Cisco Aironet 1142N Roaming/Balancing Issues

[timmotools]

Hi,

The company I am employed by has recently purchased 2 Cisco Aironet 1142N WAP's to have about 60 clients connect to these.

At the moment we have all the clients connecting to only one AP and dont connect to the other. We turn off the first AP and all the clients connect to the second, but as soon as the first has booted all of the clients connect back to the first.

There are currently clients close to both AP's.

Both AP's are using the same SSID, using Channel Negotion and selecting different channels automatically. DHCP server is not running as it is hosted on an internal server. And we are using WPA/PSK cypher.

From what I was reading, we cant use the load balancing provided on the router via the Aironet Extentions because the clients we use dont haveCisco wifi cards (these are Intercard readers with a fixed wifi card and no way to change or include software).

We have also been told to restrict the bandwidth to 2Mb/s by another company who has done the same thing.

So my question is, why are they connecting to one router? Is there something that we may have overlooked? Has someone had simmilar issues?

I have searched many questions but havn't been able to find a solution.

On the second router we get the following errors in the event log:

Sep 18 20:08:52.967

<SPAN style="COLOR: #009933" mcestyle="color: #009933;"><IMG border=0 src="http://192.168.2.11/images/event_warning.gif" width=11 height=11 mcesrc="http://192.168.2.11/images/event_warning.gif">Warning

Packet to client xxxx.xxxx.xxxx reached max retries, removing the client
Sep 18 20:08:52.964

<SPAN style="COLOR: #009933" mcestyle="color: #009933;"><IMG border=0 src="http://192.168.2.11/images/event_information.gif" width=11 height=11 mcesrc="http://192.168.2.11/images/event_information.gif">Information

Interface Dot11Radio0, Deauthenticating Station xxxx.xxxx.xxxx Reason: Previous authentication no longer valid

These error messages, when i searched them, are to do with Aironet Extentions but that has now been disabled and we are still getting them.

If you have any questions please ask me.

Regards

Tim

[Scott Fella]

Tim,

Since you only have two APs, I would set the channels manually on the AP's. for example, for the 2.4ghz set one to channel 1 and the other to channel 11. For the 5 ghz, set one to channel 56 and the other to 161. Of course you can set them to whatever, but just remember on the 2.4ghz to only use 1,6, or 11.

I would leave the data rates default if I were you for now. Depending on how large of an area you are covering, you can tweak that, but to only have 2mbps is not right.

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[timmotools]

Hi Scott

On the 2.4GHz band we are using channel 3 for the first AP and channel 9 for the second AP. For the 5GHz band we have it dissabled as it is not being used at this point in time but is there for future use.

We have the 2 AP's for a 300M area and provide access 64 Intercard clients.

Each Intercard client needs to communicate with a transaction server with no or very little delay and each reader only sends and recieves data when a card has been swiped. The size of the data sent is small. (been meaning to have a look with wireshark on the actual size of the data but havnt had a chance to ask the boss.) Also Intercard has told us that the maximum speed of the internal wifi card is 2Mb/s.

It was Intercard who suggested we have the data rate set to require 2Mb/s and leave everything else enable. This was to stop one client from hogging the bandwidth (not sure how but oh well). But with this we were getting clients loosing wifi connection on the first AP without connecting to the second AP. Now (after a bit of tweaking by my boss) we have no clients loosing connection. We have set require on 1Mb/s, enable on 2Mb/s and disable on all other speeds. But the problem here is we still dont have the clients connecting to the second AP while the first is active.

Should we go against what Intercard have told us and enable all data rates, or tweak them further? maybe enable 1 and 2Mb/s, disable all others and lower the range? any Ideas?

And should Aironet Extentions be enabled or disabled?

Regards

Tim

[mberin]

You need to set the access points to 1,6 or 11 that should help your bg spectrum, all other channels are overlapping.  Make sure that there are least amount of other wireless for the channel in the area.  Clients determine where they will roam which is usually a measure of signal quality SNR signal to noise ratio.  All other radios even your own in the same channel is interferring with your access points so make sure you do some rudimentary site surveys.  Macbooks have an airport cli command which does a simple site survey. 

Looks like the intercard is an 802.11b radio which will give you head aches.  They tend not to roam as easily and maintain connections even at degraded rates.  The best you can do is if your clients are fairly close is disable datarates below 11MB ensuring close proximity to the access points.

Hope that helps.

[Scott Fella]

Yeah just to add... Only use 1, 6 or 11. Better off using 1 and 11 since you have two AP's. 300M might be pushing the coverage unless it's wide open. Best practice is 25 clients per ap but if you don't have very much traffic then 40 or so is good. Have you checked to see if you have good coverage?

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