SBA
Service-Based Architecture: the 5GC design paradigm where network functions expose services via RESTful APIs over HTTP/2, enabling modular, cloud-native deployments.
SBA is the architectural shift that makes the 5G core look more like a cloud microservice deployment than a telecom node diagram. Instead of fixed point-to-point interfaces between boxes, control-plane functions expose services over a common bus and call each other with HTTP/2 REST APIs (JSON payloads, often with OAuth2 for authorisation). An NF that needs a service discovers a provider through the NRF, then calls it directly.
Why it matters in practice:
- Modularity — functions are split into services that can be deployed, scaled, and upgraded independently.
- Cloud-native fit — REST-over-HTTP/2 sits naturally on containers, service meshes, and Kubernetes.
- Looser coupling — adding or scaling a function doesn't mean reconfiguring its peers.
The older reference-point names (N1–N4 and friends) still exist, mostly for the user plane and the radio-facing control plane, but the SBA service interfaces (Namf, Nsmf, Nudm, and so on) are how the core's control functions actually talk among themselves.
Frequently asked questions
- Why does the 5G core use HTTP/2 and REST instead of the older Diameter and GTP-C?
- Mostly to fit cloud-native operations. REST over HTTP/2 with JSON is widely understood, plays well with containers and service meshes, and supports things like server push and multiplexing. It makes NFs easier to build as microservices, scale horizontally, and integrate with standard web tooling — which is hard to do with Diameter or GTP-C control signalling. The user plane still uses GTP-U on N3, though.
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