebyte=new byte[1024];
DatagramPacket receiver=new
DatagramPacket(receivebyte,receive
byte.length);
server.receive(receiver);
String str=new String(receiver.getData());
String s=str.trim(); //System.out.println(s);
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=new
DatagramPacket(sendbyte,sendbyte.length,addr,port);
server.send(sender);
break;
}
}
break;
}
}

catch(Exception e)
{
}
}
}
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
RESULT
Thus the program for simulating ARP /RARP protocols was executed.

EX.NO: 4 Simulation of PING and TRACEROUTE commands
AIM
To write the java program for simulating ping and trace route commands
CONCEPT
PING Command
1. The ping command is a very common method for troubleshooting the accessibility of
devices. It uses a series of Internet Control Message Protocol (ICMP) Echo messages to
determine:
 Whether a remote host is active or inactive.
 The round-trip delay in communicating with the host.
 Packet loss.
2. The ping command first sends an echo request packet to an address, and then waits for a
reply. The ping is successful only if:
 the echo request gets to the destination, and
 the destination is able to get an echo reply back to the source within a
predetermined time called a timeout. The default value of this timeout is two
seconds on Cisco routers.
TRACEROUTE Command
1. The trace route command is used to discover the routes that packets actually take when
traveling to their destination. The device (for example, a router or a PC) sends out a
sequence of User Datagram Protocol (UDP) data grams to an invalid port address at the
remote host.
2. Three data grams are sent, each with a Time-To-Live (TTL) field value set to one. The
TTL value of 1 causes the datagram to "timeout" as soon as it hits the first router in the
path; this router then responds with an ICMP Time Exceeded Message (TEM) indicating
that the datagram has expired.
3. Another three UDP messages are now sent, each with the TTL value set to 2, which
causes the second router to return ICMP TEMs. This process continues until the packets
actually reach the other destination.
4. Since these data grams are trying to access an invalid port at the destination host, ICMP
Port Unreachable Messages are returned, indicating an unreachable port; this event
signals the Trace route program that it is finished.
ALGORITHM
Ping Server
2. Import necessary packages.
3. Initialize the ping server with both sockets as null value.
4. Start the server socket.
5. At the client give the IP address of the server.
6. The client program is then started by starting socket.
7. At the receiver end, the client is pinged.
Ping Client

2. Import necessary packages.
3. Initialize the ping client with both sockets as null value.
4. Start the socket.
5. Get the IP address of the server.
6. Ping the server.
7. At the receiver end, the server is pinged.
SOURCE CODE
//pingclient.java
import java.io.*;
import java.net.*;
import java.util.Calendar;
class pingclient
{
public static void main(String args[])throws Exception
{
String str;
int c=0;
long t1,t2;
Socket s=new Socket("127.0.0.1",5555);
DataInputStream dis=new DataInputStream(s.getInputStream());
PrintStream out=new PrintStream(s.getOutputStream());
while(c<4)
{
t1=System.currentTimeMillis();
str="Welcome to network programming world";
out.println(str);
System.out.println(dis.readLine());
t2=System.currentTimeMillis();
System.out.println(";TTL="+(t2-t1)+"ms"); c++;
}
s.close();
}
//pingserver.java
import java.io.*;
import java.net.*;
import java.util.*;
import java.text.*;
class pingserver
{
{
ServerSocket ss=new ServerSocket(5555); Socket
s=ss.accept();
int c=0;
while(c<4)

{
DataInputStream dis=new DataInputStream(s.getInputStream());
PrintStream out=new PrintStream(s.getOutputStream());
String str=dis.readLine();
out.println("Reply from"+InetAddress.getLocalHost()+";Length"+str.length()); c++;
}
s.close();}}
C:>javac pingserver.java
Note: pingserver.java uses or overrides a deprecated API.
C:>java pingserver
C:>javac pingclient.java
Note: pingclient.java uses or overrides a deprecated API.
C:>java pingclient
Reply from welcome-PC/192.168.1.100;Length36; TTL=50ms
RESULT
Thus the program for simulating ping and trace route commands were executed.

