I'm almost ready to sit for the CWAP exam, but I can't seem to find a good answer to this real-life problem in either the CWAP or CWNA guides.
I have a few areas in my building (multi-floor, served by Cisco Aironet 1200's attached to WLSE; connecting via EAP-FAST) where throughput is inexplicably erratic. In these areas, I have sat at a desk and open the Cisco WLAN client utility.
Signal strength stays constantly good (> -75dBm), noise stays consistently low (< -90dBm), but throughput varies widely (sometimes it's 54Mbps, sometimes it's 1 or 2Mbps). Sometimes the connection drops altogether, even though I haven't moved, and signal strength and noise remain at the same levels as they were when I was getting 38Mbps.
Does anyone have any ideas about how I can rectify this? Any explanations as to why it's happening? I know that throughput is a function of signal strength, interference, noise floor, and distance from the AP. It seems that these elements are all constant in my situation; but the throughput is all over the place.
Any help would be greatly appreciated. Thanks!
You REALLY need to get a protocol analyzer sniffing the local traffic and see for yourself what is going on. So many different things can cause this problem that I won't even start a listing here.
Get your free omnipeak analyzer installed on a laptop with a suitable radio card and go from there. Start studying from the CWAP book at the same time. You'll be using both hand-in-hand while learning all kinds of great stuff in the 802.11 world - including what causes problems like low throughput.