NAS Dictionary (NAS: 5GMM / 5GSM)¶
A dictionary for looking up NAS — the control signaling between the UE and the AMF — by the messages, states, and procedures of its two sublayers, 5GMM (mobility management) / 5GSM (session management).
Related: Protocol Dictionary / Message Dictionary / IE Dictionary / Registration chapter
5GMM (mobility management) key messages¶
| Message | Direction | Purpose | Related procedure | Spec |
|---|---|---|---|---|
| Registration Request | UE→AMF | Request registration | Registration chapter | TS 24.501 |
| Registration Accept | AMF→UE | Accept registration | Registration chapter | TS 24.501 |
| Registration Complete | UE→AMF | Registration completion response | Registration chapter | TS 24.501 |
| Registration Reject | AMF→UE | Reject registration | Registration chapter | TS 24.501 |
| De-registration Request | UE⇔AMF | Request de-registration | De-registration | TS 24.501 |
| De-registration Accept | UE⇔AMF | Accept de-registration | De-registration | TS 24.501 |
| Service Request | UE→AMF | Connection (service) request | Service Request chapter | TS 24.501 |
| Authentication Request | AMF→UE | Send the authentication challenge | Authentication chapter | TS 24.501 |
| Authentication Response | UE→AMF | Return the authentication response | Authentication chapter | TS 24.501 |
| Security Mode Command | AMF→UE | NAS SMC (security mode instruction) | Security chapter | TS 24.501 |
| Security Mode Complete | UE→AMF | NAS SMC completion response | Security chapter | TS 24.501 |
| Configuration Update Command | AMF→UE | NW-initiated UE configuration update | Configuration update | TS 24.501 |
| Identity Request | AMF→UE | Request identity information | Identification | TS 24.501 |
| Identity Response | UE→AMF | Return identity information | Identification | TS 24.501 |
5GSM (session management) key messages¶
| Message | Direction | Purpose | Related procedure | Spec |
|---|---|---|---|---|
| PDU Session Establishment Request | UE→(AMF-transparent)SMF | Request PDU session establishment | PDU Session chapter | TS 24.501 |
| PDU Session Establishment Accept | SMF→(AMF-transparent)UE | Accept PDU session establishment | PDU Session chapter | TS 24.501 |
| PDU Session Establishment Reject | SMF→(AMF-transparent)UE | Reject PDU session establishment | PDU Session chapter | TS 24.501 |
| PDU Session Modification Request/Command | UE⇔SMF | Request/instruct PDU session modification | PDU Modification/Release | TS 24.501 |
| PDU Session Modification Complete/Reject | UE⇔SMF | Modification completion/rejection response | PDU Modification/Release | TS 24.501 |
| PDU Session Release Request/Command | UE⇔SMF | Request/instruct PDU session release | PDU Modification/Release | TS 24.501 |
| PDU Session Release Complete/Reject | UE⇔SMF | Release completion/rejection response | PDU Modification/Release | TS 24.501 |
Main 5GMM states¶
| State | Meaning |
|---|---|
| 5GMM-DEREGISTERED | The UE is not registered with the network |
| 5GMM-REGISTERED | The UE is registered with the network |
| 5GMM-REGISTERED-INITIATED | Transitional state during the registration procedure |
| 5GMM-DEREGISTERED-INITIATED | Transitional state during the de-registration procedure |
The 5GMM state is understood in correspondence with the RM state (RM-DEREGISTERED / RM-REGISTERED), which represents whether the UE is registered, and the CM state (CM-IDLE / CM-CONNECTED), which represents whether a control connection (N1/NAS signaling connection) with the UE exists. Registration status is captured by RM, and whether a signaling connection is established by CM (TS 24.501 / TS 23.501).
NAS is two-storied
NAS consists of two sublayers: 5GMM (mobility management: registration/authentication/connection) and 5GSM (session management: PDU sessions). 5GSM messages pass transparently through the AMF and are processed by the SMF (see N11). Numeric values such as message type values and IEIs follow the relevant chapters of TS 24.501 (this dictionary is for conceptual organization).