Simulate and implement go back n sliding window protocol.

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# include <iostream>
# include <conio.h>
# include <stdlib.h>
# include <time.h>
# include <math.h>
# define TOT_FRAMES 500
# define FRAMES_SEND 10
using namespace std;

class gobkn
{
private:
int fr_send_at_instance;
int arr[TOT_FRAMES];
int arr1[FRAMES_SEND];
int sw;
int rw;
public:

gobkn();
void input();
void sender(int);
void reciever(int);

};

gobkn :: gobkn()
{
sw = 0;
rw = 0;
}

void gobkn :: input()
{
int n;
int m;
cout << "Enter the no of bits for the
sequence no ";
cin >> n;
m = pow (2 , n);
int t = 0;
fr_send_at_instance = (m / 2);

for (int i = 0 ; i < TOT_FRAMES ; i++)
{
arr[i] = t;
t = (t + 1) % m;
}

sender(m);
}

void gobkn :: sender(int m)
{
int j = 0;

for (int i=sw ; i<sw+fr_send_at_instance ; i
++)
{
arr1[j] = arr[i];

j++;

}

for (int i = 0 ; i < j ; i++)
cout << " SENDER : Frame " << arr1[i] <<
" is sent\n";
reciever (m);
}

void gobkn :: reciever(int m)
{
time_t t;
int f;
int f1;
int a1;
char ch;

srand((unsigned) time(&t));
f = rand() % 10;
if (f != 5)
{
for (int i = 0 ; i < fr_send_at_instance ; i

++)
{
if (rw == arr1[i])
{
cout << "RECIEVER : Frame " <<

arr1[i] << " recieved correctly\n";

rw = (rw + 1) % m;

}
else
cout << "RECIEVER : Duplicate

frame " << arr1[i] << " discarded\n";

}
a1 = rand() % 15;
if (a1 >= 0 && a1 <= 3)
{
cout << "(Acknowledgement " <<

arr1[a1] << " & all after this lost)\n";

sw = arr1[a1];
}
else
sw = (sw + fr_send_at_instance) %

m;
}
else
{
f1 = rand() % fr_send_at_instance;
for (int i = 0 ; i < f1 ; i++)
{
if (rw == arr1[i])
{
cout << " RECIEVER : Frame " <<

arr1[i] << " recieved correctly\n";

rw = (rw + 1) % m;
}
else
cout << " RECIEVER : Duplicate

frame " << arr1[i] << " discarded\n";
}
int ld = rand() % 2;
if (ld == 0)

cout << " RECIEVER : Frame " <<

arr1[f1] << " damaged\n";
else

cout << " (Frame " << arr1[f1] <<

" lost)\n";

for (int i = f1 + 1 ; i <
fr_send_at_instance ; i++)

cout << " RECIEVER : Frame " << arr1[i]

<< " discarded\n";
cout << " (SENDER TIMEOUTS -->
RESEND THE FRAME)\n";
sw = arr1[f1];
}
cout << "Want to continue...";
cin >> ch;

if (ch ==

'y')
sender(m);
else
exit(0);
}

int main()
{

gobkn gb;
gb.input();
getch();
return 0;
}

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Output:-