5G Network Functions

Network Function Functional description

AMF: the following functionality is included in the Access and Mobility Management function (AMF):

  • RAN CP interface (N2) termination
  • NAS (N1) termination, NAS ciphering and integrity protection
  • Management of registration
  • Management of connection
  • Management of reachability
  • Mobility management
  • Lawful intercept
  • SM messages transportation between UE and SMF
  • Transparent proxy for SM messages routing
  • Access authentication and authorization
  • SMS messages transportation between UE and SMSF
  • Security Anchor Functionality (SEAF)
  • Management of location services for regulatory services
  • Location Services messages transportation between UE and LMF as well as between RAN and LMF
  • ID allocation for EPS bearer to interwork with EPS
  • event notification of UE mobility

SMF: the following functionality is included in the Session Management function (SMF):

  • Session Management
  • allocation & management of UE IP address
  • DHCPv4 and DHCPv6 functions
  • ARP proxying
  • UP function selection and control
  • traffic steering configuration
  • Interfaces termination towards Policy control functions
  • Lawful intercept
  • Collection of charging data and charging interfaces support
  • charging data collection control and coordination at UPF
  • NAS messages SM parts termination
  • Notification of DL data
  • AN specific SM information initiation
  • SSC mode of a session determination
  • Functionality of roaming

UPF: the following functionality is included in the User plane function (UPF):

  • Intra-/Inter-RAT mobility anchor point
  • Data Network’s external PDU Session point of interconnect
  • routing & forwarding of packet
  • Inspection of packet
  • User Plane part of policy rule enforcement
  • Lawful intercept
  • Reporting of usage of traffic
  • User plane QoS handling
  • Traffic verification of UL
  • uplink and downlink transport level packet marking
  • the packet buffering and data notification triggering in DL
  • one or more end marker sending and forwarding to the source NG-RAN node
  • ARP proxying

PCF: the following functionality is included in the Policy Control Function (PCF):

  • unified policy framework support
  • Control Plane function is provided with policy rules
  • Access to subscription information

NEF: the following functionality is included in the Network Exposure Function (NEF)

  • capabilities and events exposure
  • The information is provided securely from external application to 3GPP network
  • internal-external information translation
  • information is received by the Network Exposure Function from other network functions
  • a PFD Function may also be supported

NRF: the following functionality is included in the Network Repository Function (NRF):

  • service discovery function is supported
  • the NF profile of available NF instances and their supported services can be maintained

UDM: the following functionality is included in the Unified Data Management (UDM):

  • 3GPP AKA Authentication Credentials generation
  • User Identification Handling
  • de-concealment of privacy-protected subscription identifier is supported
  • Access authorization
  • UE's Serving NF Registration Management
  • service/session continuity
  • MT-SMS delivery support
  • Lawful Intercept
  • Subscription management
  • SMS management

AUSF: the following functionality is included in the Authentication Server Function (AUSF):

  • authentication for 3GPP access and untrusted non-3GPP access

N3IWF: the following functionality is included in the N3IWF:

  • IPsec tunnel establishment
  • N2 and N3 interfaces termination
  • control-plane NAS (N1) signalling relaying between the UE and AMF in UL and DL
  • N2 signalling handling from SMF
  • IPsec Security Association establishment
  • user-plane packets relaying between the UE and UPF in UL and DL
  • N3 UL user-plane packet marking
  • Enforcing QoS
  • Local mobility anchor
  • AMF selection

AF: the following functionality is included in the Application Function (AF):

  • influence of application on traffic routing
  • Accessing Network Exposure Function
  • the Policy framework interaction for policy control