User Plane Function Functional Description.

Below are the Functionalities supported by User Plane Function (UPF), a single Instance of UPF may implement some are all Functionalities.

Anchor point for Intra-/Inter-RAT Mobility

External PDU Session point of interconnect to Data Network.

Packet routing & forwarding (e.g. support of Uplink classifier to route traffic flows to an instance of a data network, support of Branching point to support multi-homed PDU Session).

Packet inspection (e.g. Application detection based on service data flow template and the optional PFDs received from the SMF in addition).

User Plane part of policy rule enforcement, e.g. Gating, Redirection, Traffic steering).

Lawful intercept

Traffic usage reporting.

QoS handling for user plane, UL/DL rate enforcement, Reflective QoS marking in DL.

Uplink Traffic verification

Transport level packet marking in the uplink and downlink.

Downlink packet buffering and downlink data notification triggering.

Sending and forwarding of one or more "end marker" to the source NG-RAN node.

ARP proxying and / or IPv6 Neighbour Solicitation Proxying functionality for the Ethernet PDUs. The UPF responds to the ARP and / or the IPv6 Neighbour Solicitation Request by providing the MAC address corresponding to the IP address sent in the request.