In the previous article, we talked about how to check if a specific Wi-Fi network is supporting IEEE 802.11v, from the access point perspective. Like anything in Wi-Fi, we need support from both the access point and the STAs in order for it to work.
So in this article, we are going to explain how we can validate is a specific client device supports 802.11v.
I would like to address special thanks to Phil Morgan for providing useful information and giving me the idea to write this follow up post.
If you want to check if a client device supports 802.11k, feel free to check this other article: https://www.semfionetworks.com/blog/wireshark-how-to-check-if-a-wi-fi-network-supports-80211k
So if you are performing your own packet captures, make sure you enable 802.11v support on the access point first.
Once again, looking at the association request frame in order to find 802.11v support, we need to focus on the Extended Capabilities Information Element number 127 and look at the 4th bit of the 3rd octet. This bit is most commonly named the "BSS Transition bit". If the bit is set to "1", the client device support 802.11v.
The following screenshot shows the BSS Transition bit of an association request sent by a Samsung Galaxy S7 Edge. This is taken from the .pcap files available on Mike Albano's website.
So if you are not sure if a specific client supports 802.11v, you can head over to his website and perform a quick research. You can even download a .pcap file for every device containing an association request.
Validate client 802.11v support on a Cisco WLC
So once the client is associated to the Wi-Fi, head over to the "Monitor" page, on the left menu, select "Clients". This will open up a new page displaying all the client devices connected to your different Wi-Fi networks supported by the controller.
Click on the mac address of the client that you want to study. This will open up a new page providing more detailed information related to this specific client.
On this page, you will be able to see if it support IEEE 802.11v, as shown below, under the "802.11v BSS Transition" sub-section:
Update (2019): Using the WLAN Pi and Profiler
All you need is a WLAN Pi. On the latest version of the WLAN Pi image (1.7+), you will be able to use the program called profiler developed by @Watkinschoffer and @wifinigel!
This program broadcast a special beacon frame that tricks the client device in thinking that the Wi-Fi network supports pretty much everything and is using the maximum capabilities defined in the 802.11 specifications.
You can start the program from your WLAN Pi using the following command:
(Image from the github documentation page)
The profiler tool would require an entire dedicated blog article and does way more than just validate 802.11v. I invite you to check it out and try it out yourself.
For more information, please head over to the gitub page: https://github.com/WLAN-Pi/profiler
Thank you for reading!
written by François Vergès