Challenge 3 : AMF

Welcome to the AMF (Access and Mobility Management Function) section, where we’ll explore its crucial role in managing user access and mobility in 5G. Discover how the AMF facilitates authentication, security, and seamless handovers between cells. In addition, we’ll provide step-by-step guidance on how to configure it correctly with different parameters.

Access & Mobility Management Function (AMF)

The Access & Mobility Management Function (AMF) is a crucial control plane component within the 5G core network. It assumes several essential functions and responsibilities, including:

• Registration Management allows a UE to register and deregister with the 5G system. A UE must complete the registration procedure to receive authorization to use 5G services.
• Connection Management establishes and releases the control plane signaling connections between the UE and AMF (across N1 interface). N1 signaling connection moves the UE from CM-Idle to CM-Connected.
• Reachability Management ensures that a UE is always reachable, i.e., it is possible to page the UE when there is a requirement to establish a mobile terminated connection. When a mobile-terminated communication (e.g., an incoming call) needs to reach the UE, the network initiates a paging procedure to locate the specific UE. The Reachability Management function handles this paging process, making sure that the network can find the UE efficiently.
• Mobility Management maintains UE location knowledge, enabling seamless handovers between base stations. Periodic registration updates serve as keep-alive signals to ensure continuous connectivity and verify UE availability within the network’s coverage. It facilitates uninterrupted communication as the UE moves across different areas.

AMF: Configuration

To configure the AMF, you must provide the necessary information in the file located at “~/free5gc/config/amfcfg.yaml”

• ngapIpList: <eth0 IP address> : represents a list of one or more IP addresses associated with the N2 interface (NGAP). The NGAP is a Control Plane signaling protocol between gNB and the AMF.
• registerIPv4: <eth0 IP address>
• bindingIPv4: <eth0 IP address>
• port: 8000
• mcc: 208
• mnc: 93
• snssaiList : ( sst = 1, sd = 010203 ) : used to uniquely identify a Network Slice. The S-NSSAI contains two components: the SST (Slice/Service Type) and an optional SD (Slice Differentiator).
• supportedDnnList: internet

To obtain the IP address of the “eth0” interface, you can execute the “ifconfig” command and extract the IP corresponding to the interface.

Ifconfig

Navigate to the AMF configuration file and modify the mentioned attributes with their respective values.

vim ~/free5gc/config/amfcfg.yaml