Anna University Netsim Experiment Manual

1

Experiment Manual

2

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3

NetSim Experiment Manual

Contents

1. Hamming Code ..................................................................................... 4

2. Transmission Flow Control .................................................................... 9

3. Sliding Window Protocol ..................................................................... 15

4. High Level Data Link Control ............................................................... 31

5. Client – Server Model .......................................................................... 45

6. Socket Program for Talk ...................................................................... 53

7. CSMA/CA and CSMA/CD ..................................................................... 59

8. Network Topology –Star, Bus, Ring ..................................................... 67

9. Distance Vector Routing ...................................................................... 75

10. Link State Routing ............................................................................... 82

11. Congestion Control Algorithm ............................................................. 89

12. Encryption and Decryption ................................................................ 100

Appendix 1: Programming exercise -How to practice without NetSim ........ 109

Appendix 2: Creating .exe file using Dev C++ .............................................. 113

4

1. Hamming Code

1.1 Objective:

Implementation of Error Detection/Error Correction Techniques

1.2 Theory:

Hamming code is for Single Bit Error Detection and Correction. It is based on Parity (Even /

Odd Parity).

It allows any single bit error to be detected and corrected. It involves adding one or four

check bits (depending on the formula) to the data for error detection as well as error

correction. These bits are called Check Bits. In order to find the number of check bits

introduced in the message bits, there is a general formula.

Formula:

For a message of size m bits and r check bits, then the condition (m + r + 1) < = 2 r should be

valid.

Example:

Consider the message size (m) of 4 bits and we will find out the number of check bits

according to the formula,

When r = 3 we have,

4 + 3 + 1 = 8 and 2 3 is 8 and so the number of Check Bits to be introduced is 3.

1.3 Algorithm:

Read the contents of the input file i.e. the input data, type of parity and the error data from the

„Input.txt‟ and store it in variables like the above method.

1. Get the length of the input data and calculate the number of Check Bits to be

introduced according to the condition (m + r + 1) <= 2r. Where m is length of the

original data and r is the number of check bits to be introduced in the string.

2. If the passed flag (type of parity) is 2, then it is Even parity, else it is Odd parity.

5

3. Place the Check Bits at the appropriate position according to the principle explained

above (Calculation and Placement of Check Bits in Hamming Code) for the Input data

and for the Error data.

4. Compare the Check Bits values of the Original Input Data and the Error Data values.

Keep a note of the Check Bit Position where the value differs.

5. Add all the position of the Check Bits where the values differ. The resultant value

gives the position of the error bit in the Error Data of length ( m + r ) i.e. the total

length which includes the length of the Input Data Bits and the Check Bits.

1.4 Procedure:

In NetSim, Select “Programming Error Correcting Code Hamming Code”.

Step 1:

In the left panel, select the Mode as Sample. Select Parity as “Odd”, input data and error

position and click Run.

So presently NetSim will run Hamming code already present in the software and will display

the result graphically

Select the

Mode

Select the Parity

6

Result:

After you click RUN button you can see the Hamming string, Original data and Error data in

binary format as shown in the following screen shots

Output

Enter the Data

Select the Error Position

Click run to execute

Click here to view the Concept,

Algorithm, Pseudo code and Flow

chart

7

Step 2:

Open Dev C++ or any GNU C compiler based IDK and copy the code that is opened when

the Interface Source Code link is clicked.

The user needs to edit this code at the following location.

int fnHamming()

{

// Write your own code here

return iErrorPosition;

}// End of Function fnhammingErrorPosition.

So the user needs to add the user code, create exe and attach it with NetSim to run.

The User code which is to be added is given below

int fnHamming()

{

/////* User code part start */

iMessageLength = strlen(szOriginalString); // Get the Input Length

iCheckCount = fnGetCheckbitscount(iMessageLength);

// Allocate the Required Memory for Original Hamming String

szHammingOriginal = malloc(iMessageLength + iCheckCount + 1);

// Position the Check Bits into the Original Hamming String

szHammingOriginal = fnPositionCheckBits(iMessageLength, iCheckCount,

iParitytype, szOriginalString, 'O');

// Allocate the Required Memory for Error Hamming String

szHammingError = malloc(iMessageLength + iCheckCount + 1);

// Position the Check Bits into the Error Hamming String

szHammingError = fnPositionCheckBits(iMessageLength, iCheckCount,

iParitytype, szErrorString, 'E');

// Get the error position

iErrorPosition = fnErrorPosition(szHammingOriginal, szHammingError, strlen(

szHammingOriginal), iCheckCount);

/////* User code part end */

return iErrorPosition;

}// End of Function fnhammingErrorPosition.

Create .exe file (Appendix 2: Creating .exe file using Dev C++)

In the left panel, select the Mode as User. Select the .exe file created above.

Select Parity as “Odd”, input data and error position and click Run.

So presently NetSim will run Hamming code which is written by the user and will display the

result graphically.

In case of any error, “ERROR IN USER CODE” message will be displayed.

Note- How to practice this experiment without using NetSim

8

Users who do not have a licensed version of NetSim in their PC's, can practice as explained

below.

First, run the exercise in sample mode. The user would see that an Input.txt file is created in

Win OS temp folder (this can be reached by typing %temp%/NetSim in Windows run

window). This input file should be read by the user code and it should generate an Output.txt.

This Output.txt file is read by NetSim and shown graphically to the user.

User can follow the steps provided in Appendix 1: Programming exercise - How to practice

without NetSim.

Given below are sample Input.txt and Output.txt files for this experiment for users to verify

& validate their code

Input.txt file contents

Parity=Odd

Data=Netsim

Error_Position=1

Data_Bits_Original=010011100110010101110100011100110110100101101101

Data_Bits_Error=010011100110010101110100011100110110100101101100

Output.txt file contents

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3>5>7>9>11>13>15>17>19>21>23>25>27>29>31>33>35>37>39>41>43>45>47>49>51>53>0>1>

3>6>7>10>11>14>15>18>19>22>23>26>27>30>31>34>35>38>39>42>43>46>47>50>51>54>1>0

>

5>6>7>12>13>14>15>20>21>22>23>28>29>30>31>36>37>38>39>44>45>46>47>52>53>54>1>0

>

9>10>11>12>13>14>15>24>25>26>27>28>29>30>31>40>41>42>43>44>45>46>47>1>0>

17>18>19>20>21>22>23>24>25>26>27>28>29>30>31>48>49>50>51>52>53>54>0>1>

33>34>35>36>37>38>39>40>41>42>43>44>45>46>47>48>49>50>51>52>53>54>0>1>

3>5>7>9>11>13>15>17>19>21>23>25>27>29>31>33>35>37>39>41>43>45>47>49>51>53>1>0>

3>6>7>10>11>14>15>18>19>22>23>26>27>30>31>34>35>38>39>42>43>46>47>50>51>54>0>1

>

5>6>7>12>13>14>15>20>21>22>23>28>29>30>31>36>37>38>39>44>45>46>47>52>53>54>1>0

>

9>10>11>12>13>14>15>24>25>26>27>28>29>30>31>40>41>42>43>44>45>46>47>1>0>

17>18>19>20>21>22>23>24>25>26>27>28>29>30>31>48>49>50>51>52>53>54>0>1>

33>34>35>36>37>38>39>40>41>42>43>44>45>46>47>48>49>50>51>52>53>54>0>1>

1>2>3>

9

2. Transmission Flow Control

2.1 Objective

Implementation of Stop and Wait Protocol and sliding window

2.2 Theory

Stop and Wait is a reliable transmission flow control protocol. This protocol works only in

Connection Oriented (Point to Point) Transmission. The Source node has window size of

ONE. After transmission of a frame the transmitting (Source) node waits for an

Acknowledgement from the destination node. If the transmitted frame reaches the destination

without error, the destination transmits a positive acknowledgement. If the transmitted frame

reaches the Destination with error, the receiver destination does not transmit an

acknowledgement. If the transmitter receives a positive acknowledgement it transmits the

next frame if any. Else if its acknowledgement receive timer expires, it retransmits the same

frame.

2.3 Algorithm

1. Parse the Input.txt file and store the data file path and index from the file. Store the

index value to the local variable err (Error Probability value)

2. Call the in-built function form packet and pass data file path, which is got by parsing

the file Input.txt.

3. Repeat the loop until the transmitting list (transmitting node) becomes empty

10

a. Get the first frame of the transmitting list and transmit to destination.

b. Call the Error Check function, pass the frame got and the variable err value as

parameters. The returned value is stored in a local variable iret.

c. If the value of the iret is 0 (No Error Condition),

i. Form the positive acknowledgement and place it in the transmission

list of Node2.

ii. To form positive acknowledgements create a new frame and set the

data field as "POS". Then set this frame as the first frame of Node2.

iii. Get the acknowledgement value from the receiving node‟s

transmission list.

1. If the acknowledgement has error or the timer has expired

a. Resend the same frame

2. If the acknowledgement has no error nor the timer has expired

b. Delete the first frame from the transmission list of

Node1.

c. Delete the acknowledgement frame from Node2

transmission list.

d. If the value of the iret is 1 (Error Condition),

i. Resend the first frame of the transmitting list to destination.

2.4 Procedure

In NetSim, Select “Programming Transmission Flow Control”.

The scenario will be obtained as shown below. Follow the steps.

Step 1:

In the left panel, select the Mode as Sample. Select the algorithm as Stop and Wait. Create a

small text file (within 15000 bytes) and set it as input. Also set the Bit error rate (BER) and

click Run.

So presently NetSim will run Stop and Wait code already present in the software and will

display the result graphically

11

Result:

Select the Mode

Select the Algorithm

Choose the required data

Choose the bit error rate



chart

Output Table


12

2.5 Inference

Due to increase in the error rate, no of errored packets also increase. If errored packets

increase no of retransmitted packets also increase.

Step 2:

For user to write their own C Code in NetSim and check the result, click on Interface Source

Code (present in Help in the left pane).

Open Dev C++ or any GNU C compiler based IDK and copy the code from the Interface

Source Code.

The user needs to edit the Interface Source Code at the following location.

void stopandwait(int errrate)

{


}



void stopandwait(int errrate)

{


// Repeat the loop until transmission list of the transmitting

// node becomes empty

while(nodelist_sw->txframe != NULL)

{

// Get the current transmitting frame reference

transframe_sw = ret_txframe_SW ();

// Write the content into the output file. Data Value is written

//into the file

fprintf(fp_sw,"DT>%d>%s>%s>\n",transframe_sw->iframe,transframe_sw-

>szsrcaddr,transframe_sw->szdestaddr);

/*

Call the default function defined in the header file main1.h

Store the return value to the local variable iret_sw.

The Passed arguments

1. errrate -- This is the variable passed to the function (got from

the function call of the retErrorrate)

2. transframe_sw -- This is Eth_frame_sw reference that has the

Transmitting frame got from the function call ret_txframe_SW

*/

iret_sw=intro_error_SW(errrate,transframe_sw);

13

// Write the content into the output file. Error value is written into

//the file

fprintf(fp_sw,"EV>%d>%s>%s>\n",iret_sw,transframe_sw-

>szsrcaddr,transframe_sw->szdestaddr);

// Check if the frame is Positive or Negative

if(iret_sw == 0)// Positive acknowledgment in the network

{

// Form the Ack frame according to the iret_sw value

form_ack_SW (transframe_sw,1);// Positive Acknowledgement

// Call the ret_ackframe_sw function and get the acknowledgement

frame

//reference from the tranmitting list of the receiving node

ackframe_sw=ret_ackframe_sw ();

// Write the content into the file. Positive Ack value

fprintf(fp_sw,"ACK>POS>%s>%s>\n",ackframe_sw->szsrcaddr,ackframe_sw-

>szdestaddr);

// Acknowledgement frame is made so delete the transmitted frame

from

//the transmitting list of the source node

del_frame_SW(transframe_sw ->ipack,transframe_sw ->iframe);

// User defined function call to delete the Acknowledgement frame

del_ackframe_sw ();

}

}


}



Select the algorithm as Stop and Wait. Create a small text file (within 15000 bytes) and set it

as input. Also set the Bit error rate (BER) and click Run.

So presently NetSim will run Stop and Wait code which is written by the user and will

display the result graphically.


Note- How to practice this experiment without using NetSim:


below.





14


without NetSim.


& validate their code. The Output.txt file will vary based on the Data_file. In this case, the

size of Data_File file is 11,305 bytes.


Algorithm=Stop_and_Wait

Data_File=C:\Users\Tetcos\Desktop\ data.txt>

BER=0

*Note- Create any file of size <15000 Byte. Type the location of the file in Data_File.


