Implement the data link layer framing methods such as character stuffing.

Implement the data link layer framing methods such as character stuffing.

Introduction to character stuffing method of framing for Data Link Layer: The framing method gets around the problem of resynchronization after an error by having each frame start with the ASCII character sequence DLE STX and the sequence DLE ETX. If the destination ever losses the track of the frame boundaries all it has to do is look for DLE STX or DLE ETX characters to figure out. The data link layer on the receiving end removes the DLE before the data are given to the network layer. This technique is called character stuffing.

Program Algorithm:

Begin

Step 1: Initialize I and j as 0

Step 2: Declare n and pos as integer and a[20],b[50],ch as character

Step 3: read the string a

Step 4: find the length of the string n, i.e n-strlen(a)

Step 5: read the position, pos

Step 6: if pos > n then

Step 7: print invalid position and read again the position, pos

Step 8: endif

Step 9: read the character, ch

Step 10: Initialize the array b, b[0…5] as ’d’, ’l’, ’e’, ’s’, ’t’,’x’ respectively

Step 11: j=6;

Step 12: Repeat step[(13to22) until i<n

Step 13: if i==pos-1 then

Step 14: initialize b array,b[j],b[j+1]…b[j+6] as‘d’, ‘l’, ‘e’ ,’ch, ’d’, ‘l’,‘e’ respectively

Step 15: increment j by 7, i.e j=j+7

Step 16: endif

Step 17: if a[i]==’d’ and a[i+1]==’l’ and a[i+2]==’e’ then

Step 18: initialize array b, b[13…15]=’d’, ‘l’, ‘e’ respectively

Step 19: increment j by 3, i.e j=j+3

Step 20: endif

Step 21: b[j]=a[i]

Step 22: increment I and j;

Step 23: initialize b array,b[j],b[j+1]…b[j+6] as‘d’, ‘l’,‘e’,’e’,‘t’, ‘x’,‘\0’ respectively

Step 24: print frame after stuffing

Step 25: print b

End

Program Code: //Program for Character Stuffing

#include<stdio.h>

#include<string.h>

#include<process.h>

void main()

{

int i=0,j=0,n,pos;

char a[20],b[50],ch;

printf("Enter string\n");

scanf("%s",&a);

n=strlen(a);

printf("Enter position\n");

scanf("%d",&pos);

if(pos>n)

{

printf("invalid position, Enter again :");

scanf("%d",&pos);}

printf("Enter the character\n");

ch=getche();

b[0]='d';

b[1]='l';

b[2]='e';

b[3]='s';

b[4]='t';

b[5]='x';

j=6;

while(i<n)

{

if(i==pos-1)

{

b[j]='d';

b[j+1]='l';

b[j+2]='e';

b[j+3]=ch;

b[j+4]='d';

b[j+5]='l';

b[j+6]='e';

j=j+7;

}

if(a[i]=='d' && a[i+1]=='l' && a[i+2]=='e')

{

b[j]='d';

b[j+1]='l';

b[j+2]='e';

j=j+3;

}

b[j]=a[i];

i++;

j++;

}

b[j]='d';

b[j+1]='l';

b[j+2]='e';

b[j+3]='e';

b[j+4]='t';

b[j+5]='x';

b[j+6]='\0';

printf("\nframe after stuffing:\n");

printf("%s",b);

}

Program Output:

Enter string

MLRITM

Enter position

2

Enter the character

frame after stuffing:

dlestxMdldleLRITMdleetx

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(program exited with code: 0) Press return to continue