Controllerless Networks

Hi

I was visiting a customer today and saw a very odd behavior.

The network is a school with 32 instant APs one 225 iAP as the preferred VC and the rest 105 iAPs.

My customer tested walking aroud in the building and sometimes his iPad would not roam from AP to AP, sometimes it just took some time before the iPad connected again sometimes he had to shut the WIFI on the iPad and turn it on again and sometimes the iPad connected and got an IP address but had no internet connection.

We also saw the last behavior when sitting at a table not moving around. His iPad was connected but had no internet connection. Around him was 2 iPhones, an iPad and a Surface PRO3 witch had no problem in connecting to the same SSID, and had internet access.

The setup is 4 SSID´s one for school equipment (PSK) one for the students own equipment (PSK), one Guest network with clearpass guest authentication and one SSID for AppleTV´s (PSK)

all of these SSID's has seperate VLANs on the wired network witch consists of 2 Aruba s2500 in stack mode as core and some Cisco SG300 in the 3 other wiring closets.

They are seing alot of problems with roaming on that network mostly on iPads on different software levels.

The instant cluster is running 6.4.2.0-4.1.1.1_46936 software.

We have the whole system on airwave but the only thing i could se when his client was connected without internet was that his MAC address was connected and had an IP address but without any visible hostname.

Airwave stated that his client had a high noise floor (-89) and a lot of lost frames.

I am pretty certain that the problem is on the iPad but how do i start troubleshooting a iPad ?? or could thier be some setting on an instant network that will enable iPads to roam better
?

Best Regards Jens  W 

Hi

The Client match feature is on.

They are only seeing the problem on the one SSID but that is the mission critical one.

So the problem can also be on the on the other SSID but they just have any focus one them.

The AppleTV's that are wireless also is experiencing some problems though.

Regards Jens

With roaming issues the two big things we should always check for is ClientMatch and the ARM TX power. Typically the TX power should be set at minimum 12 and maximum 18, unless a specific use case exists for something different. If the power is too high the client will sometimes become "sticky" and refuse to roam to a better AP.

MAX and MIN TX is actually set as low as 9 and 6 respectivly.

This is because the AP sits in such close proximity to each other.

There is one AP in every class room and they are no more than 5-7 Meters apart.

Jens

Hey,

If you need hands on help on the location, feel free to contact me.

/Niklas

I'd rather have some clues to how to troubleshoot such a problem with IPads, what could be wrong and what can one do on an IPad in regards to trouble shooting.

Regards Jens 

How is the settings on the SSID?

Do you have 801.11r enabled?

Hi the setting are as shown in the screenshots.

The customer has on his own set all 5Ghz channels to statinary channels after reading this:

https://discussions.apple.com/thread/6601963?start=2025&tstart=0

I have only read some of this loooong discussion and can't find any solid evidence that shows that this should be a viable solution.

Anyway I would never set any channel manually neither on 2,4 or 5 Ghz.

I dont know about you ?

Regards Jens 

Hi,

Apple have som issues with 802.11.r & k (fastroaming) please remove the options on the SSID.

in the first screenshot under Broadcast, set it to ALL or ARP, this will reduce the traffic on the APs.

KP-Niklas is right.

Please change "Broadcast" to ALL for all of your SSIDs.

Also remove 802.11r and 802.11k because a number of clients have issues with them.

Can we have a screenshot of your ARM settings, as well as your dashboard of your AP utilization?

Hi thank you for your responses.

I have attached screenshot of ARM settings

Regards Jens

Hi,

How is your transmit rates under the SSID's ? to get better roaming set the maxumim til 54 and minimum 11, for 2,4 GHz, and 54 as max and min 12 for 5 GHz.

try to roam with the new settings and report back :) 

/Niklas

Hi

I have changed them.

I have attached an overview over the AP's

Regards Jens

Something is wrong.  You have the minimum of 6 and maximum of 9, but some access points are still outside of that power:

Also, what is your regulatory domain?  I see that there are some DFS channels in use and we need to remove those.  Also, under ARM we need to make sure wide channels is "none" or "disabled"

The regulatory domain is Denmark (DK)

the power levels where adjusted because of the AP's are placed very close to each other.

Hmm I had not seen that the Min and Max TX not where applied.

There is alot of 2,4 radios where it is ignored but all of the 5ghs radios ignores them apperently.

How can that be??

If I understand what you mean with removing all DFS channels correctly I would be stuck with only channels 36, 40, 44, 48 is that correct?

And what about the +channels should I deactivate those to ? 

Regards Jens 

Denmark = Europe

I have the list of non DFS channels from here

http://en.wikipedia.org/wiki/List_of_WLAN_channels

What is the reason for not using those channels ?

I am wrong.  Your channels are fine based on EU

We need to find out why your access points are not paying attention to the power settings.

OK

Yes that is very odd that they ignore the setting.

I have found out though that the 5Ghz radios has channels set manually wich also sets tha TX power manually, so they are alle 20.

The client has set the channels manually because of this discussion on apple.com

https://discussions.apple.com/thread/6601963?start=2025&tstart=0

Do you have any input on this "solution"

*Regards Jens

They need to allow the channels and power to be automatic.  The power needs to have a max of 18, otherwise that creates roaming problems.

OK I will inform the client,and make the required changes.

What do I do about those AP's that ignores the 2,4Ghz tx max.

The AP's are set to ARM assigned on the 2,4 radio

Regards Jens

I have just checked the AP list again and now all AP's exept one are at its MAX TX of 9.

Would also look like that the MAX is to low since they all use MAX.

But the distance between the AP's is some placeses below 7m with a wall between them.

What should the max be, to be sure that we do not an single AP with alot of power and clientmatch problems.

Set the MAX TX to 15 and minimum to 9. Its a good middelway for AP TX power in Schools in Denmark, Bulding materials etc will have an effect on this.

Thank you I will inform my customer and get these changes implemented

The changes are made, and the AP's seem to find a TX level of 12 to 15 so the levels seem fine.

The AP util/Noise/errore page under Controller monitoring also looks better now.

I have told the customer to test the roaming the next couple of days, and report back.

Hi

The customer has done some testing now, and they still see the problems described in the first post.

IPad simply drop the connection sometimes when roaming, and sometimes need resetting WIFI on the IPad in order to connect again.

Regards Jens

Please post the list of the access points again with the power and utilization.