EX.NO:5 Creation of sockets for HTTP web page upload and download
AIM
To write a java program for creating socket for HTTP web page upload and download.
CONCEPT
HTTP
1. The Hypertext Transfer Protocol (HTTP) is a protocol used mainly to access data on the
World Wide Web.
2. HTTP functions as a combination of FTP and SMTP.
3. SMTP messages are stored and forwarded, but HTTP messages are delivered
immediately.
4. The commands from the client to the server are embedded in a request message. The
contents of the requested file or other information are embedded in a response message.
ALGORITHM
Step1: Set a server port as 80.
Step2: Using HTTP services create a Socket for server by specifying the server port
Step3: Use HTTP socket for connecting the client to the URL.
Step4: Use BufferedReader to output stream to place the response from the server by the client.
Step5: Close the Connection as soon the request is been serviced. Use Malformed URL
exception If any errors in grabbing the server
SOURCE CODE
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.*;
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);
}
}
CLIENT SIDE OUTPUT
When you execute the client code, the following output appears on client side:
SERVER SIDE OUTPUT
When you execute the server code, the following ouptut apppears on server side:
After receiving the image, the server displays the image as shown below:

RESULT
Thus the program for creating sockets for HTTP web page upload and download was
implemented.

EX.NO:6 Implementation of RPC (Remote Procedure Call)
AIM
To write a java program to implement RPC (remote procedure call
CONCEPT
1. RPC is a powerful technique for constructing distributed, client-server based applications,
based on extending the notion of conventional or local procedure calling.
2. The transport independence of RPC isolates the application n from the physical and logical
elements of the data communications mechanism and allows the application to use a variety of
transports.
3. When an RPC is made, the calling arguments are passed to the remote procedure and the caller
waits for a response to be returned from the remote procedure.
4. RPC specifically supports network applications.
ALGORITHM
1. Start.
2. Create a server socket at the server side.
3. Create a socket at the client side and the connection is set to accept by the server socket using
the accept () method.
4. In the client side the command to be executed is given as input.
5. The command is obtained using the readLine () method of Buffer Reader.
6. Get the runtime object of the runtime class using getruntime ().
7. Execute the command using the exec () method of runtime.
8. Stop.
SOURCE CODE
Client
import java.io.*;
import java.net.*;
import java.util.*;
class Clientrpc
{
{
try
{
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 String");
String str=in.readLine();
dout.writeBytes(str+'n'); clsct.close();
}
catch (Exception e)

{
}
}
}
Server
import java.io.*;
import java.net.*;
import java.util.*;
class Serverrpc
{
{
try
{
ServerSocket obj=new
ServerSocket(139); while(true)
{
Socket obj1=obj.accept();
Process p=Runtime.getRuntime().exec(str);
}
}
catch(Exception e)
{
}
}
}
SAMPLE INPUT &OUTPUT
Server
Y:networksremote>java
Serverrpc Client
Y:networksremote>java
Clientrpc Enter String
calc
RESULT
Thus the RPC program was implemented.

EX.NO:7 Implementation of Sub netting
AIM
To write a program to implement sub netting and find the subnet masks.
CONCEPT
If an organization was granted a large block in class A or B, it could divide the addresses
into several contiguous groups and assign each group to smaller networks (called subnets) or, in
rare cases, share part of the addresses with neighbors.
ALGORITHM
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
SOURCE CODE
import java.util.Scanner;
class Subnet{
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 = ");
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++)
lip[i/8] = new String(lip[i/8]+lbip[i]);
System.out.print("Last address is = ");
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;
}
}
C:>javac Subnet.java
C:>java Subnet
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
RESULT
Thus the program for sub netting was implemented.

EX.NO: 8a Applications using TCP Sockets (like Echo client and echo server)
AIM
To write a java program for Echo client and echo server using TCP Sockets.
CONCEPT
1. The Echo server simply receives data from its client and echoes it back.
2. The Echo server is a well-known service that clients can rendezvous with on port 7.EchoClient
creates a socket thereby getting a connection to the Echo server.
3. It reads input from the user on the standard input stream, and then forwards that text to the
Echo server by writing the text to the socket.
4. The server echoes the input back through the socket to the client. The client program reads and
displays the data passed back to it from the server.
ALGORITHM
1. Create two programs one for the server side and one for the client side
2. In the server side, create a server socket.
3. The return value of the accept () method is assigned to a new socket created.
4. Send the input received from the client at the server side back to the client.
5. In the client side, create a socket to connect to the server.
6. Create the object of DataInputStream to accept input from the server
7. Display the input received from the server.
SOURCE CODE
//echo client.java
import java.io.*;
import java.net.*;
import java.util.*;
public class echoclient
{
{
Socket c=null; DataInputStream
usr_inp=null;
DataInputStream din=new DataInputStream(System.in);
DataOutputStream dout=null;
try
{
c=new Socket("127.0.0.1",5678);
usr_inp=new DataInputStream(c.getInputStream()); dout=new
DataOutputStream(c.getOutputStream());
}

