Network slicing: everybody has its own view.

It's been a while. I have been reading and trying to grasp the concept of network slicing. Each SDO has its own vision of it and tries to profile the vision according to its interests and expertise.

I think all starts with the NGMN whitepaper that describes the design considerations for 5G networks, having network slicing as a key enabler to make it happen.

It describes the content of the slices, its purpose and the desire that the configuration matches a business purpose. This is very interesting: previous developments in telecommunications had an inverse approach: create something and then find the application, or tweak it for a desired necessity. In here, the business need is established before the creation of a service. This calls for the creation of a flexible enough system that covers the worst case scenario of applicability of the technology, in this case, 5G.

NGMN provides a wishlist of desired capabilities of Network Slicing in order to fulfill the needs of the main use cases proposed for 5G. Establishes the proper definitions to concepts so SDOs, manufacturers and developers can talk in the same language. Doesn't say how, does not specify the technologies or their interaction. It is just a wishlist.

The architectural view is simple:

These three layers resemble the division that most proponents have for their systems: a business entity; an instantiation of that business requirement; and a "place" where everything happens.

In ETSI point of view, they want to leverage on their NFV architectural framework and its management and orchestration scheme, which is pretty solid.

The strong quality of ETSI is that controls the life-cycle of VNF: from the management of the order from the business/operation entity, down to the instantiation in the infrastructure. And these VNFs are constituent parts of the services implemented in a Network Slice. Having control of the life-cycle of the VNFs guarantees a great interaction with ONF’s SDN architecture. A good document to check out is this one.

Now, regarding ONF, their vision on Network Slicing goes along with SDN and its application to 5G. ONF leverages in that relationship to power the association between NFV and SDN to make the slicing concept come to reality. Even though ONF does not talk about slicing inside its definition of the SDN paradigm, the way an SDN controller presents the resources to applications (via NBI) complies with the definition and concept of network slicing. That resource representation that is inside a client context (inside the SDN controller) is similar to the notion of Network Slice depicted by NGMN. Since the network view is focused in the controller, ONF points out that they rely on the APIs exposed to applications and resources in order to receive/deliver orders and commands. A great document that shows this point of view is the TR-526. It would be great to have a standard way to express the requirements to the resource context. Also I think it is necessary to establish a way to perform the segmentation of the resources from the Infrastructure Provider point of view. A standardized way to express those requirements is also desirable. ONF states that they can define and instantiate an end to end slice, but since there is no way (at the moment) to have a full data plane segmentation, this is not entirely true.

3GPP's view is more elaborate: this because it takes possible scenarios, establishes interfaces and entities that would handle the message call flows among them. It is great that leverage on well known procedures such as Attachment request messages to illustrate how an UE would suggest the core network which resources are needed and which network slice is desired. They have the power to talk in those terms since they have been standardizing the way mobile networks operate. Since an UE has requirements to choose a service to connect to, a more elaborate way to express those parameters is needed. This involves more signaling exchange with new entities inside the core network and interactions (not mentioned) with OSS/BSS and MANO entities that would administer the infrastructure and the proper way to deploy the network functions as desired by the business entities. The specification that describes the whole process is 28.801.

I expect that as I continue reading and advancing in the next topics (5G architecture and security) it could be possible to understand the relationship between these three building blocks of my research. This way, I can begin to assess the architecture, spot weaknesses and propose a complete architecture that provides a secure environment to deploy services using network slices in 5G networks. Also I would like to improve my writing style... and there is only one way to do it.

Comments are welcome.