DT>1>node1>node2>

EV>0>node1>node2>

ACK>POS>node2>node1>

DT>2>node1>node2>

EV>0>node1>node2>


DT>3>node1>node2>

EV>0>node1>node2>


DT>4>node1>node2>

EV>0>node1>node2>


DT>5>node1>node2>

EV>0>node1>node2>


DT>6>node1>node2>

EV>0>node1>node2>


DT>7>node1>node2>

EV>0>node1>node2>


DT>8>node1>node2>

EV>0>node1>node2>


*Note- Output.txt content will vary depending on the file size

15

3. Sliding Window Protocol

3.1 Objective

Implementation and study of Go Back-N and Selective Repeat protocols

3.2 Part A – Go Back-N

3.2.1 Theory

Go Back N is a connection oriented transmission. The sender transmits the frames

continuously. Each frame in the buffer has a sequence number starting from 1 and increasing

up to the window size. The sender has a window i.e. a buffer to store the frames. This buffer

size is the number of frames to be transmitted continuously. The size of the window depends

on the protocol designer.

3.2.2 Operations

A station may send multiple frames as allowed by the window size.

Receiver sends an ACK i if frame i has an error. After that, the receiver discards all

incoming frames until the frame with error is correctly retransmitted.

If sender receives an ACK i it will retransmit frame i and all packets i+1, i+2,... which

have been sent, but not been acknowledged

3.2.3 Algorithm

1. The source node transmits the frames continuously.

2. Each frame in the buffer has a sequence number starting from 1 and increasing up

to the window size.

3. The source node has a window i.e. a buffer to store the frames. This buffer size is

the number of frames to be transmitted continuously.

4. The size of the window depends on the protocol designer.

5. For the first frame, the receiving node forms a positive acknowledgement if the

frame is received without error.

16

6. If subsequent frames are received without error (up to window size) cumulative

positive acknowledgement is formed.

7. If the subsequent frame is received with error, the cumulative acknowledgment

error-free frames are transmitted. If in the same window two frames or more

frames are received with error, the second and the subsequent error frames are

neglected. Similarly even the frames received without error after the receipt of a

frame with error are neglected.

8. The source node retransmits all frames of window from the first error frame.

9. If the frames are errorless in the next transmission and if the acknowledgment is

error free, the window slides by the number of error-free frames being transmitted.

10. If the acknowledgment is transmitted with error, all the frames of window at

source are retransmitted, and window doesn‟t slide.

11. This concept of repeating the transmission from the first error frame in the

window is called as GO BACK-N transmission flow control protocol.

3.2.4 Procedure

In NetSim, Select “Programming Sliding Window Protocol”.


Step 1:

In the left panel, select the Mode as Sample. Select the algorithm as Go Back N. Create a

small text file (within 100 Kbytes) and set it as input. Also set the Bit error rate (BER),

Sequence number and click Run.

So presently NetSim will run Go Back N code already present in the software and will


17

Step 2:

Select the Mode

Select Go Back N

Choose the input

data file

Choose the Bit

Error Rate

Choose the

Sequence Number




chart

18

Result:

After you click RUN button you can see the output as shown in the following screen shots

Step 3:




void fnGoBackN()

{


}



void fnGoBackN() { /////* User code part start */ double nFileSize=0; // stores file size of a input file long nPacketSize = 1500; // constant packet size 1500 int nNoofPackets; int i; int packet_num=1,window_start=1,count=0; int flag=0; int nErrorflag; int packets_to_send;

Output Table

19

nFileSize = get_file_size(); // calculate the total no of packets. The ceil function rounds up to nearest integer. // ceil return double so typecast to int. nNoofPackets = (int)ceil(nFileSize / nPacketSize); while(nNoofPackets) { packets_to_send = min(nNoofPackets,nWindowSize); write_output(1,packets_to_send,0); flag=0; packet_num=window_start; count=0; for(i=0;i<packets_to_send;i++) { nErrorflag = g_fnDecideError_GBN(nErrorrate,nPacketSize); write_output(2,packet_num,nErrorflag); // Packet writing packet_num++; if(!nErrorflag && !flag) { window_start++; count++; } if(nErrorflag) flag=1; } write_output(3,0,0); // Ack writing nNoofPackets = nNoofPackets- count; } /////* User code part end */ }

Creating a .exe file is explained in the end of this manual marked “Appendix 2: Creating .exe

file using Dev C++”


Select the algorithm as Go Back N. Create a small text file (within 100 Kbytes) and set it as

input. Also set the Bit error rate (BER), Sequence number and click Run.

So presently NetSim will run Go Back N code which is written by the user and will display

the result graphically.




below.

20



window).

This input file should be read by the user code and it should generate an Output.txt. This

Output.txt file is read by NetSim and shown graphically to the user.


without NetSim.




Algorithm=Go_Back_N

Data_File=C:\Users\Tetcos\Desktop\data.txt>

Bit_Error_Rate=5

Sequence_Number=3

Window_Size=7

*Note- Create any file of size <100 KByte. Type the location of the file in Data_File.


CNT>7>FRAMES>TRANSMIT>

DT>1>node1>node2>

EV>1>node1>node2>

DT>2>node1>node2>

EV>0>node1>node2>

DT>3>node1>node2>

EV>0>node1>node2>

DT>4>node1>node2>

EV>0>node1>node2>

DT>5>node1>node2>

EV>0>node1>node2>

DT>6>node1>node2>

EV>0>node1>node2>

DT>7>node1>node2>

EV>0>node1>node2>



DT>1>node1>node2>

EV>0>node1>node2>

DT>2>node1>node2>

21

EV>0>node1>node2>

DT>3>node1>node2>

EV>0>node1>node2>

DT>4>node1>node2>

EV>0>node1>node2>

DT>5>node1>node2>

EV>0>node1>node2>

DT>6>node1>node2>

EV>0>node1>node2>

DT>7>node1>node2>

EV>0>node1>node2>



DT>8>node1>node2>

EV>0>node1>node2>



22

3.3 Selective Repeat

3.3.1 Theory:

Selective repeat is Similar to Go Back N. However, the sender only retransmits frames for

which an ACK is received.

Advantage over Go Back N:

Fewer retransmissions.

Disadvantages:

More complexity at sender and receiver

Receiver may receive frames out of sequence

3.3.2 Algorithm:

1. The source node transmits the frames continuously.

2. Each frame in the buffer has a sequence number starting from 1 and increasing up

to the window size.

3. The source node has a window i.e. a buffer to store the frames. This buffer size is

the number of frames to be transmitted continuously.

4. The receiver has a buffer to store the received frames. The size of the buffer

depends upon the window size defined by the protocol designer.

5. The size of the window depends according to the protocol designer.

6. The source node transmits frames continuously till the window size is exhausted.

If any of the frames are received with error only those frames are requested for

retransmission (with a negative acknowledgement)

7. If all the frames are received without error, a cumulative positive

acknowledgement is sent.

8. If there is an error in frame 3, an acknowledgement for the frame 2 is sent and

then only Frame 3 is retransmitted. Now the window slides to get the next frames

to the window.

9. If acknowledgment is transmitted with error, all the frames of window are

retransmitted. Else ordinary window sliding takes place. (* In implementation

part, Acknowledgment error is not considered)

23

10. If all the frames transmitted are errorless the next transmission is carried out for

the new window.

11. This concept of repeating the transmission for the error frames only is called

Selective Repeat transmission flow control protocol.

3.3.3 Procedure:

In NetSim, Select “Programming Sliding Window Protocol”.


Step 1:

In the left panel, select the Mode as Sample. Select the algorithm as Selective Repeat. Create

a small text file (within 100 Kbytes) and set it as input. Also set the Bit error rate (BER),

Sequence number and click Run.

So presently NetSim will run Selective Repeat code already present in the software and will


Select the Mode

Select the algorithm

24

Result:

After you click RUN button you can see the output as shown in the following screen shots

Choose the input

data file

Choose the Bit

Error Rate

Choose the

Sequence Number


Output Table



chart

25

Step 2:




void selRep(char* szstr,char* error_rate, char* szPasWindowSize)

{


}



void selRep(char* szstr,char* error_rate, char* szPasWindowSize) { /////* User code part start */ int nFileSize=0; // stores file size of a input file struct stat fInfo; // to get file information long int nPacketSize = 1500; // constant packet size 1500 int nWindowSize; // stores window size int nPasWindowSize; int nNoofPackets=0; // stores no of packets int nNoErrorPacket=0; int nNoofPacketsSent =0; // stores no of packets sent int nPacketCount=0; char *pszPath = NULL; int nLoop=0; // looping variable int nLoop1=0; int nErrorBit=0; // To store 0/1 0---- no error 1----- error int nErrorPacketIndex[100]={0}; // To store 0/1 0---- no error 1----- error int nErrorPacketValue[100]={0}; // To store 0/1 0---- no error 1----- error int nErrorFlag=0; // To indicate error is there in the last packet int nErrorPacketCount=0; // Stores error packets count FILE *fpTemp=NULL; // file pointer to write Temp.txt int nErrorrate=0; // Stores Error rate int nErrorWindowSize=0; int nalreadyError=0; nPasWindowSize = atoi(szPasWindowSize); nWindowSize = nPasWindowSize; nErrorrate = atoi(error_rate); // converts error rate from strings to fpTemp = fopen(szOutput_path_SR,"w");// open output.txt file with write mode fpTemp = fopen(szOutput_path_SR,"a+");// open output.txt file with append mode

26

stat(szstr,&fInfo); nFileSize = fInfo.st_size; // find the file size of a given input file printf("%d\n",nFileSize); nNoofPackets = nFileSize / nPacketSize; // calculate the tital no of packets if((nFileSize%nPacketSize)>0) // in the given file nNoofPackets = nNoofPackets + 1; while (nNoErrorPacket<nNoofPackets) // If no of packets successfully sent packet is less than { // total no of packets nLoop1=0; nErrorFlag = 0; nWindowSize =nPasWindowSize; for (nLoop = 0; nLoop<nWindowSize; nLoop++) // if any error in the last window { if(nErrorPacketIndex[nLoop] == 1) // set the error flag as 1 { nErrorFlag = 1; break; } } if(nErrorFlag == 0) nalreadyError = 0; else if((nErrorFlag ==1) && (nalreadyError == 1)) nErrorPacketCount = 0; if(nErrorFlag ==0) // re initialise the values { for(nLoop=0;nLoop<nWindowSize;nLoop++) { nErrorPacketIndex[nLoop]=0; nErrorPacketValue[nLoop]=0; } nErrorPacketCount = 0; } if(nErrorFlag == 0) { if((nNoofPackets - nNoErrorPacket) < nWindowSize) // If no of packets - no of packets sent nWindowSize = nNoofPackets - nNoErrorPacket; // is less than the window size // make the difference as window size fprintf(fpTemp,"CNT>%d>FRAMES>TRANSMIT>\n",nWindowSize); for(nLoop = 0; nLoop<nWindowSize ; nLoop++) // up to the window size { nErrorBit = g_fnDecideError_SR(nErrorrate,nPacketSize); // call function to decide error if(nErrorBit == 0) // if there is no error { nNoofPacketsSent++; // increment nNoErrorPacket++;

27

nPacketCount++; fprintf(fpTemp,"DT>%d>node1>node2>\n",nPacketCount); fprintf(fpTemp,"EV>%d>node1>node2>\n",nErrorBit); nErrorPacketIndex[nLoop]=0; nErrorPacketValue[nLoop]=nPacketCount; } else if(nErrorBit == 1) { nNoofPacketsSent++; nPacketCount++; fprintf(fpTemp,"DT>%d>node1>node2>\n",nPacketCount); fprintf(fpTemp,"EV>%d>node1>node2>\n",nErrorBit); nErrorPacketIndex[nLoop] = 1; nErrorPacketValue[nLoop]=nPacketCount; } } fprintf(fpTemp,"ACK>POS>node1>node2>\n"); } else if(nErrorFlag == 1) { nalreadyError = 1; if((nNoofPackets - nNoErrorPacket-nErrorPacketCount) < nWindowSize) nErrorWindowSize = nNoofPackets - nNoErrorPacket-nErrorPacketCount; else nErrorWindowSize = nWindowSize; fprintf(fpTemp,"CNT>%d>FRAMES>TRANSMIT>\n",nErrorWindowSize); for(nLoop=0; nLoop<nWindowSize; nLoop++) // searching the whole window for errors { if(nErrorPacketIndex[nLoop] == 1) { nErrorPacketCount++; nErrorBit = g_fnDecideError_SR(nErrorrate,nPacketSize); if(nErrorBit == 0) { nNoErrorPacket++; //nPacketCount++; fprintf(fpTemp,"DT>%d>node1>node2>\n",nErrorPacketValue[nLoop]); fprintf(fpTemp,"EV>%d>node1>node2>\n",nErrorBit); nErrorPacketIndex[nLoop1]=0; nErrorPacketValue[nLoop1] = nErrorPacketValue[nLoop]; } else if(nErrorBit == 1) { fprintf(fpTemp,"DT>%d>node1>node2>\n",nErrorPacketValue[nLoop]); fprintf(fpTemp,"EV>%d>node1>node2>\n",nErrorBit);

