This counts notification payloads received by this specific Phase-1 tunnel, per its description, the per-tunnel drill-down from cisgIpsSgGlobalInNotifys. It lets an admin see which specific peer is sending an unusual volume of status/error notifications, which combined with the more specific delete-request counters helps pinpoint whether that peer is experiencing its own instability. A tunnel with a notably higher InNotifys count than its peers, even while carrying similar traffic volume, suggests that specific remote device is reporting more errors or state changes than the rest of the VPN population.