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Guest Blogger
Posts: 150
Registered: ‎12-04-2012

Channel Utilization Limits

What is the best way to determine channel utilization on a radio. Is the QBSS the best way since its coming from the radio itself ? Different measuring tools can report different values, but most are in the ball park.

What % is everyone using for maximum channel utilization for data - XX% ?

What % is everyone using for maximum channel utilization for voice over wifi - XX% ?

Thanks !

MVP
Posts: 1,434
Registered: ‎10-25-2011

Re: Channel Utilization Limits

Hi George,
Currently for our 2.4Ghz networks we use between 50-75% for campus style networks and 75%+ for public hotspots just because 2.4Ghz is overwhelmed and do not want to be triggered every 5 min.
For 5ghz, we tend to set something lower something between 35-50%
For voice, we haven't set anything up but i would assume in the areas of 35%-50%? Could be too low.
Pasquale Monardo | Senior Network Solutions Consultant
ACDX #420 | ACMP
[If you found my post helpful, please give kudos!]
Guest Blogger
Posts: 150
Registered: ‎12-04-2012

Re: Channel Utilization Limits

Thank you for the quick reply. Do you use the QBSS for your channel utilization measuring stick ?

MVP
Posts: 1,434
Registered: ‎10-25-2011

Re: Channel Utilization Limits

Because we use Airwave to trigger us. We use currently the trigger for Channel Utilization only. No QBSS currently.

It is configured as follows

For 75 minutes if a channel is
Time busy: 50%
Interference: 50%

Then alert us.

This was obviously tweaked over and over and found that these values with this time period worked best for this environment.

Hope this helps.
Pasquale Monardo | Senior Network Solutions Consultant
ACDX #420 | ACMP
[If you found my post helpful, please give kudos!]
Guest Blogger
Posts: 150
Registered: ‎12-04-2012

Re: Channel Utilization Limits

Isnt AirWave getting the Channel Util from the AP radio ?

MVP
Posts: 1,434
Registered: ‎10-25-2011

Re: Channel Utilization Limits

I would assume so but documentation does not confirm this nor does it mention how it gets that value.
Pasquale Monardo | Senior Network Solutions Consultant
ACDX #420 | ACMP
[If you found my post helpful, please give kudos!]
Guru Elite
Posts: 21,269
Registered: ‎03-29-2007

Re: Channel Utilization Limits

[ Edited ]

gstefanick wrote:

What is the best way to determine channel utilization on a radio. Is the QBSS the best way since its coming from the radio itself ? Different measuring tools can report different values, but most are in the ball park.

What % is everyone using for maximum channel utilization for data - XX% ?

What % is everyone using for maximum channel utilization for voice over wifi - XX% ?

Thanks !


Gstefanik,

 

The QBSS is probably the most convenient method, when you are trying to troubleshoot voice, from the AP itself that is in the area, IF you are doing a packet capture at the same time.  The QBSS IE is by default off on Aruba controller-based APs, but is on by default on Aruba Instant APs when you designate a SSID as "voice".

 

Airwave does collect channel utilization from Cisco and Aruba access points historically.  Aruba controllers needs to have AMON turned on to send this to Airwave.  This number is typically reported once per minute by the access point using the GUI and CLI of the controller.

 

Some use the Channel Utilization numbers from a laptop spectrum analyzer, because it shows the number in realtime without  having to do a packet capture.   That number should be used in conjunction with the number seen on the AP itself, because some analyzers use the utilization numbers from the built in laptop adapter, so the mileage may vary.

 

I want to say that channel utilization is situation-based and the ideal answer to "how much" for data and voip networks is always "less than you have right now".  I don't like to see 20% channel utilization when nothing should be going on (overnight).  Depending on the circumstances, it could shoot up into the 70% and your network can still function, depending on the application.

 

 



Colin Joseph
Aruba Customer Engineering

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

Guru Elite
Posts: 21,269
Registered: ‎03-29-2007

Re: Channel Utilization Limits


gstefanick wrote:

What is the best way to determine channel utilization on a radio. Is the QBSS the best way since its coming from the radio itself ? Different measuring tools can report different values, but most are in the ball park.

What % is everyone using for maximum channel utilization for data - XX% ?

What % is everyone using for maximum channel utilization for voice over wifi - XX% ?

Thanks !


Gstefanik,

 

The QBSS is probably the most convenient method, when you are trying to troubleshoot voice, from the AP itself that is in the area, IF you are doing a packet capture at the same time.  The QBSS IE is by default off on controller-based APs, but is on by default in Instant APs when you designate a SSID as "voice".

 

Airwave does collect channel utilization from Cisco and Aruba access points historically.  Aruba controllers needs to have AMON turned on to send this to Airwave.  This number is typically reported once per minute by the access point using the GUI and CLI of the controller.

 

Some use the Channel Utilization numbers from a laptop spectrum analyzer, because it shows the number in realtime without  having to do a packet capture.   That number should be used in conjunction with the number seen on the AP itself, because some analyzers use the utilization numbers from the built in laptop adapter, so the mileage may vary.

 

I want to say that channel utilization is situation-based and the ideal answer to "how much" for data and voip networks is always "less than you have right now".  I don't like to see 20% channel utilization when nothing should be going on (overnight).  Depending on the circumstances, it could shoot up into the 70% and your network can still function, depending on the application.

 

 



Colin Joseph
Aruba Customer Engineering

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

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