28

//nErrorPacketIndex[nLoop] = 1; //nErrorPacketValue[nLoop]=nNoofPacketsSent; nErrorPacketIndex[nLoop1] = 1; nErrorPacketValue[nLoop1] = nErrorPacketValue[nLoop]; //nLoop1++; } nLoop1++; } } if((nNoofPackets - nNoErrorPacket) < nWindowSize) // If no of packets - no of packets sent nWindowSize = nNoofPackets - nNoErrorPacket;//-nErrorPacketCount ; // is less than the window size // make the difference as window size else nWindowSize = nWindowSize - nErrorPacketCount; //fprintf(fpTemp,"CNT>%d>FRAMES>TRANSMIT>\n",nWindowSize); for(nLoop=0;nLoop<nWindowSize; nLoop++) { nErrorBit = g_fnDecideError_SR(nErrorrate,nPacketSize); if(nErrorBit == 0) { nNoofPacketsSent++; nNoErrorPacket++; nPacketCount++; fprintf(fpTemp,"DT>%d>node1>node2>\n",nPacketCount); fprintf(fpTemp,"EV>%d>node1>node2>\n",nErrorBit); nErrorPacketIndex[nLoop1]=0; nErrorPacketValue[nLoop1]=nPacketCount; } else if(nErrorBit == 1) { nNoofPacketsSent++; nPacketCount++; fprintf(fpTemp,"DT>%d>node1>node2>\n",nPacketCount); fprintf(fpTemp,"EV>%d>node1>node2>\n",nErrorBit); nErrorPacketIndex[nLoop1] = 1; nErrorPacketValue[nLoop1]=nPacketCount; } nLoop1++; } fprintf(fpTemp,"ACK>POS>node1>node2>\n"); } } fclose(fpTemp); /////* User code part end */ }

Creating a .exe file is explained in the end of this manual marked “Appendix 2: Creating .exe

file using Dev C++”

29


Select the algorithm as Selective Repeat. Create a small text file (within 100 Kbytes) and set

it as input. Also set the Bit error rate (BER), Sequence number and click Run.

So presently NetSim will run Selective Repeat code which is written by the user and will





below.






without NetSim.




Algorithm=Selective_Repeat

Data_File=C:\Users\Tetcos\Desktop\data.txt>

Bit_Error_Rate=5

Sequence_Number=3

Window_Size=4

*Note- Create any file of size <100 KByte. Type the location of the file in Data_File.



DT>1>node1>node2>

EV>0>node1>node2>

DT>2>node1>node2>

30

EV>0>node1>node2>

DT>3>node1>node2>

EV>0>node1>node2>

DT>4>node1>node2>

EV>1>node1>node2>



DT>4>node1>node2>

EV>0>node1>node2>

DT>5>node1>node2>

EV>0>node1>node2>

DT>6>node1>node2>

EV>1>node1>node2>

DT>7>node1>node2>

EV>0>node1>node2>



DT>6>node1>node2>

EV>0>node1>node2>

DT>8>node1>node2>

EV>0>node1>node2>



31

4. High Level Data Link Control

4.1 Objective:

Implementation of High Level Data Link Control

4.2 Part A - Bit Stuffing

4.2.1 Theory:

When data is transmitted, the transmitter should distinguish between the start and the end of

the data. This is done to ensure that the receiving node reads the data completely. This is

accomplished by appending a unique pattern of bit stream before and after the data. Care

should be taken to ensure that this unique pattern does not occur in the data itself. If the

pattern appears in the data then the data is broken. The process of appending a unique pattern

and breaking the pattern is known as framing.

Bit Stuffing is one of the framing methods, in which each frame begins and ends with a

special bit pattern „0111110‟, called a flag byte.

Whenever the sender‟s data link layer encounters six consecutive 1‟s in the data, it

automatically stuffs a 0 bit into the outgoing bit stream to break the pattern.

4.2.2 Algorithm:

1. Get the Value of Destination Address, Source Address, Data, CRC Polynomial and

Error Status by reading Input.txt.

2. Call the function fnASCII_to_Binary () to get the Binary Values for each

characters in the Data field.

3. Call the function fnBitStuffing () to do the bit stuffing process.

4. Calculate the checksum by calling the function fnCheckSum_Calculation.

5. Initialize nLoop1, nCount and nIndex to zero.

6. Combine the Destination Address, Source Address and Binary Values in single

character array.

32

7. Loop through all the bits

Check nLoop_Length >= 0 && nLoop_Length < 8

Check pszBits [nLoop_Length] == 1

Increment nCount by 1

Stuffed Destination Address [nIndex] = „1‟

Check nCount == 5

Increment nIndex by 1


nCount = 0


Else

nCount = 0



Check nLoop_Length == 7

Stuffed Destination Address [nIndex] = „\0‟

nIndex = 0

8. Similarly repeat step6 for the Source Address and Binary Values for the stuffing

process.

9. Call the function fnDestuffing () to do the destuffing process.

10. Initialize nLoop1, nCount and nIndex to zero.

11. Loop through all the bits

Check pszBits [nLoop_Length] == 1

Increment nCount by 1

Check nCount == 5

Loop through all the bits

pszBits [nIndex] = pszBits [nIndex + 1]


nCount = 0

Else

nCount = 0

12. Call the function fnBinary_to_ASCII () to get the ASCII values and the message

sent by the Transmitter.

13. Write those values into Output.txt.

33

4.2.3 Procedure:

In NetSim, Select “Programming Framing Sequence Bit Stuffing”.


Step 1:

In the left panel, select the Mode as Sample. Continue with the steps as shown below and

click Run.

So presently NetSim will run Bit Stuffing code already present in the software and will


Select the Mode

Enter the Destination

address

Enter the Source

address

Enter the Data




chart

Select the Error Condition

34

Result:

Step 2:




Source Code.

In User Mode, the user needs to edit the Interface Source Code at the following location.

void fnBitStuffing()

{


}


The User code which is to be added is given below:

void fnBitStuffing() { /////* User code part start */

int nCount = 0, nLoop1 = 0, nIndex = 0, nLoop2 = 0; int nLoop_Length = 0; char *pszBits; int nTotalLength; fnCheckSum_Calculation(); strcpy(szCheckSum_Sender, szCheckSum_Value); for (nLoop1 = g_nLength, nLoop2 = 0; nLoop1 < (g_nLength + MAX_CHECKSUM_DIGIT); nLoop1++, nLoop2++) { szBinaryValues[nLoop1] = szCheckSum_Sender[nLoop2]; } szBinaryValues[nLoop1] = '\0';

Output Data

35

//Merge all the Binary Values in Single Array pszBits = (char *)malloc(MAX_SIZE * sizeof(char)); strcpy(pszBits, szDestinationAddress); strcat(pszBits, szSourceAddress); strcat(pszBits, szBinaryValues); nTotalLength = strlen(pszBits); sz_Stuffed_DestinationAddress = (char *) malloc(15 * sizeof(char)); sz_Stuffed_SourceAddress = (char *)malloc(15 * sizeof(char)); sz_Stuffed_BinaryValues = (char *) malloc(MAXBITS * sizeof(char)); for(nLoop_Length = 0; nLoop_Length < nTotalLength; nLoop_Length++) { if(nLoop_Length >= 0 && nLoop_Length < 8) { if(pszBits[nLoop_Length] == '1') { nCount++; sz_Stuffed_DestinationAddress[nIndex] = '1'; if(nCount == 5) { nIndex++; sz_Stuffed_DestinationAddress[nIndex] = '0'; nCount = 0; } nIndex++; } else { nCount = 0; sz_Stuffed_DestinationAddress[nIndex] = '0'; nIndex++; } if(nLoop_Length == 7) { sz_Stuffed_DestinationAddress[nIndex] = '\0'; nIndex = 0; } } if(nLoop_Length >= 8 && nLoop_Length < 16) { if(pszBits[nLoop_Length] == '1') { nCount++; sz_Stuffed_SourceAddress[nIndex] = '1'; if(nCount == 5) { nIndex++; sz_Stuffed_SourceAddress[nIndex] = '0'; nCount = 0; } nIndex++; } else { nCount = 0; sz_Stuffed_SourceAddress[nIndex] = '0'; nIndex++; } if(nLoop_Length == 15) { sz_Stuffed_SourceAddress[nIndex] = '\0';

36

nIndex = 0; } } if(nLoop_Length >= 16 && nLoop_Length < nTotalLength) { if(pszBits[nLoop_Length] == '1') { nCount++; sz_Stuffed_BinaryValues[nIndex] = '1'; if(nCount == 5) { nIndex++; sz_Stuffed_BinaryValues[nIndex] = '0'; nCount = 0; } nIndex++; } else { nCount = 0; sz_Stuffed_BinaryValues[nIndex] = '0'; nIndex++; } sz_Stuffed_BinaryValues[nIndex] = '\0'; } } free(pszBits); /////* User code part end */ }



Repeat the steps done for Sample mode and click Run.

So presently NetSim will run Bit Stuffing code which is written by the user and will display





below.





37


without NetSim.


& validate their code.


Destination Address=11111111

Source Address=01111110

Data=11111

CRC Polynomial=10011

Error status=0

Seed value=0


Message=11111>

1=49>1=49>1=49>1=49>1=49>

Binary Values=0011000100110001001100010011000100110001>

CRC Polynomial=10011>

CheckSumSender=1010>

<Stuffing>

Destination Address=111110111>

Source Address=011111010>

Data=00110001001100010011000100110001001100011010>

<DeStuffing>

Destination Address=11111111>

Source Address=01111110>

Data=00110001001100010011000100110001001100011010>

Error Status=0>

CheckSumReceiver=0000>

Binary Values=0011000100110001001100010011000100110001>

1=49>1=49>1=49>1=49>1=49>

Message=11111>

*Note- Output.txt content will vary depending on the file contents.

38

4.3 Part B - Character Stuffing

4.3.1 Theory:

When data is transmitted, the transmitting node should distinguish between the start and the

end of the receiving node to read the data completely. This is accomplished by appending a

unique pattern of bit stream before and after the data.

Care is taken that this unique pattern does not occur in the data. If the pattern appears in the

data, it is broken. The process of appending a unique pattern and breaking the pattern is

known as framing.

Character stuffing is one of the framing methods, in which each frame starts with DLE STX

(Starting delimiter) character sequence and ends with DLE ETX (Ending delimiter) character

sequence.

Characters for DLE STX or DLE ETX may occur in the data. To solve this problem the

transmitting node inserts a DLE character just before each DLE character occurring in the

data.

4.3.2 Algorithm:

1. Get the Value of Starting Delimiter, Destination Address, Source Address, Data,

Checksum and Ending Delimiter by reading Input.txt.

2. Call the function fnCharacterStuffing () to do the character stuffing process.

3. Loop through all the bytes in Destination Address

Check szDestinationAddress [nLoop1] != „\0‟

sz_Stuffed_DestinationAddress [nIndex] = szDestinationAddress [nLoop1]


Check szDestinationAddress [nLoop1] == szStartingDelimiter [0]

sz_Stuffed_DestinationAddress [nIndex] = szStartingDelimiter [0]


Check szDestinationAddress [nLoop1] == szEndingDelimiter [0]

sz_Stuffed_DestinationAddress [nIndex] = szEndingDelimiter [0]


Increment nLoop1 by 1

sz_Stuffed_DestinationAddress [nIndex] = '\0';

4. Similarly repeat step3 for Source Address, Data and Checksum.

5. Call the function fnDeStuffing () to do the destuffing process.

39

6. Copy all the bytes from Stuffed Destination Address to Destuffed Destination Address

7. Loop through all the bytes in Destuffed Destination Address

Check sz_Destuffed_DestinationAddress [nLoop1] != „\0‟

Check sz_Destuffed_DestinationAddress [nLoop1] ==

szStartingDelimiter [0] && sz_Destuffed_DestinationAddress [nLoop1] ==

szEndingDelimiter [0]

Check nIndex < strlen (sz_Destuffed_DestinationAddress)

sz_DeStuffed_DestinationAddress [nIndex] =

sz_DeStuffed_DestinationAddress [nIndex + 2];


nIndex = 0

Else if sz_Destuffed_DestinationAddress [nLoop1] ==

szStartingDelimiter [0] || sz_Destuffed_DestinationAddress [nLoop1] ==

szEndingDelimiter [0]

Check nIndex < strlen (sz_Destuffed_DestinationAddress)

sz_DeStuffed_DestinationAddress [nIndex] =

sz_DeStuffed_DestinationAddress [nIndex + 1];


nIndex = 0

Increment nLoop1 by 1

8. Similarly repeat step7 for Source Address, Data and Checksum and write those values

into Output.txt.