{
}
if(c!=null || usr_inp!=null || dout!=null)
{
String unip; while((unip=din.readLine())!=null)
{
dout.writeBytes(""+unip);
dout.writeBytes("n"); System.out.println("n the echoed message");
System.out.println(usr_inp.readLine()); System.out.println("n enter your
message");
}
System.exit(0);
}
din.close(); usr_inp.close(); c.close();
}
}
//echoserver.java
import java.io.*;
import java.net.*;
public class echoserver
{
{
ServerSocket m=null; Socket c=null;
DataInputStream usr_inp=null;
DataInputStream din=new DataInputStream(System.in); DataOutputStream dout=null;
try
{
m=new ServerSocket(5678); c=m.accept();
}
catch(IOException e) {}
if(c!=null || usr_inp!=null)
{
String unip;
while(true)
{
System.out.println("nMessage from Client..."); String m1=(usr_inp.readLine());
System.out.println(m1); dout.writeBytes(""+m1); dout.writeBytes("n");
}
}
dout.close(); usr_inp.close(); c.close();
}
}

C:>java echoserver
Message from Client...
hi
Message from Client...
how are u?
C:>java echoclient
hi
the echoed message
hi
enter your message
how are u?
the echoed message
how are u?
RESULT
Thus the java program for Echo client and echo server using TCP Sockets was created.

EX.NO: 8b Applications using TCP Sockets (like Chat)
AIM
To write a java program for chat using TCP Sockets.
CONCEPT
1. It uses TCP socket communication .We have a server as well as a client.
2. Both can be run in the same machine or different machines. If both are running in the
machine, the address to be given at the client side is local host address.
3. If both are running in different machines, then in the client side we need to specify the ip
address of machine in which server application is running.
ALGORITHM
Server
1. Start the program
2. Create server and client sockets.
3. Use input streams to get the message from user.
4. Use output streams to send message to the client.
5. Wait for client to display this message and write a new one to be displayed by the
server.
6. Display message given at client using input streams read from socket.
Client
1. Start the program
2. Create a client socket that connects to the required host and port.
3. Use input streams read message given by server and print it.
4. Use input streams; get the message from user to be given to the server.
5. Use output streams to write message to the server.
SOURCE CODE
Client
/talkclient.java
import java.io.*; import java.net.*; public class talkclient
{
{
Socket c=null; DataInputStream usr_inp=null;
try
{
c=new Socket("127.0.0.1",1234);
}

if(c!=null || usr_inp!=null || dout!=null)
{
String unip;
System.out.println("nEnter the message for server:"); while((unip=din.readLine())!=null)
{
dout.writeBytes(""+unip);
dout.writeBytes("n");
System.out.println("reply"); System.out.println(usr_inp.readLine());
System.out.println("n enter your message:");
}
System.exit(0);
}
din.close(); usr_inp.close(); c.close();
}
}
Server
//talkserver.java import java.io.*; import java.net.*; public
class talkserver
{
{
ServerSocket m=null; Socket c=null;
DataInputStream usr_inp=null;
try
{m=new ServerSocket(1234);
c=m.accept();
}
if(c!=null||usr_inp!=null)
{
String unip; while(true)
{
System.out.println("nmessage from client:"); String m1=usr_inp.readLine();
System.out.println(m1); System.out.println("enter your message:");
unip=din.readLine(); dout.writeBytes(""+unip); dout.writeBytes("n");
}
}
dout.close(); usr_inp.close(); c.close();
}
}

C:>javac talkserver.java
Note: talkserver.java uses or overrides a deprecated API.
C:>java talkserver
message from client:
hi
enter your message:
hi
message from client:
what about u?
C:>javac talkclient.java
Note: talkclient.java uses or overrides a deprecated API.
C:>java talkclient
Enter the message for server:
hi
reply
hi
enter your message:
what about u?
reply
RESULT
Thus the java program for chat using TCP Sockets was executed.

