Laboratory 5 - Ethernet LAN Simulation


Objectives

  1. Learn to use the OpNet network simulator to simulate an Ethernet network
  2. Gain more experience with the use of OpNet and its device and network models
  3. Gain a better feeling for how a shared media network like Ethernet behaves under different loads and traffic patterns

Preparation

This week, you will be doing another lab using the OpNet simulater - this one simulates a common shared-media LAN, an Ethernet.

This lab is using an experiment from the lab manual that accompanies the class textbook. The book is Network Simulation Experiments Manual by Emad Aboelela (see the Amazon listing for more information). I have a copy of the book, and the entire contents are available in PDF form for download at no cost to anyone who bought a new copy of the Computer Networks textbook by Peterson and Davie. Also, the EE 543 class is using the same lab manual and they have downloaded these experiments, so we will use them. You will be doing experiment 1, Ethernet.

In Lab Activities

Boot your machine up in Windows - things should go more smoothly this week. Log in and start OpNet. You might want to double-check some settings first:

  1. Open the Preferences page from the Edit menu.
  2. Enter "license" into the Find box; it should show you a list of the license-related settings.
  3. Make sure that license_server is set to localhost.
  4. Set license_server_standalone to TRUE.
  5. Go back to the Find box and enter "mod".
  6. Check the mod_dirs setting. This is a list of the directories where OpNet will look for models to use in simulations; it's similar to the PATH in Linux. The first directory in the list is where your models will be saved; make sure that this is a subdirectory under Z:\ and use Windows Explorer to make sure that directory exists.
  7. Click OK.

Open the Ethernet experiment in a browser and follow the instructions.

NOTE: the first instructions, under the Startup Wizard: Initial Topology is missing a step. After you select the X Span and Y Span and click Next, you are in the Select Technologies dialog. You need to find the ethcoax model family and change the Include to "Yes".

You should end up with the graph of traffic received vs. traffic sent - capture this graph to put in your lab report. Once you have completed the experiment, do the questions at the end. These involve creating additional scenarios, rerunning the simulation, and graphing some network statistics. Capture each graph for inclusion in your lab report.

This lab is similar to the tutorial - the experiment has a step-by-step process to follow. Unlike the tutorial, you get a chance to see how to set up the parameters of the simulation, like the settings that control the traffic load on the network. Try to figure out what the graphs look like - if you miss setting a parameter somewhere, the simulation results might be a lot different than what you expect. Also, OpNet might occasionally do some things incorrectly; in particular, if you select all of the workstations on the LAN and set a parameter for them, even if you check the Apply Changes to Selected Objects, it appears that it might not always do it. So if your results are looking a little odd, re-read the experiment, then double-check the parameters to make sure they got set correctly.

Lab Report

Your lab report should include the following information:

Make sure that you are following Anthony's submission guidelines. Write up a reasonable lab report. As you discovered last week, you'll need to save the report as a PDF file so it is a reasonable size.

The lab write-up is due by the end of the day Wednesday (i.e. 11:59 PM) for the Tuesday lab section and by the end of the day Friday for the Thursday lab section.