Interpreting Prizm Bandwidth Charts? How do I do that?

How do I convert the Prizm bandwidth charts to mb/sec? For example, if the Bytes Transmitted chart peaks out at 150M on a 10 sec bar, what does that mean in mbps? Do I have to take 10 minute block from the chart (600 seconds) and divide the peak for that graph bar (150,000,000) by 600? That would mean that the AP averaged .25 mbps over that period?

When I look at the RF traffic graph, it shows 250Kbps at the same time as the 150mb bandwidth bar. So that agrees with my calculation. Thus, is this correct then? Passing 150mb of bandwidth is only putting a 250kbps load on the AP? With 40 users all set for anywhere from 1mbps to 4mbps on their SMs, I find this difficult to believe at prime-time.

Any comments?

I’ve been struggling to understand Prizm’s bandwidth graphs since day one, for reasons like what you posted. I’ve learned to ignore anything but the interface charts, but even those are strange with sudden spikes up to 8 MB/sec (how this is achieved on the RF interface of a 900 MHz SM at 1X I will never know…).

I think what that is supposed to represent is total bytes transferred between polls, instead of normalized to something sane and rational like bits per second. I believe the default Prizm polling period is indeed 10 minutes, and the bars in that graph seem to support that (6 segments per hour).

so, for that 150 MB in 10 minutes you’d get:

150 MB / 600 sec = 0.25 MBps = 250 KBps * 8 (bytes to bits conversion) = 2000 Kbps or 2 Mbps.

Dunno what was so hard about putting in normal bandwidth graphs. Hopefully Wireless Manager has 'em.