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April 22, 2019

The importance of engineering cloud-native and service based architecture layers for 5G Core Network Functions

Author: Balaji Thangavelu, Principal Consultant, Engineering Services

Service Oriented Architecture is a paradigm that has been around for a long time in the IT industry. Its success through deployments across vertical-industries has proven benefits  such as an extensible architecture, loosely coupled services, parallel development, higher availability and scalability. I am glad to see it crossing the boundary and coming into Network Engineering with the advent of Network Function Virtualization(NFV). Especially, its adoption into the 5G world in the form of 'Service Based Architecture(SBA)' is going to benefit the entire network ecosystem.

cloud-native approach to deploying the 5G Core VNFs(Virtual Network Functions) that follow the service based architecture model unlocks new stream of benefits for mobile operators. These benefits would be closely associated with scale and resilience of network functions. In simplistic terms, cloud-native is an approach to building and running applications that exploits the advantages of cloud computing delivery model. The cloud-native landscape is very vast and is constantly evolving.  Let us narrow down our focus and look at it in the context of 5G Core network VNFs.

In this blog post, I have shared my thoughts on how service-based architecture(SBA) and cloud-native implementation are an integral part to the overall design of the 5G core network. I have also highlighted key reasons as to why it is important to engineer these layers carefully to achieve the right balance between scale and service availability. Let us first understand a little bit about Service Based Architecture and cloud-native in context with 5G.

Overview of Service-based architecture:

The below figure from 3GPP specification provides a glimpse on service based architecture. The 5G Core Network Functions that are attached to the service-bus in the figure below, comply to RESTful API interface to consume and produce services. Every Network Function service registers itself with a Network Repository Function. Further, the service-based interfaces (Nxxxf) use HTTP/2 protocol with JSON as the application layer serialization protocol.

3GPP 5G SBA.jpg

Benefits of SBA in context to 5G:

  • Network slicing is a powerful feature offered by 5G which will deliver multitude of vertical industry use cases.  And Service Based Architecture underpins the implementation of Network slicing .
  • Delivers time-to-market benefits as it allows parallel development, integration and rollout of new Network functions/services without disrupting any of the existing services.
  • Mobile operators can extend the boundaries of innovation by offering Network Function access to external applications through Network Exposure Function(NEF)


Overview of cloud-native approach

Cloud native technologies empower organizations to build and run scalable applications in modern, dynamic environments such as public, private, and hybrid clouds. Containers, service meshes, microservices, immutable infrastructure, and declarative APIs exemplify this approach.

As mentioned earlier, the cloud-native concept is a vast area with multitude of technologies. You can read more about it here.

Nowadays, containerization technologies have become synonymous with cloud-native approach. This also brings us to the interesting question of Openstack vs Kubernetes. In order to not digress from the topic of this blog, we can keep it short and say that both technologies are here to stay and complement each other in the 5G ecosystem.

The below simple block diagram would give us an idea as to which of the 5G layers the SBA and cloud-native implementations are applied.

SBA and CNA2.jpg

Now coming to the pertinent question....

Why is the important to engineer the cloud-native and service based architecture layers of 5G core?

Let us understand this question better by taking a deployment use-case of involving couple of the 5G Core Network  functions - Access and Mobility management Function(AMF) and Session management function(SMF). The Service Based Interface (SBI) from these functions are referenced as Namf and Nsmf  

When these 2 SBA functions are deployed on a cloud-native environment managed by Kubernetes being the container orchestrator, it will look something similar to the one shown in the figure below.

SBA CNA K8S2.jpg

AMF and SMF perform some of the defined signaling procedures together before establishing PDU session (data connection in layman terms) for UE(user equipment). Such procedures will happen through exchange of dialogues and information over service-based interface across containers and PODs.

So without getting into further technical depths, we can qualify that any simple 3GPP defined 5G signaling procedure would involve interactions among VNFs. Now when we put this together with the scale of subscriber base, services to be supported, it becomes important to tune the performance of those containerized VNFs in a cloud-native environment. This is determined by various factors like the volume of transactions over service-based interface, signaling-procedure/service-processing-complexity, service-topology that it needs to serve etc.

And I have highlighted few more of such factors that would drive the engineering requirements: 

  •    Volume of transactions over the service-based interfaces.
  •    Instance modelling and templates for 5GC VNFs based on Network slicing use cases.
  •    Co-location vs distribution of 5GC VNFs at worker nodes
  •    Clustering 5GC VNFs at the stack.
  •    Clustering 5GC VNFs at POD/containerization layer
  •    Container/POD replication rules driven by application and system states


Such parameters and engineering requirements greatly vary based on the context of the Mobile Operators in terms of their deployment path, use-cases, subscriber base, multi-vendor VNFs. Most importantly, such engineering requirements need ways to be controlled & automated in one of the below layers

  •         Service Based Architecture (SBA): within the 5G Core VNF application design/configuration.
  •         Cloud-native: within container or container orchestration layer configuration.


5G and cloud-native technologies provide the framework and design constructs to fulfill requirements associated with scalability, agility and resilience. However, the key to success lies in identifying the right deployment use-cases and engineering requirements. Once fully understood, it needs the solution imbibed with efficient automation.

While mobile operators and solution-providers across the globe focus to channel their investments in completing successful 5G trials throughout 2019, there needs to be parallel exercise to address the right-level of engineering and validation in labs and pre-production environments. Picking this later in the deployment cycle would not only cost time and money, but may lead to operational overheads, falling behind the market. And it would be a collaborative effort from solution providers, system integrators, network engineering and operations team of Mobile operators.

Connect with us to know more on how we can collaborate in your network transformation journey and how we can help you succeed in your 5G or SDN/NFV journey.



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