Open5GS Core Network Overview

Open5GS is an open-source 5G SA (Standalone) and 4G LTE core network implementation that fully complies with 3GPP specifications.

Architecture Overview

                                    ┌─────────────┐
                                    │    NSSF     │
                                    └──────┬──────┘
                                           │
┌─────────────┐    ┌─────────────┐    ┌────┴────┐    ┌─────────────┐
│    gNB      │───▶│    AMF      │───▶│   NRF   │◀───│    UDM      │
└─────────────┘ N2 └──────┬──────┘    └────┬────┘    └──────┬──────┘
                          │                │                │
                          │           ┌────┴────┐    ┌──────┴──────┐
                          │           │   SCP   │    │    UDR      │
                          │           └─────────┘    └─────────────┘
                          │ N11
                    ┌─────▼─────┐
                    │    SMF    │
                    └─────┬─────┘
                          │ N4
                    ┌─────▼─────┐
                    │    UPF    │────▶ Internet
                    └───────────┘ N6

Network Functions

Control Plane Functions

NF	Full Name	Function
AMF	Access and Mobility Management Function	Access and mobility management, handles N1/N2 signaling
SMF	Session Management Function	Session management, controls UPF
NRF	Network Repository Function	NF registration and discovery
UDM	Unified Data Management	User data management
UDR	Unified Data Repository	User data storage
AUSF	Authentication Server Function	Authentication service
NSSF	Network Slice Selection Function	Network slice selection
PCF	Policy Control Function	Policy control
BSF	Binding Support Function	Binding support
SCP	Service Communication Proxy	Service communication proxy

User Plane Functions

NF	Full Name	Function
UPF	User Plane Function	User plane processing, packet forwarding

Interfaces

Interface	Connection	Protocol	Description
N1	UE ↔ AMF	NAS	Non-Access Stratum signaling
N2	gNB ↔ AMF	NGAP/SCTP	RAN control plane
N3	gNB ↔ UPF	GTP-U	User data tunnel
N4	SMF ↔ UPF	PFCP	Session management
N6	UPF ↔ DN	IP	Data network connection
N11	AMF ↔ SMF	HTTP/2	Session management requests

Key Features

• ✅ 5G SA Core Network: Complete 5G standalone support
• ✅ 4G EPC: Backward compatible with 4G LTE
• ✅ WebUI: Graphical subscriber management
• ✅ MongoDB: Persistent user data storage
• ✅ Containerization: Docker deployment support
• ✅ Kubernetes: Cloud-native deployment support

System Requirements

• OS: Ubuntu 22.04 LTS (recommended)
• RAM: 4GB+
• Storage: 10GB+
• MongoDB: 4.4+

Configuration Files

Open5GS configuration files are located at /etc/open5gs/:

/etc/open5gs/
├── amf.yaml
├── smf.yaml
├── upf.yaml
├── nrf.yaml
├── udm.yaml
├── udr.yaml
├── ausf.yaml
├── nssf.yaml
├── pcf.yaml
├── bsf.yaml
└── scp.yaml

Log Files

Log files are located at /var/log/open5gs/:

# View AMF logs
sudo tail -f /var/log/open5gs/amf.log

# View UPF logs
sudo tail -f /var/log/open5gs/upf.log

Next Steps

• Installation - Detailed installation steps
• Configuration - NF configuration guide
• Subscriber Management - Add and manage subscribers