EX.NO: 8c Applications using TCP Sockets (like file transfer)
AIM
To write a java program for file transfer using TCP Sockets.
CONCEPT
Our application has a client and a server. Our aim is to send a file from the client
machine to the server machine.
ALGORITHM
Server
1. Import java packages and create class file server.
2. Create a new server socket and bind it to the port.
3. Accept the client connection
4. Get the file name and stored into the BufferedReader.
5. Create a new object class file and realine.
6. If file is exists then FileReader read the content until EOF is reached.
Client
3. Now connection is established.
4. The object of a BufferReader class is used for storing data content which has been retrieved
from socket object.
5. The content of file is displayed in the client window and the connection is closed.
SOURCE CODE
Client
import java.io.*; import java.net.*;
import java.util.*; class Clientfile
{
{
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)
{
}
}
}
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)
{
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("-1n");
} }
catch(Exception e)
{
System.out.println(e);}
}
}

C:>java Clientfile
Enter the file name:
one.txt
Enter the new file name:
two
hiiiiiiiiiiiiiiiiiiiii
C:>java Serverfile
hiiiiiiiiiiiiiiiiiiiii
RESULT
Thus the java program file transfer application using TCP Sockets was executed.

EX.NO:9a Applications using TCP and UDP Sockets (like DNS)
AIM
To write a java program for DNS application.
CONCEPT
1. The DNS client program sends a request to a DNS server to map the e-mail address to the
corresponding IP address.
2. When the Internet was small, mapping was done by using a host file. The host file had
only two columns: name and address.
3. The host that needs mapping can contact the closest computer holding the needed
information. This method is used by the Domain Name System (DNS).
ALGORITHM
Server
Step1: Start the program.
Step2: Create the socket for the server.
Step3: Bind the socket to the port.
Step4: Listen for the incoming client connection.
Step5: Receive the IP address from the client to be resolved.
Step6: Get the domain name for the client.
Step7: Check the existence of the domain in the server.
Step8: If domain matches then send the corresponding address to the client.
Step9: Stop the program execution
Client
Step1: Start the Program.
Step2: Create the socket for the client.
Step3: Connect the socket to the Server.
Step4: Send the host name to the server to be resolved.
Step5: If the server corresponds then print the address and terminate the process
SOURCE CODE
// UDP DNS Server
Udpdnsserver.java
import java.io.*;
import java.net.*;
public class udpdnsserver
{
private static int indexOf(String[] array, String str)
{
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
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();
}}
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
RESULT
Thus the DNA application program was executed.

EX.NO:9b Applications using TCP and UDP Sockets (like SNMP)
AIM
To write a java program for SNMP application.
CONCEPT
1. Simple Network Management Protocol (SNMP) is a framework for managing devices in
an internet using TCP/IP.
2. It provides a set of fundamental operations for monitoring and maintaining an internet.
3. SNMP uses the concept of manager and agent
– A manager is a host that runs the SNMP client program.
– A managed station called an agent, is a router that runs the SNMP server
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.
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
SOURCE CODE
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
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
*/
public String getAsString(OID oid) throws IOException {
ResponseEvent event = get(new OID[]{oid});
return event.getResponse().get(0).get Variable().toString();
}
/**
* This method is capable of handling multiple OIDs
* @param oids
* @return
*/
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;
}
}
Hardware: x86 Family 6 Model 23 Stepping 10 AT/AT COMPATIBLE – Software: Windows
2000 Version 5.1 (Build 2600 Multiprocessor Free)
RESULT
Thus the SNMP application was implemented.

EX.NO:9c Applications using TCP and UDP Sockets (like file transfer)
AIM
To write a java program for SNMP application.
CONCEPT
Our application has a client and a server. Our aim is to send a file from the client
machine to the server machine.
ALGORITHM
Server
3. Accept the client connection
4. Get the file name and stored into the BufferedReader.
5. Create a new object class file and realine.
6. If file is exists then FileReader read the content until EOF is reached.
Client
3. Now connection is established.
4. The object of a BufferReader class is used for storing data content which has been retrieved
from socket object.
5. The content of file is displayed in the client window and the connection is closed.
SOURCE CODE
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)
{
}
}}
Server
import java.io.*;
import java.net.*;
import java.util.*;
class Serverfile
{
{
try
{
ServerSocket obj=new ServerSocket(139);
while(true)
{
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("-1n");
} }
catch(Exception e)
{ System.out.println(e);
}
}
}
C:>java Clientfile
Enter the file name:
copy.txt

Enter the new file name:
new
hiiiiiiiiiiiiiiiiii
C:>java Serverfile
hiiiiiiiiiiiiiiiiii
RESULT
Thus the file transfer application was executed.

