# Rust design

How the core keeps 5G network-function boundaries explicit.

Product: 5G Core

Human documentation: https://www.1sc.dev/docs/core/rust-design

Documentation index: https://www.1sc.dev/llms.txt

## Service map

| Boundary | Owns | Talks to |
| --- | --- | --- |
| AMF | N2 signaling, NAS registration, access and mobility coordination | AUSF, UDM, NSSF, SMF |
| AUSF / UDM / UDR | Authentication and subscriber data | AMF, each other |
| NSSF / PCF | Slice selection and session policy | AMF, SMF |
| SMF | PDU-session control state and UPF programming | AMF, PCF, UPF |
| UPF | N3 GTP-U user-plane handling for the supported lab path | SMF, gNB |
| NRF | Network-function registration and discovery | Control-plane network functions |