This read-only counter tracks how many times the RADIUS authentication server has sent back an explicit EAP-Success message for this session, confirming the supplicant successfully authenticated to the backend server. An administrator treats this as the authoritative tally, from the backend's perspective, of successful logins for that client over time. For example, comparing this counter to the higher-level authenticated-transition counter helps confirm the backend success signal is correctly propagating into the overall session state machine.