Hello Cisco Community,
I have two pairs of Cisco 8510 Controllers with software version: 8.5.171.0. These Controllers generate more than 50.000 of the following log messages per hour:
[SA]apf_utils.c:219 Could not check supported rates. Invalid Supported Rates from station . Length :0. Mobile MAC: 00:c0:af:11:22:33
Initially I thought that this must be a client problem, because the message indicates that the client is using a rate which is not configured or supported by the Controllers. But during investigation I noticed that this issue affects many, many different types of clients. The log message does not name the affected access point, frequency band or SSID.
I checked 30 log messages an all of them affected clients in a specific SSID in the 2.4 GHz band. Many different access points and areas are affected. The sample included approximately 20 different clients and at least 4-5 different device types (MAC OUI from different vendors).
Data rates 1-11 Mbps are "disabled". 12 Mbps is "mandatory" rate and all rates above are "supported".
I selected an area where the log stated that more than three clients use the unsupported rates. I converted one AP to Sniffer mode and captured the specific channel. I filtered on the specific clients which I saw in the Syslog messages and data rates below 12 Mbps (wlan.addr == xx:xx:xx:xx:xx:xx && wlan_radio.data_rate < 12).
All frames with less than 12 Mbps which were captured are Probe Request Frames with the SSID name and broadcast destination address. They were send with 1 Mbps, which shall be normal behavior for these frames.There were no low data rate frames, beside these Probe Requests in the pcap file, but the Controllers created log messages related to "invalid supported rates" at the same timeframe. The timestamps of the logs and Probe Requests did not match. There were many more Probe Requests than log messages.
So the question is why do the Controllers spam the log servers with these messages when there are no (data-)frames with invalid supported rates in the air (capture file)?
As far as I know there is no possibility in AireOS to filter specific messages. Log level is already set to "Errors". Log "discriminator" is not available.
Do you have any idea what is causing that problem and how to solve it? Or any idea how to work around this issue?
||| Please rate helpful posts. Thanks! |||
