Sliding Window Protocol Program in C and C++

Here you will get sliding window protocol program in C.

In computer networks sliding window protocol is a method to transmit data on a network. Sliding window protocol is applied on the Data Link Layer of OSI model. At data link layer data is in the form of frames. In Networking, Window simply means a buffer which has data frames that needs to be transmitted.

Both sender and receiver agrees on some window size. If window size=w then after sending w frames sender waits for the acknowledgement (ack) of the first frame.

As soon as sender receives the acknowledgement of a frame it is replaced by the next frames to be transmitted by the sender. If receiver sends a collective or cumulative acknowledgement to sender then it understands that more than one frames are properly received, for eg:- if ack of frame 3 is received it understands that frame 1 and frame 2 are received properly.

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In sliding window protocol the receiver has to have some memory to compensate any loss in transmission or if the frames are received unordered.

Efficiency of Sliding Window Protocol

η = (W*t_x)/(t_x+2t_p)

W = Window Size

t_x = Transmission time

t_p = Propagation delay

Sliding window works in full duplex mode

It is of two types:-

1. Selective Repeat: Sender transmits only that frame which is erroneous or is lost.

2. Go back n: Sender transmits all frames present in the window that occurs after the error bit including error bit also.

Sliding Window Protocol Program in C

Below is the simulation of sliding window protocol in C.

#include<stdio.h>

int main()
{
    int w,i,f,frames[50];

    printf("Enter window size: ");
    scanf("%d",&w);

    printf("\nEnter number of frames to transmit: ");
    scanf("%d",&f);

    printf("\nEnter %d frames: ",f);

    for(i=1;i<=f;i++)
        scanf("%d",&frames[i]);

    printf("\nWith sliding window protocol the frames will be sent in the following manner (assuming no corruption of frames)\n\n");
    printf("After sending %d frames at each stage sender waits for acknowledgement sent by the receiver\n\n",w);

    for(i=1;i<=f;i++)
    {
        if(i%w==0)
        {
            printf("%d\n",frames[i]);
            printf("Acknowledgement of above frames sent is received by sender\n\n");
        }
        else
            printf("%d ",frames[i]);
    }

    if(f%w!=0)
        printf("\nAcknowledgement of above frames sent is received by sender\n");

    return 0;
}

Output

Enter window size: 3

Enter number of frames to transmit: 5

Enter 5 frames: 12 5 89 4 6

With sliding window protocol the frames will be sent in the following manner (assuming no corruption of frames)

After sending 3 frames at each stage sender waits for acknowledgement sent by the receiver

12 5 89
Acknowledgement of above frames sent is received by sender

4 6
Acknowledgement of above frames sent is received by sender

Sliding Window Protocol Program in C++

Below is the simulation of sliding window protocol in C++.

#include<iostream>

using namespace std;

int main()
{
    int w,i,f,frames[50];

    cout<<"Enter window size: ";
    cin>>w;

    cout<<"\nEnter number of frames to transmit: ";
    cin>>f;

    cout<<"\nEnter "<<f<<" frames: ";

    for(i=1;i<=f;i++)
        cin>>frames[i];

    cout<<"\nWith sliding window protocol the frames will be sent in the following manner (assuming no corruption of frames)\n\n";
    cout<<"After sending "<<w<<" frames at each stage sender waits for acknowledgement sent by the receiver\n\n";

    for(i=1;i<=f;i++)
    {
        if(i%w==0)
        {
            cout<<frames[i]<<"\n";
            cout<<"Acknowledgement of above frames sent is received by sender\n\n";
        }
        else
            cout<<frames[i]<<" ";
    }

    if(f%w!=0)
        cout<<"\nAcknowledgement of above frames sent is received by sender\n";

    return 0;
}

Comment below if you have any queries regarding above program.