Open5GS Configuration

This page details the configuration parameters for Open5GS network functions.

Configuration Overview

All configuration files are located at /etc/open5gs/ in YAML format.

AMF Configuration

AMF (Access and Mobility Management Function) is the entry point for the 5G core, handling N2 connections from gNB.

Config file: /etc/open5gs/amf.yaml

amf:
  sbi:
    server:
      - address: 127.0.0.5
        port: 7777
    client:
      nrf:
        - uri: http://127.0.0.10:7777

  ngap:
    server:
      - address: 192.168.1.10  # Address for gNB connection
        port: 38412

  guami:
    - plmn_id:
        mcc: 001
        mnc: 01
      amf_id:
        region: 2
        set: 1
        pointer: 0

  tai:
    - plmn_id:
        mcc: 001
        mnc: 01
      tac: 1

  plmn_support:
    - plmn_id:
        mcc: 001
        mnc: 01
      s_nssai:
        - sst: 1
          sd: 000001

  security:
    integrity_order: [NIA2, NIA1, NIA0]
    ciphering_order: [NEA0, NEA1, NEA2]

  network_name:
    full: Open5GS
    short: O5GS

  amf_name: open5gs-amf0

Key Parameters

Parameter	Description
ngap.server.address	IP address for gNB connection, must be reachable
guami	Globally Unique AMF Identifier
tai	Tracking Area Identity, must match gNB config
plmn_support	Supported PLMN and slice info
s_nssai	Network Slice Selection Assistance Information

SMF Configuration

SMF (Session Management Function) manages PDU sessions.

Config file: /etc/open5gs/smf.yaml

smf:
  sbi:
    server:
      - address: 127.0.0.4
        port: 7777
    client:
      nrf:
        - uri: http://127.0.0.10:7777

  pfcp:
    server:
      - address: 127.0.0.4
    client:
      upf:
        - address: 127.0.0.7

  session:
    - subnet: 10.45.0.1/16
      gateway: 10.45.0.1
      dnn: internet

Key Parameters

Parameter	Description
pfcp.client.upf	UPF PFCP address
session.subnet	IP address pool for UEs
session.dnn	Data Network Name

UPF Configuration

UPF (User Plane Function) handles user data forwarding.

Config file: /etc/open5gs/upf.yaml

upf:
  pfcp:
    server:
      - address: 127.0.0.7

  gtpu:
    server:
      - address: 192.168.1.10  # Address for gNB connection

  session:
    - subnet: 10.45.0.1/16
      gateway: 10.45.0.1
      dnn: internet
      dev: ogstun

Key Parameters

Parameter	Description
gtpu.server.address	Address for receiving gNB GTP-U data
session.dev	TUN interface name

Common Configuration Scenarios

Modify PLMN

PLMN (Public Land Mobile Network) consists of MCC and MNC:

# All NFs need modification
plmn_id:
  mcc: 460    # China
  mnc: 00     # Operator code

Files to modify:

• amf.yaml
• smf.yaml
• nrf.yaml
• ausf.yaml
• udm.yaml
• pcf.yaml
• nssf.yaml

Configure Multiple Slices

# amf.yaml
plmn_support:
  - plmn_id:
      mcc: 001
      mnc: 01
    s_nssai:
      - sst: 1        # eMBB
        sd: 000001
      - sst: 2        # URLLC
        sd: 000002
      - sst: 3        # mMTC
        sd: 000003

External gNB Connection

If gNB is on a different machine:

# amf.yaml
ngap:
  server:
    - address: 0.0.0.0  # Listen on all interfaces
      port: 38412

# upf.yaml
gtpu:
  server:
    - address: 0.0.0.0  # Listen on all interfaces

Configuration Validation

After modifying config, validate syntax:

# Test AMF config
sudo open5gs-amfd -c /etc/open5gs/amf.yaml -t

# Test SMF config
sudo open5gs-smfd -c /etc/open5gs/smf.yaml -t

Restart services to apply changes:

sudo systemctl restart open5gs-amfd
sudo systemctl restart open5gs-smfd
sudo systemctl restart open5gs-upfd

Next Steps

• Subscriber Management - Add UE subscriber info
• srsRAN Configuration - Configure gNB for core network