Wireless Access

Hi,

I am using an 620 controller with an 105 AP however i would like to know how the controller manage the air time when having both 802.11b and 802.11n clients connected.

From what i know 802.11b uses more air time then 802.11n. when we active bandsteering and perfered-access the controller will manage to change the faster clients to diferent frequency (2.4 or 5GHz) from the slower clients. However, what i really want to know is how that process is done? the controller moves 802.11n clients to a differnete channel leaving 802.11b clients on an another channel? how the controller do to separate the faster clients from the slower clients... since if they all stay together the slower will say the transference rate to the faster clients.

Thanks for the help...

best regards

Gonçalo Azevedo

When "fair-access" is enabled, the controller gives 802.11n clients more "tokens" so that they have more time to transmit.  This is not related to band steering.

And in preferred-access? how the controller do to not penalize the 802.11n clients when there are 802.11b clients connected?

I know that band-steering is not the same that preferred-access. band sterring is the controoler moves the faster clients with 5Ghz capabilities to different channels leving this way less clients in 2.4Ghz...

Thanks for the anwser.

Best regards

Gonçalo Azevedo

The controller can decide when it is servicing clients how much airtime it gives to each type of client.  When the QOS  setting is normal, it does not do this.  When it is fair access or preferred, it gives 802.11n clients more airtime by servicing them more frequently, in general.

so when i have 802.11b clients, my connection in 802.11n will get penalized due to lower rates consecutively more air time from 802.11b clients?

Regardless of manufacturer, this is what happens in one form or another.  How MUCH it happens depends on how far away the 802.11b clients are from the access point and how much traffic they have to transmit.

that is bad news...

I was thinking that this problem of slower clients penalize faster clients was solved in more advanced controllers....

So if i have 1 client 802.11b and 100 802.11n this b client will penalize the rest of the clients kepping then to transmit at full speed... due to more air time and consequtivly slower rates from the 802.11b clients

Aruba's "fair access" and "preferred access" setting is designed to mitigate that behavior.

and how the controller mitigate that behavior in preferred-access?

"The controller can decide when it is servicing clients how much airtime it gives to each type of client.  When the QOS  setting is normal, it does not do this.  When it is fair access or preferred, it gives 802.11n clients more airtime by servicing them more frequently, in general."

afarouk,

Wouldn't he also have to remove the 1 and 2 basic rates, as well as increase the beacon rate to 5 to accomplish that?

He also would not want to do that in combination with Airtime fairness, right?

now i am lost!!!

what do you mean by remove the 1 and 2 mbps data rate?

Goncaloazevedo

Read this on page 51 (http://www.arubanetworks.com/wp-content/uploads/802_11nVRDV8_20110913.pdf), as well as the general premise of how ARM works. CJoseph is giving you the answer, there is more detail in the VRD.