Loosing packets when roaming

Unanswered Question
Sep 13th, 2008


I have a warehouse with a quite simple setup.

Its 2x 3750E switches and 2x 4402 controllers.

The accespoints are 16 x 1252.

When i drive around in the warehouse with a continuos ping running, i loose one and sometimes 2 pings when roaming.

The WLC's are running 5.1.151

Help !


I have this problem too.
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grzegorz.ciolek Sun, 09/14/2008 - 02:17


Are you using CCX?

What type of vendor adapter do you have in mobile stations?

Which supplicant are you using? (WZC does not support CCX)

Are you using WPA or WPA 2 (WPA does not support roaming)

What security are you using? (PSK, 802.1X or 802.1X+CCKM)

There is many factors which have influence on roaming. Give us more info.



pbuch Sun, 09/14/2008 - 12:28

Thanks :-)

It's Intermec terminals on the rolling equipment. Only WPA is supported.

We are using WPA-PSK right now.

I will collect more info tomorrow


Scott Fella Sun, 09/14/2008 - 12:36

Like Greg mentioned, wpa does not support fast roaming which causes you to loose connection for a while. Caching support in WPA2 allows you to reconnect to an access point that you've recently connected to without the need to re-authenticate again. Without PMK (as in WPA2) you can expect re-authentication to take around one second, which can cause your application to break.

pbuch Thu, 09/18/2008 - 22:05

Just tested yesterday with a normal laptop.

Configured a wireles SSID on the a radios, WPA2-PSK. When driving around in the warehouse, the pc was loosing lots of packets.

Sometimes it was roaming withiut loosing a ping, but in other cases loosing op to 5 pings. The warehouse is empty and signal is fine.

Scott Fella Fri, 09/19/2008 - 05:21

You have 2 WLC's, is your mobility setup correctly? As far as LAP's go, are they all on one wlc or did you split them up?

pbuch Fri, 09/19/2008 - 23:27

Same mobility group on both WLC's.

It's 2 x 4402-12 and all AP's are on the same controller. I will end up with 16-18 AP's but at this time only 10 of them are installed.


Scott Fella Sat, 09/20/2008 - 05:38

I don't know why you would loose that many pings during a roam. If you feel comfortable, can you post your show run-config so I can look at if the configuration need something changed.

Scott Fella Sun, 09/21/2008 - 05:01

I hear you. Can you post the show run-configuration. You posted the show running-configuration.

Try disabling Aggressive Load Balancing and WMM unless your scanner supports that. I will wait to see the run-configuration.

Scott Fella Sun, 09/21/2008 - 12:30

You only have 7 ap's on this controller but you said you had a total of 10. If you have 10 and a user roams from an ap on this controller to an ap on the other controller, you will have timeouts. This because you also don't have both controllers configured in the mobility group setting. Also you need to configure the service port with an ip address that is not routable in your network. Just configure the port but don't attach that to the network. After you makes these changes and you still have issues, disable aggressive load balancing and WMM and see if that helps.


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