4.3.3 Procedure:

In NetSim, Select “Programming Framing Sequence Character Stuffing”.


Step 1:

In the left panel, select the Mode as Sample. Continue with the steps as shown below and

click Run.

So presently NetSim will run Character Stuffing code already present in the software and will


40

Click Run to execute

Select the mode

Enter starting

Delimiter

Click here to view the

Concept, Algorithm, Pseudo

code and Flow chart

Enter Destination

address

Enter Source Address

Enter input data

Enter Checksum

Enter ending delimiter

41

Result:

Step 2:




Source Code.


void fnCharacterStuffing()

{


}



void fnCharacterStuffing() { /////* User code part start */ int nLoop1 = 0, nIndex = 0; sz_Stuffed_DestinationAddress = (char *)malloc(100 * sizeof(char)); sz_Stuffed_SourceAddress = (char *)malloc(100 * sizeof(char));

Character stuffed output

42

sz_Stuffed_Data = (char *)malloc(100 * sizeof(char)); sz_Stuffed_CheckSum = (char *)malloc(100 * sizeof(char)); while(szDestinationAddress[nLoop1] != '\0') { sz_Stuffed_DestinationAddress[nIndex] = szDestinationAddress[nLoop1]; nIndex++; if(szDestinationAddress[nLoop1] == szStartingDelimiter[0]) { sz_Stuffed_DestinationAddress[nIndex] = szStartingDelimiter[0]; nIndex++; } if(szDestinationAddress[nLoop1] == szEndingDelimiter[0]) { sz_Stuffed_DestinationAddress[nIndex] = szEndingDelimiter[0]; nIndex++; } nLoop1++; } sz_Stuffed_DestinationAddress[nIndex] = '\0'; nLoop1 = nIndex = 0; while (szSourceAddress[nLoop1] != '\0') { sz_Stuffed_SourceAddress[nIndex] = szSourceAddress[nLoop1]; nIndex++; if (szSourceAddress[nLoop1] == szStartingDelimiter[0]) { sz_Stuffed_SourceAddress[nIndex] = szStartingDelimiter[0]; nIndex++; } if (szSourceAddress[nLoop1] == szEndingDelimiter[0]) { sz_Stuffed_SourceAddress[nIndex] = szEndingDelimiter[0]; nIndex++; } nLoop1++; } sz_Stuffed_SourceAddress[nIndex] = '\0'; nLoop1 = nIndex = 0; while (szData[nLoop1] != '\0') { sz_Stuffed_Data[nIndex] = szData[nLoop1]; nIndex++; if (szData[nLoop1] == szStartingDelimiter[0]) { sz_Stuffed_Data[nIndex] = szStartingDelimiter[0]; nIndex++; } if (szData[nLoop1] == szEndingDelimiter[0]) { sz_Stuffed_Data[nIndex] = szEndingDelimiter[0]; nIndex++; } nLoop1++; } sz_Stuffed_Data[nIndex] = '\0'; nLoop1 = nIndex = 0; while (szCheckSum[nLoop1] != '\0') { sz_Stuffed_CheckSum[nIndex] = szCheckSum[nLoop1]; nIndex++;

43

if (szCheckSum[nLoop1] == szStartingDelimiter[0]) { sz_Stuffed_CheckSum[nIndex] = szStartingDelimiter[0]; nIndex++; } if (szCheckSum[nLoop1] == szEndingDelimiter[0]) { sz_Stuffed_CheckSum[nIndex] = szEndingDelimiter[0]; nIndex++; } nLoop1++; } sz_Stuffed_CheckSum[nIndex] = '\0'; free(szDestinationAddress); free(szSourceAddress); free(szData); free(szCheckSum); /////* User code part end */ }



Repeat the steps done for Sample mode and click Run.

So presently NetSim will run Character Stuffing code which is written by the user and will





below.






without NetSim.



44


Starting Delimiter=t

Destination Address=tetcosit

Source Address=welcomen

Data=netsimsw

Checksum=simulate

Ending Delimiter=o


Stuffing>

Destination Address=ttettcoositt>

Source Address=welcoomen>

Data=nettsimsw>

Checksum=simulatte>

DeStuffing>

Destination Address=tetcosit>

Source Address=welcomen>

Data=netsimsw>

Checksum=simulate>


45

5. Client – Server Model

5.1 Objective:

Study of Socket Programming and Client – Server model

5.2 Theory:

The socket is a fundamental concept to the operation of TCP/IP application software. It is

also an interface between the application and the network. The exchange of data between a

pair of devices consists of a series of messages sent from a socket on one device to a socket

on other.

Once the socket is configured, the application can send the data using sockets for network

transmission and receive the data using sockets from the other host. A socket communication

can be connection oriented (TCP sockets) or connectionless (UDP sockets).

There is a receiver (TCP) server, which listens to the sender (TCP) client communications.

There can be two-way communication.

5.3 Algorithm:

Server:

1. Create a socket using address family (AF_INET), type (SOCK_STREM) and protocol

(TCP)

2. Initialize the address family, port no and IP address to communicate using sockets

3. Bind a local address and port number with a socket

4. Listen for an incoming socket connection

5. Accept an incoming connection attempt on a socket

6. Receive an incoming message

7. Write that incoming message to Output.txt

8. Send ACK to received socket

9. Call step 5 to receive the message once again

10. Close file

46

11. Close socket

Client:


(TCP)

2. Initialize the address family, port no and IP address to communicate using sockets

3. Establish Connection with destination IP

4. Send the data using the socket id

5. Close the socket connection

5.4 Procedure:

Step:1

To begin with the experiment, open NetSim.

Click on Programming from the menu bar and select PC to PC Communication and then

select Socket Programming

When you select the User mode, you have to write your own program in C/C++, compile and

link to NetSim software for validation. Click on the F1 (Help) for details on how to proceed

with your own code.

The scenario will be obtained as shown below. Follow the steps

Select Mode

Select Protocol

Select Operation

Click Run to start

transmission

Click here to view Concept,

Algorithm, and Pseudo Code

& Flowchart

47

Under Input there are two things,

1. When Operation is Client, then the Server’s IP Address (Ex: 192.168.1.2) should

be given in the Server IP Address field.

2. When Operation is Server, then the Server’s IP Address (Ex: 192.168.1.2) would

be automatically filled in the Local IP Address field.

If the Operation is Server, the scenario will be obtained as shown below,

If the Operation is Client, the scenario will be obtained as shown below,

Server

Side

Client

Side

48

Step: 2

TCP

First the Server should click on the Run button after which the Client should click on

the Run button to Create the socket

Client should click on the Connect button to establish the connection with server.

The Client should click on the Send button to transmit the data to the Server.

The Client should click on the Close button to terminate the Connection with Server.

If the Data is successfully transmitted then the Sent Data would be Received in the

Server System.

UDP

First the Server should click on the Run button after which the Client should click on

the Run button to Create the socket

The Client should click on the Send button to transmit the data to the Server.

The Client should click on the Close button to terminate the Connection with Server.

If the Data is successfully transmitted then the Sent Data would be Received in the

Server System.

Enter Destination

IP Address Enter data to be

transmitted

49

5.5 Result:

User Mode (TCP)




Source Code.


int fnTcpServer()

{


return 0;

}


The User code which is to be added is given below:-

int fnTcpServer()

{


nSocketfd =(int) socket(AF_INET,SOCK_STREAM, 0);

serv_addr.sin_family = AF_INET;

serv_addr.sin_port = htons(SERVER_PORTNUMBER);

Received

data

50

serv_addr.sin_addr.s_addr = htonl(INADDR_ANY);

nBindfd = bind(nSocketfd, (struct sockaddr *) &serv_addr, sizeof(serv_addr));

#ifndef _NETSIM_SAMPLE

nListenfd = listen(nSocketfd, 5);

#else

nListenfd = listen(nSocketfd, 1);

#endif

nServerLen = sizeof(serv_addr);

if (fnWriteOutput() == 1)

{ /*if socket creation,bind and listen failed function will terminate*/

closesocket(nSocketfd);

return 0;

}


nNewsocketfd =(int) accept(nSocketfd, (struct sockaddr *) &cli_addr,

&nServerLen);

nLoopCount++;

memset(szData, 0, sizeof(szData)); /*Clear the array*/

nReceivedbytes =(int) recv(nNewsocketfd, szData, sizeof(szData), 0);

fnWriteOutput();

nSendbytes =(int) send(nNewsocketfd, pszBuffer, strlen(pszBuffer), 0);

#else

while (1)

{

nNewsocketfd =(int) accept(nSocketfd, (struct sockaddr *) &cli_addr,

&nServerLen);

nLoopCount++;

memset(szData, 0, sizeof(szData)); /*Clear the array*/

nReceivedbytes =(int) recv(nNewsocketfd, szData, sizeof(szData), 0);

fnWriteOutput();

nSendbytes =(int) send(nNewsocketfd, pszBuffer, strlen(pszBuffer), 0);

if( nTCPServerCloseFlag == 1) /*break the loop when user send close the

connection*/

break;

}

#endif


////* User code part end */

return 0;

}

User Mode (UDP)




Source Code.

51


int fnUdpServer()

{


return 0;

}



int fnUdpServer()

{


nSocketfd = (int)socket(AF_INET,SOCK_DGRAM, 0); /*Server side socket

creation*/


serv_addr.sin_addr.s_addr = htonl(INADDR_ANY);

serv_addr.sin_port = htons(SERVER_PORTNUMBER); /* Server port number 6000*/


nBindfd = bind(nSocketfd, (struct sockaddr *) &serv_addr,

sizeof(serv_addr));

fnWriteOutput();


memset(szData, 0, sizeof(szData)); //Clear the array

nReceivedbytes = recvfrom(nSocketfd, szData, sizeof(szData), 0,(struct

sockaddr *) &serv_addr, &nServerLen);

fnWriteOutput();

#else

while(1)

{

memset(szData, 0, sizeof(szData)); //Clear the array

nReceivedbytes = recvfrom(nSocketfd, szData, sizeof(szData), 0,(struct

sockaddr *) &serv_addr, &nServerLen);

fnWriteOutput();

}

#endif



return 0;

}



Repeat the steps performed for Sample Mode and click Run.

52

So presently NetSim will execute code written by the user and will display the result

graphically.




below.






without NetSim.


& validate their code. User must run the exe at both client and server and use the respective

Input.txt file. Inside Input.txt file at Client system, use the server system IP address in

“Destination IP Address” and client system IP address instead of “192.168.0.147:-Hello

World”

For TCP

Input.txt file contents at Server system

Protocol=TCP

Operation=Server

Input.txt file contents at Client system

Protocol=TCP

Operation=Client

Destination IP Address=192.168.0.130

192.168.0.147:-Hello World

Output.txt file contents at Server system

Socket Created

Bind Succeed

Listen Succeed

For UDP

Input.txt file contents at Server system

Protocol=UDP

Operation=Server

Input.txt file contents at Client system

Protocol=UDP

Operation=Client

Destination IP Address=192.168.0.130

192.168.0.147:-Hello World

Output.txt file contents at Server

system

Socket Created

Bind Succeed

53

6. Socket Program for Talk

6.1 Objective:

Write a socket Program for Echo/Ping/Talk commands.

6.2 Theory:

The socket is a fundamental concept to the operation of TCP/IP application software. It is

also an interface between the application and the network. The exchange of data between a

pair of devices consists of a series of messages sent from a socket on one device to a socket

on other. Once the socket is configured, the application can send the data using sockets for

network transmission and receive the data using sockets from the other host. A socket

communication can be connection oriented (TCP sockets) or connectionless (UDP sockets).

There is a receiver (TCP/UDP), which listens to the sender (TCP/UDP) communications.

There can be two-way communication.

6.3 Algorithm

6.3.1 Send


(TCP)

2. Initialize the address family, port no and IP address to communicate using sockets.

3. Establish Connection with destination IP

4. While new messages are typed by user

4.1. Send the data using the socket id

5. Close the socket connection if user types “<close>”

6.4 Procedure:

To begin with the experiment, open NetSim

Click on Programming from the menu bar and select PC to PC Communication and then

select Chat Application



with your own code.

