5.35 Support of Per Slice UP Resource Allocation and Usage Reporting by the UP Function

29.2443GPPInterface between the Control Plane and the User Plane nodesRelease 17TS

5.35.1 General

A UP Function may serve PDU sessions belonging to different network slices (i.e. S-NSSAIs).

UP resources allocation per network slice may be achieved by:

a) the UP function allocating UP resources based on the Network Instance IE (and other N4 information such as PDU session type, IP Address Pool ID, ATSSS Control Information), with distinct Network Instance values being configured in the CP function and UP Function for different network slices; or

NOTE 1: The above behavior does not require support of any specific PFCP protocol extension and can be supported by UP function implementations complying with earlier releases of the specification.

b) the UP function allocating UP resources based on the Network Instance IE and S-NSSAI IE (and other N4 information such as PDU session type, IP Address Pool ID, ATSSS Control Information), if the feature "Per Slice UP Resource Management" is supported by the UP function and if the UP function is configured to do so by operator policy.

A UP function that supports allocating UP resources based on the Network Instance IE and S-NSSAI IE (and other N4 information) and that is configured to do so by operator policy, shall:

– indicate support of the feature "Per Slice UP Resource Management" in the UP Function Features IE during the PFCP association setup procedure; and

– allocate resources in the UP function using the Network Instance and, if available, the S-NSSAI.

A UP function that does not support allocating UP resources based on the Network Instance IE and S-NSSAI IE or that is not configured to do so by operator policy shall allocate UP resources based on the Network Instance IE (and other N4 information).

If the UP function supports the UE IP Address Usage Reporting feature (see clause 5.21.3.2), the UP function shall report the UP IP address usage as specified in clause 5.21.3.2, by reporting the UE IP address usage:

a) per Network Instance, if the UP function does not support allocating UP resources based on the Network Instance IE and S-NSSAI IE or it is is not configured to do so by operator policy; or

NOTE 2: This allows to report UE IP address usage per network slice when using a distinct Network Instance value per network slice.

b) per Network Instance and S-NSSAI, if the UP function supports allocating UP resources based on the Network Instance IE and S-NSSAI IE and is configured to do so by operator policy. In this case, the UP Function shall report the UE IP address usage information associated with a specific S-NSSAI, as specified in clause 5.21.3.

NOTE 3: If the UP function indicates that it supports the "Per Slice UP Resource Management" feature and if this feature is also supported by the CP function, the CP function can instruct the UP function to allocate UP resource taking into account the network slice by including the Network Instance IE and S-NSSAI IE in the PFCP session establishment procedure. Otherwise, a separate Network Instance needs to be configured for each S-NSSAI if support of multiple slices is needed.