Cisco Support Community
Showing results for 
Search instead for 
Did you mean: 
Community Member

CAPWAP header size

I did a capture with wireshark on the port where our 3500 AP is connected and I have a ton of errors for the CAPWAP header.

The "Expert Info" Message is (Warn/Malformed): Wrong Calculate length (11) =! header lenght (15) ! (May be try to use Cisco Wireless Controller Support Preference ?)

I did a capture at the end of the day when I was the only one in the office (PC, iPhone, a couple of iPads) and I did it during the middle of the day with a good number of clients connected a lot more Apple products. It seems to have a lot more of those errors with apple devices. In fact, that is how I fist noticed it. I was trying to trouble shoot an AP that was dropping apple products.

Has anyone here encountered this problem and if so do you have a fix?

Community Member

CAPWAP header size

In Wireshark, go to the Edit Menu -> Preferences -> Protocols

Select CAPWAP and tick the box Cisco Wireless Controller Support.

Wireshark cannot decode the CAPWAP messages and will always throw a malformed error without this turned on. It's likely that it's not a real error.

You were most likely only seeing this with capwap-control plane traffic.

**Please rate if this answer was helpful. Thank you**

CreatePlease to create content