Choosing 2.4ghz channels?

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I am finding that I need to insert more access points into our system to give better coverage for our weaker devices. We have roughly 34 APs: 7363s, 7962s and 7372s

As I am doing this, I am noticing that the APs are seeing a lot more of the other APs, especially in the 2.4ghz channels. I was running the 2.4ghz in a three channel mode to only allow channels 1, 6 and 11.

If the APs are seeing more APs on the same channel, shouldn't that cause some problems?

Would it not be beneficial to run all 11 channels? Sure there are some overlap, but I would think it would be easier to avoid co channel interference.

Lastly, 9.7 firmware includes an option to "disable channelfly after x minutes", from what I gather it also remembers the channelfly data per AP. To me this seems like the perfect solution: Enable all 11 channels, run channel fly for a couple of days, let channelfly figure which channel is best on which AP, and then check the "disable after x minutes" option leaving the APs on the channel which channefly likes.

Any thoughts would be appreciated,
Bob
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Bob Williamson

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Posted 4 years ago

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Bill Burns, AlphaDog

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In dense, controlled wifi environments without a lot of interference or rogue access points:
Limiting your APs to channels 1,6 and 11 is a good practice.

Before you decide to use other channels you should understand that there's an "advantage" to APs on the same channel being able to hear each other:
WiFi devices on the same channel read/understand setback/timer values from adjacent APs and behave accordingly. This reduces collisions.
This feature won't work if the adjacent same-channel APs are too far away to detect timer values or carrier.
WiFi devices on overlapping (but not identical) channels may not sense carrier from adjacent APs and may attempt to talk over each other.

In "carrier"/ISP WiFi systems, the assumption is a "dirty" WiFi environment with a lot of interference from non-WiFi and/or distant WiFi devices.
In that case, it makes sense to use non-standard channels to avoid interference.
Channel-Fly seems intended for that kind of environment.
Then you might as well leave it on and take advantage of It's multi-day predictive analysis.

Running channel-fly for any length of time in a dense environment (of Ruckus APs) tends to result in excessive channel-changes. (especially in the first few hours)
You could try turning it on at a time (weekend/holiday) when there aren't a lot of clients.

Disable channelfly after "x" minutes is an interesting choice.
I think channelfly will restart after every AP power-cycle.
To get a sense of what will happens w/ channelfly enabled (like after a power outage) you should monitor logs for AP channel changes the first time you try it.

I'm not sure how your APs are "seeing" "other" APs.
Are they seeing other ruckus APs that you manage or are they seeing APs that are not controlled by you?
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Bob Williamson

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Thank you for your help. When I monitor one of my existing APs, it shows it's neighbors (other ruckus APs which are legit) and their strengths that it can see them at. This is almost always 2.4ghz. That is what I meant by "seeing" other APs. From what I gather, this is not as big of an issue I thought. They do recommend turning down 2.4ghz if the neighbor APs are above 80%.

As for the Channefly auto disable. I realize it is more complex, but I was thinking if I ran Channelfly over a weekend, or for an hour after an AP restarts, it would tend to get end up on the better channels. I have found that the amount of channel changes has decreased a lot with 9.7 probably because it keeps a history of the channel optimization that it had already done.

Bob
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Michael Brado, Official Rep

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If your clients can use all 2.4G channels, then you are not limited to background
scanning. Channelfly use of all 11 channels ought to result in ~34% performance
increase. Be aware that Channelfly is designed such that each AP will go briefly
off-channel to each of the 11 channels, and builds a table of interference seen.
You will see frequent channel changing in the first day (or two) in most cases, as
the APs adjust, but the result should be optimized soon.

While these first days may include channel changes, they will decrease after the
first couple days, but it's best to give the APs real use over weekend evaluation.
Once applied and settled down, you can adjust the MTBC (mean time between
changes) to regulate channel change frequency. This may be preferable to
turning Channelfly off after X minutes.

One reason clients aren't as affected by Ruckus channelfly assigning channels
other than 1/6/11, is our directed antenna arrays which send energy only toward
associated clients, radiating less in other directions, combining beamflex benefits
with Channelfly.
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Bob Williamson

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Michael,

I will take a look at the MTBC option. I was wondering/expecting that "turn off Channelfly after x minutes" would allow the APs to avoid intereference by juggling the channels whenever an AP was rebooted, but was unsure if that would work.

Is there a particular statistic that shows an estimate of the interference from other channels?

Thanks,
Bob
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Robert Brooks

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Hi - This is an interesting conversation as I have been looking into this myself recently and have just changed from a full 11 channel 2.4ghz available to restricting available channels to just 1,6 and 11. I understand that Beamflex will "point' the RF at the client but of course in a dense environment you also have to think about the clients that are not able to direct their RF energy. So we come back to - I think - just enabling 1,6, and 11 in dense environments ( so nothing overlaps and things on the same channel co-operate ).

I struggle with what is the best practice though ?