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NightShade1
Posts: 2,393
Registered: ‎10-25-2011
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How to correctly configure airtime fairness

Hello

I got a quetion regarding this

I got 2 SSIDs

If i go to QoS 802.11g traffic managment profile

On proportional BW allocation


If i put 50% to one SSID and another 50% to the other SSID

does this mean that for example i got a througput of 300mbs in the 2.4ghz band

it will divide 150mbs for 1 ssid and the other 150 for the other ssid?

 

If that true let say i don thave noone using the SSID A and i got like 15 users using SSID B

Will the total trhougput of the SSID B will be still 150mbs? or it will be 300mbs? as the SSIDA is not being used?

 

Besides this it will make sure one  or a group of slower clients  wont monopolize the whole BW as i got staton shapping policy on fair access.

 

Im correct or im missing something? or i misunderstood?

 

Thanks

 

 

 

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Product Manager - Aruba Networks
Alternetworks Corp
Moderator
cjoseph
Posts: 12,162
Registered: ‎03-29-2007

Re: How to correctly configure airtime fairness

With Airtime fairness, you should only chose one or the other:

 

Fair Access, Preferred Access, etc, OR SSIDs as percentage of Airtime.

 

You should also only configure Airtime fairness when everything else is good with your network and you want certain clients to have an advantage over other.

 

Using Fair, Preferred or Normall access is good for when you just simply want 802.11n clients to have an advantage over regular clients.

 

Using the SSID as percentage of Airtime is when you want all devices connecting to a certain SSID to have an advantage or preferred access over another SSID.

 

Both approaches should not be mixed, because the effect is not measureable or predictable.

 

Colin Joseph
Aruba Customer Engineering
MVP
NightShade1
Posts: 2,393
Registered: ‎10-25-2011

Re: How to correctly configure airtime fairness

So on the share porcentage i select 0%?

And then on station shaping policy fair access?

 

okay in this scenario i got like 90% of the clients with n card... thats whyi though it would be a good idea to turn on the fair access

 

i wanted to know this because when you are first configuring this it automatically put 100%

 

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Product Manager - Aruba Networks
Alternetworks Corp
MVP
NightShade1
Posts: 2,393
Registered: ‎10-25-2011

Re: How to correctly configure airtime fairness

Actually i just dont configure the shape %... i just pick fair access and thats it..

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Product Manager - Aruba Networks
Alternetworks Corp
Moderator
cjoseph
Posts: 12,162
Registered: ‎03-29-2007

Re: How to correctly configure airtime fairness

Fair access is the recommendation of the High Density VRD, yes.

 

Colin Joseph
Aruba Customer Engineering
MVP
NightShade1
Posts: 2,393
Registered: ‎10-25-2011

Re: How to correctly configure airtime fairness

Thanks Collin

i corrected this configuration! and with your explanation i do undesrtand better how to use it thanks

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Product Manager - Aruba Networks
Alternetworks Corp
Contributor II
nilslau03
Posts: 72
Registered: ‎01-04-2012

Re: How to correctly configure airtime fairness

Question:

 

When is better to use airtime fairness compared to SSID preference? If i have one AP broadcasting the Corporate SSID and the Guest SSIDt, then it would make sense to provide more BW to the Corporate SSID? However, does giving n clients fairness help the user experience without worrying on SSID preference?

 

Thanks

Nils.

 

Moderator
cjoseph
Posts: 12,162
Registered: ‎03-29-2007

Re: How to correctly configure airtime fairness

Most people do not touch either parameter.

 

 Airtime fairness is to either give 802.11n vs. non-802.11n the same or disporportionate amounts of airtime.

 

The SSID preference was designed for if you have a multi-tenant WLAN and you would want to give one more airtime than another.

 

Both are designed parcel out bandwidth when you do not have enough in the first place.  If you do not have that problem, I would leave them at the defaults.

Colin Joseph
Aruba Customer Engineering
Frequent Contributor II
istong
Posts: 116
Registered: ‎02-10-2011

Re: How to correctly configure airtime fairness

And the affect of preferred would be?

Moderator
cjoseph
Posts: 12,162
Registered: ‎03-29-2007

Re: How to correctly configure airtime fairness

[ Edited ]

802.11n clients get more airtime than a/b/g clients.  It would be to deal with the fact that you have a few a/b/g clients and 802.11n clients are starved for Airtime.  The High Density VRD suggests that this is on Fair-Access for High Density Environments.

Colin Joseph
Aruba Customer Engineering