3600 AP’s With AC Modules Randomly Rebooting

[dan ricketts]

Has anybody noticed 3600 AP’s With AC Modules Randomly Rebooting?

Cannot seem to narrow down the issue.  Looks like it could be one the following issues, the AP is not requesting enough power from the switch or the switch is not keeping up with the power demands of the AP’s or bad code (Currently running 7.6.130)

We have 80 AP’s only 5 are having the issue.   AP models in our wireless environment 3600’s w AC mod, 3700’s, and 1242’s.  Access switches are 4510 with SUP 8E's and dual 6000 Watt power supplies.

Tried the following:

I hardcoded the power to the AP’s and that did not work.

Switched AP’s to the backup controller

Switched the AP’s to different blades

Switched the AP to different switch

Replaced patch cable to AP

Replaced AP

Removed the AC Modules and of course the AP stopped rebooting

[Scott Fella]

I have not seen that issue to be honest. I also run the 3602 with an AC module at home.  Have you tried to reseat the module and or see if you see any AP crash logs?

-Scott

[dan ricketts]

Hello Scott,

Thank you, for the feedback.  Yes, I reseated the AP module and I replaced it.  The crash logs are  clean.

[George Stefanick]

I have some in production and we haven't notice anything in the logs. But I also haven't gone looking for trouble either :) 

How do you know they are having a problem ? Logs ? 

[dan ricketts]

I first noticed the issue while walking through my office.  I saw the AP turn off and back on.

I am using SolarWinds to monitor the up-time of the AP's.  You can also see the up time of the AP's on the controller.  The logs are clean.

[dan ricketts]

Notes from Tac:  (I really don't want to go to 8.0 Code yet)

I have receive the files from the switch and I was able to notice that the access points are connected to several ports on the switch and they are being powered via PoE.

The power negotiation looks ok on some access points that have up to 20 watts of power but there are some access points that are only obtaining 15.4.

These model of access points require up to 20 watts of power but it depends on what they are doing, radios enabled etc; this means that it they are getting 15.4 watts they should continue to work just fine but the story changes when they have the ac module installed since they require more power to keep the module up so the minimum increases.

I believe the issue might be with either the switch not providing enough power or the access point not requesting enough for its module, bringing itself down. There are several bugs regarding the AC module on the 7.6 version so the first recommendation that I can provide at this point is the following:

- Is there a way to upgrade the WLC to 8.0?

- Is it possible to remove the AC module on several APs and test if the problem is only present with access points with the module?

If we can determine that the module is the cause of the issue then we can investigate this further on 7.6 if necessary but if this has already been addressed by the developers, a fix might already been in place on the new versions. This is why an upgrade is recommended.

Let me know your thoughts and how you would like to proceed.

I will be waiting for your reply.

[Leo Laohoo]

The switch is a 4500 chassis?  By default, 4500/6500 chassis have link state logging status disabled.  You may want to enable the ports of the APs so if there are any changes to the links, like power, you'll see it in the logs. 

Can you post the output to the command "sh interface <BLAH>" to one of the APs where the module is rebooting?  I want to first determine if you've got a cabling issue or a line fault. 

Next, can you also post the output to the command "sh module"?  I want to determine if your line cards support TDR. 

[dan ricketts]

Replacing the A/C Modules solved the issues.  Cisco replaced the A/C Modules and the problem stopped.