Monday, January 18, 2016

Perform a wifi roaming test in LAB

Some time I need to make wifi client roam from one AP to another to reproduce issues reported by customers. This is not really straight forward if you don't have a large area to setup two access points and walk far enough so that client may decide to roam naturally. A workaround would be to make two shielding boxes and place the two APs inside the boxes. Open one and close the other. The client will connect to the AP in the opened box. To make the client roam to the 2nd AP, close the fist box and open the 2nd box :-)

I made the shielding box using a plastic box and aluminium foil, apply several layers of aluminium foil for better shielding,

If you leave your AP in default settings the client will not really roam as the transmit power of the AP is too strong to be shielded by aluminium foil. Therefore we need to adjust few things to make sure that the roaming test is successful,

1) Reduce the transmit power of the AP to minimum. The example below is from Aerohive HiveManager(,

2) Lowering Tx power is not enough, you should also disable all the lower data rates except for 54Mbps. Clients usually roam based on SNR. With lower power to be able to use 54Mbps data rates the client need high SNR and will roam easily as you open and close the boxes' lids,

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