54

The scenario will be obtained as shown below. Follow the steps

Step 1:

Step 2:

Select Mode

Select Protocol

Enter Destination IP address

Enter User Name

Click Run to start

transmission

Click here to view Concept,

Algorithm, and Pseudo Code

& Flowchart

Enter the data to

send

Click Send

Button

55

Step 3:

User Mode (TCP)


int fnTcpSend()

{


fnWriteOutput_TCP_Send();

return 0;

}



int fnTcpSend()

{


int nSendbytes;

nSocketfd = socket(AF_INET,SOCK_STREAM, 0);


serv_addr.sin_port = htons(PORTNUMBER );

serv_addr.sin_addr.s_addr = inet_addr(server_ip);

nConnectfd = connect(nSocketfd, (struct sockaddr *)

&serv_addr,sizeof(serv_addr));

while(getnewmessage())

{

nSendbytes = send(nSocketfd, szData, strlen(szData), 0);

_strupr(szData);

Receiver Data

56

if(!strcmp(szData,closedata))

break;

}



return 0;

}

User Mode (UDP)


int fnUdpSend()

{


fnWriteOutput_UDPSend();

return 0;

}



int fnUdpSend()

{


int nSendbytes;

nSocketfd = socket(AF_INET,SOCK_DGRAM, IPPROTO_UDP);


serv_addr.sin_port = htons(PORTNUMBER );

serv_addr.sin_addr.s_addr = inet_addr(server_ip);


while(getnewmessage())

{

nSendbytes = sendto(nSocketfd, szData, strlen(szData), 0,(struct

sockaddr *) &serv_addr, nServerLen);

if(nSendbytes < 0)

{

fprintf(fpOutput,"Could not receive : %d\n" ,

WSAGetLastError());

fflush(fpOutput);

return -1;

}

_strupr(szData);

if(!strcmp(szData,closedata))

break;

}

closesocket(nSocketfd); /* close the socket*/

57


return 0;

}



below.






without NetSim.

Note


& validate their code. Both the user must run the exe at the same time and use the respective

Input.txt file. Inside Input.txt file at both the user, set the ServerIp as the IP address of the

other user.

For TCP

Input.txt file contents at Chat user 1

Protocol=TCP

ServerIp=192.168.0.134


Protocol=TCP

ServerIp=192.168.0.145

Output.txt file contents at both Chat user 1 and 2

Socket created

Bind done

Listen completed

Waiting for client to connect...

Connected to client

58

For UDP


Protocol= UDP

ServerIp=192.168.0.134


Protocol=UDP

ServerIp=192.168.0.145

Output.txt file contents at both Chat user 1 and 2

Socket created

Bind done

59

7. CSMA/CA and CSMA/CD

7.1 Objective:

To create scenario and study the performance of network with CSMA / CA protocol and

compare with CSMA/CD protocols.

7.2 Part A – CSMA/CA

7.2.1 Theory:

Wireless LAN is basically a LAN that transmits data over air, without any physical

connection between devices. The transmission medium is a form of electromagnetic

radiation. Wireless LAN is ratified by IEEE in the IEEE 802.11 standard. In most of the

WLAN products on the market based on the IEEE 802.11b technology the transmitter is

designed as a Direct Sequence Spread Spectrum Phase Shift Keying (DSSS PSK) modulator,

which is capable of handling data rates of up to 11 Mbps. The underlying algorithm used in

Wireless LAN is known as the CSMA/CA – Carrier Sense Multiple Access/Collision

Avoidance algorithm.

7.2.2 Procedure:

How to Create Scenario & Generate Traffic:

Please navigate through the below given path to,

Create Scenario: New Internetworks”.

7.2.2.1 Sample Inputs:

Follow the steps given in the different samples to arrive at the objective.

In this Sample,

Total no of APs (Access Points) used: 1

Total no of Wireless Nodes used: 5

60

The AP and Wireless Nodes are interconnected as shown below:

Set the below properties for AP, Wireless Nodes and Wireless Link and Application

properties.

Click and drop the Application, set properties and run the simulation.

Inputs for the Sample experiment are given below:

Access Point Properties: In the Experiment, for AP, the following properties have to be set

by Right clicking on the AP Properties

Global Properties

X/Lat 150

Y/Lon 110

Interface1_WLAN Properties

RTS_Threshold 1000

Wireless Link Properties: Set Channel Characteristics as No Path Loss

Wireless Node Properties: In the Experiment, for each Wireless Node, the following

properties have to be set by Right clicking on the Wireless Node Properties.

61

Global Properties

2(Wireless Node B)

X/Lat 125

Y/Lon 130

3(Wireless Node C)

X/Lat 150

Y/Lon 140

4(Wireless Node D)

X/Lat 170

Y/Lon 135

5(Wireless Node E)

X/Lat 185

Y/Lon 125

6(Wireless Node F)

X/Lat 180

Y/Lon 105

For all wireless Nodes, set the below properties

Wireless Node Properties All Nodes

Transport Layer Properties

TCP Disable

Interface1_Wireless Properties

RTS_Threshold 1000

Application Properties:

Select the Application Button and click on the gap between the Grid Environment and the

ribbon. Now right click on Application and select Properties.

62

NOTE: The procedure to create multiple applications are as follows:

Step 1: Click on the ADD button present in the bottom left corner to add a new application.

Application Properties

Source_ID 2(Wireless

Node B)

3(Wireless

Node C)

4(Wireless

Node D)

5(Wireless

Node E)

6(Wireless

Node F)

Destination_ID 3(Wireless

Node C)

4(Wireless

Node D)

5(Wireless

Node E)

6(Wireless

Node F)

2 (Wireless

Node B)

Application Type Custom Custom Custom Custom Custom

Packet Size

Distribution Constant Constant Constant Constant Constant

Value (bytes) 1472 1472 1472 1472 1472

Packet Inter Arrival Time


Value (micro secs) 10000 10000 10000 10000 10000

Simulation Time - 100 Sec

(Note: The Simulation Time can be selected only after the following two tasks,

Set the properties for the Wireless Nodes, AP, Wireless Link and Application.

Click on Run Simulation button.

63

7.3 Part B - CSMA/CD

7.3.1 Theory:

Carrier Sense Multiple Access Collision Detection (CSMA / CD)

This protocol includes the improvements for stations to abort their transmissions as soon as

they detect a collision. Quickly terminating damaged frames saves time and bandwidth. This

protocol is widely used on LANs in the MAC sub layer. If two or more stations decide to

transmit simultaneously, there will be a collision. Collisions can be detected by looking at the

power or pulse width of the received signal and comparing it to the transmitted signal. After a

station detects a collision, it aborts its transmission, waits a random period of time and then

tries again, assuming that no other station has started transmitting in the meantime.

7.3.2 Procedure:

How to create a scenario and generate traffic:

Create Scenario: New Legacy Networks CSMA/CD

7.3.2.1 Sample Inputs:

To perform this sample experiment, five nodes and one

hub are considered.

Click and drop Hub on the environment builder.

Click and drop 5 Wired Nodes.

Connect the Wired nodes to the hub through Wired

link as shown in figure.

64

In the Experiment, for each Node, the following properties have to be set by Right clicking

on the Node Properties.

Hub Properties: Accept default properties of Hub.


Select the Application Button and click on the gap between the Grid Environment and the

ribbon. Now right click on Application and select Properties.


Step 1: Click on the ADD button present in the bottom left corner to add a new application.

65


Source_ID 2(Wireless

Node B)

3(Wireless

Node C)

4(Wireless

Node D)

5(Wireless

Node E)

6(Wireless

Node F)

Destination_ID 3(Wireless

Node C)

4(Wireless

Node D)

5(Wireless

Node E)

6(Wireless

Node F)

2 (Wireless

Node B)

Application Type Custom Custom Custom Custom Custom

Packet Size


Value (bytes) 1472 1472 1472 1472 1472



Value (micro secs) 10000 10000 10000 10000 10000



Set the properties for the Nodes & The Hub

Click on Run Simulation button).

7.3.3 Result:

(Throughput Comparison between CSMA/CA and CSMA/CD protocols)

0

1

2

3

4

5

6

7

CSMA/CA CSMA/CD

Thro

ugh

pu

t(M

bp

s)

Throughput

66

(Collision count comparison between CSMA/CA and CSMA/CD protocols)

7.3.4 Inference:

In case of wireless LAN, an acknowledgment packet is transmitted by the receiver node to

the transmitter. Moreover, WLAN is an infrastructure based network i.e. a centralized device

(Access Point) is controlling the network. Hence all the packets are transmitted to the

destination via the Access Point (AP) i.e. packets transmitted by the source are first received

by AP, which is then retransmitted by the AP to the destination. Furthermore, wireless

links/medium supports half-duplex transmission. Due to this nature of packet hopping,

acknowledgment overheads and transmission, the throughput is less compared to Ethernet.

Unlike CSMA/CD (Carrier Sense Multiple Access/Collision Detect) which deals with

transmissions after a collision has occurred, CSMA/CA acts to prevent collisions before they

happen. The collision avoidance concept in wireless LAN protocol, avoids the possibility of

collision of data frames. In CSMA/CA, as soon as a node receives a packet that is to be sent,

it checks to be sure the channel is clear (no other node is transmitting at the time). If the

channel is clear, then the packet is sent. If the channel is not clear, the node waits for a

randomly chosen period of time, and then checks again to see if the channel is clear. This is

the primary reason for wireless LAN having less collision count than Ethernet. In addition,

RTS/CTS is also implemented to reduce collision.

0

10000

20000

30000

40000

50000

60000

70000

CSMA/CA CSMA/CD

No

. of

Pac

kets

Collision count

67

8. Network Topology –Star, Bus, Ring

8.1 Part A- Star

8.1.1 Theory:

In local area networks with a star topology, each network host is connected to a central

switch with a point-to-point connection. In Star topology every node (computer workstation

or any other peripheral) is connected to central node called switch. The switch is the server

and the peripherals are the clients. The network does not necessarily have to resemble a star

to be classified as a star network, but all of the nodes on the network must be connected to

one central device. All traffic that traverses the network passes through the central switch.

The star topology is considered the easiest topology to design and implement. An advantage

of the star topology is the simplicity of adding additional nodes.

8.2 Procedure:

How to Create Scenario & Generate Traffic:

Please navigate through the below given path to,

Create Scenario: “Simulation New Internetworks”.

Sample Inputs:


In this Sample,

Total no of switch used: 1

Total no of Wired Nodes used: 6

The switch and Wired Nodes are interconnected as shown below:

68

Set the below properties for switch, Wired node and Wired Link.

Click and drop the Application, set properties and run the simulation.

Inputs for the Sample experiment are given below:

Switch Properties: Accept the default properties of switch

Wired Node Properties:

Wired Node Properties All Nodes

Transport Layer Properties

TCP Disable

Wired Link Properties:

Wired Link Properties All Links

Uplink Speed (Mbps) 100

Downlink Speed(Mbps) 100

Uplink BER No Error

Downlink BER No Error

69


Application

Properties

2(Wired

Node B)

3(Wired

Node C)

4(Wired

Node D)

5(Wired

Node E)

6(Wired

Node F)

7(Wired

Node F)

Destination 3(Wired

Node C)

4(Wired

Node D)

5(Wired

Node E)

6(Wired

Node F)

7(Wired

Node B)

2(Wired

Node B)

Application Type Custom Custom Custom Custom Custom Custom

Packet Size

Distribution Constant Constant Constant Constant Constant Constant

Packet Size (Bytes) 10000 10000 10000 10000 10000 10000



Packet Inter

Arrival Time (µs)

1000 1000 1000 1000 1000 1000



Set the properties for the Switch, Wired Node, Wired Link and Application.


70

8.3 Part B- Token Bus

8.3.1 Theory:

Token bus is a LAN protocol operating in the MAC layer. Token bus is standardized as per

IEEE 802.4. Token bus can operate at speeds of 5Mbps, 10 Mbps and 20 Mbps. The

operation of token bus is as follows

Unlike token ring in token bus the ring topology is virtually created and maintained by the

protocol. A node can receive data even if it is not part of the virtual ring, a node joins the

virtual ring only if it has data to transmit. In token bus data is transmitted to the destination

node only where as other control frames is hop to hop. After each data transmission there is a

solicit_successsor control frame transmitted which reduces the performance of the protocol.

8.3.2 Procedure:


Create Scenario: “Simulation New Legacy NetworkToken Bus”.

Sample Input:

In this Sample experiment 6 Nodes and 1 Hub need to be clicked and dropped onto the

Environment Builder.