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 Functionalities
Routing, Transportation, Traffic sources, queuing disciplines, QoS
Wireless
Ad hoc routing, mobile IP, sensor-MAC
Tracing, visualization and various utilities
NS (Network Simulators)
Most of the commercial simulators are GUI driven, while some network simulators are
CLI driven. The network model / configuration describe the state of the network (nodes, routers,
switches, and links) and the events (data transmissions, packet error etc.). Important outputs 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 variants" 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
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 more packets of data travelling across a computer
network fail to reach their destination. Packet loss is distinguished as one of the three main error
types encountered in digital communications; the other two being bit error and 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 transport layer 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. In
communication networks, such as Ethernet or packet radio, throughput or network. Throughput
is the average rate of successful message delivery over a communication channel. The
throughput is usually measured in bits per second (bit/s or bps), and sometimes in data packets
per second or data packets per time slot. This 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 value of delay, the
more difficult it is for transport layer protocols to maintain high bandwidths. 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 the system 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.
RESULT
Thus the study of Network simulator (NS2) was studied.

EX.NO:11 Case study on routing algorithms
AIM
To study the link state routing algorithm.
Link State routing
Routing is the process of selecting best paths in a network. In the past, the term routing
was also used to mean forwarding network traffic among networks. However this latter function
is much better described as simply forwarding. Routing is performed for many kinds of
networks, including the telephone network (circuit switching), electronic data networks (such as
the Internet), and transportation networks. This article is concerned primarily with routing in
electronic data networks using packet switching technology.
In packet switching networks, routing directs packet forwarding (the transit of logically
addressed network packets from their source toward their ultimate destination) through
intermediate nodes. Intermediate nodes are typically network hardware devices such as routers,
bridges, gateways, firewalls, or switches. General-purpose computers can also forward packets
and perform routing, though they are not specialized hardware and may suffer from limited
performance. The routing process usually directs forwarding on the basis of routing tables which
maintain a record of the routes to various network destinations. Thus, constructing routing tables,
which are held in the router's memory, is very important for efficient routing. Most routing
algorithms use only one network path at a time. Multipath routing techniques enable the use of
multiple alternative paths.
In case of overlapping/equal routes, the following elements are considered in order to decide
which routes get installed into the routing table (sorted by priority):
1. Prefix-Length: where longer subnet masks are preferred (independent of whether it is
within a routing protocol or over different routing protocol)
2. Metric: where a lower metric/cost is preferred (only valid within one and the same
routing protocol)
3. Administrative distance: where a lower distance is preferred (only valid between different
routing protocols)
Routing, in a more narrow sense of the term, is often contrasted with bridging in its assumption
that network addresses are structured and that similar addresses imply proximity within the
network. Structured addresses allow a single routing table entry to represent the route to a group
of devices. In large networks, structured addressing (routing, in the narrow sense) outperforms
unstructured addressing (bridging). Routing has become the dominant form of addressing on the
Internet. Bridging is still widely used within localized environments.
ii. Flooding
Flooding s a simple routing algorithm in which every incoming packet is sent through
every outgoing link except the one it arrived on. Flooding is used in bridging and in systems such
as Usenet and peer-to-peer file sharing and as part of some routing protocols, including OSPF,
DVMRP, and those used in ad-hoc wireless networks. There are generally two types of flooding
available, Uncontrolled Flooding and Controlled Flooding. Uncontrolled Flooding is the fatal
law of flooding. All nodes have neighbors and route packets indefinitely. More than two
neighbors create a broadcast storm.
Controlled Flooding has its own two algorithms to make it reliable, SNCF (Sequence

