Session/Flow Tracking

OIDs here track individual sessions or traffic flows for specific tunneling and NAT protocols — PPTP session flow-control state, CGNAT flow-deletion reasons, and per-session flow limits or routing technology. Admins use the flow-deletion-reason counters to distinguish normal session teardown, a client's TCP connection ending cleanly, from abnormal terminations, and configure per-session flow limits to cap how many concurrent flows one subscriber can consume, protecting shared NAT resources from being monopolized. Because this theme spans PPTP, CGNAT, and mobile-data protocols, the specific mechanism, flow control, flow deletion, or flow limits, is protocol-specific even though all three describe a flow within a session.