we could not find roaming client that sends reassoc frame.

does any of dlink, cisco, netgear adapters refered in this blog send reassoc ?

has anyone verified it?

please give feedback and link for driver and model, make of adapter for
win7, win xp

also how to configure roaming behaviour of client; we want client to roam when
signal becomes week not untill signal is totally lost

thanks
sivak

I only ask because you’ve confused me a bit… I can understand that logic if you are turning down the TX power on your APs. However, if you are referring to the TX power on the clients I don’t understand what bearing that has on roaming. The TX power of the client has nothing to-do with roaming it’s the RX power of the signal from the AP that the client uses to determine if it should roam or not along with a host of other variables. Perhaps you’re just turning down the TX power because of channel overlap and mobile device density?

“The variable of most importance will always be received signal strength. As the received signal from the original AP grows weaker and a station hears a stronger signal from another known access point, the station will initiate the roaming process.”

Thanks!

Thanks for the comment Dan.

It was a while ago now that I looked at this but I do recall there was some utility from RAlink that you could use to set a number of the options you described above.

Any thoughts as to why you needed to reduce the TX power to 10%…. that’s not very much given that the maximum by FCC specs in the US is 100mW.

In any event thanks for the information.

Cheers!

Driver Version 3.2.1.0 dated 4/25/2011 from Ralink website.
The DeviceManager\wifi adapter\Advanced Properties = Multimedia Gaming Environment is Enabled.

HKEY_LocalMachine\System\ControlSet001\Control\Class\{xxxxxxxxxxxxx}009\FastRoamingSensitivity = 4
HKEY_Local_Machine\System\ControlSet001\Control\Class\{xxxxxxxxxxxxx}009\Default\FastRoamingSensitivity = 4

HKEY_Local_Machine\System\ControlSet001\Control\Class\{xxxxxxxxxxxxx}009\TXPower = 10
HKEY_Local_Machine\System\ControlSet001\Control\Class\{xxxxxxxxxxxxx}009\Default\TXPower = 10

HKEY_Local_Machine\System\CurrentControlSet\Control\Class\{xxxxxxxxxxxx}009\Profile\Station\MyProfileName\TXPower = 10

Forcing the TXPower down to 10% and increasing the Roaming to the Max of 4 resolves these issues in our environment.

Hi Vidal,

We went to great pains to collect a lot of packet traces. I examined the wireless traces myself and it was pretty clear that the issue was with the client adapter. It’s the client adapter’s responsibility to roam and when to roam, the wireless network just advertises availability.

We tried all methods of encryption including un-encrypted and wide open, still the same roaming issues persisted.

With that said we have seen some ‘odd’ behavior from time to time with different clients, many of which have been resolved with subsequent software and driver upgrades.

Thanks for the comment!

I had the same scenario (didn’t want to roam until it had lost complete signal) after deploying a WLAN using WS5100 Switch with WPA/PSK encryption.

My clients are Talkman T2x (Text-to-Speech solution by Vocollect) and they lost communication with the server every time the roam is needed.

We apparently solved the problem changing the encryption to WEP.

Are you sure that the problem is in the clients and not with the RFS7000?

We had intermittent issues with the Netgear WDNS3100 as well when we would roam between Access Ports/Points. We ultimately replaced all of them with Cisco 802.11a/b/g Wireless PCI card which works flawlessly. Unfortunately we had to buy the expansion kit for the HP Thin Clients which added to the amount of work and cost but it was well worth the effort to be assured that the COWS would roam without issue.

I’m not sure why the other vendors/chipsets can’t get this one right?

Cheers!

Hi Suner,

Unfortunately I had to drop the D-Link adapter… even with Fast roaming enabled (85dB) the adapter seemed to throw fits from time to time. Initially we thought it might have to-do with the WPA/TKIP/802.1x configuration with Windows XP and the re-authentication as the STA roamed from AP to AP but even in a open network we had issues. While the adapter seems to work fine once your connected and in-mobile it was hit or miss once you started moving or if you just picked up… walked 200 ft and tried to work again. It was definitely MUCH better behaved with Fast roaming enabled but it was no where near where we needed it to be.

We’ve since gone back and starting using the Netgear WDNA3100 which is based on an Atheros chipset. While this adapter might be a few more $$$ it appears to be much more consistent than the D-Link or Linksys adapters in terms of roaming and even in terms of authentication time using WPA/TKIP/802.1x.

Thanks for the comment!

Since you refer to “iwconfig” I’m suspecting that you are using a Linux operating system and not Windows XP. I haven’t tested the hardware with any of the Linux distributions only with Windows XP and Windows XP Embedded.

Thanks for the information regarding Linux!