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How to correctly configure airtime fairness

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  • 1.  How to correctly configure airtime fairness

    Posted Sep 14, 2012 07:53 PM

    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

     

     

     



  • 2.  RE: How to correctly configure airtime fairness
    Best Answer

    EMPLOYEE
    Posted Sep 15, 2012 11:07 AM

    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.

     



  • 3.  RE: How to correctly configure airtime fairness

    Posted Sep 15, 2012 11:13 AM

    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%

     



  • 4.  RE: How to correctly configure airtime fairness

    Posted Sep 15, 2012 11:14 AM

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



  • 5.  RE: How to correctly configure airtime fairness

    EMPLOYEE
    Posted Sep 15, 2012 11:18 AM

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

     



  • 6.  RE: How to correctly configure airtime fairness

    Posted Sep 15, 2012 11:24 AM

    Thanks Collin

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



  • 7.  RE: How to correctly configure airtime fairness

    Posted Mar 18, 2013 12:50 PM

    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.

     



  • 8.  RE: How to correctly configure airtime fairness

    EMPLOYEE
    Posted Mar 18, 2013 01:27 PM

    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.



  • 9.  RE: How to correctly configure airtime fairness

    Posted Mar 18, 2013 04:58 PM

    And the affect of preferred would be?



  • 10.  RE: How to correctly configure airtime fairness

    EMPLOYEE
    Posted Mar 18, 2013 05:16 PM

    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.



  • 11.  RE: How to correctly configure airtime fairness

    Posted Mar 19, 2013 11:02 AM

    Ok from I understand we can have 3 SSID being broadcasted but what it matters is how many users we have connecting at the same time, in addition to what type of connection (n/a/b/g). If we have a mixed of clients then it make sense to allow more time for n clients to transmit so b clients does not starve air time from other users. I was just wondering if we can tell the access point to listen more to clients connecting to a specific SSID than Guest. If we have 10 clients connecting to the Access Point which 3 are only guest and 7 are corporate clients, then I wanted the Access Point to allow corporate clients to transmit and hold the connection to guest only after corporate clients finish transmitting sort of priority queuing in the air. If I restrict the bandwidth for the guest role would it help to prevent guest users for consuming more air time than corporate users?



  • 12.  RE: How to correctly configure airtime fairness

    EMPLOYEE
    Posted Mar 19, 2013 11:06 AM

    Theoretically, yes.

     

    You are still restricted to the aggregate throughput, however.



  • 13.  RE: How to correctly configure airtime fairness

    Posted Mar 19, 2013 11:18 AM

    Thank you.