@shiqol wrote:
I find channel busy report on Aruba AirWave but what does it really refer to..?and what is it 100% absolute number..? does it refer to radio frequency capacity..? how do it being calculate..?
Yes, it is radio frequency capacity from the point of view of the access point that is measuring it. There is no magic number and some of the "capacity" you have control over and some of it, you do not. Non-RF interference, and RF interference from external access points are two examples of RF utilization you have no control over. The power of your own access points, the channels you choose for them, whether or not you have broadcasts and mutlicast filtering enabled, whether you choose to remove lower rates, how many SSIDs you are broadcasting, and how many clients you allow on each access points are examples of things you have control over.
Typically, you should look at the RF utilization on the radio band of an access point overnight when there are few to no clients on the radios, like at midnight. The RF utilization should approach 1-4% of the spectrum at that time. Anything more than 4% and most likely you are creating your own "interference". If it is above 4% overnight, I would consider:
- Lowering the maximum transmit power on that band by 3db for those radios (I would only go to a minimum of 9)
- Making sure that broadcast filtering is on all of your SSIDs (instant) and Virtual APs (controller-based)
- Making sure you have no more than 4 SSIDs broadcasting on an AP and if you have more, consider how you could possibly remove or consolidate them.
- Consider removing the "lower" rates from your SSIDs to increase the rate at which the access points beacon, which reduces utilization. It will also encourage clients to roam more quickly to access points that they should be on, instead of sticking to APS further away and dragging down performance.
Long story short, in Airwave I would look at the utilization graph in airwave on the radio of an access point on a week's time interval and plot it against the number of clients. If the utilization is above 5% overnight, use the methods above to figure out how to reduce the part that you have control over. After you make the changes, look at the utilization the next night and see if it drops to under 5% to see how much of a difference you made. In your week graph, see if the rise in utilization correlates to how many clients are associated to that radio. If it does, determine if too many clients end up on that radio (more than 40) and consider reducing the transmit power on that radio or removing lower rates to encourage clients to move. 24 hours later, look at the weekly graph and see if the number of clients has reduced and if the utilizaton has reduced as well.
The utilization for an access point's radio differs based on location and use. You should look at your utilization a week at a time to baseline if your clients have greater utilization when you see complaints. If they do, use the methods above to make changes to the things you have control over...
http://community.arubanetworks.com/t5/Technology-Blog/Removing-the-Bottleneck-in-Wireless/ba-p/77978