What is AMF ( Access and Mobility management function)?

The Access and Mobility management function (AMF) is a control plane function that performs mobility management. The AMF maintains the NAS (Non-Access Stratum) signaling connection with the UE and it manages the registration process. The AMF is also responsible for the registration process of the User equipment, reachability management, connection management, and mobility management all to be performed by the Access and Mobility management function.

The 5G Core AMF receives all connection and session-related information from the User equipment. It is responsible for handling connection and mobility management tasks. All messages which are related to session management are forwarded over the N11 reference interface to the SMF (Session management function). GUAMI (Globally unique AMF Identifier ) is an identifier to identify various AMF instances as multiple instances are running in the network. The Non-3GPP Interworking function (N3IWF) is responsible for routing messages outside the 5GRAN.

The AMF implements NAS (Non-Access Stratum) Ciphering and Integrity protection algorithms. The AMF typically queries the 5G SBA (Service-based Architecture) NRF (Network Repository Function ) to discover and select the available SMF instances in the network. It manages handovers between gNBs. 5G Core AMF receives all connection and session-related information from the UE (N1/N2) however it is responsible for handling connection and mobility management tasks.