DFS channel changes occuring with some frequency

[fraser_hess]

We have 40x AP330 in an office building in Denver. This week I discovered that we have having a number of DFS related channel changes the 5GHz band. According to the logs, in the last 30 days DFS has detected radar 59 times on 17 access points. Every 40MHz wide channel has been identified in the messages at least once. The data has a pattern that matches business hours. It never occurs on the weekend (for the last 90 days), it rarely occurs after business hours on the week days.

We are 7 miles from the edge of the nearest air force, around 10 miles to Centennial Airport (APA), and just over 12 miles to Denver International.

Is this a high instance of DFS channel changes? Are we too close to the AFB? If not, how would we go about finding the source? Our office is actually built on an old air force base but we'd assumed any radar was long gone.

Anyone else have experience with DFS they'd like to share?

[fraser_hess]

Thanks for these answers. We are running HiveOS 6.5r9a.

I think we will be dropping to non-DFS 20MHz wide channels. Next year we should have ac/ax hardware and we'll try again on a newer code base.

[samantha_lynn]

We generally don't recommend using DFS channels, for just this reason. Every time an emergency signal needs that channel, your client device will be moved to a different channel, regardless of how far along that device is in sending or receiving data. Being close to airports and military will increase your changes of getting interrupted on a DFS channel, but this could also happen if an emergency vehicle drives past your location. So even without your nearby neighbors, DFS isn't ideal as you are at risk for interruptions with no warning. We can choose to use any channels and disable DFS channels so this isn't a risk? Or is there a reason you need to use the DFS channels as well?

[AnonymousM]

Fraser,

What HiveOS are these AP330s running? Aerohive made some vast improvements to false detections with the later code revisions (8.x - which the older .11n APs may not support unfortunately).

But to answer your questions, we've got a myriad of APs (lots of AP230s now) scattered throughout the country and when we were running the older 6.x codes, it was almost not possible for us to use the DFS channels. As we've migrated sites to the 8.x code train, we've seen vast improvements in the false detection of DFS events. They still happen, but no where to the extent of before