Technology Integrator May 2012 : Page 32

IPIQ If the server is setup correctly, the resulting output will look like the following: TCP average throughput of 35.1 Mbps per second. After com-pleting the client test, the server will also display the cumulative results for each test. Proceed to perform multiple tests in different locations, particu-larly at the edge of network coverage. If comparing more than one wireless network, it is important to perform each comparative test from as close to the same location (including height) each time the test is done. Any variation can cause the test results to inac-curately reflect the true performance. If the testing is done in an environment where multiple wireless networks are present, then it is advisable to perform several tests from each location during the course of a day or multiple days. This level of testing will take lon-ger but should result in a more reliable result. Testing UDP Throughput UDP test mode simulates real-time streaming applications such as VOIP and Video Streaming. To test UDP throughput, the server side must be restarted with the following command: Iperf –s –u (Note: To stop Iperf at anytime enter “ctrl –c”) &#0d;Ý>“«iÊVˆi˜ÌÊ1&#0c;*ÊVœ““>˜`ÊÃÌÀˆ˜}\Ê«iÀvÊqVÊ£™Ó°£Èn°£ää°£Ó™Ê –w 64kb –l 64kb –M 1400 –i 1 –t 10 –u –b 35m UÊqÕÊÈ}˜ˆvˆiÃÊ̅iÊ1&#0c;*ÊÌiÃÌÊ>˜`Ê̅i UÊqLÊÈ}˜ˆvˆiÃÊ̅iÊ1&#0c;*ÊL>˜`܈`̅°Ê­Îx“ÊrÊÎx&#1f;LˆÌÃÊ«iÀÊÃiV]Ê default is 1Mbit per sec.) The output should look something like the following: Output of Iperf server setup Client Setup 1. Verify that the wireless client computer is connected to the SSID of the access point and can ping the server’s IP address. 2. Open a cmd (command prompt) window on the client com-puter (can be found in Start -> All Programs -> Accessories). 3. Change the directory to the location that Iperf was installed (i.e. cd c:\Iperf). Testing TCP Throughput After setting up Iperf, we are now ready to test throughput. The default test mode for Iperf is TCP, which simulates bi-directional IP application communication. The majority of IP applications use TCP, including the World Wide Web, E-mail and File Transfer. The TCP command string on the client side takes the following format: Iperf –c –w 64kb –l 64kb –M 1400 –i 1 –t 10 (Using this command string, Iperf would report results every one second and run for 10 seconds) UÊqVÊ­*Ê>``ÀiÃÃʜvÊÃiÀÛiÀ® UÊqÜÊ­œ˜ÞÊÕÃi`Ê܈̅Ê7ˆ˜`œÜÃÊÛiÀȜ˜]ÊëiVˆvˆiÃÊ܈˜`œÜÃÊÈâi® UÊqÊ­œ˜ÞÊÕÃi`Ê܈̅Ê7ˆ˜`œÜÃÊÛiÀȜ˜]ÊëiVˆvˆiÃÊ«>VŽiÌʏi˜}̅® UÊq&#1f;Ê­œ˜ÞÊÕÃi`Ê܈̅Ê7ˆ˜`œÜÃÊÛiÀȜ˜]ÊëiVˆvˆiÃÊ̅iʓ>݈“Õ“Ê &#1f;/1ÊÈâi® UÊqˆÊ­ˆ˜ÌiÀÛ>Ê̜ÊÀi«œÀÌÊ̅ÀœÕ}…«ÕÌʈ˜ÊÃiVœ˜`î UÊqÌÊ­>“œÕ˜ÌʜvÊ̈“iÊ̜ÊÀ՘ÊÌiÃÌʈ˜ÊÃiVœ˜`î If Iperf is operating correctly you should see something similar to this: Example of UDP throughput data using Iperf Example of TCP throughput data using Iperf Once the test is complete, the cumulative results are dis-«>Þi`ʜ˜Ê̅iʏ>ÃÌʜÕÌ«ÕÌʏˆ˜i°Ê˜Ê̅ˆÃÊiÝ>“«i]Ê`ÕÀˆ˜}Ê̅iÊ 10-second interval, 41.9 Mbytes of data were transferred at a 32 ˜Ê̅ˆÃÊiÝ>“«i]Ê`ÕÀˆ˜}Ê̅iÊ£ä‡ÃiVœ˜`ʈ˜ÌiÀÛ>]Êx™°{&#1f;LÞÌiÃʜvÊ data were transferred at a UDP average throughput of 49.8 Mbps per second. The average jitter was 1.280 ms. The packet loss per-centage was (0.085%) with 145 of 169745 packets lost. The greater the UDP data rate, the greater the likelihood that your packet loss percentage will increase. While wireless networking can be a challenge, there are steps that can be taken to ensure optimal performance and user satisfac-tion. Testing both signal strength and data throughput will help identify potential holes in network coverage and allow network installers to take the appropriate steps to ensure an optimal wireless ˜iÌܜÀŽÊiÝ«iÀˆi˜Vi°Ê CR May 2012 U CustomRetailer

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