We have an unusual glitch that mostly seems to impact one interface on a Cisco ISR 4331 router. The glitch is missing receive bandwidth data during periods of congestion as shown in the screen shots below. This seems to mostly happen at night when we are copying backups between sites across the WAN. We are using DMVPN tunnels on the ISR routers and so have chosen to monitor the tunnel interface instead of the physical interface, since all of the data on the physical interface is encrypted. I'm going to start monitoring the physical interface as well to see if both the physical and tunnel interfaces are missing receive bandwidth at the same times or not.
If I hover the mouse over the section indicated above where there is a gap this is what I see:
Has anyone else encountered this? I did open a support case on it but the diagnostic logs only went back a few days and it's been about a week since we last saw that glitch happen. They are leaving the case open so when it does happen again I can run another diagnostic and supply them the logs again.