5G Network Slicing is a new concept to allow differentiated treatment to network traffic depending on each customer's or use case’s requirements. With slicing, it’s now possible for Mobile Network Operators (MNO) to consider customers or use cases as different context types with each having different service requirements. These requirements are governed in terms of what slice types each context is eligible to use based on Service Level Agreements and subscriptions. In order to orchestrate and manage 5G network slicing, the Linux Foundation Open Network Automation Platform (ONAP) project has come with E2E slice management architecture with different choices based upon various 3GPP defined components with specific roles (e.g CSMF, NSMF, NSSMF). In this blog, we shall uncover the architecture of NSSMF and its interaction with other components.
3GPP - 3rd Generation Partnership Project
BSS - Business Support System
E2E - End to End
CSMF - Communication Service Management Function
NSMF - Network Slice Management Function
NSSMF - Network Slice Subnet Management Function
NSI - Network Slice Instance
NSSI - Network Slice Subnet Instance
ONAP - Open Network Automation Platform
OSS - Operations Support System
SO - Service Orchestrator
In ONAP, options 1 & 4 from the various slice management architecture choices are supported — see Figure-1.
Essentially, the choices have evolved from the requirements of service providers and open source community contributors. In Architecture Choice#1, CSMF, NSMF, and NSSMF are internal components of ONAP in reference design and implementation. In this option, OSS/BSS can integrate with the runtime component CSMF hosted in SO for business and operational needs. In Choice#4, CSMF and NSMF are internal components of ONAP and hosted in a runtime component called SO. In Figure-1, CSMF takes the business requirements from OSS/BSS and transforms communication service requirements to network slice requirements and is consumed by NSMF. Moreover, NSMF is responsible for the management and orchestration of NSI and derive network slice subnet requirements. In choice#4, NSSMF is an external component and is responsible for the management and orchestration of NSSI. ONAP has implemented standard APIs defined by 3GPP towards NSSMF and the same is  listed below in Table-1.
As we uncover architecture choice#4, NSSMF performs communication with the ONAP NSMF component and that integration is done using the standard RestAPI interface as per Table-1 shown above. In our NSSMF architecture as shown below in Figure-2, consists of various elements and is defined as:
We have done a webinar on deep dive on NSSMF architecture wherein we talked about insights and how the slice event lifecycle is processed by NSSMF and provisioning a commercial 5GC Network functions with a demo. You can refer to the video for details. Also, if you want to try out this NSSMF in your setup, reach out to us at firstname.lastname@example.org