This is not meant to be a bash post or anything like that, but more of a “public service announcement” for anyone who might have to deal with this scenario in the future and cannot find a ton of info online; I know I couldn’t.
I was on a work-related call today regarding a project to bring in a vendor that was going to leverage the 5 GHz Wi-Fi channels that we typically leave out of our channel plans for their own autonomous Wi-Fi network to provide connectivity for their client devices. Those unused channels are in the UNII-2e (or UNII-2C for the initiated) band, specifically 112-132. That’s not a small amount of spectrum that we give up, but we do it as part of our partnership with vendors who need the spectrum in order to provide their own networks for their solutions. I know what you’re thinking… We picked those specific channels because traditionally they’ve been known to have more problems than others with DFS events, but I can neither confirm nor deny that! Those channels were selected before my time here so I’ll claim plausible deniability on that one :). Anyway, nothing new for us there and back to the story…
It was noted on the call that Meraki does not allow channels 116-132 to be used and my antennas (wireless pun) immediately went up. “Hold up, flag on the play! That CAN’T be right. Are you sure?” is what I was thinking to myself. Admittedly, while I have worked on some Meraki tasks and troubleshot a few things since starting here, I have not completely delved into the world of Meraki to say much, if anything, definitively about their solution. So I kept my mouth shut and scrambled to log into our Meraki dashboard, trying to confirm what was said by someone who wasn’t even on our team; surely they had to be mistaken. And then I saw it…
First, I clicked on the “Channel width” settings (screenshot below) because it was the first thing I saw under the “5 GHz radio settings” when creating a new profile under “Wireless -> Radio Settings”. This suggested to me that at least some of those channels should be allowed since there are 25 x 20 MHz channels in the 5 GHz band (if you don’t count the 3 additional channels that UNII-4 provides) and (25 – 5) is still 20 in my world… Despite what the world has become. Odd, but not exactly what I was looking for.
Second, I found this section right underneath the channel width section so I clicked on the green link to look at the channels used by Auto Channel.
And there it was… Channels 116-132 greyed out and not selectable. Surely, this has to be a mistake I thought. Prior to my start in Wi-Fi (I think sometime around 2006), the Terminal Doppler Weather Radar (TDWR) channels were restricted for use by the FCC, as there were claims that some wireless devices (not necessarily Wi-Fi) were causing interference to the TDWR systems. However, those channels were eventually allowed for use again in 2014 in this FCC Report and Order and until today, I haven’t come across another Wi-Fi vendor that doesn’t allow those channels to be used. We asked for some time to confirm and off I went to research.
As I typically do for questions that I cannot find the answers to, I reached out to the community. I went to the #meraki channel on the Wi-Fi Pros Slack and asked if anyone knew what was up. I got replies from a few people, including a helpful Meraki employee who confirmed what we saw. That employee additionally offered that to use those channels, firmware would have to be developed to enable them and their APs would also have to be recertified to use them which takes time and costs money. There’s also this Cisco blog that backs up that claim if you’re interested. It was also noted in that thread, that you can see the discrepancy in supported frequencies if you look close enough at the AP datasheets. I know I would have missed that otherwise!
Alright, that sucks… But why 116 and 132 also? While 132 does indeed fall into the unsupported range, 116 should technically be “supported” by the way the datasheet reads, right?
Well, I found this snippet in paragraph 14, under the Terminal Doppler Weather Radar Interference Issues section of that same FCC R&O:
grantee will provide owners, operators and installers of these devices with instructions that a master or client device within 35 km of a TDWR location must be separated by at least 30 megahertz (center-to-center) from the TDWR operating frequency and procedures for registering the devices in an industry-sponsored database
116 and 132 both fall into that 30 MHz of frequency (center-to-center) rule which is likely why Meraki chose to disable those channels, but that begs the question. Why aren’t other vendors doing this then? Am I missing something? I have my thoughts and opinions about this, but as I mentioned at the beginning, this is not meant to be a bash post, just simply a PSA. Consider yourself warned!
If things change in the future or I’m wrong about something, I’ll be sure to update this post.
Less than 24 hours after publishing this post, I received information from our account team that they have enabled channels 116 and 132 for us. Additionally, they are working to verify that they can enable the TDWR channels (120, 124, and 128) and that it should only take about 2 weeks if so; no new firmware or recertification required. And unofficially, all Meraki customers will be able to take advantage of this at some point soon as well!
Well, how about that folks? I guess some stories CAN have a happy ending. I also want to say that after writing this post, I realized I could have and probably should have handled this situation differently. I never reached out to our account team to give them an opportunity to respond and figure things out and for that I’m sorry. In my defense, the information I received from that helpful Meraki employee in Slack made me believe that there wasn’t a short term fix and so I wanted to get the word out into the streets while a) it was fresh on my mind and b) I had the energy to write this post. In the end, hindsight is always 20/20, but I do want to offer that to Meraki for not giving them a chance and for reacting so swiftly. In the end, I think their customers win.
And to those thinking it, no, I wasn’t asked to provide this update or to apologize to anyone. This came from my own conscious. When you know better, you do better and I just felt like I could have handled things differently.