Add the testbed to "Favorites" view and then you will see the list of devices in the testbed.
Then Click on "Start Capture" button in the main toolbar.
You can double click on a device node in Favorites view to start the session. You can start as many sessions as you want to different devices.
When you are done, click on "Finish Capture" button on the main toolbar and a wizard will popup helping you put steps into a testcase of your choice.
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