Mixing high-end and low-end controller APs?

[Just Someone YKnow]

We are a very small rural K-12 school district with a single building and a deployment of 50 3802i APs and a 5520 controller. This year due to coronavirus we have very suddenly gone 1-to-1 and the wifi is of course being pounded. We do not have the budget available to buy a large pile of more 3802i to handle the additional load.

In order to maximize performance of the high end 3802i Cisco APs, I am contemplating shifting support for 2.4gz onto a lesser Cisco AP alongside it.

It seems a huge waste of an expensive 3802i AP to have it running in 5 ghz and 2.4 ghz because in 5 ghz mode it uses 4 ac channels, but in 2.4 ghz mode it can only use 1 channel.

If I can change the 3802i to have both radios at 5 ghz, then I have 8 active ac channels per 3802i, significantly increasing the bandwidth it can support...

But then we completely stop supporting the old 2.4 ghz band and older devices won't be able to connect.

It looks like I should be able to pair the 3802i with a significantly lower cost controller-based Cisco AP such as the 1815i, which is about 1/3rd the cost of a 3802i.

I would put it in classrooms on the ceiling alongside the 3802i. I would set the 1815i to only operate on the 2.4ghz band, as its limited 5ghz capabilities may negatively impact the 3802i channel usage.

As far as I can tell, the Cisco CleanAir capability on the 3802i would work in concert with the lesser 1815i, even with the 3802i in straight 5ghz mode and not using 2.4ghz.

Has anyone else tried combining high and low end controller-based Cisco APs like this?

[Leo Laohoo]

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@Just Someone YKnow wrote:

I would put it in classrooms on the ceiling alongside the 3802i. I would set the 1815i to only operate on the 2.4ghz band, as its limited 5ghz capabilities may negatively impact the 3802i channel usage.

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Wait.  What are trying to accomplish?  You want to put TWO (2) APs in a classroom:  One doing 2.4 Ghz and another to do 5.0 Ghz?  

Is this some kind of a joke?

[Scott Fella]

Let me add to what Leo already mentioned. Knowing that it’s no ideal to do that, a single ap in a 1x1 works well as long as you tweak what you currently have. 5ghz is always what you want your devices to connect to to get the best experience for the users. An ap can handle both with no issues, but again, you need to try to tweak your environment so that devices in or very near that ap can only assisting that ap. You don’t want devices moving around being sticky. So tweak the power and disable data rates as much as you can to achieve associations from that classroom or adjacent.

[Leo Laohoo]

At the end of the day, wireless clients (and not APs) make the final decision which AP to join and what radio to use.  

2800/3800 have THREE (3) radios:  A 5.0 Ghz, 2.4 Ghz and a "micro" 5.0 Ghz.  If Flexible Radio Assignment (FRA) is enabled, the AP will determine how "dirty" the 2.4 Ghz channel is.  If it is dirty enough, the AP will disable the 2.4 Ghz and activate the micro-5.0 Ghz to serve wireless clients.  

If you still have 2.4 Ghz wireless clients then it could mean the wireless clients do not have 5.0 Ghz radio.  If it does have a 5.0 Ghz radio, update the firmware of the wireless NIC.  

I do not recommend using 80- or 160 Mhz channel bonding.  The only time you can "get away" with 80- or 160 Mhz channel bond is when you're on a wide open field and no neighbours.  

[patoberli]

To add to the previous posts, what do you actually mean with 1-to-1?

Is that 1 to 1 video stream? In other words, you have now one teacher per student (which I absolutely don't think)?

Normally a 3800 should happily provide enough speed for 30-60 clients doing light usage on the Wi-Fi. Of course, this would change if everyone of them uses high quality video streaming. But assuming your students are anyway mostly at home, they shouldn't create any load at all on your wireless infrastructure. 

How many classrooms do you have? I mean with 50 APs you probably have 30-50 classrooms (although one teacher and no student per room should not cause any issues at all). Or do you currently cover 2-4 rooms with one AP?