GL’s Message Automation & Protocol Simulation (MAPS™) 5G N4 Interface Emulator can emulate PFCP messages and signaling specification as defined by 3GPP standards. As seen in the network diagram, N4 is the reference point in the control and user plane separation (CUPS) architecture.
The PFCP is found on the N4 reference point between SMF and UPF (User Plane Function). SMF carries the policy rules attained from the PCF regarding packet handling, forwarding, and usage reporting to the UPF, also implements CUPS in 5G core networks, providing control plane tunnel management and user plane Protocol Data Unit (PDU) sessions.
MAPS™ 5G N4 can emulate and test SMF and UPF elements. SMF in the 5G N4 interface is primarily concerned with managing the UE’s PDU sessions. Its responsibilities include the establishment, modification, and release of the PDU sessions. UPF in the CUPS architecture is responsible for handling user data and reporting the traffic usage data to the SMF.
The CP function controls the packet processing in the UP function by establishing, modifying or deleting PFCP Session contexts and by provisioning rules in UPF regarding packet handling, forwarding, and usage reporting.
At the N4 interface level procedures SMF and UPF nodes are used to manage and establish the items that are not related to a specific N4 session.
Besides emulating network elements SMF and UPF, the emulator also supports error tracking, regression testing, conformance testing, load testing/call generation. It can run pre-defined test scenarios against 5G interface test objects in a controlled & deterministic manner.
MAPS™ 5G N4 Interface Emulator supports powerful utilities like Message Editor, Script Editor, and Profile Editor which allow new scenarios to be created or existing scenarios to be modified using messages and parameters.
GL’s MAPS™ 5G N4 also supports user-plane packet transmission and reception with the purchase of Mobile Traffic Core - GTP (ETH101) licenses and supports simulation of user-plane Gateway traffic in 5G and LTE network with purchase of Mobile Traffic Core – Gateway (ETH102) licenses.
5G N4 Testing Features
- Emulates 5G Core network functions - SMF and UPF
- Supports 5G Control plane and User plane
- Supported Traffic types include Mobile Traffic, and Packet Traffic
- Generates and process PFCP (valid and invalid) messages
- Supports customization of call flow and message templates using Script and Message Editor
- Ready-to-use scripts for quick testing
- Supports scripted call generation and automated call reception
- Supports GTP Traffic (GTP User Plane Data), HTTP traffic generation capability
- Provides Call Statistics and Events Status
- Automation, Remote access, and Schedulers to run tests 24/7
Supported Protocols Standards
3GPP TS 23.501 
IETF RFC 768
IETF RFC 791 
IETF RFC 2460 
5G N4 Interface Procedure
In 5G N4 interface, MAPS™ acts as either SMF to test UPF or UPF to test SMF emulating the following call control procedure.
- MAPS™ N4 Emulator supported Procedures are -PFCP Session Establishment Procedure, PFCP Session Modification Procedure, and PFCP Session Deletion Procedure.
Node Related Procedures:
- PFCP Heartbeat
- PFCP Association Setup
- PFCP Association Update
- PFCP Association Release
- PFCP Version Not Supported
- PFCP Node Report
PFCP Session related messages:
- PFCP Session Establishment
- PFCP Session Modification
- PFCP Session Deletion
- PFCP Session Report
The below figures depict the Call Control Procedure simulation across 5G N4 interface between SMF and UPF.