Wrong AP Association

[juanchop246]

Hi

We have a WLC 5508 (IOS 7.4.100) with 11 AP (1042N) distributed in several floors. The issue happened when the clients move to one floor to another, because they dont roam to the nearest AP automatically with better SNR , until the Wireless interfaces its manually disable/enable.

We have been proved with Windows Clients and MAC Client, but the behavior its the same.

Thank you in advance for your recommendations to improve this behavior.

Regards

[Scott Fella]

Clients choose the AP's they roam to and AP's that they might put in their list as a possible candidate.  Proper AP placement is required in order to have clients roam to an AP in which is preferred by you.  Unless you place a strong signal in the walking or roaming are of the client, the client will always usually choose an AP that it has good signal with and usually line of site.  SO now if the client turns a corner or enters a stairwell, well that signal drops because the client device saw that as the best AP and now its not.  There is nothing you can do on the WLC configuration side, but really how to place your access points properly for a preferred roaming situation.

Thanks,

Scott

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[juanchop246]

Hi Scott

But it is normal that a client associated with a AP in the fifth floor moves to the second floor and maintain this association, even if the SNR its low compare with the Second Floor AP?

The wierd thing is that when we disable/Enable the wireless interface in the client, they inmediatly associate with the second floor AP.

Thanks

[Leo Laohoo]

The wierd thing is that when we disable/Enable the wireless interface in the client, they inmediatly associate with the second floor AP.

That's still the client making the decision.   You could try to upgrade/update the wireless NIC drivers.

Depending on the manufacturer, you can also specify which radio to prefer.  Personally, I'd enable 802.11a as a preferred radio if you have dense AP deployment.

[Amjad Abdullah]

Juan: I suggest you try with different wireless adapters from different vendors. You'll probably see different behaviors for different vendors.

I've seen scenarios where a part of a school was covered with about 20 APs and when the client moves around all the APs it only roams once! (although, we wanted it to roam like 19 times but it did not).

So, it is a client behavior that you see. voice handsets seem to do better roaming. If you have a WiFi phone you can test with it.

HTH

Amjad

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[Scott Fella]

Like Leo mentioned its the client. So if you stand by an outside window, you would be able to see APs from multiple floors if not all. This is due to AP placements. Now you can tweak your environment, but you would have to understand the RF and understand what the tweaks do. You still can't prevent a Client to associate to an AP further away because it seems like the best choice. You can upgrade the device drivers like Leo mentioned, but you have to understand the the AP and or WLC isn't responsible for that.

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[bischoffb]

I have seen this as well and discovered that the WLC RRM configuration parameters have a large impact to how the client roams. The RRM must compliment the site survey and AP placement location. However, I've not figured out the best combination between both yet.

[cnewman]

I have the same issues you guys have been seeing.

Found this in the newly updated release notes dated 03/20/2013

CSCud37324

Symptom: Clients experience poor performance, and erratic roaming due to the beacon loss of the WLAN. Conditions: Beacon loss occurs for the WLAN. Workaround: None.

Anyone find a work around for the issue.  Bug shows None.  I hope you have not been broken for months.

CVN

[Abhishek Abhishek]

Clients always choose to associate with the Access-Points which has the strong signal. In this query i can suggest you to change the environment as per the RF standards.

As this issue happened when the clients move from one floor to another and they don’t roam to the nearest AP automatically with better SNR. I can suggest you to upgrade your device and their drivers

[Amjad Abdullah]

Clients always choose to associate with the Access-Points which has the strong signal.

This could be true if the client sends "Association Request" frame. (i.e. it is not associated and wants to perform a new association). Then the client will start associatoin process (by firstly sending probe request) to the AP with the strongest signal.

However, if the clietn is already associated to one AP and there is another AP with a stronger signal it is not a must that the client will move to associate with the AP with the stronger signal. That all depends on the roaming algorithm built on the client.

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[Jaaazman777]

Hello!

There is nothing you can do on the WLC configuration side, but really how to place your access points properly for a preferred roaming situation.

You can upgrade the device drivers like Leo mentioned, but you have to understand the the AP and or WLC isn't responsible for that.

 That all depends on the roaming algorithm built on the client.

What is the purpose of roaming settings on WLC if it is client prerogative to take the roaming decision?

"802.11b > Client Roaming"

Does this config concerns only CCX clients?

Besides, what type of devices support CCX ?

[Scott Fella]

The WLC can try to influence the roaming, but as we all know from experience, the final decision maker is the client device itself.  So depending on the client device model and firmware, the roaming can vary.  The WLC along with AP's in general can't tell a wireless client what AP it should be associated to, or what AP it will associate to.... it like telling my daughter to do something when whe is watching TV.... not going to happen:)

http://www.cisco.com/web/partners/pr46/pr147/partners_pgm_concept_home.html

Thanks,

Scott

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[Jaaazman777]

Speaking about CCX

Here we can see Versions and Features of different CCX

http://www.cisco.com/web/partners/pr46/pr147/program_additional_information_new_release_features.html

If CCX is not supported on the client, does it mean that client just cannot use definite set of Cisco features, defined for each CCX version, or it means that client is not Cisco compatible and can have any problems like poor performance, low speed, connection issues?

Besides, can we totally believe NCS, when it tells us, that CCX is not supported for the client?