Persistency and Origin-State-ID AVP (RFC 6733, §8.6 and §8.16).
Persistency (saving the state of IPoE hosts on the compact flash) for Gx sessions is not supported. This means that, on reboot, the node restores the subscriber-hosts from the persistency but the Gx session awareness for the recovered hosts is lost. Any previously applied QoS or filter overrides are lost. However, subscriber-strings (subscriber-id, sub-profile, sla-profile, aa-profile) can be made persistent and can be preserved across reboots.
The Origin-State-Id (OSI) AVP is not stored in persistency. If the node reboots, the Origin-State-ID AVP is set to boot time (UTC).
The Origin-State-Id AVP is contained in the CER messages and application messages that are sent from the node to the PCRF/DRA. In the other direction, sent by the PCRF to the node, the OSI is ignored.
To restore a lost session after the reboot, the node initiates a CCR-I message for every host that has recovered from persistency. The CCR-I contains the new session-id and origin-state-id. Based on this CCR-I, it is expected that the PCRF returns the most current policy for the host.