71


Application

Properties

2(Wired

Node B)

3(Wired

Node C)

4(Wired

Node D)

5(Wired

Node E)

6(Wired

Node F)

7(Wired

Node F)

Destination 3(Wired

Node C)

4(Wired

Node D)

5(Wired

Node E)

6(Wired

Node F)

7(Wired

Node B)

2(Wired

Node B)


Packet Size





Packet Inter

Arrival Time (µs)

1000 1000 1000 1000 1000 1000

Link Properties:

Link Properties Values to be Selected

Error Rate (bit error rate) 0





72

8.4 Part C - Token Ring

8.4.1 Theory

Token ring is a LAN protocol operating in the MAC layer. Token ring is standardized as per

IEEE 802.5. Token ring can operate at speeds of 4mbps and 16 mbps. The operation of token

ring is as follows

When there is no traffic on the network a simple 3-byte token circulates the ring. If the token

is free (no reserved by a station of higher priority as explained later) then the station may

seize the token and start sending the data frame. As the frame travels around the ring ach

station examines the destination address and is either forwarded (if the recipient is another

node) or copied. After copying4 bits of the last byte is changed. This packet then continues

around the ring till it reaches the originating station. After the frame makes a round trip the

sender receives the frame and releases a new token onto the ring.

8.4.2 Procedure


Create Scenario: “Simulation New Legacy NetworkToken Ring”.

73

Sample Input

In this Sample experiment 6 Nodes and 1 Concentrator need to be clicked and dropped onto

the Environment Builder.


Application

Properties

2(Wired

Node B)

3(Wired

Node C)

4(Wired

Node D)

5(Wired

Node E)

6(Wired

Node F)

7(Wired

Node F)

Destination 3(Wired

Node C)

4(Wired

Node D)

5(Wired

Node E)

6(Wired

Node F)

7(Wired

Node B)

2(Wired

Node B)


Packet Size





Packet Inter

Arrival Time (µs)

1000 1000 1000 1000 1000 1000

Concentrator Properties:

Concentrator Properties Values to be Selected

Data Rate(Mbps) 16

Error Rate (bit error rate) No error





74

8.5 Result

Throughput Comparison between Bus, Ring and Star

8.6 Inference

Due to more overheads and complicated ring maintenance procedure token bus always less

than token rings. Star topology throughput is higher than other topology (Bus and Ring)

because Star has higher data rate.

0

10

20

30

40

50

60

70

80

90

Bus Ring Star

Thro

ugh

pu

t

Sample Experiments

Throughput

75

9. Distance Vector Routing

Objective: Write a C/C++ program to verify the distance vector routing algorithm

9.1 Theory

Distance Vector Routing is one of the routing algorithms used in a Wide Area Network for

computing shortest path between source and destination. The router is one of the main

devices used in a wide area network. The main task of the router is routing. It forms the

routing table and delivers the packets depending upon the routes in the table – either directly

or via an intermediate device (perhaps another router).

Each router initially has information about its all neighbors (i.e., it is directly connected).

After a period of time, each router exchanges its routing table among its neighbors. After

certain number of exchanges, all routers will have the full routing information about the area

of the network. After each table exchange, router re-computes the shortest path between the

routers. The algorithm used for this routing is called Distance Vector Routing.

9.2 Algorithm

Repeat the following steps until there is no change in the routing table for all routers.

Take the Next Router routing table and its neighbor routing table.

Add the router entry that is not in your own routing table, but exists in any one of the

other routing tables. If the new router entry exists in more than one neighbor, then find

the minimum cost among them. The minimum cost value details are taken as a new entry:

such as source router, intermediate router, destination router and cost value, etc.

Update the source router routing table cost value if both the destination router and the

intermediate router field value have the same value as any one of the neighbors‟ routing

entry.

Update the source router‟s routing table entry with the new advertised one if the

intermediate router value in the source table is not same, but the cost value is greater than

the its neighbor‟s entry.

Write the next stage of routing table into the file.

76

Repeat steps 1 to 5 for all routers.

Check whether any changes are made in any of the routers. If yes, then repeat the above

steps, otherwise, quit the process.

9.3 Procedure:


Click on Programming from the menu bar and select Distance Vector Routing

Step 1:




with your own code.

Select the Mode

Click Run to execute the Program

Connect the Routers

77

9.4 Results (to be filled up by the students):

Step 2:




Source Code.


void fnDistVectAlgorithm()

{


}


Output Table

78

The User code which is to be added is given below:-

void fnDistVectAlgorithm()

{


do// This do while... loop is to update the table information till it

knows all the router's information present in the network.

{

// I for//To go to No of router

for(nRouterTable=1;nRouterTable<=g_nNoOfRouters;nRouterTable++)

{// II for //Select the source router

for(nNeighbour=1;nNeighbour<=g_nNoOfRouters;nNeighbour++)

{// III for//move to all router

if(Table[nRouterTable].nCostID[nNeighbour]==1)

{// I if //select the neigh router

int nDestID=1;

for(nDestID=1;nDestID<=g_nNoOfRouters;nDestID++)

{// IV for //select the routing table of

neigh

if(nDestID!=nRouterTable)

{// II if

if((Table[nRouterTable].nDestID[nDestID] == 0) &&

(Table[nNeighbour].nDestID[nDestID]!=0))// ||

{// III if //This loop is to

check whether the neighbour router is DESTINATION or not.

Table[nRouterTable].nDestID[nDestID] = nDestID;

Table[nRouterTable].nNextHop[nDestID] = nNeighbour;

Table[nRouterTable].nCostID[nDestID]=(Table[nNeighbour].nCostID[nDestID]+1);

}

else

if((Table[nRouterTable].nNextHop[nDestID]!=nDestID||Table[nRouterTable].nCostID[nDe

stID]!=1)&&(Table[nNeighbour].nDestID[nDestID]!=0))

{// else if

// This loop is to check

whether the neighbour router is the destination or not and also check whether the

cost ID is 1 or not.

if(Table[nRouterTable].nCostID[nDestID]>Table[nNeighbour].nCostID[nDestID])

{//IV if

//This loop is to find

the least cost path

Table[nRouterTable].nDestID[nDestID] = nDestID;

Table[nRouterTable].nNextHop[nDestID] = nNeighbour;

Table[nRouterTable].nCostID[nDestID]=(Table[nNeighbour].nCostID[nDestID]+1);

}//end IV if

}//end else if

}// end II if

}//end IV for

}// end I if

}//end III for

79

}// end II for

nStage++;

fnDisplay(nStage);

}while(nStage<2);


}



Click on 1 router and another router consecutively to connect them. Click Run.

So presently NetSim will run Distance Vector Routing code which is written by the user and

will display the result graphically.




below.






without NetSim.




Router_ID=1>Router_Name=Router_1>No_Of_Neighbour=1>Neighbours_ID=2

Router_ID=2>Router_Name=Router_2>No_Of_Neighbour=4>Neighbours_ID=1>3>6>5

Router_ID=3>Router_Name=Router_3>No_Of_Neighbour=2>Neighbours_ID=2>4


Router_ID=5>Router_Name=Router_5>No_Of_Neighbour=1>Neighbours_ID=2


80


0>1>2>1>0

0>2>1>1>0

0>2>3>1>0

0>2>5>1>0

0>2>6>1>0

0>3>2>1>0

0>3>4>1>0

0>4>3>1>0

0>4>6>1>0

0>5>2>1>0

0>6>2>1>0

0>6>4>1>0

1>1>2>1>0

1>1>3>2>2

1>1>5>2>2

1>1>6>2>2

1>2>1>1>0

1>2>3>1>0

1>2>4>2>6

1>2>5>1>0

1>2>6>1>0

1>3>1>2>2

1>3>2>1>0

1>3>4>1>0

1>3>5>2>2

1>3>6>2>4

1>4>1>3>3

1>4>2>2>6

1>4>3>1>0

1>4>5>3>3

1>4>6>1>0

1>5>1>2>2

1>5>2>1>0

1>5>3>2>2

1>5>4>3>2

1>5>6>2>2

1>6>1>2>2

1>6>2>1>0

1>6>3>2>4

1>6>4>1>0

1>6>5>2>2

2>1>2>1>0

2>1>3>2>2

2>1>4>3>2

2>1>5>2>2

2>1>6>2>2

2>2>1>1>0

2>2>3>1>0

81

2>2>4>2>6

2>2>5>1>0

2>2>6>1>0

2>3>1>2>2

2>3>2>1>0

2>3>4>1>0

2>3>5>2>2

2>3>6>2>4

2>4>1>3>6

2>4>2>2>6

2>4>3>1>0

2>4>5>3>6

2>4>6>1>0

2>5>1>2>2

2>5>2>1>0

2>5>3>2>2

2>5>4>3>2

2>5>6>2>2

2>6>1>2>2

2>6>2>1>0

2>6>3>2>4

2>6>4>1>0

2>6>5>2>2

82

10. Link State Routing

Objective: Write a C/C++ program to verify the Link state routing Algorithm.

10.1 Theory:

The router is one of the main devices used in a wide area network. The main task of the

router is routing. It forms the routing table and delivers the packets depending upon the routes

in the table – either directly or via an intermediate device (perhaps another router).

Link state algorithm is a method used to find the shortest path between a source router and a

destination router based on the distance and route the packets through that route.

10.2 Algorithm:

1. Start with the router: the root of the tree

2. Assign a cost of 0 to this router and make it the first permanent router.

3. Examine each neighbor router of the router that was the last permanent router.

4. Assign a cumulative cost to each router and make it temporary.

5. Among the list of temporary routers

5. a. Find the router with the smallest cumulative cost and make it permanent.

5. b. If a router can be reached from more than one direction

5. b. 1. Select the direction with the shortest cumulative cost.

6. Repeat steps 3 to 5 until every router becomes permanent.

10.3 Procedure:

Step 1:


Click on Programming from the menu bar and select Shortest Path. In shortest path select

Link State Routing algorithm.

83



link to NetSim software for validation. Click on F1 (Help) link for details on how to proceed

with your own code.


Connect the Routers

Click Run to execute the Program

Select Link State

Select Mode

Output

table

84

Inference (to be filled up by the students):

Here, Router 1 is taken as the source and Router 3 as the destination. The paths are connected

with input as the distance. The figure indicated in green line shows the shortest path.

Step 2:




Source Code.


void fnDijkstra()

{


}



void fnDijkstra() { /////* User code part start */

//Write your own code for Link State Algorithm HERE

int i, j; // Temporary loop variables char szString[_MEM_BUFFER2]; char* szToken; int iNo; //total number of nodes used in the graph. pszFile = (char*) malloc(sizeof(char) * _MEM_BUFFER2); szInput_path = (char*) malloc(_MEM_BUFFER2 * sizeof(char)); strcpy(szInput_path, szTempPath); strcat(szInput_path, "/Input.txt"); strcpy(pszFile, szInput_path); fp = fopen(pszFile, "r"); szToken = (char*) malloc(sizeof(_MEM_BUFFER2)); fgets(szString, _MEM_BUFFER2, fp);//skip the first line fgets(szString, _MEM_BUFFER2, fp); szToken = strtok(szString, "="); szToken = strtok(NULL, "="); iNo = atoi(szToken); strcpy(pszFile, ""); strcpy(pszFile, szOutput_path); fpOutput = fopen(pszFile, "w+");

85

if (iNo <= 11) { fnInitialize(iNo); } else { fclose(fp); } for (i = 0; i < iNo; i++) { for (j = 0; j < iNo; j++) { distanceMatrix[i][j] = 999; } } strcpy(pszFile, szInput_path); fp = fopen(pszFile, "r"); fgets(szString, _MEM_BUFFER2, fp); fgets(szString, _MEM_BUFFER2, fp); fgets(szString, _MEM_BUFFER2, fp);//skip first three line from input.txt //parsing the input file and storing the values into distance matrix for (i = 0; i < iNo; i++) { fgets(szString, _MEM_BUFFER2, fp); szToken = strtok(szString, ">"); j = 0; while (szToken != NULL) { /* While there are tokens in "string" */ if (atoi(szToken) == 999) { // Do Nothing } else // To make a Adjacency Matrix { distanceMatrix[i][j] = atoi(szToken); //distanceMatrix[j][i]=atoi(szToken); } /* Get next token: */ j++; szToken = strtok(NULL, ">"); } } // Tokenizing next two line for storing the source and destination node.

