Due: See class webpage.

1. Comparing different TCP protocols

In this project we will use the ns-2 network simulator to evaluate variants of TCP and see the effect mixing different TCP protocols.

We will evaluate the following flavors of TCP:

• Reno
• Vegas

on the given network topologies.

2. Simulation Network

Use the following network topology in the simulation:

There is an FTP/TCP flow from A1 to D1 and another from A2 to D2.

Note that the propagation delay from A1 to D1 is almost twice as large as the propagation delay from A2 to D2.

Use packet length of 1250 bytes.

Set the window_ variable for all TCP agents to 100000 to ensure that the receiver window size does not become a bottleneck.

3. Simulation Scenarios

Simulate the following scenarios:
1. Both the flows: A1->D1, A2->D2 use TCP "Reno".
   Both the flows start at time t=0s.
   Run the simulation for 500s.

   Plot the congestion windows (0.1 sec increment) for both the flows as a function of time on the same graph.

   Plot the throughput (1 sec increment) for both the flows as a function of time on the same graph.

   Compute the average throughput for each flow and enter in a provided answer HTML page.

2. Repeat the simulation experiment in part (1) with both flows using TCP "Vegas".

3. Repeat the simulation experiment in part (1) with flow A1 -> D1 using TCP "Reno" and flow A2 -> D2 using TCP "Vegas"

4. Repeat the simulation experiment in part (1) with flow A1 -> D1 using TCP "Vegas" and flow A2 -> D2 using TCP "Reno"

4. The NS Simulation Program

The NS program should be named hw5.tcl and must accept 2 input parameters:

ns hw5.tcl TCP-TYPE-1 TCP-TYPE-2

You can obtain the parameter TCP-TYPE-1 with

set param1 [lindex $argv 0]

and the parameter TCP-TYPE-2 with

set param2 [lindex $argv 1]

Use the following command to create a TCP agent of type TCP-TYPE-1 and a TCP agent of type TCP-TYPE-2:

set tcp1 [new Agent/TCP/$param1] set tcp2 [new Agent/TCP/$param2]

Connect the tcp1 to node A1 and its sink to node D1. Connect the tcp2 to node A2 and its sink to node D2. This way, you don't need to write 4 seperate NS programs and you can run the 4 different experiment using the following 4 commands:

Experiment 1: ns hw5.tcl Reno Reno Experiment 2: ns hw5.tcl Vegas Vegas Experiment 3: ns hw5.tcl Reno Vegas Experiment 4: ns hw5.tcl Vegas Reno

5. Programming Note

Due to file size restrictions enforced by ITD on students accounts, you need to open the trace files as follows:

[open "| grep r > out.tr" w]

instead of the "traditional" way: [open "out.tr" w]

The "grep" command will filter out the "r" line (receive events) which are the only lines in the trace file that is useful in computing the throughput. This way, you generate a lot less output data.

6. Turn in

• Get a copy of this asnwer HTML page and save it as: ~/cs558/hw5/hw5-ans.html: RIGHT click and SAVE

  You must fill in the throughput values for each of the flows.

  You must make the following plots:

  • Reno-CWND.gif: CWND plot of 2 Reno flows
  • Reno-TPut.gif: Throughput plot of 2 Reno flows

  • Vegas-CWND.gif: CWND plot of 2 Vegas flows
  • Vegas-TPut.gif: Throughput plot of 2 Vegas flows

  • LongVegas-CWND.gif: CWND plot of Long Vegas and Short Reno flow
  • LongVegas-TPut.gif: Throughput plot of Long Vegas and Short Reno flow

  • ShortVegas-CWND.gif: CWND plot of Short Vegas and Long Reno flow
  • ShortVegas-TPut.gif: Throughput plot Short Vegas and Long Reno flow

  Make sure your answer webpage is viewable using the following URL:

  file:///home/YOURID/cs558/hw5/hw5-ans.html

• Turn in a copy of your hw5.tcl NS program using the command:

  /home/cs558000/turnin hw5.tcl hw5