5.7.1.4 QoS Rules

The UE performs the classification and marking of UL User plane traffic, i.e. the association of UL traffic to QoS Flows, based on QoS rules. These QoS rules may be explicitly provided to the UE (i.e. explicitly signalled QoS rules using the PDU Session Establishment/Modification procedure), pre-configured in the UE or implicitly derived by the UE by applying Reflective QoS (see clause 5.7.5). A QoS rule contains the QFI of the associated QoS Flow, a Packet Filter Set (see clause 5.7.6) and a precedence value (see clause 5.7.1.9). An explicitly signalled QoS rule contains a QoS rule identifier which is unique within the PDU Session and is generated by SMF.

There can be more than one QoS rule associated with the same QoS Flow (i.e. with the same QFI).

When the UE informs the network about the number of supported Packet Filters for signalled QoS rules for the PDU Session (during the PDU Session Establishment procedure or using the PDU Session Modification procedure as described in clause 5.17.2.2.2 after the first inter-system change from EPS to 5GS for a PDU Session established in EPS and transferred from EPS with N26 interface), the SMF shall ensure that the sum of the Packet Filters used by all signalled QoS rules for a PDU Session does not exceed the number indicated by the UE.

A default QoS rule is required to be sent to the UE for every PDU Session establishment and it is associated with a QoS Flow. For IP type PDU Session or Ethernet type PDU Session, the default QoS rule is the only QoS rule of a PDU Session which may contain a Packet Filter Set that allows all UL packets and in this case, the highest precedence value shall be used for the QoS rule.

NOTE 2: How the UE evaluates UL packets against the Packet Filter Set in a QoS rule is described in clause 5.7.1.5.

NOTE 3: The QoS rule pre-configured in the UE is only used together with option 1a for control QoS Flows as described in clause 5.7.1.3. How to keep the consistency of QFI and Packet Filter Set between UE and network is out of scope in this release of the specification.

For Unstructured type PDU Session, the default QoS rule does not contain a Packet Filter Set and in this case the default QoS rule defines the treatment of all packets in the PDU Session.

As long as the default QoS rule does not contain a Packet Filter Set or contains a Packet Filter Set that allows all UL packets, Reflective QoS should not be applied for the QoS Flow which the default QoS rule is associated with and the RQA should not be sent for this QoS Flow.