Overloaded Peer Detection

The SMF determines whether or not the GTP-C peer entity is overloaded based on the received Overload Control Information (OCI) IE information in any of the following GTP-C messages.

  • Create Session Request

  • Create Bearer Response

  • Modify Bearer Request

  • Update Bearer Response

  • Delete Session Request

  • Delete Bearer Response

  • Modify Bearer Command

  • Delete Bearer Command

  • Bearer Resource Command

Note that all the GTP-C messages include the OCIs of cnSGWc, MME or S4-SGSN, and TWAN or ePDG except for Delete Bearer Command and the Bearer Resource Command messages.

The SMF receives OCI that corresponds to multiple GTP-C entities in a single message (for example, the OCI of cnSGWc and MME or S4-SGSN). The SMF service pod parses and stores all such OCI IEs received in a single message.

The SMF considers the GTP-C peer as overloaded when one of the following conditions is met.

  • the validity period of the OCI expires

  • the OCI is received as 0

In the case of geo redundancy (GR), it is expected that fresh cache records are built by the new instance with time based on OCI received from new messages.

When the primary cache pod is inactive, the secondary cache pod becomes active and serves all the cache requests.