Difficulty with Apple iOS devices

[Evan Wheatley]

Hey All,

I'm seeing a problem with Apple iOS devices connecting from one SSID and then connecting immediately to another. I've tried to replicate this fault with non Apple iOS devices, but I'm unable.

Environment:

Single 5508 WLC running 7.2.110.0

AIR-LAP1142N-A-K9 AP's

WLC is in clients head office, MPLS to their branch sites. AP's are in FlexConnect mode, with AP and FlexConnect groups for the AP's at the branch. 3 x SSIDs; Corporate (802.1X), Guest (Web-Auth) & Non-Corp (PSK).

Scenario:

Client is connected to the Corporate SSID with his iPad (new model, running iOS 5.1.1). No problem with access, he is able to roam throughout the building with good SNR/RSSI. He wants to test the other SSID's, he attempts to connect directly to the Guest or Non-Corp and gets an error message on the client saying 'Unable to Connect' or 'Unable to Join'. Debugs on the WLC for the client shows no connection attempt, no errors. I can see the client disconnect from the Corporate SSID, but nothing for the Guest or Non-Corp SSID.

If the client then disconnects and forgets the Corporate SSID from the wireless profiles on their iPad, waits 20-30 seconds (I can see the client disconnect cleanly from the WLC) and then attempts to connect to the Guest or Non-Corp SSID's - he doesn't have a problem. He immediately associates, and is able to connect. If he then tries to connect directly to another SSID, while still associated to another from the same WLC/AP – he gets the error again. Forget/wait 20-30 seconds, attempt to connect – no problem.

We've tested with several iPhones (4 & 4S), iPads (2 & new model) - all running the same Apple iOS (5.1.1).

I unfortunately can't do much troubleshooting with TAC on this as the client is no longer onsite, and I don't have a 5508 in our lab that I can currently test with. Has anyone else experienced as similar issue? I've tried playing with beacon intervals, etc to no avail.

Thanks,

Evan.

[Scott Fella]

If you want to switch between SSIDs, you need to enable Fast SSID on the wlc.

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[Scott Fella · Accepted solution]

Q. What is Fast SSID Changing?

A. Fast SSID Changing allows clients to move between SSIDs. When the client sends a new association for a different SSID, the client entry in the controller connection table is cleared before the client is added to the new SSID. When Fast SSID Changing is disabled, the controller enforces a delay before clients are allowed to move to a new SSID. For information on how to enable Fast SSID Changing, refer to the Configuring Fast SSID Changing section of the Cisco Wireless LAN Controller Configuration Guide, Release 7.0.116.0.

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[Evan Wheatley]

Thanks Scott, I'll change the setting and see if the client can test. I'm pretty confident after reading everything I can find in the last 5 minutes about Fast SSID changing.

Best,

Evan.