Page 10 - 3GPP_Highlights_I4

TECHNICAL HIGHLIGHTS

OPEN APIs FOR THE SERVICE-

BASED ARCHITECTURE

By Lionel Morand, 3GPP TSG CT Chair

Interconnected on a logically shared infrastructure or service
Core network as a Service bus, NFs offer services accessible to any other authorized NF
through APIs (Application Programming Interfaces) named
service-based interfaces (SBI). Services exposed by an NF
The fifth generation of mobile networks defined by 3GPP, has (service producer) to another NF (service consumer) are
not only introduced 5G NR (New Radio), but has also brought described using API specifications that identify the set of
in a new core network relying on an open and modular service accessible service data and indicate the authorized operations
platform: the Service-Based Architecture (SBA). on these service data.
SBA provides a cloud-native service framework in which
mobile core network functionalities (authentication, mobility
management, etc.) are supported by Network Functions
(NFs), self-contained software applications that can be run on
commercial off-the-shelf hardware hosted
by cloud infrastructure.
Control Plane
3rd Pty App
NF NF NRF NF NF NEF

NF AMF NF NF SMF

User Equipment Radio Access Network User Plane Data Network

AMF Access and Mobility management Function
NEF Network Exposure Function TM
NF Network Function
NRF NF Repository Function
SMF Session Management Function
In this service platform, every NF can expose services and
consume services provided by other NF. Since NFs are loosely Design principles and documentation
coupled and interfaced with APIs, they can be easily deployed guidelines for 3GPPRESTful APIs
anywhere, on demand, without impact on the existing ones.
New services or service instances are published in a centralized
repository – the Network Repository Function (NRF) – In order to speed up and ease the development of new APIs
accessible to all the NFs to discover the services available in the while ensuring reusability and interworking with existing
network and retrieve required routing information to interact ones, 3GPP has specified in 3GPP TS 29.501 a set of design
with the NFs supporting the services. principles and documentation guidelines for the specifications
of the APIs used over SBIs. This set of recommendations is
These services can also be made open to third-party not restricted to SBIs but is also pertinent for any API defined
applications through a dedicated NF, the Network Exposure by 3GPP, including northbound APIs, APIs used for 3rd party
Function (NEF). The NEF exposes secured APIs to external or exposure, management/orchestration, charging or media
internal applications for a robust but easy access to the core streaming. The aim of 3GPP TS 29.501 is to provide an overall
network services and capabilities supported by the NFs.
consistency at the 3GPP level for the design and description of
The adoption of the SBA with APIs exposing services has the different APIs.
contributed to migrate the mobile core network, traditionally The main principle for the design of 3GPP API can be simply
conceived as a walled garden relying on telco-specific point- summarized as follows: API should be designed as RESTful API
to-point protocols (e.g., Diameter), to a scalable, resilient and whenever possible.
extensible service-oriented environment, more open to third-
party developers and vertical industries for the creation of on-
demand tailored services.
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10 3GP P Highlights ne w slet t er