DSCP Marking for N3/S5-U/S2-B over PFCP

Transport Level Marking

Transport level marking is the process of marking traffic with a DSCP value based on the locally configured mapping from the QCI and optionally the ARP priority level. For EPC, the S-GW and P-GW perform transport level marking on a per EPS bearer basis. For 5GC, the S-GW and P-GW perform transport level marking on a per QoS flow basis.

The UPF performs transport level marking with a DSCP value based on the mapping from the 5QI, the Priority Level (if explicitly signaled), and optionally the ARP priority level configured at the SMF. The CP function controls transport level marking by providing the DSCP in the ToS or Traffic Class within the Transport Level Marking IE in the FAR (associated to the PDR matching the traffic to be marked).

The UP function performs transport level marking for the detected traffic and sends the marked packet to the peer entity. The CP function changes transport level marking by changing the Transport Level Marking IE in the related FAR.