This Counter64 totals every IP datagram this VPN virtual router has received from its interfaces, counting even datagrams that later turn out to be errored. It gives an admin the baseline inbound traffic volume for that particular virtual router instance, useful for spotting a sudden drop-off that signals an upstream link outage. For example, comparing this counter across two virtual routers sharing the same physical box can reveal that one VPN customer's traffic has stopped arriving while the other's has not.