Number Controlled Flooding) and RPF (Reverse Path Flooding). In SNCF, the node attaches its
own address and sequence number to the packet, since every node has a memory of addresses
and sequence numbers. If it receives a packet in memory, it drops it immediately while in RPF,
the node will only send the packet forward. If it is received from the next node, it sends it back to
the sender.
Algorithm
There are several variants of flooding algorithm. Most work roughly as follows:
1. Each node acts as both a transmitter and a receiver.
2. Each node tries to forward every message to every one of its neighbors except the source
node.
This results in every message eventually being delivered to all reachable parts of the network.
Algorithms may need to be more complex than this, since, in some case, precautions have to be
taken to avoid wasted duplicate deliveries and infinite loops, and to allow messages to eventually
expire from the system. A variant of flooding called selective flooding partially addresses these
issues by only sending packets to routers in the same direction. In selective flooding the routers
don't send every incoming packet on every line but only on those lines which are going
approximately in the right direction.
Advantages
 If a packet can be delivered, it will (probably multiple times).
 Since flooding naturally utilizes every path through the network, it will also use the
shortest path.
 This algorithm is very simple to implement.
Disadvantages
 Flooding can be costly in terms of wasted bandwidth. While a message may only have
one destination it has to be sent to every host. In the case of a ping flood or a denial of
service attack, it can be harmful to the reliability of a computer network.
 Messages can become duplicated in the network further increasing the load on the
networks bandwidth as well as requiring an increase in processing complexity to
disregard duplicate messages.
 Duplicate packets may circulate forever, unless certain precautions are taken:
 Use a hop count or a time to live count and include it with each packet. This value should
take into account the number of nodes that a packet may have to pass through on the way
to its destination.
 Have each node keep track of every packet seen and only forward each packet once
 Enforce a network topology without loops
iii . Distance vector
In computer communication theory relating to packet-switched networks, a distance-
vector routing protocol is one of the two major classes of routing protocols, the other major
class being the link-state protocol. Distance-vector routing protocols use the Bellman–Ford
algorithm, Ford–Fulkerson algorithm, or DUAL FSM (in the case of Cisco Systems’ protocols)
to calculate paths.
A distance-vector routing protocol requires that a router informs its neighbors of topology
changes periodically. Compared to link-state protocols, which require a router to inform all the
nodes in a network of topology changes, distance-vector routing protocols have less
computational complexity and message overhead.
The term distance vector refers to the fact that the protocol manipulates vectors (arrays)

of distances to other nodes in the network. The vector distance algorithm was the original
ARPANET routing algorithm and was also used in the internet under the name of RIP (Routing
Information Protocol). Examples of distance-vector routing protocols include RIPv1 and RIPv2
and IGRP.
Method
Routers using distance-vector protocol do not have knowledge of the entire path to a
destination. Instead they use two methods:
1. Direction in which router or exit interface a packet should be forwarded.
2. Distance from its destination
Distance-vector protocols are based on calculating the direction and distance to any link in a
network. "Direction" usually means the next hop address and the exit interface. "Distance" is a
measure of the cost to reach a certain node .The least cost route between any two nodes is the
route with minimum distance. Each node maintains a vector (table) of minimum distance to
every node. The cost of reaching a destination is calculated using various route metrics. RIP uses
the hop count of the destination whereas IGRP takes into account other information such as node
delay and available bandwidth.
Updates are performed periodically in a distance-vector protocol where all or part of a
router's routing table is sent to all its neighbors that are configured to use the same distance-
vector routing protocol. RIP supports cross-platform distance vector routing whereas IGRP is a
Cisco Systems proprietary distance vector routing protocol. Once a router has this information it
is able to amend its own routing table to reflect the changes and then inform its neighbors of the
changes. This process has been described as ‗routing by rumor‘because routers are relying on
the information they receive from other routers and cannot determine if the information is
actually valid and true. There are a number of features which can be used to help with instability
and inaccurate routing information.
EGP and BGP are not pure distance-vector routing protocols because a distance-vector
protocol calculates routes based only on link costs whereas in BGP, for example, the local route
preference value takes priority over the link cost.
Count-to-infinity problem
The Bellman–Ford algorithm does not prevent routing loops from happening and suffers
from the count-to-infinity problem. The core of the count-to-infinity problem is that if A tells B
that it has a path somewhere, there is no way for B to know if the path has B as a part of it. To
see the problem clearly, imagine a subnet connected like A–B–C–D–E–F, and let the metric
between the routers be "number of jumps".
Now suppose that A is taken offline. In the vector-update-process B notices that the route
to A, which was distance 1, is down – B does not receive the vector update from A. The problem
is, B also gets an update from C, and C is still not aware of the fact that A is down – so it tells B
that A is only two jumps from C (C to B to A), which is false. This slowly propagates through
the network until it reaches infinity (in which case the algorithm corrects itself, due to the
relaxation property of Bellman–Ford).
RESULT
Thus the case study about the different routing algorithms to select the network path with
its optimum and economical during data transfer was performed.

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