Frequent client disconnection on specific AP's

[TGF_Cisco]

Hi

There are frequent disconnections only for a few clients connecting on specific floors.

Seems to be something to do with the access point or the path ..

The signal strength drops intermittently

what would be the steps to isolate the issue                  

[Dave Anthony David]

Did you check the interference on that specific floor?

You can use inSSIDer software to check the channels, signal strength.

[TGF_Cisco]

Discovery phase statistics
- Discovery requests received.............................. 10
- Successful discovery responses sent...................... 10
- Unsuccessful discovery request processing................ 0
- Reason for last unsuccessful discovery attempt........... Not applicable
- Time at last successful discovery attempt................ Mar 29 17:38:09.190
- Time at last unsuccessful discovery attempt.............. Not applicable

Join phase statistics
- Join requests received................................... 5
- Successful join responses sent........................... 5
- Unsuccessful join request processing..................... 0
- Reason for last unsuccessful join attempt................ Not applicable
- Time at last successful join attempt..................... Mar 29 17:38:20.030
- Time at last unsuccessful join attempt................... Not applicable

Configuration phase statistics
- Configuration requests received.......................... 15
- Successful configuration responses sent.................. 5
- Unsuccessful configuration request processing............ 0
- Reason for last unsuccessful configuration attempt....... Not applicable
- Time at last successful configuration attempt............ Mar 29 17:38:20.221

--More-- or (q)uit
- Time at last unsuccessful configuration attempt.......... Not applicable

Last AP message decryption failure details
- Reason for last message decryption failure............... Not applicable

Last AP disconnect details
- Reason for last AP connection failure.................... Data transfer message received from an unsupported AP

Last join error summary
- Type of error that occurred last......................... AP got or has been disconnected
- Reason for error that occurred last...................... Data transfer message received from an unsupported AP
- Time at which the last join error occurred............... Mar 29 17:12:04.596
                                                                                Ethernet Mac : c8:4c:75:61:11:da  Ip Address : 172.19.6.21

Could this be causing some issue?? It had been working fine but all of a sudden there are disconnections.. Users are not able to connect for more than 5 mins.. 

Are there any debug commands that would be able to isolate the issue?

[Dave Anthony David]

Could you tell us what is the WLC model/version and model of AP you are using?

[TGF_Cisco]

Hello

I am using  AIR-LAP1142N-E-K9 (12.4(23c)JA) and  AIR-CT5508-K9 (7.0.98.0) on all the access points.

[TGF_Cisco]

There seems to be freqent disassociations

07/18/2012 15:26:17	18 min 25 sec	host/L05558		2c-ap5-beg	Ctr1	Xx> Main > 2C	YY-users	802.11g	2.3
07/18/2012 15:21:16	5 min 0 sec	host/L05558		2c-ap6-mid	Ctr1	Xx> Main > 2C	YY-users	802.11g	1.3		New association detected
07/18/2012 15:11:15	10 min 0 sec	host/L05558.		2c-ap5-beg	Ctr1	Xx> Main > 2C	YY-users	802.11g	8.4		New association detected
07/18/2012 15:06:15	5 min 0 sec	host/L05558.		2a-ap3-beg	Ctr2	Xx> Main > 2A	YY-users	802.11n_2.4GHz	<0.1		No longer seen from controller
07/18/2012 14:56:14	10 min 0 sec	host/L05558.		3a-ap8-beg	Ctr2	Xx> Main > 3A	YY-users	802.11n_2.4GHz	<0.1		New association detected
07/18/2012 14:51:14	5 min 0 sec	host/L05558.		2a-ap3-beg	Ctr2	Xx> Main > 2A	YY-users	802.11n_2.4GHz	<0.1		New association detected
07/18/2012 13:50:33	55 min 40 sec	host/L05558.		3a-ap8-beg	Ctr2	Xx> Main > 3A	YY-users	802.11n_2.4GHz	0.2		Disassociation detected
07/18/2012 13:45:32	5 min 0 sec	host/L05558.		2a-ap3-beg	Ctr2	Xx> Main > 2A	YY-users	802.11n_2.4GHz	<0.1		New association detected
07/18/2012 13:25:30	20 min 1 sec	host/L05558.		3a-ap8-beg	Ctr2	Xx> Main > 3A	YY-users	802.11n_2.4GHz	0.2		New association detected
07/18/2012 13:20:30	5 min 0 sec	host/L05558.		2a-ap4-end	Ctr2	Xx> Main > 2A	YY-users	802.11n_2.4GHz	<0.1		New association detected

[Leo Laohoo]

What is the signal strength the clients are seeing the wireless?

What radio?

[TGF_Cisco]

Disconnections are happening on 802.11n 2.4GHZ primarily but not restricted to that frequency. Please check the same log given previously.

Signal strength visibly drops when I try to connect on Wifi in that floor.

What else could I run to diagnose the issue?

[Leo Laohoo]

Disconnections are happening on 802.11n 2.4GHZ primarily but not restricted to that frequency.

Sounds like a combination of channel interferrence (as 2.4 Ghz has only 3 non-overlapping channel) and low wireless signal.

Can you describe the physical location of the clients in relation to the WAP?

Are the clients in one floor and the WAP in another floor?

Are the clients in one side of the building and the WAP in another side of the building?

[TGF_Cisco]

Let me give a more precise scenario

The problem I am assuming only exists in the 8th floor . No other complaints.

2 WAP-  8A- Beg, 8A -Mid

1. 8A- Beg - connecting to controller 1 - On controller 1 "n" is enabled on 5 GHZ and not enabled on 2.4 Ghz
2.  8A -Mid- Connecting to controller 2 - on controller 2  "n" is enabled on 2.4 Ghz  and not enabled on 5 Ghz

This is how we got this implemented long back and had no issues so far until a month ago.

Will this cause an issue? Which is the preferred way of setting n parameters? I guess it would be best to enable n on both the frequencies? I would like to go more in depth about configuring n parameters and fine tuning them so that we dont face such issues again in other floors and hope to resolve the current issue.

thanks

[Reginald Pugh]

How many users?.  Are they startng to bring on more devices/count ? See if there are other SSIDs stronger in the area. If you have 802.11n enabled on 2.4GHz this can be a problem- less channels to work with .-Interference?

[fbarboza]

Hi ,

Please upload the show msglog of the WLC, the show run-config and let us know the WLAN with the issue and the access point name or MAC address where the issue is occuring.