// Tokenizing for the source node

fgets(szString, _MEM_BUFFER2, fp); szToken = strtok(szString, "="); szToken = strtok(NULL, "="); source = atoi(szToken); --source; // Tokenizing for the destination node

fgets(szString, _MEM_BUFFER2, fp); szToken = strtok(szString, "="); szToken = strtok(NULL, "="); destination = atoi(szToken); --destination; fclose(fp); // Initializing the Path Array and The Include Array

// For Include Array

for (i = 0; i < iNo; i++) { if (i == source) include[i] = 1; else

86

include[i] = 0; }//end of for loop // For Distance Array for (i = 0; i < iNo; i++) { if (i == source) distance[i] = 0; else { if (distanceMatrix[source][i] == 999) { distance[i] = 999; } else { distance[i] = distanceMatrix[source][i]; } } }//end of for loop // For Initialising Path Array for (i = 0; i < iNo; i++) { if (distanceMatrix[source][i] == 999) { path[i] = 999; } else { path[i] = source; } }//end of for loop iFlag = 0; //main iteration phase for Dijkstra's Algorithm while (iFlag == 0) { //find out the minimum distance from the availabe nodes not included

min = 999; node = 999; for (i = 0; i < iNo; i++) { if (include[i] == 0) { if (min == 999) { min = distance[i]; node = i; } else { if ((distance[i] < min) && (distance[i] != 999)) { min = distance[i]; node = i; } } } } if (node != 999) include[node] = 1;

// Checking if node exists which has an edge to the source node

if (min != 999) { for (i = 0; i < iNo; i++) { // for nodes not included, we proceed

if (include[i] == 0) { // to check if Edge exists between 'i' and 'node'

if (distanceMatrix[i][node] == 999) { //do nothing } else { if ((distance[node] == 999) && (distance[i] == 999)) {//do nothing } else if (distance[i] == 999) // For

inifinity

{ distance[i] = distance[node]

87

+ distanceMatrix[i][node]; path[i] = node; } else if ((distance[node] + distanceMatrix[i][node]) < distance[i]) { distance[i] = distance[node] + distanceMatrix[i][node]; path[i] = node; } } } }//end of for loop } //Checking if all the nodes has been included.

for (i = 0; i < iNo; i++) { iFlag = 1; if (include[i] == 0) { iFlag = 0; break; } } }//end of while (!0) // To generate the output file into 'output.txt

fprintf(fpOutput, ">>>\n"); // Print the distance Array

fprintf(fpOutput, "Distance>"); for (i = 0; i < iNo; i++) fprintf(fpOutput, "%d>", distance[i]); // Print the Path Arrray

fprintf(fpOutput, "\nPath>"); for (i = 0; i < iNo; i++) fprintf(fpOutput, "%d>", path[i] + 1); fclose(fpOutput); /////* User code part end */

}



Select Algorithm as Link State and the remaining input parameters and click Run.

So presently NetSim will run Link State Routing code which is written by the user and will



NOTE: Please insert the correct code according to the algorithm selected. The codes for other

algorithm are provided in NetSim Installation CD.

88



below.






without NetSim.




Algorithm=Link_State

No_of_Router=3

Distance:

999>2>78>

2>999>54>

78>54>999>

Source_Router=1

Destination_Router=3


1>2>3>

1>2>

1>3>

1>

>>>

Distance>0>2>56>

Path>1000>1>2>


89

11. Congestion Control Algorithm

11.1 Objective:

Study of Network Simulator (NetSim) and simulation of Congestion Control Algorithm

Part A – Network Simulator (NetSim)

11.2 Theory:

What is NetSim?

NetSim is a network simulation tool that allows you to create network scenarios, model

traffic, and study performance metrics.

What is a network?

A network is a set of hardware devices connected together, either physically or logically. This

allows them to exchange information.

A network is a system that provides its users with unique capabilities, above and beyond what

the individual machines and their software applications can provide.

What is simulation?

A simulation is the imitation of the operation of a real-world process or system over time.

Network simulation is a technique where a program models the behavior of a network

either by calculating the interaction between the different network entities (hosts/routers, data

links, packets, etc) using mathematical formulae, or actually capturing and playing back

observations from a production network. The behavior of the network and the various

applications and services it supports can then be observed in a test lab; various attributes of

the environment can also be modified in a controlled manner to assess how the network

would behave under different conditions.

What does NetSim provide?

Simulation: NetSim provides simulation of various protocols working in various networks as

follows: Internetworks, Legacy Networks, BGP Networks, Advanced Wireless

Networks, Cellular Networks, Wireless Sensor Networks, Personal Area Networks,

LTE/LTE-A, IOT(Internet of Things) and Cognitive Radio Networks. Users can open the

http://en.wikipedia.org/wiki/Router

http://en.wikipedia.org/wiki/Data_link

http://en.wikipedia.org/wiki/Data_link

http://en.wikipedia.org/wiki/Packet_(information_technology)

90

experiment and save experiments as desired. The different experiments can also be analyzed

using the analytics option in the simulation menu.

Programming: NetSim covers various programming exercises along with concepts,

algorithms, pseudo code and flowcharts. Users can also write their own source codes in

C/C++ and can link them to NetSim.

Some of the programming concepts are Address resolution protocol (ARP), Classless inter

domain routing (CIDR), Cryptography, Distance vector routing, shortest path, Subnetting etc.

Basics: NetSim basics, gives a brief introduction and theoretical knowledge on different

Internetworks, Legacy Networks, BGP Networks, Advanced wireless Networks, Cellular

Networks and devices. Basics also provide more than 200 animations for better

understandability of networking concepts.

help: NetSim help, provides a detail help through user manual and Experiment manual.

Part B – Congestion Control Algorithm

11.3 Theory:

One of the important functions of a TCP Protocol is congestion control in the network. Given

below is a description of how Old Tahoe and Tahoe variants (of TCP) control congestion.

Old Tahoe:

Congestion can occur when data arrives on a big pipe (i.e. a fast LAN) and gets sent out

through a smaller pipe (i.e. a slower WAN). Congestion can also occur when multiple input

streams arrive at a router whose output capacity is less than the sum of the inputs. Congestion

avoidance is a way to deal with lost packets.

The assumption of the algorithm is that the packet loss caused by damaged is very small

(much less than 1%), therefore the loss of a packet signals congestion somewhere in the

network between the source and destination. There are two indications of packets loss: a

timeout occurring and the receipt of duplicate ACKs

91

Congestion avoidance and slow start are independent algorithms with different objectives.

But when congestion occurs TCP must slow down its transmission rate and then invoke slow

start to get things going again. In practice they are implemented together.

Congestion avoidance and slow start requires two variables to be maintained for each

connection: a Congestion Window (i.e. cwnd) and a Slow Start Threshold Size (i.e. ssthresh).

Old Tahoe algorithm is the combination of slow start and congestion avoidance. The

combined algorithm operates as follows,

1. Initialization for a given connection sets cwnd to one segment and ssthresh to 65535

bytes.

2. When congestion occurs (indicated by a timeout or the reception of duplicate ACKs),

one-half of the current window size (the minimum of cwnd and the receiver‟s advertised

window, but at least two segments) is saved in ssthresh. Additionally, if the congestion is

indicated by a timeout, cwnd is set to one segment (i.e. slow start).

3. When new data is acknowledged by the other end, increase cwnd, but the way it increases

depends on whether TCP is performing slow start or congestion avoidance.

If cwnd is less than or equal to ssthresh, TCP is in slow start. Else TCP is performing

congestion avoidance. Slow start continues until TCP is halfway to where it was when

congestion occurred (since it recorded half of the window size that caused the problem in step

2). Then congestion avoidance takes over.

Slow start has cwnd begins at one segment and be incremented by one segment every time an

ACK is received. As mentioned earlier, this opens the window exponentially: send one

segment, then two, then four, and so on. Congestion avoidance dictates that cwnd be

incremented by 1/cwnd, compared to slow start‟s exponential growth. The increase in cwnd

should be at most one segment in each round trip time (regardless of how many ACKs are

received in that RTT), whereas slow start increments cwnd by the number of ACKs received

in a round-trip time.

Tahoe (Fast Retransmit):

The Fast retransmit algorithms operating with Old Tahoe is known as the Tahoe variant.

92

TCP may generate an immediate acknowledgement (a duplicate ACK) when an out-of-order

segment is received out-of-order, and to tell it what sequence number is expected.

Since TCP does not know whether a duplicate ACK is caused by a lost segment or just a re-

ordering of segments, it waits for a small number of duplicate ACKs to be received. It is

assumed that if there is just a reordering of the segments, there will be only one or two

duplicate ACKs before the re-ordered segment is processed, which will then generate a new

ACK. If three or more duplicate ACKs are received in a row, it is a strong indication that a

segment has been lost. TCP then performs a retransmission of what appears to be the missing

segment, without waiting for a re-transmission timer to expire.

11.4 Procedure:

Go to Simulation New Internetworks

Sample Inputs:


Sample 1.a: Old Tahoe (1 client and 1 server)

In this Sample,

Total no of Node used: 2

Total no of Routers used: 2

The devices are inter connected as given below,

Wired Node C is connected with Router A by Link 1.

Router A and Router B are connected by Link 2.

Wired Node D is connected with Router B by Link 3.

93

Set the properties for each device by following the tables,


Application Type Custom

Source_Id 4(Wired Node D)

Destination_Id 3(Wired Node C)

Packet Size

Distribution Constant

Value (bytes) 1460

Inter Arrival Time

Distribution Constant

Value (micro secs) 1300

Node Properties: In Transport Layer properties, set

TCP Properties

MSS(bytes) 1460

Congestion Control Algorithm Old Tahoe

Window size(MSS) 8

Router Properties: Accept default properties for Router.

Link Properties Link 1 Link 2 Link 3

Max Uplink Speed (Mbps) 8 10 8

Max Downlink Speed(Mbps) 8 10 8

Uplink BER 0.000001 0.000001 0.000001

Downlink BER 0.000001 0.000001 0.000001

94


Upon completion of simulation, “Save” the experiment.

(Note: The Simulation Time can be selected only after doing the following two tasks,

Set the properties of Node, Router& Link

Then click on Run Simulation button).

Sample 1.b: Tahoe (1 client and 1 server)

Open sample 1.a, and change the TCP congestion control algorithm to Tahoe (in Node

Properties). Upon completion of simulation, “Save” the experiment as sample 1.b.

Sample 2.a: Old Tahoe (2 clients and 2 servers)

In this Sample,

Total no of Wired Nodes used: 4



Wired Node A and Wired Node B are connected with Router C by Link 1 and Link 2.

Router C and Router D are connected by Link 3.

Wired Node E and Wired Node F are connected with Router D by Link 4 and Link 5.

Wired Node A and Wired Node B are not transmitting data in this sample.

95


Application Properties Application 1 Application 2


Source_Id 5 6

Destination_Id 1 2

Packet Size

Distribution Constant Constant

Value (bytes) 1460 1460

Inter Arrival Time

Distribution Constant Constant

Value (micro secs) 1300 1300


Step 1: Click on the ADD button present in the bottom left corner to add a new

application.

96


TCP Properties

MSS(bytes) 1460

Congestion Control Algorithm Old Tahoe

Window size(MSS) 8


Link Properties Link 1 Link 2 Link 3 Link 4 Link 5

Max Uplink Speed

(Mbps)

8 8 10 8 8

Max Downlink Speed

(Mbps)

8 8 10 8 8

Uplink BER 0.000001 0.000001 0.000001 0.000001 0.000001

Downlink BER 0.000001 0.000001 0.000001 0.000001 0.000001




Set the properties of Node , Router & Link


Sample 2.b: Tahoe (2 clients and 2 servers)

Do the experiment as sample 2.a, and change the congestion control algorithm to Tahoe.


97

Sample 3.a: Old Tahoe (3 clients and 3 servers)

In this Sample,

Total no of Nodes used: 6



Wired Node A, Wired Node B & Wired Node C is connected with Router D by Link 1,

Link 2 & Link 3.

Router D and Router E are connected by Link 4.

Wired Node F, Wired Node G & Wired Node H is connected with Router E by Link 5,

Link 6 & Link 7.

Wired Node A, Wired Node B and Wired Node C are not transmitting data in this sample.


Application

Properties

Application 1 Application 2 Application 3


Source_Id 6 7 8

Destination_Id 1 2 3

Packet Size

Distribution Constant Constant Constant

Value (bytes) 1460 1460 1460

98

Inter Arrival Time

Distribution Constant Constant Constant

Value (micro sec) 1300 1300 1300


TCP Properties

MSS(bytes) 1460 1460 1460

Congestion Control

Algorithm

Old Tahoe Old Tahoe Old Tahoe

Window size(MSS) 8 8 8


Link

Properties

Link 1 Link 2 Link 3 Link 4 Link 5 Link 6 Link 7

Max Uplink

Speed

(Mbps)

8 8 8 10 8 8 8

Max

Downlink

Speed(Mbps)

8 8 8 10 8 8 8

Uplink BER 0.000001 0.000001 0.000001 0.000001 0.000001 0.000001 0.000001

Downlink

BER 0.000001 0.000001 0.000001 0.000001 0.000001 0.000001 0.000001

Simulation Time- 10 Sec



Set the properties of Node, Router & Link


99

Sample 3.b: Tahoe (3 clients and 3 servers)

Do the experiment as sample 3.a, and change the TCP congestion algorithm to Tahoe. Upon

completion of simulation, “Save” the experiment.

