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Old 09-03-2010, 04:35 PM   #1 (permalink)
timlang
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Join Date: Sep 2010
Model: 9700
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Question No BB Wifi Connectivity with multiple APs (roaming)

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I am having a very strange problem with all our blackberries (about 12 Bold 9700 units) at our main office:

We have a SonicWall NSA240 UTM Router with 4 SonicPoint-N wiress access point radios. These sonicpoint share the same profile (ie: a single SSID/access profile across all of them to facilitate wireless roaming throughout our facility).

All Laptops (PC and MAC), Iphone and Ipads are working great. But I am having a strange problem with all our blackberries:

When I enable only one single sonicpoint (disable all the others), the blackberry works fine with the sonicpoint. As soon as I have more than one sonicpoint enabled, the blackberry will connect to one and get an IP address, work for a few seconds or minutes, but once it notices the other APs, it looses data connectivity (ie: cannot ping back to the gateway or out into the world). As soon as I disable all but one sonicpoint, it works fine again.

I am not using any MAC or RADIUS access control. Just simple WPA-PSK security (I have experimented using WPA, WPA2 and WPA/WPA2 Auto, as well as AES, TKIP and Auto encrpyption - all with similar results).

In looking at the wifi diagnostics in the blackberry, and the sonicpoint station status - the blackberry is not roaming excessively. After I turn on additional stations (beyond the first one), and the blackberry looses connectivity - I can see that it is still associated with the first (closest) station it originally connected to, but no data is flowing.

This problem is not intermittent - it happens 100% of the time that I have more than one sonicpoint turned on. Here is the process to recreate the issue:

1) Disable all but one sonicpoint-N (call it Unit 'A')
2) Blackberry connects properly, and has data connectivity, can ping gateway, etc
3) Enable another sonicpoint in the network (Unit 'B', much further away from where I am doing this testing, but still within range)
4) Within about 60 seconds of the 2nd sonicpoint coming online, the blackberry looses data connectivity and cannot ping the gateway. It remains in this state indefinitely, until I disable all but one sonic point. It still shows that it associated with unit 'A', still has its IP address, and both the berry and the sonicpoint station status for unit 'A' shows my blackberry with strong signal strength.

It does not matter which sonicpoint I use to connect as the first unit, second unit etc (as long as it is in range of course), so the problem isn't specific to a particular sonicpoint.

I have tried changing the sonicpoint radio band to standard - 20Mhz, and have disabled Aggregation in trying to troubleshoot this, but neither seems to help.

I did some packet traces (the Sonicwall devices have a built-in packet trace utility) to see what was going on. With only one sonicpoint turned on, I can do a ping from the BB to 8.8.8.8 and in the packet trace I see the outgoing requests from the BB, and the return ICMP responces from that address (which are successfully received on the BB).

Once I enable more sonicpoints and the blackberry goes into the state of no-connectivity, I do the same ping. I can see in the packet trace, the outgoing requests, AND I can see the same responces being sent back to the BB. In fact, the packet traces from when it was working, and NOT working looked identical. So the problem has to be that that BB is not receiving/accepting the return packets from the AP for some reason.


Again, this problem ONLY exists with blackberries (all other wifi devices work fine).

Do blackberries not support wireless roaming between APs? I put in a support ticket with SonicWall, but they had no idea what the problem was.

Any suggestions would be greatly appreciated.

Thanks!
/-Tim

Last edited by timlang : 09-03-2010 at 05:27 PM. Reason: fixed typos
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