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Showing posts with the label WLC

Cisco WLC: Per-client Packet Capture

Sometimes, you just want to capture the packets associated with a particular wireless client and see what the heck is going on with that client. Often, it may not be practical to do an over-the-air packet capture, as perhaps the client is at a remote location or just just don't have access to a wireless capture card.


I recently had an issue trying to understand why an Android device that I was trying to 'on-board' using Cisco's ISE wouldn't access the Google Play store. I desperately wanted to capture the over-the-air frames from the client to have a look at what the client was doing.


After a quick 'Google' around, I found an intriguing set of Cisco WLC CLI commands that allow a packet capture of traffic for a wireless client. This can all be done without having to change the AP mode, or reboot the AP etc. In summary, the feature allows packets to be captured for a specified wireless client that is sending/receiving traffic to/from an AP. The AP will continue …

Cisco DTLS License

The whole area around the free DTLS license that can be obtained for Cisco WLCs has always been a bit of a head-scratcher for me.

I'm never sure whether I need the additional license or I already have it to be honest. Anyhow, today on my home lab I tried to have a look at some features which required DTLS between the AP & WLC, only to find that my 2504 did not support the option (the option was grayed out).

After some digging around on the Cisco forums, I found that the following licensing link can be used to obtain the DTLS entitlement license with very little fuss at all:

https://tools.cisco.com/SWIFT/LicensingUI/loadDemoLicensee?FormId=4090

The information to be entered can be found on the WLC inventory page. Only the model number & serial number are required.

Within seconds, I had the license (which can be downloaded directly or sent by email) and applied it to my 2504 (Management > Software Activation > Commands > Install License)

Issue: Having to log back in on Apple devices on a Cisco wireless guest network

I'm documenting this for my own reference as much as anything, to avoid having to look this information up (yet again).

(This description assumes that the use-case is for a guest network, but will apply to any layer-3 authenticated wireless network)

It is a common occurrence on Cisco wireless networks (using a WLC of some type) to have complaints from guest users that they have to keep logging back in to the guest network after their device has gone in to sleep mode. They are often put in to sleep when they are enveloped in some type of holder or covering system that has a built-in magnet to make them sleep when they are not in use (this is very typical on iPad holders/covers).

The reason for the annoying issue of having to log back in to the guest network is that the WLC has a user idle timeout setting which expires (by default) after 5 minutes. So, when a device is put in to sleep mode, the WLC will not hear from it for a while and then after  5 minutes will terminate its sessio…

Fast SSID Change - Out Of The Shadows

There are many configuration settings on a piece of networking kit that are just 'there'.

They sit there year after year just minding their own business being a quiet little chunk of configuration sitting in their default state not doing anyone any particular harm. Then, occaisionally, you come across some obscure case that causes you to actually pay attention to what exactly that particular setting is 'bringing to the party'.

One particular instance I came across recently is the 'Fast SSID Change' setting on a Cisco WLC.

From memory, it's been sat there for quite a while on many of the controllers I've installed, sitting dutifully in its default state of 'Disabled'. I've never really paid it much attention as it doesn't (on the face of it) seem to cause anyone any particular problems.

However, I recently ran in to a situation where a customer had some Apple iPads that he wanted to connect to an SSID that was mapped to an internal corpo…