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Network Testing and Emulation Solutions

LANforge WiFi Station Reset Testing

Goal: Use the WiFi Port Reset plugin to emulate restarting of stations associated to your WiFi network.

Requires LANforge 5.2.12 or later. Restarting a WiFi station exercises the whole network stack because it forces negotiation across the wired network: your AP, your DHCP server, your AP controller, and possibly your RADIUS server. Performing this test at an unusually high frequency is a challenging robustness test for your wireless topology and can expose possible race conditions when large numbers of stations reset simultaneously while passing traffic. This cookbook assumes the System Under Test is your AP and that a CT520 (or better) is emulating stations to be reset on the network.
 
  1. Create WiFi stations

    1. In the Ports tab, select wiphy0 and click Create screenshot

    2. In the Create VLANS window, craft ten wifi stations: screenshot

      1. Select WiFi STA

      2. For MAC address, choose xx:xx:xx:*:*:xx

      3. Select DHCP-IPv4

      4. Enter Quantity 10

      5. Specify 0 for STA ID

      6. The example SSID for this cookbook is jedtest

      7. ...and then click Apply

    3. You will see ten stations created: screenshot

  2. Create Connections to Stations

    1. In the Layer-3 tab, click Create screenshot

    2. Create station download traffic screenshot

      1. This example connection is named sta-trf

      2. Connection Type is LANforge / TCP

      3. This example resource is kedtest, where our stations live

      4. The Endpoint A Port will be the station sta0,

      5. and the Endpoint B Port will be upstream of the ap, eth1.

      6. We'll set the Min Tx Rate for both sides to 265 Kbps

      7. and set the PDU Size to TCP Pld (1,460 B).

      8. ...then click OK

    3. Test this station by selecting it and clicking Start screenshot

    4. Click Stop when you are done testing the connection

    5. Click Modify for sta-trf and we will batch create nine more: screenshot

    6. Click Batch Create in the Create-Modify Cross Connect window screenshot

    7. Create nine more cross connects like this one: screenshot

      1. Set Quantity to 9

      2. Set Number of Digits to 2

      3. We are not changing the B-side port, so we do not need to increment it. Set the Port Increment B to 0

    8. Select all connections and click Start screenshot

    9. Connections should not show dropped packets in the __Rx Drop % A or Rx Drop % B__ columns screenshot

  3. Configure Port Reset Script

    1. In the Port Manager tab, select stations sta0 - sta9 screenshot

    2. In the LANforge Manager windows, select the Plugins→Port Reset Test option screenshot

    3. In the Port Reset Test window, you will see the ten ports already selected. We will configure quick resets for this test: screenshot

      1. Set Concurrent Ports to Reset to 5

      2. Set Minimum Time between Resets to 5 seconds

      3. and Maximum Time between Resets to 20 seconds

      4. ...and click Start

  4. Observe Results

    1. The Port Reset Test Results window will show the list of ports getting reset. screenshot

    2. The Layer-3 tab will show the amount of lost and dropped packets. screenshot

    3. We can graph the throughput of the connections with the Dynamic Report menu option screenshot

    4. In the Dynamic Reports window, we are graphing the Rx-Bps for each connection in axis-A, and in axis-B we are graphing the Rx-Bps for the upstream port, eth1 screenshot

    5. You will also want to watch for warnings and failures. In the Alerts tab, you will see persistent alerts. The alerts in this picture can be safely ignored: screenshot

    6. Check the LANforge Wireless Events window.You will see station connects and disconnects and failure notices. The messages shown in this picture are normal: screenshot

    7. In the LANforge Messages window, you will see connection warnings. Connections will warn when their IP changes, and this is normal, as shown in this picture: screenshot

    8. And in the Event Log tab, you can review more detailed link-up, link-down and connection events that occur with these station restarts: screenshot

    9. Use these monitoring sources to check for undesirable trends:

      • Undesirable slowing trend in traffic
      • stations that do no return
      • DHCP failures or pool exhaustion
      • or uncommonly long station re-association events
      .

  5. Halt the test when you are finished. screenshot


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