Decrypt Errors occuring in WLC Log

Unanswered Question
Dec 11th, 2008
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Hi all,

we see a strange message in our WLC logs, which occurs quite often (>10 times a day):

Decrypt errors occurred for client [MAC-Adress] using WPA key on 802.11b/g interface of AP [MAC-Adress]

The MAC-Adresses of the affected clients are varying as well as the APs reporting the error.

The clients are Notebooks, Cisco IP-Phones and Nokia-DualBand-Phones.

Even more frequently we see the following message in the log:

%ETHOIP-3-PING_TRANSMIT_FAILED: ethoip_ping.c:227 send_eoip_ping: Failed to tx Ethernet over IP ping rc=5.

We use TKIP as Encryption and EAP-Fast as well as LEAP as Authentication (Cisco ACS).

The WLC is an 2106, the APs are 1242AG.

We don't recognize any problems placing calls or talking over these phones. It's just these messages in the log that concern me.

Anyone else got these messages (and hopefully fixed them :))



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jcosgrove Thu, 12/11/2008 - 05:44
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I get these as well. My laptop standard is the Dell 1490 card. I am using 1130AG as well as som 1200 ap's all running lwapp on WiSM controllers running 5.1.151 code.

I have not read a solution or known cause for this yet. I also can't seem to trace any client issues back to these messages as well so not sure if this is only an informational type message that happens under normal circumstances.

Hope someone has more insite into this or a cure if needed.

dennischolmes Thu, 12/11/2008 - 06:55
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Some clients support certain encryption cyphers and some support others. Verify that your clients are using what is configured on the controller for the SSID. For instance, WPA can be set for TKIP or AES and a key management scheme must be set. Verify that these all match the config on the client.

CFayNTAdmin83 Thu, 12/11/2008 - 07:01
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Hi Everyone, you can count me in as well for getting the decrypt errors. However the only difference is that I'm not using WPA on the network that this is happening on. The wlan that is reporting this for me is just a simple WEP key. I'm thinking this is related to encryption since TKIP is also based on RC4. I also have other WLANS where I use WPA2 Enterprise with AES (PEAP MS-CHAPv2) and I do not see the decrypt errors for those clients. Also, to further expand on this I haven't noticed any client problems either. Maybe this is a bug that doesn't cause denial of service. I'd love to get rid of them though! This is with a 4402 WLC and 1242AG AP's...

dennischolmes Thu, 12/11/2008 - 07:07
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It is related to encryption. See above.

kwonza Tue, 12/30/2008 - 10:17
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We have verified all of our encryption configurations on both WLC-WLANs and clients are matching. We continue to receive these errors on all of our controllers. Is this a bug? We are running the following code (

SJessulat_2 Tue, 01/13/2009 - 02:26
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Hi all,

i found out how to get rid of the following messages:

%ETHOIP-3-PING_TRANSMIT_FAILED: ethoip_ping.c:227 send_eoip_ping: Failed to tx Ethernet over IP ping rc=5.

The reason was another WLC, which was entered as a mobility neighbour but was turned off. If You delete this entry from the mobility group, the messages will no longer occur in the log.




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