WLAN Clients sometimes lose association with Cisco 1242AG AP

[Frank Anstoetz]

Hi WLAN experts,

our customer is using 1242AG APs (SW 12.3(8)JA2) in a warehouse environment. WLAN clients are handheld scanners. For a couple of weeks they observed that clients lose their association with some of the APs. This problem seems to exist for many handhelds and in at least four different areas of the warehouse. When analyzing the "sh tech" of one affected AP we found that "power save" mode is on for all clients, so we suspect that the problem might have something to do with clients resuming from power save and losing their association then. Does anybody have experience with similar problems?

Thanks & best regards,

Frank.

[Dhiresh Yadav]

Hi,

What do you see in "sh logging" when this happens ? I assume you dont have any controller.

Regards

Dhiresh

[Frank Anstoetz]

"sh log" on one of the affected APs looks like this:

---snip---

Oct  6 04:13:56.348: %DOT11-6-ROAMED: Station 2002.af29.ffec Roamed to 001b.54ec.8660
Oct  6 04:13:56.349: %DOT11-6-DISASSOC: Interface Dot11Radio0, Deauthenticating Station 2002.af29.ffec Reason: Disassociated because sending station is leaving (or has left) BSS
Oct  6 04:13:59.552: %DOT11-6-ROAMED: Station 2002.af29.b8a6 Roamed to 001b.54ec.82b0
Oct  6 04:14:24.229: %DOT11-6-ASSOC: Interface Dot11Radio0, Station   2002.af29.5208 Reassociated KEY_MGMT[NONE]
Oct  6 04:14:40.956: %DOT11-6-ROAMED: Station 2002.af29.5208 Roamed to 001b.54ec.82b0
Oct  6 04:14:40.956: %DOT11-6-DISASSOC: Interface Dot11Radio0, Deauthenticating Station 2002.af29.5208 Reason: Disassociated because sending station is leaving (or has left) BSS
Oct  6 04:15:26.371: %DOT11-6-ASSOC: Interface Dot11Radio0, Station   6021.c0cd.d0e1 Reassociated KEY_MGMT[NONE]
Oct  6 04:15:43.161: %DOT11-6-ROAMED: Station 6021.c0cd.d0e1 Roamed to 001b.54ec.82b0
Oct  6 04:15:43.161: %DOT11-6-DISASSOC: Interface Dot11Radio0, Deauthenticating Station 6021.c0cd.d0e1 Reason: Disassociated because sending station is leaving (or has left) BSS
Oct  6 04:16:04.564: %DOT11-6-ASSOC: Interface Dot11Radio0, Station   2002.af29.ffec Reassociated KEY_MGMT[NONE]
Oct  6 04:16:21.254: %DOT11-6-ROAMED: Station 2002.af29.ffec Roamed to 001b.54ec.82b0
Oct  6 04:16:21.255: %DOT11-6-DISASSOC: Interface Dot11Radio0, Deauthenticating Station 2002.af29.ffec Reason: Disassociated because sending station is leaving (or has left) BSS
Oct  6 04:16:33.148: %DOT11-6-ASSOC: Interface Dot11Radio0, Station   2002.af29.b3da Reassociated KEY_MGMT[NONE]
Oct  6 04:17:02.237: %DOT11-6-ROAMED: Station 2002.af29.b3da Roamed to 001b.54ec.8660
Oct  6 04:17:02.237: %DOT11-6-DISASSOC: Interface Dot11Radio0, Deauthenticating Station 2002.af29.b3da Reason: Disassociated because sending station is leaving (or has left) BSS
Oct  6 04:17:09.728: %DOT11-6-ROAMED: Station 2002.af29.5e86 Roamed to 001b.54ec.8660
Oct  6 04:17:09.728: %DOT11-6-DISASSOC: Interface Dot11Radio0, Deauthenticating Station 2002.af29.5e86 Reason: Disassociated because sending station is leaving (or has left) BSS
Oct  6 04:17:12.878: %DOT11-6-ASSOC: Interface Dot11Radio0, Station   2002.af29.ffec Reassociated KEY_MGMT[NONE]
Oct  6 04:17:29.568: %DOT11-6-ROAMED: Station 2002.af29.ffec Roamed to 001b.54ec.82b0
Oct  6 04:17:29.568: %DOT11-6-DISASSOC: Interface Dot11Radio0, Deauthenticating Station 2002.af29.ffec Reason: Disassociated because sending station is leaving (or has left) BSS
Oct  6 04:17:50.660: %DOT11-6-ASSOC: Interface Dot11Radio0, Station   2002.af29.ffec Reassociated KEY_MGMT[NONE]
Oct  6 04:18:10.862: %DOT11-6-ROAMED: Station 2002.af29.5e86 Roamed to 001b.54ec.8660
Oct  6 04:18:10.862: %DOT11-6-DISASSOC: Interface Dot11Radio0, Deauthenticating Station 2002.af29.5e86 Reason: Disassociated because sending station is leaving (or has left) BSS
Oct  6 04:18:31.332: %DOT11-6-ROAMED: Station 2002.af29.ffec Roamed to 001b.d444.2a40
Oct  6 04:18:31.332: %DOT11-6-DISASSOC: Interface Dot11Radio0, Deauthenticating Station 2002.af29.ffec Reason: Disassociated because sending station is leaving (or has left) BSS
Oct  6 04:18:45.254: %DOT11-6-ASSOC: Interface Dot11Radio0, Station   2002.af29.5e86 Reassociated KEY_MGMT[NONE]

---snap---

I have recommended to enter some debugs carefully to get more information why this frequent deauths are happening.:

debug dot11 events
debug dot11 packet
debug dot11 aaa authenticator process
debug dot11 aaa authenticator state-machine

Customer btw told me that problem is not seen on clients where they disabled power save mode. So it must be related to power save in some way which also gives us a workaround here. However i would still appreaciate ideas what might be the cause of the problem as power save is part of the standard and should not lead to disassociation...

[Dhiresh Yadav]

Hi,

I will ask you to open a TAC case if you want to run more indepth debug commands but "sh logging" is self explanatory.

Oct  6 04:18:10.862: %DOT11-6-ROAMED: Station 2002.af29.5e86 Roamed to 001b.54ec.8660
Oct  6 04:18:10.862: %DOT11-6-DISASSOC: Interface Dot11Radio0, Deauthenticating Station 2002.af29.5e86 Reason: Disassociated because sending station is leaving (or has left) BSS

It is the client which has roamed first and not AP deauthenticated it before that. 

Any client after waking up..can decide to re-associate or associate to the same AP. If it is going to some other AP then its client decision.If you are sure that disabling Power save mode helps then its good. I think to check , you can wait for any client to wake up and see the "sh logging" and "sh dot11 wireless association mac-address" of that AP and the near by AP to see where it joined exactly. If it is not joining anywhere , then you will need to see debugs it sent re-association/association request to any AP.

Regards

Dhiresh