I believe that our AP's are being affected by DFS but need a way to "prove" this issue before getting any kind of change enacted. Using Wireshark, is there anyway that I can watch the network traffic for signs that the AP or associated clients are being affected by DFS?

I'm curious to know if there's some combination of Wireshark display filters that might help with this.


  • Did any answer help you? If so, you should accept the answer so that the question doesn't keep popping up forever, looking for an answer. Alternatively, you could provide and accept your own answer.
    – Ron Maupin
    Aug 15 '17 at 4:05

Your WLC should be able to provide this information, or you may need to hire a company to use equipment to check on this for you. You could try to look in the WAPs to see if there are any of those channels which are being skipped, but you are really going to need to know what you are doing.

DFS is something that will happen in the hardware. You could only see anything in a capture if a WAP was using a DFS channel with associations, and it detected a radar signal, then it broadcasts an 802.11h channel-switch announcement. That is not something it constantly does, so the timing of the capture is important.

  • Do you know how I filter for this in wireshark? I can leave the capture running with the appropriate filter for a while. I will also see if I can check the WLC logs.
    – Andrew
    Oct 4 '16 at 16:55
  • It's not like this happens all the time. It should happen once, after a WAP is powered up, and only if there are associations to the WAP. After that, the WAP just ignores anything on that frequency. This is not a very accurate way to do it. Your WLCs should be able to tell you about this, or you could hire a company with specialized equipment for a couple of hours.
    – Ron Maupin
    Oct 4 '16 at 16:59

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