In this, javentre writes about the reporting of the traffic on Ethernet interfaces, and that because the counter doesn't include ethernet overhead, the 30 sec rate reported by the show int command isn't an accurate measure to determine if the link is saturated.
http://networking.ventrefamily.com/2010 ... alyst.html
My question, can SNMP get the actual utilization? Or is it a similar situation where overhead isn't reported? I understand there's a MIB that controls what is requested by SNMP but I haven't found this aspect discussed in my cursory search.