What is 5G core network UPF?

UPF refers to "User Plane Function" and is an important part of the 3GPP 5G core network system architecture. It is mainly responsible for the routing and forwarding related functions of user plane data packets in the 5G core network; UPF is used in 5G edge computing And network slicing technology plays an important role in low latency and large bandwidth.

The operating environment of this tutorial: Windows 7 system, Dell G3 computer.

What is UPF

The full name of UPF in the 5G core network is "User Plane Function", which means "User Plane Function" in Chinese. Responsible for routing and forwarding related functions of 5G core network user plane data packets.

User Plane Function (UPF) is an important part of the 3GPP 5G core network system architecture and plays an important role in low latency and large bandwidth in 5G edge computing and network slicing technology.

UPF is the connection anchor between 5G networks and multi-access edge computing (MEC). All core network data must be forwarded by UPF before it can flow to the external network. MEC is the hallmark capability of 5G business applications. Based on the C/U split architecture of 5GC, the control plane NF is deployed centrally in the central DC, and the UPF sinks to the edge of the network, which can reduce transmission delays, realize local offloading of data flows, relieve the data transmission pressure of the core network, and thereby improve network data Processing efficiency meets the needs of vertical industries for ultra-low network latency, ultra-high bandwidth and security.

As the user plane network element of the 5GC network, UPF mainly supports routing and forwarding of UE business data, data and service identification, action and policy execution, etc. UPF interacts with the session management function (SMF) through the N4 interface, is directly controlled and managed by SMF, and performs business flow processing according to various policies issued by SMF.

UPF function

• serves as mobile infrastructure (Mobile Infrastructure, for example: RAN) and DN ( Data Network), completing the encapsulation and decapsulation of the GTP-U (GRPS Tunneling Protocol) protocol on UP.

• PDU (Protocol Data Unit, Protocol Data Unit) session anchor (Session Anchor) used for mobility within RAT (Radio Access Technologies, wireless access technology) or between RATs Point), including sending one or more End Marker Packets to gNB (NG-RAN node).

• Packet routing and forwarding: When UPF is between multiple PSA (PDU session anchors), that is, when UPF is used as I-UPF (Intermediate UPF, intermediate UPF), it will act as an uplink The role of link classifier (UL-CL) and branch point to support multi-homed PDU sessions. In the former case, traffic is directed to a specific DN based on traffic matching filters.

• Data packet inspection: use the traffic filter templates of SDF (Service Data Flow, service data flow) or receive the 3-tuple (protocol, and IP address and port of the server) sent from SMF ) PDF (Packet Flow Description) to detect the application process.

• Implementation of some user plane policy rules, such as gating, redirection, and traffic diversion.

• Provides UP's Pre-Flow QoS function to implement rate limiting (Rate Limiting) and grouping of transport layer data segments including uplink (UL) and downlink (DL) marking, as well as handling reflected QoS (DSCP) marking on the DL and traffic authentication (SDF to QoS traffic mapping) on ​​the UL.

• Provides UP traffic collection interface and traffic usage report for billing and legal interception (LI, Lawful Intercept).

Expand knowledge: explanation of related terms

##AbbreviationEnglish nameChinese nameUPFUser Plane FunctionUser Plane FunctionPFCPPacket Forwarding Control ProtocolPacket Forwarding Control ProtocolSDFService Data FlowBusiness Data FlowPDRsPacket Detection RulesPacket Detection RulesFARsForwarding Action RulesForwarding Action RulesBARsBuffering Action RulesBuffering Operational RulesQERsQoS Enforcement RulesQos Enforcement RulesURRsUsage Reporting RulesUsage reporting rulesQFIQos Flow IdentifierQoS Flow IdentifierFor more related knowledge, please visit the

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