5.17.1.2 User Plane management to support interworking with EPS

In order to support the interworking with EPC, the SMF+PGW-C provides information over N4 to the UPF+PGW-U related to the handling of traffic over S5-U. Functionality defined in TS 23.503 [45] for traffic steering control on SGi-LAN/N6 can be activated in UPF+PGW-U under consideration of whether the UE is connected to EPC or 5GC.

When the UE is connected to EPC and establishes/releases PDN connections, the following differences apply to N4 compared to when the UE is connected to 5GC:

• The CN Tunnel Info is allocated for each EPS Bearer.
• In addition to the Service Data Flow related information, the SMF+PGW-C shall be able to provide the GBR and MBR values for each GBR bearer of the PDN connection to the UPF+PGW-U.

If the UE does not have preconfigured rules for associating an application to a PDN connection (i.e. the UE does not have rules in UE local configuration and is not provisioned with ANDSF rules), the UE should use a matching URSP rule as defined in TS 23.503 [45], if available, to derive the parameters, e.g. APN, for the PDN connection establishment and associating an application to the PDN connection.

NOTE: The mapping between the parameters in the URSP rules and the parameters used for PDN connection establishment is defined in TS 24.526 [110].