3GPP 23.501 v20.2.0 — the document's own text
5.7.2.7 Default values
Taught in 14. What the network promises (The 5G system architecture, in depth), 5. The connection, and what is promised on it (The 5G system architecture, overview).
For each PDU Session Setup, the SMF retrieves the subscribed Session-AMBR values as well as the subscribed default values for the 5QI and the ARP and optionally, the 5QI Priority Level, from the UDM. The subscribed default 5QI value shall be a Non-GBR 5QI from the standardized value range.
NOTE 1: The 5QI Priority Level can be added to the subscription information to achieve an overwriting of the standardized or pre-configured 5QI Priority Level e.g. in scenarios where dynamic PCC is not deployed or the PCF is unavailable or unreachable.
The SMF may change the subscribed values for the default 5QI and the ARP and if received, the 5QI Priority Level, based on interaction with the PCF as described in TS 23.503 [45] or, if dynamic PCC is not deployed, based on local configuration, to set QoS parameters for the QoS Flow associated with the default QoS rule.
For QoS Flow(s) of the PDU Session other than the QoS Flow associated with the default QoS rule, the SMF shall set the ARP priority level, the ARP pre-emption capability and the ARP pre-emption vulnerability to the respective values in the PCC rule(s) bound to that QoS Flow (as described in TS 23.503 [45]). If dynamic PCC is not deployed, the SMF shall set the ARP priority level, the ARP pre-emption capability and the ARP pre-emption vulnerability based on local configuration.
NOTE 2: The local configuration in the SMF can e.g. make use of the subscribed value for the ARP priority level and apply locally configured values for the ARP pre-emption capability and ARP pre-emption vulnerability.
If dynamic PCC is not deployed, the SMF can have a DNN based configuration to enable the establishment of a GBR QoS Flow as the QoS Flow that is associated with the default QoS rule. This configuration contains a standardized GBR 5QI as well as GFBR and MFBR for UL and DL.
NOTE 3: Interworking with EPS is not possible for a PDU Session with a GBR QoS Flow as the QoS Flow that is associated with the default QoS rule.
The SMF may change the subscribed Session-AMBR values (for UL and/or DL), based on interaction with the PCF as described in TS 23.503 [45] or, if dynamic PCC is not deployed, based on local configuration, to set the Session-AMBR values for the PDU Session.