Wireless Access

I am observing high channel busy % along with high interference. Also a lot of clients have low SNR. Is there any way through which I can find out reasons for the same and take necessary corrective action. Are there any freeware tools ?

If you wanna know the source and you have RF protect license you can convert some APS in spectrum analyzer and find out the cause of the interference.  It will tell you if its microwave if its another 802.11 or if its bluetooth and so on... And will tell you many good things...

Do you have that licence?

Here is a link that can be helpful for you with the spectrum analyzer

http://www.arubanetworks.com/wp-content/uploads/RFSpectrumWLANsAppNote_20120514.pdf

If you dont have the license you can get basic info.

Can you run

show ap active ip-addr <ap ip address>

Check to make sure: • Channel Frame Retry Rate % is below 30%. If higher then too much interference. • Channel Noise Floor is above 80. If Noise Floor is lower then too much non-802.11 interference

Check this on 2.4ghz and also on the 5ghz if you got dual band to see

Also i notice that yhou have like too many clients on 2.4ghz channel

Could you please check if you got band steering on on the SSIDS?

This will make the capable clients of 5ghz going to 5ghz channel instead of going to 2.4ghz channel...

Remenber you got 23 usable channel on 5ghz and just 3 usable non overlapping channels on 2.4ghz.  So clients are a way more happy being on 5ghz rather than 2.ghz... what got better 2.4ghz is that it travel a bit farther than 5ghz...

Not related to the interference but be sure you got Airtime fairness on...

First check this things we can help you to tune your network...

The thing is that some people just deliver the wireless network without thinking how to deploy it correctly.  Soemtimes they just see coverage when they need to see also the High density enviroment... for example i saw that in a School that before we arrived bough another brand(will not name it but its a known brand) and they just calculate it for coverage... and its a school its a high density enviroment.....

I have deployed wireless on school and you can see like 70 or 80 kids in one AP if you dont plan this correctly. 

It also depend in what you are using it will be just for internet browsing? will you use Wireless phones? will you run Intensive intranet apps? soo many things you should take in mind before deploying it.   I have seen bad implementations  that makes the brands look bad even fi they are not bad... including Arubas deployments... and its sad because aruba is like the best brand :)

Cheers

Carlos

show ap active command gives me Frame retry rate to be 0.Channel noise shown 99.While on the dashboard i see channel busy % between 80-90 and interference between 30-40.

Band steering has not been enabled.

Attaching snapshot of system profile. I want clients to use 5 GHz band as against 2.4 GHz for benefits as pointed out. Also HT mode has been enabled in 2.4 GHz band. Is it ok to have it ? I have checked with my implementation partner, he says it is fine. but, i am not quite sure of it. How do i detect the source of interference ?

Does it show you that info for both bands? for 2.4ghz band and 5ghz band? i mean 0 of % of retries and noise over 90?

Okay to use band steering go to

ap configuration

ap group select here your ap group

go to wireless lan

go to virtual ap

go to the ap group you want to active the band steering

go to ssid and there you wil find a checkbox of band steering and you should activate it.

The airtime fairness is on QOS just create a new profile and put fair access on it and thats it click okay

Yes ht on 2.4ghz is okay... just be sure you are using 40hz channels on just A band...

I see majority of my AP's in 2.4 Ghz band only. Very few of my AP's are in 5 Ghz band, roughly 10 out of 100. And they belong to one particular group. Which setting is causing my majority of AP's to be in 2.4Ghz band ?

Above said info is seen in 2.4 Ghz band only.

My implementation partner is using HT 40 in 2.4 Ghz band, which I  think should not be the case. I raised this up with him but received an unsatisfactory answer.

20mhz should not be be used... becasue it will overlap channels.  Are you sure you have it on? you can check it really easy  you will see channels  with a plus or minus next to it.

Also you can check it on

ap group

rf managment

802.11g

ARM

and check Allowed bands for 40MHz channels it should be on  a -only

What model of AP youuu got?

Hello everyone,

Question: I am looking at a particular AP i have in a building and the output for 5GHz Channel Frame Retry Rate(%) is 33 but for the 2.4GHZ the Channel Frame Retry Rate(%) is 7. Does this indicate that i have more co-channel interferance in the 5GHz than the 2.4GHz. This does not make sense to me because the 5GHZ have 9 channels available compared to 3 on the 2.4Ghz?

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@nilslau03 wrote:

Hello everyone,

 

Question: I am looking at a particular AP i have in a building and the output for 5GHz Channel Frame Retry Rate(%) is 33 but for the 2.4GHZ the Channel Frame Retry Rate(%) is 7. Does this indicate that i have more co-channel interferance in the 5GHz than the 2.4GHz. This does not make sense to me because the 5GHZ have 9 channels available compared to 3 on the 2.4Ghz?

 

 

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You have to look at those numbers objectively AND over time..  If you don't have alot of data traffic and 33% are retries, it might seem like a little much, but let it sit for a while and see if it is sustained or it goes away.  Sometimes things happen in bursts.  Sometimes there IS interference on the 5ghz band.  Retries could also be because of congestion, not just interference.  You need to separate that out, and trend it over time.

