Student Name _________________________________  Date _____________

SEC450Wireless Roaming iLab

 

Objectives

In this lab, the students will examine the following objectives.

 

• The use of discrete event simulation with wireless nodes and wireless access points
• Examine the effect of spacing between wireless access points (WAPs) and network users and the ability to access network resources.

 

Scenario

A small company is using the topology shown below. The wireless nodes labeled station A1 through station A5 need to access the server labeled Server for A Group. The wireless nodes labeled station B1 through station B3 need to access the server labeled Server for B Group. We need to evaluate the distance requirements for the wireless nodes to be able to communicate with their preferred server.

 

Topology

 

The last page of the lab assignment document contains a full-page topology. Remove this page and use it for reference to the topology and the IP addresses.

 

Lab Procedure

 

The Week 4 iLab is entitled Wireless Roaming. The following steps show how to create the project required for the Week 4 iLab.

 

• Log into the Citrix iLab Environment (lab.devry.edu).
• Click on the OpNet Modeler icon.

 

• Click File/Open  and navigate to the F:op_modelsSEC450SEC450_WLAN.projectSEC450_WLAN file and click Open.
• In OpNet Modeler 175 with the SEC450 project open, click File/Save As.

• Save the project in the F:op_modelsSEC450 directory as WLAN_Testing.

 

 

You are now ready to begin the Wireless Roaming iLab with a project calledWLAN_Testing.

 

Initial Configuration

Both servers are associated with the Group B WAP so only the group B stations can access their server. Group A cannot access their server until they get in range to associate with the Group B WAP. Roaming functionality is enabled on the A and B stations so that they can connect to a betterWAP when the connection quality with their current WAP goes below the acceptable level.During the simulation, the Group A stations will be moved within range of the Group B WAP and then beyond the range of theGroup B WAP.

 

Preparation

Download and open the SEC450_W4_WirelessRoaming_Report.docx lab report document. This lab report document must contain all relevant configuration information, log reports, and captured screen shots as specified in the iLab assignment. All questions asked in the lab must also be answered. Your instructor will advise you of the process for submitting this assignment.

 

Note: RED text indicates the required capture of commands or windows from the OpNet program into your lab document. All completed tables and answered questions in the lab assignment must be transferred to your submitted lab document.

Task 1—Configure DES Global and Node Statistics

• Right-click on empty area of the topology window and select Choose Individual DES Statistics.

• Under Global Statistics->Wireless LAN, select Delay (sec) and Throughput (bits/sec).
• Under Node Statistics / Wireless LAN, select Data Traffic Rcvd (bits/sec) and Throughput (bits/sec).Capture a copy of the completed Choose Results dialog (<Alt><PrtSc>)and paste it into your lab document.
• Accept the Choose Results configuration by clicking the OK

Task 2—Run the Discrete Event Simulation

 

• Begin the Discrete Event Simulation by clicking on the DES main menu option and selecting Run Discrete Event Simulation.
• Use <Alt><PrtSc> to capture a copy of the Simulation Execution dialog shown below and paste it into your lab document.

 

• Click on the Close

 

 
Task 3—Analyze the WLAN and WAP DES Results

 

• Click on a blank area of the topology window and select View Results.
• Under Global Statistics for the wireless LAN, select Delay and Throughput. Make sure that the presentation is set to Stacked Statistics. Use <Alt><PtrSc> to capture this DES Graphs window and paste it into your lab document.

 

 

 

 

 

 

 

 

 

What is the average throughput for the wireless LAN?

 

 

When does the largest delay in the wireless LAN occur?

 

 

Clear the graph by clicking on the Unselect All button.

• Under Object Statistics / WLAN Network, select Group A WAP / Wireless LAN / Data Traffic Rcvd(bits/sec) and Group B WAP / Wireless LAN / Data Traffic Rcvd(bits/sec). Change the presentation style to Overlaid Statistics. Use <Alt><PrtSc> to this DES Graphswindow (as shown below) and paste it into your lab document.

 

 

The peak in the Group B WAP traffic occurs when the Group A stations come within range of the group B WAP and associate with it. The dip in the Group A WAP coincides with the association of the group A stations with the Group B WAP.

 

 

 

When does the Group A WAP traffic dip begin? _________________________

 

 

When does the Group A WAP trafficdip end?                       _________________________

 

 

What server traffic accounts for the peak in Group B traffic?       _________________________

 

 

Task 4—Analyze the Group A and Group B Server Throughput

• Clear the graph by clicking on the Unselect All button.
• Under Object Statistics / WLAN Network, select Server for A Group/ Wireless LAN / Throughput (bits/sec) and Server for B Group/ Wireless LAN / Throughput(bits/sec). Change the presentation style to Stacked Statistics. Use <Alt><PrtSc> to this DES Graphswindow (as shown below) and paste it into your lab document.

 

1. …

Explain the drop in Throughput for the Server for B Group at about 65 seconds.

 

 

 

 

 

 

Acknowledgement: The scenario used for this iLab project was adapted from one of the scenarios found in an OpNet example_networks project called WLAN.prj.

 

I would encourage you to open this project and extend your knowledge of the factors that adversely affect the performance of wireless LANs.