Section: 5.6.16.2 Application Function influence on Service Function Chaining
Content: An AF may request the steering of user plane traffic to a pre-configured chain of Service Functions on N6-LAN. In the non-roaming scenario, Application Function influence on Service Function Chaining and Application Function influence on traffic routing (as defined in clause 5.6.7) can be applicable to the same traffic simultaneously. It is assumed that a service level agreement exists between the operator and a third party that includes a list of authorized predefined Service Function Chains (SFCs), each SFC being identified based on a Service Function Chaining identifier (SFC ID). The AF may request the selected traffic flows to be steered towards a specific SFC, either at PDU Session establishment or any time after PDU Session establishment. The AF requests may be sent to the PCF via the NEF. When SFC ID is included in the AF request, the parameters listed in Table 5.6.16.2-1 may be included in the AF request. Table 5.6.16.2-1: Information element contained in AF request The PCF checks whether the SFC ID received from the AF corresponds to an authorized predefined SFC according to the service level agreement with this AF. Based on the SFC ID received from the AF, the PCF derives the TSP ID(s) (that can be different for uplink and downlink directions) and sends the TSP ID(s) and optionally Metadata (as provided by the AF) to the SMF as part of the PCC rule(s) as described in clause 6.3.1 of TS 23.503[ Policy and charging control framework for the 5G System (5GS); Stage 2 ]  [45]. The SMF behaves in the same way it is described in clause 5.6.16.1. If the SMF has received Metadata in the N6-LAN Traffic Steering Enforcement Control information of the PCC rule, the SMF forwards the Metadata to the UPF via N4 in the corresponding FAR as described in clause 5.8.5.6.