With that being said every environment is different and you have to baseline your environment when everything is normal and compare it when people complain.  For some people with a high-density environment, 30% retries is standard rush-hour.

I will monitor the access points for a week in different times of the day to see if the number change. Thank you for the advice.

The allowed bands for 40 Mhz channels is present for all. Attaching the snapshot of the same.

We are using AP model 93.

Thanks

This configuration has been applied to around 43 AP's but only 16 are working in HT40MHz channel. Why is it so ?

Yes dont use 40mhz channel on 2.4ghz...

Put a- only please if you havent

I really dont remenber  if you had to reboot the AP as well to make it work.   I remenber  i saw that in a deplloyment that someone else conbfigured a while ago then  i put it like a told you and how it should be, and i think i needed to reboot the AP

does this help?

or its the same?

I have put the recommendations.

Will need to site survey before moving to 5GHz band rite ?

After talking the 40  channels of the 2.4ghz i would like to know if it improved the expeience on 2.4ghz.

If you can steer many more clients to 5ghz that woudl be good.

If you got many many smartphones then that wont be possible,... i think most of the smartphones does not support 5ghz... maybe just the new iphone and new galaxys?

Cheers

Carlos

I have made the setting: 40 MHz band for a only, but i still see client using HT-40MHZ in g mode. Why is it so ?

You need to reboot the APs

At least when i saw that on a client which had that on... aps were still advertising the channels on 40.... i had to rebool the aps 

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@NightShade1 wrote:

You need to reboot the APs

At least when i saw that on a client which had that on... aps were still advertising the channels on 40.... i had to rebool the aps 

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You should NOT have to reboot the access points for this change to occur.

Really? mmmm well at that time  i dont know why the aps were still advertising the 40mhz band... i couldnt figure out why, then i though in rebooting them... after i rebot the APS this stop happening....  the code at was using in that time was 6.1.2.4 i bealive.

The change should be immediate.  If you made a change on the allowed channels or allowed bands for 40mhz, it should have changed immediately.  Otherwise it is a bug.

Yes guess is a bug

Here is the tread in which i said that i had to reboot the APS becasuse when i did change it it just didnt work

https://community.arubanetworks.com/t5/Campus-WLAN-and-High-Density-Wi/low-goodput/td-p/44706

i knew i wrote in a topic so i searched it... the code was 6.1.2.8

Mahesh try rebooting the aps to see if that fix it.... if it fix it then like callin says its a bug!

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@NightShade1 wrote:

Yes guess is a bug

Here is the tread in which i said that i had to reboot the APS becasuse when i did change it it just didnt work

 

https://community.arubanetworks.com/t5/Campus-WLAN-and-High-Density-Wi/low-goodput/td-p/44706

 

i knew i wrote in a topic so i searched it... the code was 6.1.2.8

 

 

Mahesh try rebooting the aps to see if that fix it.... if it fix it then like callin says its a bug!

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I personally have never seen the need to reboot to change from 20 mhz to 40mhz.  We need to  make sure that the correct parameter is being changed in the correct profile to ensure this is a bug.  A support case needs to be opened to ensure you have everything configured correctly.  I don't know why anyone would turn on 40mhz channel support on 2.4ghz in the first place.

Me neither but that was my first time on that custumer.... i dont know why the one htat configured that turned that on...

Collin

It could happen that if he had client aware checked that could be the reason of why it didnt change channel from a bounded channel to a normal channel ?

I mean after putting it that he should not use the bounded channel

Cheers

Carlos

No.  Changes like allowed channels and channel bonding take precedence and will change even if client aware is enabled.

Okay it was just an idea

But you know Collin today i went to a client which was facing lot of time outs... was a client which bough us aps 93s for some PDTs in their  pharmacies.  The thing is that well we never did a survey as they just asked us tha they wanted that.   I went to the place so well there were like this BIG RF noise and interference from neighbors that i told them that if your equiopments can do 5ghz then lets change it... they all are able to connec to 5ghz so it was all good

But when i changed guess what, it didnt changed it... i had to reboot it!.  those aps were instants APS...

But in my home i had this IAP 105 which does just like you said  i just testied it... a few mins ago.  But the APs93 of the client today didnt do it....

The other client back in the situation i had to reboot them, they were ap 93 also....

Please open a TAC case, so that they can take a closer look.

Yeah i will defenitely do when i get some time....  maybe next week because i want to know whats up with that....

Because if there is a bug in there it would be nice they put the fix in 6.1.3.8 and also in the next 6.2.x one.

I already had one open for something that seems to affect my country code and few others about the APS93 going to air monitor! they told me they would fix it on the next upcoming releases...

Anyways ill inform what the tac  says about it when i open the case!

Cheers

Carlos

Have you done a site survey of the area to see what signal strength each access point is on each channel?

Forget this post... i posted this in the wrong topic hahahah!!

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@mahesh_shirke wrote:

I am observing high channel busy % along with high interference. Also a lot of clients have low SNR. Is there any way through which I can find out reasons for the same and take necessary corrective action. Are there any freeware tools ?

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High Channel Busy either means too much coverage or too much interference or both.  Unless you can (1) remove the source of interference (2) Decrease coverage by removing access points in the Area, your options might be limited...

Guess no need to remove it but you can convert it as AM...