J.2 PCC functional element behaviour

29.2133GPPPolicy and charging control signalling flows and Quality of Service (QoS) parameter mappingRelease 17TS

A PCC functional entity supporting the Diameter message priority mechanism shall comply with IETF RFC 7944 [40].

A PCC functional element sending a request shall determine the required priority according to its policies. When priority is required, the PCC functional element shall include the DRMP AVP indicating the required priority level in the request it sends, and shall prioritise the request according to the required priority level

When the PCC functional element receives the corresponding response, it shall prioritise the received response according to the priority level received within the DRMP AVP if present in the response, otherwise according to the priority level of the corresponding request.

When a PCC functional element receives a request, it shall handle the request according to the received DRMP AVP priority level. For the response, it may modify the priority level received in the DRMP AVP according to its policies and shall handle the response according to the required priority level. If the required priority level is different from the priority level received in the request, it shall include the DRMP AVP in the response.

If:

– a PCC functional element supports using the Diameter message priority mechanism for DSCP marking purposes,

– the transport network utilizes DSCP marking, and

– message-dependant DSCP marking is possible for the protocol stack transporting Diameter,

then the PCC functional element shall set the DSCP marking for transport of the request or response according to the required priority level.

The PCC functional element decisions for a required priority and the priority level value are implementation specific.

Diameter requests related to high priority traffic (e.g. MPS, emergency) shall contain a DRMP AVP with a high priority of which the level is operator dependent.