Google Code-in

‘examples/tutorial/fifth.cc’ is a simple example that explains how to plot a TCP congestion window in ns-3. In this task, the objective is to compare the congestion window plots of two TCP variants - TCP Vegas and TCP BIC.

The steps given below should be followed to complete the task:

1. Copy fifth.cc from examples/tutorial and paste it in the scratch directory.
2. Modify the ‘examples/tutorial/fifth.cc’ program to enable TCP Vegas. You may use ‘examples/tcp/tcp-variants-comparison.cc’ as a reference.
3. Run the modified fifth.cc and plot the congestion window for TCP Vegas.
4. Repeat steps ‘B’ and ‘C’ for TCP BIC.
5. Combine both the congestion window plots to produce a single graph.
6. Use gnuplot to plot the data file. The resultant graph should be as specified:
7. Format of the graph: .png
8. Name of the image: cwnd.png
9. X-axis label: Time (in seconds)
10. Y-axis label: cwnd (in Bytes)
11. Title of the graph: Congestion Window Plot.
12. Position of the key: outside and top right corner.
13. Graph of TCP Vegas: Black dashed lines (type 2).
14. Graph of TCP BIC: Black dotted lines (type 3).
15. Send the image for evaluation.