Controller Based WLANs

Why do Broadcom 802.11n clients continuously associate and disassociate?

Question: Why do Broadcom 802.11n clients continuously associate and disassociate?

 

Product and Software: This article applies to all ArubaOS older than 3.3.2.22 or 3.4.0.6.
Symptom

802.11n clients with Broadcom chips have a connectivity issue when more than eight clients are associated on a single 11n AP, such as AP125. The problem often happens in an environment that has many clients.


The client continuously associates and disassociates.


(config) #show ap debug mgmt-frames client-mac 00:24:2c:5b:3a:a5
Traced 802.11 Management Frames
-------------------------------
Timestamp stype SA DA BSS signal Misc
Sep 3 14:04:58 assoc-resp 00:1a:1e:1c:b5:70 00:24:2c:5b:3a:a5 00:1a:1e:1c:b5:70 15 Success
Sep 3 14:04:58 assoc-req 00:24:2c:5b:3a:a5 00:1a:1e:1c:b5:70 00:1a:1e:1c:b5:70 0 -
Sep 3 14:04:42 disassoc 00:24:2c:5b:3a:a5 00:1a:1e:1c:b5:70 00:1a:1e:1c:b5:70 0 Class 3 frames from non associated STA
Sep 3 14:04:27 assoc-resp 00:1a:1e:1c:b5:70 00:24:2c:5b:3a:a5 00:1a:1e:1c:b5:70 15 Success
Sep 3 14:04:27 assoc-req 00:24:2c:5b:3a:a5 00:1a:1e:1c:b5:70 00:1a:1e:1c:b5:70 0 -
Sep 3 14:04:11 disassoc 00:24:2c:5b:3a:a5 00:1a:1e:1c:b5:70 00:1a:1e:1c:b5:70 0 Class 3 frames from non associated STA
Sep 3 14:03:26 assoc-resp 00:1a:1e:1c:b5:70 00:24:2c:5b:3a:a5 00:1a:1e:1c:b5:70 15 Success
Sep 3 14:03:26 assoc-req 00:24:2c:5b:3a:a5 00:1a:1e:1c:b5:70 00:1a:1e:1c:b5:70 0 -
Sep 3 14:02:25 assoc-resp 00:1a:1e:1c:b5:70 00:24:2c:5b:3a:a5 00:1a:1e:1c:b5:70 15 Success
Sep 3 14:02:25 assoc-req 00:24:2c:5b:3a:a5 00:1a:1e:1c:b5:70 00:1a:1e:1c:b5:70 0 -
Sep 3 14:01:19 assoc-resp 00:1a:1e:1c:b5:70 00:24:2c:5b:3a:a5 00:1a:1e:1c:b5:70 15 Success
Sep 3 14:01:19 assoc-req 00:24:2c:5b:3a:a5 00:1a:1e:1c:b5:70 00:1a:1e:1c:b5:70 0 -
Sep 3 14:00:49 assoc-resp 00:1a:1e:1c:b5:70 00:24:2c:5b:3a:a5 00:1a:1e:1c:b5:70 15 Success



The association time for most of the clients on the same AP is less than 2 minutes.
(A3600) #show ap association ap-name nap5010
Association Table
-----------------
Name bssid mac auth assoc aid l-int essid vlan-id tunnel-id phy assoc. timenum assoc Flags
nap5010 00:1a:1e:25:90:10 00:26:bb:01:08:40 y y 8 10 nap1 222 0x1089 a-HT-40sgi-2ss 1m:10 2 WA
nap5010 00:1a:1e:25:90:10 00:26:bb:01:05:8e y y 10 10 nap1 222 0x1089 a-HT-40sgi-2ss 50s 2 WA
nap5010 00:1a:1e:25:90:10 00:26:bb:03:dd:2b y y 6 10 nap1 222 0x1089 a-HT-40sgi-2ss 8s 50 WA
nap5010 00:1a:1e:25:90:10 00:26:bb:02:f4:6f y y 12 10 nap1 222 0x1089 a-HT-40sgi-2ss 54s 2 WA
nap5010 00:1a:1e:25:90:10 00:26:bb:03:dc:e1 y y 11 10 nap1 222 0x1089 a-HT-40sgi-2ss 26s 31 WA
nap5010 00:1a:1e:25:90:10 00:26:bb:03:dd:49 y y 7 10 nap1 222 0x1089 a-HT-40sgi-2ss 1m:8s 50 WA
nap5010 00:1a:1e:25:90:10 00:26:08:eb:40:3a y y 13 10 nap1 222 0x1089 a-HT-40-2ss 12s 50 WA
nap5010 00:1a:1e:25:90:10 00:26:bb:01:08:36 y y 9 10 nap1 222 0x1089 a-HT-40sgi-2ss 41s 30 WA

 

If air packet capture can be done, look at the beacon packet. The channel number in the "Packet info" section does not match the primary channel in the "Additional HT Information" section of the beacon packet. In a normal situation, both channel numbers should be same.

 

955_002.jpg

 

 

 

Solution
This issue is a bug, and it has been fixed in ArubaOS 3.3.2.22 and 3.4.0.6.

 

Upgrade the controller to the latest code.

 

If you cannot upgrade, the temporary workaround is to disable HT completely.

Version history
Revision #:
1 of 1
Last update:
‎07-03-2014 04:40 PM
 
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