Intermec wireless terminals and roaming

[mheidemann]

Im deploying Intermec terminals (2455's) in my wireless environment. The terminals are MAC authenticating back to a local ACS server and are configured with 128 bit static WEP keys. The access points are all 1200's on the same network segment and running 12.02T1 version of firmware. The access points are all configured as root access points and hard wired into Catalyst 3500 switches.

The problem I have is with roaming. When these devices roam they typically drop a few packets (observed by continuous ping) and roam seamlessly to the user but often times the device will "time out" for several minutes. The access point shows that the device is associated, but again, the device cannot communicate. I have several aeronet clients and workgroup bridges in the same environment which roam without interruption.

Any suggestions/help is appreciated!

[b.withrow]

We had similar problems (and still do to some extent) with LXE/PSC devices. One thing that fixed our issue was turning off PowerManagement on the client adapter. It was "going to sleep" and during that time losing packets which resulted in a disconnect from the host. We are told it is a flaw in the DOS driver or the IP stack (depends who you ask). And that would seem accurate, since none of our Windows based wireless clients get disconnected.

[Gianky]

We had a similar problem: after ugrading Cisco Mobility Express frmware, Intermec devices, using 2.4 Ghz band, tried to connect using 802.11b standard only, but the access points were not able to negotiate the rate below 12 Mbit/s. We set the Intermec devices using the 5 Ghz band: after this operation the roaming works fine. 

[JPavonM]

As you are using WEP, no key caching mechanism is been used, so roaming rely on full re-authentication (no SKC, OKC or FT).

Remember that associated is not the same as authenticated on L2.

Under this kind of scenarios, if there is high load in the channel it could happen that some packets maybe lost so association/authentication to the new AP maybe impacted.

Please also notice that warehouse areas are scenarios where hidden node effect could happen, specially if the amounts of goods or their distribution have changed and the AP locations have not been reconsidered.

802.11g APs don't have all technologies added to 802.11n and 802.11ac APs to perform better on these deployments so, why don't you move forward to use modern APs and stronger authentication methods like WPA2 or even 802.11i? I don't mean using state-of-the-art APs supporting 802.11ax, but maybe AC Wave 2 ones, something that can be centrally managed with solutions like Mobility Express.