We had an interesting problem. We are running 5 minute data collection on many devices and interfaces on both the ifTable and dot3StatTable. For several data collection intervals we continue to collect data from the ifTable, but had no data returned from the dot3StatTable!
Now, this was across many devices and interfaces. Is it possible that some networking event could cause the IOS agent to not report data for dot3Stat, such as a change to the spanning tree or something?
Not a lot more information on the devices (switch vs. router, for example), or IOS versions. These are all 10/100 Ethernet ports being monitored.