Riverbed Modeler

Project Lab Two

Introduction to REVERBED MODELER

Overview

This lab teaches the basics of using REVERBED MODELER Modeler Academic Edition 17.5. REVERBED MODELER’s user-friendly interface with drag-and-drop features enable students to effectively model, manage and troubleshoot real-world network infrastructures.

In this lab, the student will learn to create a new project and get familiar with the project editor. The student will learn to create different scenarios and learn to simulate and capare results for different scenarios.

In a shared Ethernet network, end systems are typically connected together using a hub. The hub retransmits any incoming frames on all outgoing lines creating a single broadcast domain for all the devices. Within this domain, the Carrier Sense Multiple Access with Collision Detection (CSMA/CD) MAC protocol is used to determine which node may transmit at any given time and to resolve collisions if two or more nodes transmit at the same time.

REVERBED MODELER provides a Virtual Network Environment that models the behaviour of networks, including its routers, switches, protocols, servers, and individual applications. The Virtual Network Environment allows IT managers, network and system planners, and operation’s staff to more effectively diagnose difficult problems, validate changes before they are implemented, and plan for future scenarios such as traffic growth and network failures.

You can do “what if” analyses (called scenarios in REVERBED MODELER) on network designs, just as you can on spreadsheets with financial business models. However, instead of looking at “bottom line” financial numbers, you will be looking at how response times, latency (delays) and other network performance measures will change under different network design approaches.

To create a network simulation (called a project in REVERBED MODELER), you specify the nodes (computers, switches, routers, etc.) in your network, the links between nodes, and the applications that will be running on the nodes.
In this lab you will learn to determine the throughput of a shared Ethernet network under load.

Lab Instructions

Step 1: Design and Configure the basic network

REVERBED MODELER consists of projects and scenarios. Scenarios may contain different versions of the same network or models of different networks. A project consists of one or more network scenarios. In this lab, you will create 2 different scenarios comparing application performance with different connection speeds.

1. Click Start → Reverbed modeler Academic Edition 17.5 → Reverbed modeler Academic Edition 17.5 NOTE: it will take some time to load. DO NOT PRESS IT AGAIN
2. You will see the license agreement – Click “I have read this SOFTWARE AGREEMENT …” to Accept it
3. You will now see the modeller.

4. To create a new project click on File → New. You will see the following dialog box.

5. Select Project and Press ok.
6. You project editor workspace will open now. Enter project name as Shared_Enernet and change scenario name to “slow_Load”

7. From the next dialog box, select “Create empty scenario” and press Next

8. From the next dialog box, select “Office” and press Next

9. Don’t change the size, just press Next.

10. In the Select Technologies window, scroll down and include the ethernet and links model families, and click on Next.

11. The setup is complete. Press Finish

12. You will now be able to see the object palette and the Project workspace. You can click-and-hold the blue colour header of them to move/arrange them to new location

13. First, we will build a LAN in which the workstations are connected together with an Ethernet hub. An easy way to create a network with a large number of nodes in Reverbed Modeler is to use the Rapid Configuration tool. Select the Topology tab => Rapid Configuration.

14. Set the Configuration to Star and click on Next. Set the Center Node Model to ethernet16_hub. Set the Periphery Node Model to ethernet_station. Set the Link Model to lOBaseT. Set the Number to 12, and click on OK to create the LAN.

15. Right click on the hub (the device at the center of the star) and choose View Node Description from the drop down menu. This device can support up to 16 Ethernet links at 10, 100, or 1000 Mbps. Note that the processing time within the device is considered to be zero, and that the hub retransmits incoming frames on all outgoing lines. Click on the close window icon to close the window. Right click on the hub and select Set Name. Set the Name to Hub. Click on OK to close the window.

Right click on one of the Ethernet stations and choose View Node Description from the drop down menu. This device generates and receives Ethernet frames at configurable rates. Note that collision detection and resolution is handled by the hub. Click on the close window icon to close the window.

16. Now we need to set up the traffic patterns for the Ethernet stations. Right click on any of the stations and choose Select Similar Nodes from the drop down menu. Next, right click on one of the stations and choose Edit Attributes. Put a check in the checkbox next to Apply Changes to Selected Objects.

17. Expand the Traffic Generation Parameters and Packet Generation Arguments attributes. Set the ON State Time to constant(1000), and the OFF State Time to constant(0). This will ensure that the stations are always sending.
18. Set the Interarrival Time (seconds) to exponential(0.004) and the Packet Size (bytes) to constant(100). Click on OK to apply the changes and close the window. Each station will now generate traffic at an average rate of one 100-byte packet every 4 milliseconds.

19. You can calculate the average traffic that each node will generate from the interarrival time and the packet size. For instance, 100 bytes/packet * 8 bits/byte * 1 packet/0.004 sec = 200 Kbps

20. We are now done building the LAN model. Now we Configure the Simulation.
21. Select the DES tab => Choose Individual Statistics.

22. Expand the Global Statistics item by click on the + sign, and the Ethernet item, and select the Delay (sec) statistic. Expand the Traffic Sink item and select the Traffic Received (bits/sec) statistic. Expand the Traffic Source item and select the Traffic Sent (bits/sec) statistic.

23. Expand the Node Statistics item and the Ethernet item. and select the Collision Count, Load (bits/sec), Traffic Forwarded (bits/sec), Traffic Received (bits/sec), and Utilization statistics.

24. Click on OK to close the window.
25. Select DES => Configure/Run Discrete Event Simulation …
26. Set the Duration to 20 and the unit to second(s).
27. Click on Apply and then close the window by click on X.
28. Now Duplicate the Scenario “Low_Load”. Let us build another scenario in which each Ethernet station generates much more traffic. This will allow us to compare the performance of the LAN under different conditions.
29. Choose Scenarios => Duplicate Scenario and name the new scenario High_Load. Click on OK to create the scenario. Now the simulation project has two scenarios.

30. Keep your project at the High_Load scenario. Right click on any of the stations and choose Select Similar Nodes. Next, right click on one of the stations and choose Edit Attributes. Put a check in the checkbox next to Apply Changes to Selected Objects. Expand the Traffic Generation Parameters and Packet Generation Arguments attributes. Set the Interarrival Time (seconds) to exponential(0.0001). Click on OK to apply the changes and close the window. Note that a shorter interarrival time means that packets will be generated more frequently.

31. Now we can run the simulation.
32. Select the Scenarios tab => Manage Scenarios…
33. Edit the Results field in both rows and set the values to <collect> or <recollect>.
34. Click on OK to run both scenarios (one after the other).

35. When the simulation has completed, click on Close to close the window.
36. Next, Inspect and Analyze the simulation Results

37. Select the Scenarios tab=> Switch to Scenario and choose the Low_Load scenario. Select the Results tab => View Results…
38. Select and expand the Global Statistics item and the Traffic Source item. Next, select the Traffic Sent (bits/sec) statistic. Also, expand the Traffic Sink item and select the Traffic Received (bits/sec) statistic.

View all statistics in this lab exercise using As Is mode. For this level of load, the received bit rate is approximately equal to the sent bit rate. Click on the Traffic Sent (bits/sec) and Traffic Received (bits/sec) statistics again to disable the preview. Note that you may always click on Show for a more detailed graph than the preview provides. Click on Close to close the View Results window.

Last Updated on February 11, 2019 by Essay Pro