The present document studies the overload control mechanisms for Rc, Re, Rf and Ro interfaces based on the conclusion of TR 29.809. For 3GPP Diameter Charging interfaces, the Diameter overload control mechanism are based on the IETF Draft "Diameter Overload Indication Conveyance" that defines the AVPs for the transport of overload information of Diameter application as well as the basic behaviour of the Diameter endpoints receiving this information. The IETF RFC 7683 is considered as the reference of the present document and not the IETF Draft draft-ietf-dime-ovli-02 referenced by TR 29.809. As per TR 29.809, the following conclusions apply and are not studied in the present document:

• How a reporting node determines it is entering into an overload condition is implementation dependent.
• How a reporting node determines the contents value of the overload report (i.e. OC-OLR AVP) is implementation dependent.
• How a reacting node achieves traffic reduction (i.e. selection of impacted sessions) is implementation dependent.

The following issues are covered by the present document:

• Application and/or modification of current failure handling functionality defined in TS 32.299 for Diameter online and offline charging in the Charging Trigger Function when reacting to overload control indication from the OCS or CDF, respectively.