Lab 6: Wireless Networks

Transcription

1 Lab 6: Wireless Networks EE299 Winter 2008 Due: In lab, the week of March Objectives This lab will show a correlation among different network performance statistics with multimedia experiences, such as video streaming, in different usage scenarios. We will use the Iperf tool (Jperf is the graphical frontend) to analyze network characteristics, including bandwidth and jitter. Specifically, we will cover: Using Iperf/Jperf to gather basic network performance statistics Relationship between streaming multimedia experience and network performance Prelab Before starting this lab, it is important that you read the How-to-Use-Jperf document (posted with the lab description on the course web page). 1 Wireless Networks In this lab, we will learn about different measures of network performance, and how these can impact multimedia experiences. The class will first form two groups to run the first experiments with their own wireless access point (AP). Next, groups will join to create a single wireless network to run more realistic experiments. 1.1 Setup Wireless Network The files you will need for the lab are available at: 1

2 Figure 1: Experimental setup. Download netlab server.zip onto the computer connected to the AP (the server ). Download netlab client.zip onto the remaining computers (the client ). Extract the zip file onto the desktop. The subsections below explain how to set up the wireless network. The network will be similar to the one in Figure 1. The shaded computer (the server) is directly connected to the wireless access point (AP), and the other two computers are set up as wireless clients Setting up the AP Unplug the network cable from the computer that will be connected to the AP. Connect the green network cable included with the AP, to both the AP and computer. Connect the AP to power. Double-click the My Computer icon on the desktop. Click Control Panel on the left sidebar. Double-click the Network Connections icon. Right-click the Local Area Connection icon. Click Enable. Right-click the Local Area Connection icon. Click Internet Protocol (TCP/IP) (DO NOT UNCHECK). Click Use the following IP address. For IP address, enter 10.0.K.1, where K is the group number in the AP name (either 1 or 2, see Setting up client below). For Subnet mask, enter Close the Network Connections window. 2

3 1.1.2 Setting up the client Double-click the My Computer icon on the desktop. Click Control Panel on the left sidebar. Double-click the Network Connections icon. Click Enable. Click View Available Wireless Networks. Be sure that the EE299Lab network is connected, take note the group number (e.g. EE299Lab group 2). Close the Wireless Network Viewer window. Click Internet Protocol (TCP/IP) (DO NOT UNCHECK). Click Use the following IP address. For IP address, enter 10.0.K.N, where K is the group number in the AP name (either 1 or 2), and N is a number starting with 1 for the server incremented for each computer setup. For Subnet mask, enter Close the Network Connections window. 1.2 Baseline Establish a baseline for the experiments in this lab by analyzing a network with no traffic. Run Iperf in server mode on the computer directly connected to the AP, and configure it to use UDP, and run Iperf in client mode on one client computer. Perform the test as explained in the Jperf How-to document. (NOTE: to start JPerf you can run the jperf.bat file in the netlab server/client folder, instead of typing out the commands in the how-to document.) During the test, you should see the performance statistics being output on the server. When the test is complete, a number of plots will open, showing the statistics graphically. Record a few of the bandwidth and jitter values, as well as the averages. 3

4 1.3 Small Group Experiments Use the same setup as before with Iperf, but this time you will play a video stream during the test. The server computer (connected directly to the AP) will run VideoLan VLC media player in streaming server mode. To start the video server, open the folder that was extracted to the desktop, and double-click the file named start video stream.bat. Once the video server is up, you can begin streaming video to other computers. Choose two client computers, and open a video stream by doing the following on each: Open the VideoLan VLC media player. Go to the File menu and select Open Network. Select HTTP/FTP/MMS, and enter the address and port of the server, where K is the group number on the AP. Make note of the Caching option at the bottom. This is the amount of time (in milliseconds) to buffer a network stream. The reason to buffer a network stream is to protect against jitter and other network degradations. Lowering this will give you a more realistic display of actual network quality. Click OK, and now the video will begin to play. Once the video streams have been started then start the Iperf test. Take note of the changes, if any, in the values reported from before as well as the quality of the video. Rerun the video experiment, but now with everyone s client computers streaming the video. How did the bandwidth and jitter change? Does the video behave differently? 1.4 Class Experiments To be able to run more realistic experiments, change the setup so that the entire class will be connected to one AP instead of in groups. Once all of the groups have finished with the initial group experiments, setup the wireless network as shown in Figure 2. Choose one computer to be the server and connect one AP directly to it, configuring it as before. Configure the remaining computers as wireless clients. Remember that you may need to change the IP address on the clients, since the group number may have changed. Run Iperf on the server computer and configure it for UDP. Choose one other computer in the room to run the Iperf client on. The remaining computers will stream the video the same way as the group experiments, however this time they will begin one at a time while Iperf is running. Start the Iperf test on the client computer, and then start video streaming on each computer one by one, with a few seconds delay between successive starts. Record the bandwidth and jitter reported by Iperf along with the number of computers currently streaming. Also take note of the quality of the video at each interval as well. When the test is complete, be prepared to discuss the results. 1.5 Cleanup When the lab is complete, please reconnect the network cables to the computers that were connected to the AP, and return the AP with its cables to the TA. Please also REBOOT the computers when you are finished using them, this will restore the previous configuration. 4

5 Figure 2: Experimental setup, all computers connected to one AP. 5