11.5 Output

Comparison Table:

TCP

Downloads Metrics

Slow start +

Congestion avoidance

Fast

Retransmit

1 client and 1

server

Throughput(Mbps) 5.926432 6.120320

Segments Retransmitted +

Seg Fast Retransmitted 195 200

2 clients and 2

servers




3 clients and 3

servers




Note: To calculate the “Throughput (Mbps)” for more than one application, add the

individual application throughput which is available in Application Metrics (or Metrics.txt) of

Performance Metrics screen. In the same way calculate the metrics for “Segments

Retransmitted + Seg Fast Retransmitted” from TCP Metrics Connection Metrics.

11.6 Inference:

User lever throughput: User lever throughput of Fast Retransmit is higher when compared

then the Old Tahoe (SS + CA). This is because, if a segment is lost due to error, Old Tahoe

waits until the RTO Timer expires to retransmit the lost segment, whereas Tahoe (FR)

retransmits the lost segment immediately after getting three continuous duplicate ACK‟s.

This results in the increased segment transmissions, and therefore throughput is higher in the

case of Tahoe.

100

12. Encryption and Decryption

Objective: Write a C/C++ program to implement Encryption and Decryption using

substitution ciphers

12.1 Theory

A substitution cipher is a method of encryption by which units of plaintext are substituted

with cipher text according to a regular system; the "units" may be single letters (the most

common), pairs of letters. The receiver deciphers the text by performing an inverse

substitution.

Each letter of the plain text is exchanged using another letter according to the key value given

by the user.

The user has to give the message and encrypt that message using the key value. The

encryption is done based on the ASCII value of the alphabetical letter and the key value.

ASCII value of each letter in the plain text is incremented by the key value. The encrypted

text is called as Cipher text.

Example - If the plain text first letter is A, ASCII value of A is 65 and the key value is 1 then

the encrypted value is 65 + 1 = 66, which is B.

Plain text : tetcos Plain text the user wants to encrypt

Key value : 1 The key value by which the plain text is encrypted

Cipher text : ufudpt Cipher text which is encrypted according to the key value.

ASCII value of each letter in the plain text is incremented by 1 (key value) and get the cipher

text.

101

12.2 Algorithm

Read the plain text and key value from the input file.

For i=1 to length (plain text)

i. Get the ascii value of ith

character.

ii. Add the key text to that ascii value.

iii. If the plain text is alphabet then the cipher text should also be alphabet

and vice versa.

iv. The alphabet series for this case is, a, b, c, d...x, y, z, a, b, c, d…

A, B, C, D…X, Y, Z, A, B, C…

v. The user should add key value according to the process to be taken, in

such a way that the series should continue as explained in the previous

point.

12.3 Procedure


Click on Programming from the menu bar, select Cryptography and then select Substitution.


Step 1:



with your own code

Continue with the steps as given for Sample mode.

102


Click here to view

concept, algorithm,

pseudo Code &

Flow chart

Click Run to

execute

Enter the Key

text

Enter the plain text

Encryption

Select Mode

Generated Cipher

text

103

Now select Decryption option and then click Run button to get back the original text.

Select Decryption

Click Run

Decrypted original text

104

Step 2:




Source Code.

For Encryption, the user needs to edit the Interface Source Code at the following location.

void fnSubstutionEncryption() {


}



void fnSubstutionEncryption() { /////* User code part start */

// Cipher Text is referenced in szTemp1_Sub_En

szTemp1_Sub_En=szCipher_Sub_En; // Make the Substitution Looping for the string

for(iloop_Sub_En=1;iloop_Sub_En<=(int)strlen(szTmp_Sub_En);iloop_Sub_En++) { // Alphabet Check (UPPER case)

if (((int)(*szPlainTxt_Sub_En) >= 65) && ((int)(*szPlainTxt_Sub_En) <= 90)) { // Get the Ascii value of the character

iTmp_Sub_En = *szPlainTxt_Sub_En; iTmp1_Sub_En = iTmp_Sub_En; // Write the character to the Output file

fprintf(fp_Sub_En,"%c>",iTmp_Sub_En); // Make the Substitution upto iKey_Sub_En times

for(iloop1_Sub_En=1;iloop1_Sub_En<=iKey_Sub_En;iloop1_Sub_En++) { if (iTmp_Sub_En > 90) iTmp_Sub_En = iTmp1_Sub_En + iloop1_Sub_En; else { iTmp_Sub_En = iTmp1_Sub_En + iloop1_Sub_En; if (iTmp_Sub_En == 91) iTmp1_Sub_En = iTmp1_Sub_En - 90 + 64; iTmp_Sub_En = iTmp1_Sub_En + iloop1_Sub_En; } fprintf(fp_Sub_En,"%c>",iTmp_Sub_En); } // Make the character to the Cipher Text

*szCipher_Sub_En=iTmp_Sub_En; fprintf(fp_Sub_En,"\n"); } // Lower Case character

105

else if (((int)(*szPlainTxt_Sub_En) >= 97) && ((int)(*szPlainTxt_Sub_En) <= 122)) { // Get the Ascii value of the character

iTmp_Sub_En = *szPlainTxt_Sub_En; iTmp1_Sub_En = iTmp_Sub_En; // Write the character to the Output file

fprintf(fp_Sub_En,"%c>",iTmp_Sub_En); // Make the Substitution upto iKey_Sub_En times

for(iloop1_Sub_En=1;iloop1_Sub_En<=iKey_Sub_En;iloop1_Sub_En++) { if (iTmp_Sub_En > 122) iTmp_Sub_En = iTmp1_Sub_En + iloop1_Sub_En; else { iTmp_Sub_En = iTmp1_Sub_En + iloop1_Sub_En; if (iTmp_Sub_En == 123) iTmp1_Sub_En = iTmp1_Sub_En - 122 + 96; iTmp_Sub_En = iTmp1_Sub_En + iloop1_Sub_En; } fprintf(fp_Sub_En,"%c>",iTmp_Sub_En); } // Make the character to the Cipher Text

*szCipher_Sub_En=iTmp_Sub_En; fprintf(fp_Sub_En,"\n"); } // Increment the Position of the Cipher Text and the PlainText

szPlainTxt_Sub_En++; szCipher_Sub_En++; } // Final String values szCipher_Sub_En--; *szCipher_Sub_En='\0'; szCipher_Sub_En=szTemp1_Sub_En; fclose(fp_Sub_En); /////* User code part end */

}


For Decryption, the user needs to edit the Interface Source Code at the following location.

void fnSubstutionEncryption() {


}



void SubstutionDecryption() { /////* User code part start */

szTemp1_Sub_De=szCipher_Sub_De;//Cipher Text is referenced in szTemp1_Sub_De

106

// Make the Substitution Looping for the string for(iloop_Sub_De=1;iloop_Sub_De<=(int)strlen(szTmp_Sub_De);iloop_Sub_De++) { // Alphabet Check (UPPER case)

if (((int)(*szPlainTxt_Sub_De) >= 65) && ((int)(*szPlainTxt_Sub_De) <= 90)) { // Get the Ascii value of the character

iTemp_Sub_De = *szPlainTxt_Sub_De; iTemp1_Sub_De = iTemp_Sub_De; // Write the character to the Output file

fprintf(fp_Sub_De,"%c>",iTemp_Sub_De); // Make the Substitution upto iKey_Sub_De times

for(iloop1_Sub_De=1;iloop1_Sub_De<=iKey_Sub_De;iloop1_Sub_De++) { if (iTemp_Sub_De > 65) iTemp_Sub_De--; else iTemp_Sub_De = 90; fprintf(fp_Sub_De,"%c>",iTemp_Sub_De); } // Make the character to the Cipher Text

*szCipher_Sub_De=iTemp_Sub_De; fprintf(fp_Sub_De,"\n"); } // Lower Case character else if (((int)(*szPlainTxt_Sub_De) >= 97) && ((int)(*szPlainTxt_Sub_De) <= 122)) { // Get the Ascii value of the character iTemp_Sub_De = *szPlainTxt_Sub_De; iTemp1_Sub_De = iTemp_Sub_De; // Write the character to the Output file

fprintf(fp_Sub_De,"%c>",iTemp_Sub_De); // Make the Substitution upto iKey_Sub_De times

for(iloop1_Sub_De=1;iloop1_Sub_De<=iKey_Sub_De;iloop1_Sub_De++) { if (iTemp_Sub_De > 97) iTemp_Sub_De--; else iTemp_Sub_De = 122; fprintf(fp_Sub_De,"%c>",iTemp_Sub_De); } // Make the character to the Cipher Text *szCipher_Sub_De=iTemp_Sub_De; fprintf(fp_Sub_De,"\n"); } else {/*No case*/} // Increment the Position of the Cipher Text and the PlainText szPlainTxt_Sub_De++; szCipher_Sub_De++; } szCipher_Sub_De--; *szCipher_Sub_De='\0'; szCipher_Sub_De=szTemp1_Sub_De; fclose(fp_Sub_De); /////* User code part end */ }

107


Select Encryption and then provide the Cipher text and Key text. Click Run.

So presently NetSim will run Encryption code which is written by the user and will display



Perform the similar steps for decryption.

NOTE: Please insert the correct code according to the algorithm selected. The codes for other

algorithm are provided in NetSim Installation CD.



below.






without NetSim.



Input.txt file contents- For Encryption:

Cryptographic_Technique=Substitution

Cryptographic_Method=Encryption

Plain_Text:

NetSim

Key_Text:

1

108


N>O>

e>f>

t>u>

S>T>

i>j>

m>n>


Input.txt file contents- For Decryption:

Cryptographic_Technique=Substitution

Cryptographic_Method=Decryption

Cipher_Text:

OfuTjn

Key_Text:

1


O>N>

f>e>

u>t>

T>S>

j>i>

n>m>


109

Appendix 1: Programming exercise -How to

practice without NetSim

Step 1: Copy Interface Source Code

Click on Interface Source Code and save the code in a text file.

For Example:

As an example, Shortest Path programming

exercise is being considered.

Open the programming exercise and select

Interface Source Code.

Save the Interface source code in another txt

file.

Step 2: Create Input.txt file

Create a new text file with the name Input.txt.

The contents of the file will vary for each programming exercises and are specified in NetSim

User Manual under programming topic.

110

For Example: Copy the input file contents from NetSim user manual and save it in a file

called Input.txt

Sample:

Algorithm=Link_State

No_of_Router=3

Distance:

999>6>5>

6>999>7>

5>7>999>

Source_Router=1

Destination_Router=2

Save it in some other location. In this example, it is saved at D:\New.

Step 3: Create .exe file

Open C editor (Turbo C, Dev C++, etc) and write the Interface source code which was saved

in the first text file. Also add the code to be written by the user in the specific sections and

compile it. Keep the .exe file.

For Example:

Now in C editor (Dev C++ IDE is used here), copy the interface source code. In the interface

source code, void fnDijkstra() is not implemented.

111

After writing the code for the function void fnDijkstra(), create .exe file. The procedure to

create .exe file is explained in Section 9.2 of NetSim User Manual.

In this example, the exe file created is LinkState.exe

Step 4: Run in command prompt

Open command prompt, and go to the folder where the .exe file is saved.

There type

<EXE Name> “<blank>“ “<Path where Input.txt is saved>”;

For Example:

In this example, the exe file LinkState.exe and Input.txt is present at “D:\New”. So in

command prompt go to the folder where exe file is saved.

112

NOTE: For Chat programming exercise (Experiment 6), type

For Sender: <EXE Name> “<blank>“ “<Path where Input.txt is saved>” “send”

For Receiver: <EXE Name> “<blank>“ “<Path where Input.txt is saved>” “receive”

Step 5: Check the output.txt file

After running in the command prompt, Output.txt file will be created at the same location

where Input.txt file is saved. User can compare and check the content of Output.txt file with

the NetSim user manual.

For Example: Here according to this example, the Output.txt file will be created at

“D:\New” folder. User can open the file and compare the content with NetSim user manual

Output.txt content.

113

Appendix 2: Creating .exe file using Dev C++

1. Open the C source code file in Dev C++. Then go to Execute Compile.

Dev C++ will create the exe file in the same location where the C source code file is

located

2. Once exe file is created , link that exe file with NetSim Programming User mode

Note: For Windows 8 and above, use Dev C++ v 5.11

Note: For Windows Vista, set up Dev C++ as shown below

In Dev C++ 4.9.9.2.exe, go to Tools->Compiler Options->Directories tab->Binaries tab

Add the following path as per your installation directory in the text box provided and click on

add button.

C:\Dev-Cpp\libexec\gcc\mingw32\3.4.2

114

In the C Includes tab add the follwing path in the text box provided and click on add button.

C:\Dev-Cpp\lib\gcc\mingw32\3.4.2\include

In the programs tab edit the following paths as shown in screenshot.

115

Technology

Anna University Netsim Experiment Manual