5.8.2.13.1 Support for unicast traffic forwarding of a 5G VN

To enable unicast traffic forwarding in a UPF, the following applies:

• The SMF provides for each 5G VN group member's N4 Session (i.e. N4 Session corresponding to PDU Session) the following N4 rules that enable the processing of packets received from this UE.
• in order to detect the traffic, a PDR containing Source Interface set to "access side" and CN Tunnel Information set to PDU Session tunnel header (i.e. N3 or N9 GTP-U F-TEID); and
• in order to forward the traffic, a FAR containing Destination Interface set to "5G VN internal".
• The SMF provides for each 5G VN group member's N4 Session (i.e. N4 session corresponding to PDU Session) the following N4 rules that enable the processing of packets towards this UE.
• in order to detect the traffic, a PDR containing Source Interface set to "5G VN internal" and Destination Address set to the IP/MAC address (es) of this 5G VN group member; and
• in order to forward the traffic, a FAR containing Outer Header Creation indicating the N3/N9 tunnel information and Destination Interface set "access side".
• If N19-based forwarding is applied, the SMF configures the group-level N4 Session for processing packets received from a N19 tunnel with the following N4 rules for each N19 tunnel.
• in order to detect the traffic, a PDR containing Source Interface set to "core side" and CN Tunnel Information set to N19 tunnel header (i.e. N19 GTP-U F-TEID); and
• in order to forward the traffic, a FAR containing Destination Interface set to "5G VN internal".
• If N19-based forwarding is applied, the SMF configures the group-level N4 Session for processing packets towards 5G VN group members anchored at other UPFs with the following N4 rules for each N19 tunnel.
• in order to detect the traffic, a PDR containing Source Interface set to "5G VN internal" and Destination Address set to the IP/MAC address (es) of UEs anchored at the peer UPF of this N19 tunnel (e.g. based on the IP address range supported by the peer UPF); and
• in order to forward the traffic to a 5G VN group member anchored at another UPF via the N19 tunnel, a FAR containing Outer Header Creation indicating the N19 tunnel information, Destination Interface set to "core side".
• The SMF configures the group-level N4 Session for processing packets received from a 5G VN group member connected via N6 with the following N4 rules.
• in order to detect the traffic, a PDR containing Source Interface set to "core side" and Source Address set to the IP/MAC address (es) of this 5G VN group member; and
• in order to forward the traffic, a FAR containing Destination Interface set to "5G VN internal".
• The SMF configures the group-level N4 Session for processing packets towards a 5G VN group member connected via N6 or packets towards a device residing in DN with the following N4 rules.
• in order to detect the traffic, a PDR containing Source Interface set to "5G VN internal" and Destination Address set to the IP/MAC address (es) of this 5G VN group member; and
• in order to forward the traffic to the 5G VN group member or device via N6, a FAR containing Destination Interface set to "core side".
• The SMF shall update N4 rules for group-level N4 Session to enable correct forwarding of packets towards UE who's PSA UPF has been reallocated and address is unchanged.
• The SMF may also configure the following N4 rules for the group-level N4 Session to process packets with an unknown destination address:
• in order to detect the traffic, a PDR containing Source Interface set to "5G VN internal", a match-all Packet Filter and a Precedence set to the lowest precedence value; and
• in order to process the traffic, a FAR containing Destination Interface set to "core side" to route the traffic via N6 by default, or in the case of local SMF configuration that N6-based forwarding is not applied a FAR instructing the UPF to drop the traffic.