Controllerless Networks

Occasional Contributor II

High 5GHz utilization; no clients connected

Hi all,


I've done a search, but the results found didn't seem to be relevant to my particular situation, so please forgive me if I'm covering old ground.


I've just done a 3 AP deployment using Aruba 305s, but have noticed that at any given time, usually one, sometimes two (but rarely all three) APs report a high utilization in the dashboard (indicated on the home screen by three orange bars next to the relevant AP.)  Clicking on this will usually show 99 as the utilization for 5GHz (this will be a solid 99 for the full duration of the period, or sometimes it fluctuates.)


I understand that the 5GHz spectrum is shared, but I'm working in a cleanroom facility with shielded walls (in addition to solid concrete externally) as the company deals with nuclear medicines.  If there were a source of interference, it's not in-house (the facility is yet to open and no other electronic equipment is on-site yet), and as such, I'd expect all three APs to experience a similar level of interference simultaneously if it were external.



I've not done any further configuration of the devices other than to set their IPs, the IP for the virtual controller, each APs name/location and a single SSID.


Any tips on where to look next would be great - I've attached a screenshot showing the issue.


Thanks in advance!

Re: High 5GHz utilization; no clients connected

If you are seeing no clients but high radio utilization, make sure you don't have a lot of multicast traffic on your wired network. If so, the radios will/could be blasting out the multicast traffic which is consuming the air. Otherwise you may need to get in there with a spectrum analyzer and see if there is a noise source you can find. 

Jerrod Howard
Sr. Technical Marketing Engineer
Occasional Contributor II

Re: High 5GHz utilization; no clients connected

Thanks Jerrod, I'll check it out.


I'm far from a networking expert, but if there's no clients, could you help me understand why an AP would be sending out multicast traffic if there's nothing connected to send it to?


EDIT: A quick follow-up; I've looked for multicast traffic using Wireshark but it's minimal.

Guru Elite

Re: High 5GHz utilization; no clients connected

I think it is time for you to open a TAC case.  We would only be here guessing the obvious.  TAC could work with specifics...

*Answers and views expressed by me on this forum are my own and not necessarily the position of Aruba Networks or Hewlett Packard Enterprise.*
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Occasional Contributor II

Re: High 5GHz utilization; no clients connected

Thanks Colin, I'll do that!

Occasional Contributor II

Re: High 5GHz utilization; no clients connected

An update to this!


I've updated to Release from and have also limited TX power to 18, and am no longer seeing this issue.


Note that I had to update firmware manually; the auto updater didn't see a newer version.


Not sure which of the two resolved the issue, but something to try if anyone else is seeing the same problem!

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