Wireless Access

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Contributor II

Look at my floorplan: Why would the Controller reuse the same channel?

(This is a screenshot of a portion of one of our campus buildings)

 

Just askin, but shouldn't the Controller (ARM) NOT be allocating channels this way? Meaning, adjacent APs shouldn't be on the same channel (149)

 

Guru Elite

Re: Look at my floorplan: Why would the Controller reuse the same channel?

If you have client aware on, and there is active client traffic on your access points, the channel will not change.



Colin Joseph
Aruba Customer Engineering

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Contributor II

Re: Look at my floorplan: Why would the Controller reuse the same channel?

(sorry for just replying)

Colin, 

Thanks... that would probably not be the case a week later, though, would it?

(Just guessing, is there a chance that these access points are far enough in distance that using the same channel might not matter?)  

 

Latest screenshot, 1 week following the initial one:

 

Guru Elite

Re: Look at my floorplan: Why would the Controller reuse the same channel?

Again, Do you have "Client Aware" unchecked in your ARM profile?  What channels does your regulatory domain profile have attached?



Colin Joseph
Aruba Customer Engineering

Looking for an Answer? Search the Community Knowledge Base Here: Community Knowledge Base

Frequent Contributor I

Re: Look at my floorplan: Why would the Controller reuse the same channel?

please attach the output for each AP that is on the same channel

"show ap arm rf-summary ap-name <the aps>" 

"show ap arm status ap-name <the aps>"

"show ap arm history ap-name <tha aps>"

 

 

 

 

Contributor II

Re: Look at my floorplan: Why would the Controller reuse the same channel?

Dugem,

Thanks for your interest.

Here are the RF summaries and ARM status reports; I'm not seeing the history command in Airwave, and I don't have full CLI access, so they'll take a little more time.

 

 

Frequent Contributor I

Re: Look at my floorplan: Why would the Controller reuse the same channel?

hi the.sleeper

 

What's not showing in airwave but is fundamental to the issue here is that the APs are on 80MHz channels (which is indeed the default, so not necessarily anything that someone chose).

 

From the ARM stats, we can see that the APs are not just on ch 149, but

rather 149E which means 149-161 as 80MHz.

 

 

From AP Marple-AP-M3533-C351-2-142506

Interface Name :wifi0 (5GHz)
Cur Chan: cca_ibss/cca_obss/cca_intf:0/23/10
Bcn fail/Bstuck reset/Scan rej(l) :403642/0/407
Current ARM Assignment :149E/12.0 <<<<<

 

It also appears that due to your locale, there are only 2 x 80 MHz channels available, which are 36E and 149E:

 

HT/VHT Channel Summary
----------------------
Bandwidth Channel range Total interference index
--------- ------------- ------------------------
40MHz 149-153 139
40MHz 36-40 224
40MHz 157-161 138
40MHz 44-48 187
80MHz 149-161 277 <<<
80MHz 36-48 411 <<<

The next thing to consider is how ARM will select channels. The table above shows a resultant number, in the case of 80MHz for 36E it is 411, and for 149E it is 277. How those numbers are derived is a topic for another time, but the net effect is that the highest number is the least desirable, and ARM will choose to put a new AP on 149E rather than choose the other option, 36E which it views as worse.

 

 

Having said that, that may or may not be the correct decision, it depends on a few things, but let's get some basic questions out of the way first.

 

a) Does your regulatory domain allow you to use UNII-2 and UNII-2e channels (or, can you share what country that this operates in)

 

b) How heavy is the requirement of needing 80MHz ? if you were to drop to 40MHz channels would anyone i) notice ii) care ?

 

c) how many APs are neighbouring around these 3 APs, e.g. how dense is this (office ? educational ?) - any other networks around (e.g. floor above is a different company etc.)

 

 

 

 

 

 

 

Contributor II

Re: Look at my floorplan: Why would the Controller reuse the same channel?

dugem,

Thank you for the explainer; sincerely fascinating. Guess its not as simple as channel number, is it.

 

answers to questions:

 

a) Does your regulatory domain allow you to use UNII-2 and UNII-2e channels (or, can you share what country that this operates in)

In US, (so no go for 132-144 I believe?)

 

b) How heavy is the requirement of needing 80MHz ? if you were to drop to 40MHz channels would anyone i) notice ii) care ?

I'll ask, but I doubt it. Just to confirm, what use-cases wilt with 40 mhz as opposed to 80mhz width?

 

c) how many APs are neighbouring around these 3 APs, e.g. how dense is this (office ? educational ?) - any other networks around (e.g. floor above is a different company etc.)

Community college, no competing networks, building is ours, this is on 3rd floor of 4-floor building... Here's a screenshot of what Visual RF thinks is coming from the floor above the one in question:

Frequent Contributor I

Re: Look at my floorplan: Why would the Controller reuse the same channel?

a) Does your regulatory domain allow you to use UNII-2 and UNII-2e channels (or, can you share what country that this operates in)

In US, (so no go for 132-144 I believe?)

>> i believe these days that in the US regdomain there is no reason that you cannot use the channels in Unii2 and Unii2-e. maybe someone else can chime in. At any rate, look into that and see if you can expand the regulatory domain profile to include these channels - it should just be a matter of opening the profile and clicking the check boxes. This will give you another 2 80 MHz channels for the APs to operate.

 

b) How heavy is the requirement of needing 80MHz ? if you were to drop to 40MHz channels would anyone i) notice ii) care ?

I'll ask, but I doubt it. Just to confirm, what use-cases wilt with 40 mhz as opposed to 80mhz width?

>> Just overall maximium throughput for the channel - but that is only a thing if a) someone is checking and b) you have clients that are capable of utilising the extra bandwidth. In you particular case, if you choose not to add extra channels, then you should reduce the channel size to 40MHz not 80 MHz

 

c) how many APs are neighbouring around these 3 APs, e.g. how dense is this (office ? educational ?) - any other networks around (e.g. floor above is a different company etc.)

Community college, no competing networks, building is ours, this is on 3rd floor of 4-floor building... Here's a screenshot of what Visual RF thinks is coming from the floor above the one in question:

 

>> Ok, it seems the design is not overly dense - you could quite easily run 80MHz if you can add the extra channels, perhaps even without them - but - i would still overall recommend to you that you run 40MHz channels.

 

 

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