Description
The Network Slice Management Function (NSMF) is a critical functional block within the 3GPP management system, defined across several specifications including TS 23.435, TS 28.530, and TS 28.531. It resides in the management plane and is responsible for the lifecycle management of a complete, end-to-end network slice. Conceptually, the NSMF acts as the 'orchestrator' for a specific network slice instance, ensuring it is created, modified, monitored, and terminated according to its service requirements.
Operationally, the NSMF receives a network slice service request, typically from a Communication Service Management Function (CSMF) or an operator. This request contains the service requirements (e.g., latency, bandwidth, device density). The NSMF's first task is to translate these service requirements into detailed network slice requirements. It then decomposes the end-to-end slice into manageable sub-network parts, known as Network Slice Subnets (NSSs), which correspond to specific technology domains like the RAN, Core, or Transport network.
For each NSS, the NSMF interacts with the corresponding Network Slice Subnet Management Function (NSSMF). The NSMF delegates the management of resources within a specific domain (e.g., provisioning Core Network functions) to the responsible NSSMF. The NSMF aggregates the responses and status from all NSSMFs to maintain a holistic view of the slice's health and performance. It is responsible for ensuring the slice meets its overall Service Level Agreement (SLA) by monitoring Key Performance Indicators (KPIs), managing faults, and triggering corrective actions like scaling resources. The NSMF exposes northbound interfaces for integration with higher-level business support systems (BSS) and operation support systems (OSS).
Purpose & Motivation
The NSMF was created to solve the problem of centralized, automated orchestration for complex end-to-end network slices. Before network slicing, network functions were managed in silos (RAN management, core management), making it impossible to guarantee an integrated service level across all domains for a specific logical network. Manual coordination between domain managers was slow and error-prone.
Its introduction in Release 15 was fundamental to realizing the 5G vision of network slicing. The NSMF provides the necessary intelligence to abstract the complexity of the underlying multi-domain, multi-vendor infrastructure. It enables operators to offer 'slices as a service' by automating the translation of business intent (from a customer or internal service team) into technical reality across the entire network. Without the NSMF, the agility, isolation, and guaranteed performance promised by network slicing would be unattainable.
Classification
Detected Changes Across Releases
from 3GPP Change RequestsSpecific changes extracted from the „Change history“ tables of 3GPP specifications (70 CRs across 5 releases). Complements the general historical overview above with the evidence-based evolution of this function.
In Release 15, the NSMF's new capabilities included introducing a management use case for network slice subnets with assigned priority, as well as defining interactions with NFV MANO for network service priority. These additions established foundational management procedures and integration points for slice lifecycle operations.
In Release 16, the NSMF saw enhancements including the decoupling of communication service and network slice management, refined network slice definitions and identifiers in the OAM space, and updates to the Network Resource Model (NRM) to align with these refined definitions. The release also introduced corrections and clarifications to procedures such as Network Slice Subnet Instance Deallocation and provided an informative annex describing a network slice journey.
- Extend roles related to 5G networks and network slicing management TS 28.530CR0022
- Add informative annex to describe a network slice journey TS 28.531CR0024
- Cleanup Network Slice related definitions in OAM space TS 28.530CR0025
- update slice NRM to align with refined slice definitions TS 28.530CR0027
- Decouple communication service and network slice TS 28.530CR0033
- Correction of missing Figure 4.1.7.1 Examples of network slice as NOP internals TS 28.530CR0035
+ 8 more changes
In Release 17, the NSMF introduced the new Network Slice Capability Exposure (NSCE) service, which provides functionality like slice API configuration and translation, application layer network slice lifecycle management, and network slice optimization based on VAL server policy. This release also added specific procedures for network slice performance and analytics monitoring and for predictive slice modification in edge-based deployments. Furthermore, it enhanced existing management procedures, including updates for the reservation and feasibility checking of network slices and their subnets, and introduced new requirements for SLA management and network service priority management.
- Add the SLA management related requirements and procedure TS 28.531CR0066
- Modification of network slice related requirements TS 28.531CR0098
- Update procedure of reservation and checking feasibility of network slice subnet TS 28.531CR0106
- Update procedure of reservation and checking feasibility of network slice TS 28.531CR0107
- Adding procedure for network service priority management TS 28.531CR0113
- Update procedure of reservation and checking feasibility of network slice subnet TS 28.531CR0114
+ 15 more changes
In Release 18, the NSMF introduced support for managing Non-Terrestrial Network (NTN) slices and added a new provisioning procedure for slice activation and deactivation using administrative state. Furthermore, key lifecycle management procedures for Network Slice and Network Slice Subnet Instances, such as Allocation, Modification, and Deallocation, were updated to support asynchronous operations for improved efficiency.
- Add management capability support for NTN TS 28.530CR0062
- Add Annex network management support for NTN architecture TS 28.530CR0063
- Add provisioning procedure for slice activation and deactivation using adminsitrative state TS 28.531CR0121
- Update Procedure of Network Slice Instance Allocation to support asynchronous operations TS 28.531CR0173
- Update Procedure of Network Slice Instance Deallocation to support asynchronous operations TS 28.531CR0174
- Update Procedure of Network Slice Instance Modification to support asynchronous operations TS 28.531CR0175
+ 18 more changes
In Release 19, the NSMF introduced enhancements for the Network Slice Capability Exposure (NSCE) service, specifically improving the slice requirement verification and alignment capability and the network slice allocation procedure in an NSaaS model. It also added support for late notifications within the network slice adaptation procedures and introduced predictive slice modification for inter-PLMN slice service continuity. Furthermore, the release expanded management capability support to include Non-Terrestrial Networks (NTN).
- Enhancements to Network slice allocation procedure in NSaaS model TS 23.435CR0004
- Enhancements to Slice requirement verification and alignment capability TS 23.435CR0005
- Enhancements to Slice requirement verification and alignment capability TS 23.435CR0017
- Enhancements to Slice requirement verification and alignment capability TS 23.435CR0022
- Rel-19 CR TS 28.530 Update management capability support for NTN TS 28.530CR0073
- Add late notification to the network slice adaptation procedures TS 23.435CR0011
+ 3 more changes
Explore further
Broader topics and technologies where NSMF plays a role.
Defining Specifications
3GPP specifications that define or reference NSMF, with the latest known release. Sourced from the 3GPP document catalog — see methodology.
| Specification | Title | Release |
|---|---|---|
| TS 23.435 vj30 | Network Slice Capability Exposure Procedures | Rel-19 |
| TS 23.700 vk00 | XR Services Application Enablement Layer | Rel-20 |
| TS 26.501 vj30 | 5G Media Streaming (5GMS) Architecture | Rel-19 |
| TS 28.530 vj00 | Network Slicing Concepts & Requirements | Rel-19 |
| TS 28.531 vk00 | Management and Orchestration | Rel-20 |
| TS 28.801 vf10 | Management and Orchestration of Network Slicing | Rel-15 |
| TS 28.805 vg10 | Management of Communication Services in 5G | Rel-16 |