Wireless Access

Hi,

Has anyone experienced situation where MS Surface Pro 6 constantly prefers 2.4GHz band while connected to Aruba WLAN, while when in home (non-corporate) environment happily connects to 5GHz?

Obviously, the decision which band to go with is made by client, but I cannot figure out what is it in our corporate environment that is causing Surface to make such decision. Can it be anything to do with Basic Rates we are using (currently running both 802.11a and 802.11g on BR of 18/24), or would expect it more to be caused by RSSI level perceived by Surface NIC as major trigger? Any thoughts/suggestions/ideas welcome.

Hi NesaM,

Iam affraid this question cant be answered right. "It depends" on a very lot of factors. Every type of device have another algoritme for this proces. For example; The apple team have a lot of employees that work on an algoritme that make desiscion based on past experience on a channel.

But there are a lot of other factors, not only RSSI strength, or device capabilities. wlanpro have some good document called "the green diamond", its a fictive name ;)

https://www.wlanpros.com/resources/decoding-green-diamond-understanding-client-behavior/

"Wouldn’t it be nice if we could look inside our client devices and see what their “Green Diamond” algorithm is doing to choose between access points? But client device manufacturers hold this information very close to the chest. These trade secrets, or secret sauce, are the bane of all Wireless LAN Professionals."

Best options you have when you have issues with bandsteerings (bandsteering is not 802.11 standardized) is to disbale 2.4GHz if you can. Or make two seperant ssid for 2.4 and the 5Ghz band, example:

- 2.4Ghz SSID: "HomeLAB - Slow"

- 5Ghz SSID: "HomeLAB - Fast"

...People will always want to go "Fast" until do dont can ;)

Other things you can try are lower the 2.4GHz txpower then your 5Hz (6dBm offset will equal the cellsize). Or disbable the lower data rates to optimized roaming.

And  start with checking if your client wlan driver is up-to-date.

Hi Marcel,

Thank you for replying to my message, and advice offered. Our Max/Min Tx EIRP for both a and g are already offset by 6dBm, so I suppose that next thing is to look at available documentation on Surface Pro makes band selection.

Lower reates are already disabled on our WLAN, for both a (18/24/36/48/54) and g bands (12/18/24/36/48/54).

The fact that when not connected to Aruba WLAN those devices are joining 5GHz band seems to point to something in the way we configured our network.

What does "show ap bss-table"  shows you? Are only the surfaces shown this issue or other clients to? Is bandsteering enabled (with preferd 5ghz) enabled? Clientmatch? Firmware release?

Maybe you can create an new AP-Group with a test AP and SSID with some different settings?

Also check this document about the through of bandsteering, give you some idea of the principals.

https://www.networkcomputing.com/wireless-infrastructure/4-wifi-band-steering-myths