3802i AP will not power on unless CDP is enabled, but that spams switch logs with duplex mismatch

[keithsauer507]

I found one of our 18 AP's was cycling red, green, blue on the LCD.  I enabled SSH on the AP and saw in the logs that it seemed to indicate the PoE negotiation was failing (LLDP).  The other end is a Cisco 3750X with both CDP and LLDP enabled globally, but on a few of the 3802i AP ports the command no cdp enable is on, and working fine for many of these AP's.  For some reason I had to go into this interface and run cdp enable and now this particular 3802i AP negotiated up from 15 watts to 30 watts and the radios became active.

I'm not sure why some of these AP's need CDP and some do not.  Now my switch is spamming me in the logs which is why I turned CDP off on this AP in the first place.  I read this is a bug.

%CDP-4-DUPLEX_MISMATCH: duplex mismatch discovered on GigabitEthernet5/0/8 (not half duplex), with 1600mdAP3 GigabitEthernet0 (half duplex). (ptn-access-c-5)

The controller is a 5508 WLC running 8.3.141.0.

Any way to keep CDP enabled but to stop that logging?  I think I can just disable all logging on that port.  

[Karsten Iwen]

It would be better to fix the root cause of this problem. If I remember right there was a bug causing this in your release and some of the following releases. And 8.3.141.0 is already deferred and you should move away from that release. 8.5.140.0 could be more suitable for your needs.

[keithsauer507]

I'm seeing it looks resolved in 83 mr5 (8.3.150.0) which was just released today.  The release notes are not yet linked to the download page, but by guessing the URL (based on the previous release URL) I found the notes here:

https://www.cisco.com/c/en/us/td/docs/wireless/controller/release/notes/crn83mr5.html

The bug is listed in Table 15, Resolved Caveats:

CSCvi02106

CDP-4-DUPLEX_MISMATCH log is seen when 2800/3800 & 1560 APs are connected to a Cisco Switch

I was thinking of going to 8.3.150.0 or 8.5.140.0.  Our environment is mixed between the 3502 and 3802i lightweight access points.

Anyway I downloaded both releases for now and will research further and try to decide which train I want to stay on and schedule install for Saturday 4/27.

[Leo Laohoo]

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@keithsauer507 wrote:

I was thinking of going to 8.3.150.0 or 8.5.140.0.  Our environment is mixed between the 3502 and 3802i lightweight access points.

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This is a known bug. 

8.5.140.0 still support 3500 APs.  

Recommend you consider going to 8.5.140.0 due to stability.

[keithsauer507]

I was considering the 8.5 train as well, but as far as the bug CSCvi02106 goes, it is not addressed in the release notes for 8.5.140.0.  And according to the bugs, its not fixed in any 8.5 release.

Right now I have the switch logs changed to error, which looses some visibility.

Known Fixed Releases:

(3)

8.3(146.1)

8.3(144.8)

8.3(140.5)

[patoberli]

Will this be an issue for you? I mean it's just a cosmetically issue and has no influence on the daily usage. In my case I never saw this message with 8.5.140.0 and many 2802i running attached to Cisco switches.

[keithsauer507]

Wel it floods the switch logs making it impossible to see important messages, especially if it drops those messages out of the log buffer.  So I have to set the logging to only show errors, limiting the level of detail that we would rather see with warnings or debugging.

We have 3802i AP's so although you are not seeing the issue, you are not using the same model AP's that we are.  I certainly could go 8.5.140 fingers crossed, but if its not resolved I'm not sure its as wise to go DOWN versions, so downgrade to 8.3.160 from 8.5.140.  That 8.5 was released in November 2018, I would think we should be due for a .150 soon being that its almost May.

[patoberli]

Here is the beta thread for the successor of 8.5.140.0: https://community.cisco.com/t5/other-wireless-mobility-subjects/8-5-mr5-interim-build-availability/td-p/3832744
The builds are "ready for production" based on Cisco terminology. So you could download it there.

[patoberli]

I also back Leos suggestion for going to 8.5.140.0. Running very stable and is the last train (8.5) that supports the 3500 series.

[keithsauer507 · Accepted solution]

We went to 8.3.150.0 on our 5508 WLC this past weekend with no issues at all.

There are no more CDP duplex mismatch errors on Cisco switch logs from 3802i AP's.

So far we are up for 3 days, 21 hours and 54 minutes.

I just have one AP out of 18 showing connected via PoE/Medium Power (15.4 W) and it looks like because the switchport that AP5 was connected to had the no cdp enable command on it (to prevent the CDP duplex mismatch switch logs).  I ran cdp enable on that switchport and this one access point came to life and went to full power.

We have 9 3802i AP's and 9 3502i AP's in our environment.