OPEN SHORTEST PATH FIRST PROTOCOL

PROGRAM:

#iinclude<stdio.h>

#include<string.h>

int main()

{

int count,src_router,i,j,k,w,v,min;

int cost_matrix[100][100],dist[100],last[100];

int flag[100];

printf("\n Enter the no of routers");

scanf("%d",&count);

printf("\n Enter the cost matrix values:");

for(i=0;i<count;i++)

{

for(j=0;j<count;j++)

{

printf("\n%d->%d:",i,j);

scanf("%d",&cost_matrix[i][j]);

if(cost_matrix[i][j]<0)

cost_matrix[i][j]=1000;

}

}

printf("\n Enter the source router:");

scanf("%d",&src_router);

for(v=0;v<count;v++)

{

flag[v]=0;

last[v]=src_router;

dist[v]=cost_matrix[src_router][v];

}

flag[src_router]=1;

for(i=0;i<count;i++)

{

min=1000;

for(w=0;w<count;w++)

{

if(!flag[w])

if(dist[w]<min){

v=w;

min=dist[w];

}

}

flag[v]=1;

for(w=0;w<count;w++)

{

if(!flag[w])

if(min+cost_matrix[v][w]<dist[w])

{

dist[w]=min+cost_matrix[v][w];

last[w]=v;

}

}

}

for(i=0;i<count;i++)

{

printf("\n%d==>%d:Path taken:%d",src_router,i,i);

w=i;

while(w!=src_router)

{

printf("\n<--%d",last[w]);

w=last[w];

}

printf("\n Shortest path cost:%d",dist[i]);

}

}

  

  

OUTPUT:

"open.c" 65L, 1011C written

[ME04@TELNET ~]$ cc open.c

[ME04@TELNET ~]$ ./a.out

 Enter the no of routers 4

 Enter the cost matrix values:

0->0:1

0->1:4

0->2:6

0->3:8

1->0:4

1->1:6

1->2:5

1->3:9

2->0:1

2->1:3

2->2:2

2->3:0

3->0:4

3->1:2

3->2:6

3->3:8

 Enter the source router:3

3==>0:Path taken:0

<--3

 Shortest path cost:4

3==>1:Path taken:1

<--3

 Shortest path cost:2

3==>2:Path taken:2

<--3

 Shortest path cost:6

3==>3:Path taken:3

 Shortest path cost:8