5G-NR: Session Rules

                                                  UPF Control plane




 Parameters for N4 session management

These parameters are used by SMF to control the functionality of the UPF as well as to inform SMF about events occurring at the UPF.

The N4 Session Establishment procedure as well as the N4 Session Modification procedure provide the control parameters to the UPF, the N4 Session Release procedure removes all control parameters related to an N4 session, and the N4 Session Level Reporting procedure informs the SMF about events related to the PDU Session that are detected by the UPF.

The parameters over N4 reference point provided from SMF to UPF comprises an N4 Session ID and may also contain:

- Packet Detection Rules (PDR) that contain information to classify traffic (PDU(s)) arriving at the UPF;

- Forwarding Action Rules (FAR) that contain information on whether forwarding, dropping or buffering is to be applied to a traffic identified by PDR(s);

- Multi-Access Rules (MAR) that contain information on how to handle traffic steering, switching and splitting for a MA PDU Session;

- Usage Reporting Rules (URR) contains information that defines how traffic identified by PDR(s) shall be accounted as well as how a certain measurement shall be reported;

- QoS Enforcement Rules (QER), that contain information related to QoS enforcement of traffic identified by PDR(s);

- Session Reporting Rules (SRR) that contain information to request the UP function to detect and report events for a PDU session that are not related to specific PDRs of the PDU session or that are not related to traffic usage measurement.

- Trace Requirements;

- Port Management Information Container in 5GS;



 Packet Detection Rule

The following table describes the Packet Detection Rule (PDR) containing information required to classify a packet arriving at the UPF. Every PDR is used to detect packets in a certain transmission direction, e.g. UL direction or DL direction.

Table Attributes within Packet Detection Rule




N4 Session ID

Identifies the N4 session associated to this PDR. NOTE 5.


Rule ID

Unique identifier to identify this rule.



Determines the order, in which the detection information of all rules is applied.



Source interface

Contains the values "access side", "core side", "SMF", "N6-LAN", "5G VN internal".

Combination of UE IP address (together with Network instance, if necessary), CN tunnel info,


UE IP address

One IPv4 address and/or one IPv6 prefix with prefix length (NOTE 3).

packet filter set, application ID, Ethernet PDU Session



Network instance (NOTE 1)

Identifies the Network instance associated with the incoming packet.

Information and QFI are used for traffic detection.

Source interface identifies the


CN tunnel info

CN tunnel info on N3, N9 interfaces, i.e. F-TEID.

interface for incoming packets


Packet Filter Set

Details see clause 5.7.6.

where the PDR applies, e.g. from access side (i.e. up-link),


Application ID


from core side (i.e. down-link),


QoS Flow ID

Contains the value of 5QI or non-standardized QFI.

from SMF, from N6-LAN (i.e. the


Ethernet PDU Session Information

Refers to all the (DL) Ethernet packets matching an Ethernet PDU session, as further described in clause and in TS 29.244 [65].

DN or the local DN), or from "5G VN internal" (i.e. local switch).


Framed Route Information

Refers to Framed Routes defined in clause 5.6.14.

Details like all the combination possibilities on N3, N9 interfaces are left for stage 3 decision.

Packet replication and detection carry on information

Packet replication skip information NOTE 7

Contains UE address indication or N19/N6 indication. If the packet matches the packet replication skip information, i.e., source address of the packet is the UE address or the packet has been received on the interface in the packet replication skip information, the UP function neither creates a copy of the packet nor applies the corresponding processing (i.e., FAR, QER, URR). Otherwise the UPF performs a copy and applies the corresponding processing (i.e., FAR, QER, URR).



Carry on indication

Instructs the UP function to continue the packet detection process, i.e., lookup of the other PDRs without higher precedence.


Outer header removal

Instructs the UP function to remove one o