Clients sticking and seem to not roam

[chris.thomas]

In our warehouse operations we have Datalogic brand Falcon X3 hand held wireless scanners.  Users drive forklifts rapidly through the warehouse and use the scanners.  When we had Cisco 1200 series autonomous access points there were no problems.  We just installed all new CAP 2702 model FlexConnect access points and a new 5508 controller.  Now the Falcon clients "stick" to a distant AP and do not seem to roam.  The same type of clients associating to access points that are NOT FlexConnect do not have this problem.  Can anyone suggest measures to (1) troubleshoot, or (2) resolve?  Thank you.   We configured "Optimized Roaming" on the controller but that only made matters much worse so we backed that off.

[snoozeroo]

This is a guess based on my experience with other mfg's APs: a new AP may have a stronger transmitter, but not a stronger receiving antenna. If so, the AP is always shouting to the client device, so the client device doesn't disconnect from it, while in fact the AP can no longer 'hear' the client device, because its receiving antenna isn't that strong. So there is no conversation actually happening, but the client doesn't realize it.

Solutions if this is the case:

(a) reduce the transmitting power of the AP, and/or

(b) increase the sensitivity of the client's disconnect/roam threshold (dBmW closer to 0/less negative; shorter time period, smaller increment of dBmW delta). Different devices have diff configurable parameters like this, and obviously consider upgrading the device firmware if you can to get better options.

Hope that might help someone.

[R0n1n]

Is the SSID in use by these scanners using the same vlan across all APs? Is that vlan consistant across all of the switches as well?