This Counter64 totals incoming packets that referenced a non-existent Phase-1 control tunnel, occurring during processing across all current and previous tunnels, per its description - meaning a peer sent a message tagged with a tunnel/SA identifier this device no longer recognizes. It commonly happens when one side has already torn down a tunnel while the other side is still unaware and keeps sending traffic referencing the old tunnel ID. A steady low rate of this counter is often benign residual traffic after normal tunnel teardown, but a sustained high rate on one peer relationship would suggest the two sides have fallen out of sync about tunnel state.