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Stop-n-Wait vs. Sliding-Window

1. Background

To compare the efficiencies of "stop-n-wait" and "sliding-window", I built a virtual network environment with 6 nodes and 2 traffic models which are 1 CBR, and 1 each aimed protocol, and run both protocols in the same condition such as queue limit, bandwidth, delay, etc. I compared two protocols in two different situation; one is in normal condition which means there is no packet loss ; the other is in congested condition which means there are some packet loss. To see parameter values, please refer to the ns scripts which attached below.

2. How these 2 protocols work in normal condition..?

1. stop-n-wait protocol 2. sliding window protocol ( window size = 4 )

Black packet is for "stop-n-wait" traffic while red packets are for CBR traffic.
Black packets are for "sliding window" traffic while red packets are for CBR traffic.

With nam graph, we could see the total packets and ACKs sent and received. In "stop-n-wait", totally 5 packets are transmitted successfully.
With nam graph, we could see the total packets and ACKs sent and received. In "sliding window", totally 19 packets are transmitted successfully.

Here is ns script for the above simulation.
You can also download ns script and nam file. Here is ns script for the above simulation.
You can also download ns script and nam file.

3. How these 2 protocols work in congested condition..?

stop-n-wait hardly be congested ! Followings show that even in congested condition, sliding window has better performance.

1. stop-n-wait protocol 2. sliding window protocol ( window size = 8 )

Black packet is for "stop-n-wait" traffic while red packets are for CBR traffic.
Black packets are for "sliding window" traffic while red packets are for CBR traffic.

In "stop-n-wait", totally 7 packets are transmitted successfully.
In "sliding window", totally 17 packets are transmitted successfully even in congested condition.

Here is ns script for the above simulation.
You can also download ns script and nam file. Here is ns script for the above simulation.
You can also download ns script and nam file.

4. Result

As "sliding window" doesn't waste network bandwidth compared with "stop-n-wait", both in normal and in congested condition, "sliding window" show better performance than "stop-n-wait".

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1. stop-n-wait protocol	2. sliding window protocol ( window size = 4 )
Black packet is for "stop-n-wait" traffic while red packets are for CBR traffic.	Black packets are for "sliding window" traffic while red packets are for CBR traffic.
With nam graph, we could see the total packets and ACKs sent and received. In "stop-n-wait", totally 5 packets are transmitted successfully.	With nam graph, we could see the total packets and ACKs sent and received. In "sliding window", totally 19 packets are transmitted successfully.
Here is ns script for the above simulation. You can also download ns script and nam file.	Here is ns script for the above simulation. You can also download ns script and nam file.