Data flooding

It seems that many CDNs are blasting out far more data than our SMs are configured to accept, but those superfluous packets are aggregated into our MRTG graphs for the AP's traffic.

My question is this: is there a way to determine the actual level traffic the AP is transmitting and receiving over RF, which doesn't include the  packets  discarded before they are transmitted? I'm not unwilling to do some math in my MRTG configs, but the only counts I see for discards are for packet counts, not octet counts

Where are you gathering the statistics - SMs or AP?