Assignment 7

                   CS594-ipp05  revised: 10/14/05

Assigned: 10/20/05
Due: 6:00pm 10/28/05 

Objective:  ns familiarity

Points: 22

Description:


  To run ns (and xgraph and nam) on the CS linuux lab machines (cetus/hyrdra)
you'll need to add some things to your path and environment, 
    see ~dunigan/ipp05/ns/README

1. Modify the finish procedure in ~dunigan/ipp05/ns/ns-simple.tcl to report
   the final data rate of the simulation and the number of packets 
   retransmitted.
	a) run the script and report bandwidth and retransmits (Tahoe)
        b) modify the TCP/Agent to be Reno and run the script and report
            bandwidth and retransmits 
	c) modify the TCP/Agent to be Newreno and run the script and report 
            bandwidth and retransmits   
	d)  modify the TCP/Agent to be  Sack1 (you must also modify the Sink to
	    be Agent/TCPSink/Sack1)  and run the script and report
            bandwidth and retransmits
	e)  explain the relative difference in performance of the 4 tests above
    You can comment out the nam stuff in the finish procedure if it annoys you.

2.  Add a "record" procedure to ns-simple.tcl  to write out the
    current simulation time (e.g., set now [$ns now] ) and
    cwnd value (e.g. [$tcp set cwnd_]) to a file every 0.1 seconds.
    plot the cwnd files on one graph for the 4 test cases in 1 above.
    Submit a gif/png/jpg/ps/pdf file with your tcl
    Use your favorite plotting program, or xgraph, or gnuplot.
    For gnuplot template see ~dunigan/ipp05/ns/sample.plot

3. generate the Tcl for the nodes and duplex-links for the network
   topology shown in the text Figure 11.3.   (It doesn't need to be
   a runnable ns tcl script, just Tcl for the topology).



 paste all of you results into an ANSWERS file that you submit with your
 plot file (gif/png/jpg/ps/pdf) and documented tcl source code.
 Put all of your files in a directory and then "cd"
 into that directory and from one of the lab machines use ~cs594ipp/594submit
 Protect your directory with "chmod" so others can't profit from your work.