How can we select specific channels in 5Ghz range?

[technician3]

We are a school with 8 AP330 and 1 AP230 devices. As you can see from Image1 they are only utilising 4 channels amongst the 9 devices, 36,40,44,48. I've tried to go in and select specific channels (see Image2) but the map continues to show the 4 channels being used.

Originally I had to go and set the DFS setting in the Radio Profile to access the additional channels however this setting, while still ticked, is not greyed out and cannot be changed (Image3).

Any help would be much appreciated as there is overlap of same channel traffic happening which I would like to eliminate.

Thanks

[technician3]

Hi Brian, I've jumped onto one of the APs and the region code is set to World, and the country code is for the UK 826. Since we are in NZ should that be changed or do they have similar channel options?

[technician3]

Thanks for the reply Brian, we are using HiveManager version 8.1r2. Will work through your suggestions when I'm next on site and see what comes back 🙂

[AnonymousM · Accepted solution]

Nathan,

Lots of reasons can go into why the APs chose the channels they chose. First and foremost, what HiveOS are you running? Aerohive has made many changes (improvements mostly) in the newer HiveOS platform, specifically the 8.x code train for ACSP (Aerohive Channel Selection Protocol).

Also what country code is on the APs? A "show boot-param" should show that. Different regions allow different channel sets.

If you SSH into your AP(s), you can run a few commands to see the logic behind the channel chosen. Start with "show acsp channel-info". This will show you the "cost" that is associated with each channel available. The lowest cost will be the channel that was most likely selected by the AP (at least after the initial ACSP scan was done).

To see more details around how the cost was calculated, run "show acsp channel-info detail". A deeper breakdown of the factors that influence the cost value are shown.

Older HiveOS codes put an arbitrary high default weighted cost (16-24 base) on the DFS channels, hence the limited or lack of selection of those channels. The newer HiveOS has removed that base cost value so that all available channels are on an even playing field for selection based on the environment and your local regulatory body.

If you see any cost of 32768, that means that the AP will not be using that channel ever for whatever reason. Reasons can be local regulatory bodies restriction of certain channels based on AP country code, a DFS hit ("show interface wifi1 dfs" can show some info around this), or a manual channel exclusion ("interface wifi1 radio channel exclude <channel number>"). Newer code may simply remove this channel from the before mentioned commands vs. setting the max value to the weight.

If you are using 40 MHz wide channels (and it doesn't look like you are), Aerohive always bonds up in my experience, so every upper secondary channel will show the 32768 value. By this I mean, you will only see 36+ and 44+ in a deployment and shouldn't also see 40- or 48-. See below on a quick "show acsp channel-info" on an AP set to 40 MHz wide channels, with channel 149 excluded and no DFS enabled.

Lowest cost channel: 44, lowest-cost: 0

Channel 36 Cost: 13 

Channel 40 Cost: 32767 (offset)

Channel 44 Cost: 0 

Channel 48 Cost: 32767 (offset)

Channel 153 Cost: 32767 (offset)

Channel 157 Cost: 7 

Channel 161 Cost: 32767 (offset)

Channel 165 Cost: 32767 (offset)

We can also see with a simple "show acsp" that channel 44 was indeed the selected channel (as above it shows that channel had the lowest cost).

AH-42db80#show acsp

Interface Channel select state Primary channel Channel width Power ctrl state   Tx power(dbm) Use Last Selection   

--------- --------------------- ---------------- ------------- --------------------- ------------- ---------------------

Wifi0   Disable(Link down)  Down       20      Disable(Link down)  Down     Channel:No Power:No 

Wifi1   Enable        44        40      Enable        20      Channel:No Power:No

Here is Aerohive latest ACSP guide - http://docs.aerohive.com/330000/docs/guides/AerohiveChannelSelectionProtocol.pdf

Hope this helps.