Virtualized Network Function Manager

Description

The Virtualized Network Function Manager (VNFM) is a critical entity within the ETSI-defined NFV Management and Orchestration (MANO) architecture, standardized by 3GPP for telecom environments. Its primary responsibility is the full lifecycle management of one or more Virtualized Network Function (VNF) instances. The VNFM operates based on deployment and configuration information provided in a VNF Descriptor (VNFD) and receives instructions from a higher-level orchestrator, typically the NFV Orchestrator (NFVO).

Lifecycle management encompasses several key procedures. For instantiation, the VNFM interprets the VNFD, requests resources from the NFVI, and coordinates the deployment and configuration of the VNF's constituent Virtualized Network Function Components (VNFCs). For scaling, the VNFM can execute horizontal scaling (adding/removing VNFC instances) or vertical scaling (modifying resources of existing VNFCs) based on policy triggers or direct requests. It also manages software updates and upgrades of VNF instances, ensuring minimal service disruption. Furthermore, the VNFM performs healing operations by monitoring the health of VNF instances and automatically recovering from failures, such as by re-instantiating a faulty VNFC.

The VNFM exposes northbound interfaces, primarily towards the NFVO, for receiving lifecycle management directives and providing notifications. A key interface is the Ve-Vnfm-em reference point, used for VNF lifecycle management. It also has southbound interfaces to interact with the VNF instances themselves, often using a proprietary interface for element management, and to the Virtualized Infrastructure Manager (VIM) to manage the underlying compute, storage, and network resources. The VNFM maintains state information for each managed VNF instance, which is essential for consistent operations.

In practical deployments, a VNFM can be generic, managing a wide range of VNF types from different vendors, or specific to a particular VNF or vendor. The choice impacts interoperability and feature support. The VNFM's role is pivotal for automating network operations, enabling zero-touch provisioning, and ensuring the high availability and elasticity required for modern cloud-native 5G core networks and network slices.

Purpose & Motivation

The VNFM was created to solve the operational complexity introduced by virtualizing network functions. Simply running network software on commercial off-the-shelf (COTS) hardware was insufficient; a new management paradigm was needed. Traditional network element management systems (EMS) were designed for physical appliances and could not handle the dynamic nature of virtualized resources, such as instantiation on-demand, elastic scaling, and automated recovery.

The VNFM addresses this by providing a standardized, automated manager for the software lifecycle of VNFs. It abstracts the complexity of the underlying virtual infrastructure, allowing the network orchestrator to issue intent-based commands (e.g., "scale this VNF") without needing to know the specifics of the hypervisor or cloud platform. This separation of concerns is a cornerstone of the NFV MANO architecture, enabling multi-vendor interoperability and preventing vendor lock-in at the infrastructure layer.

Historically, without a VNFM, operators would have to manually provision VMs, install VNF software, and configure connections—a process that could take days or weeks. The VNFM automates these tasks, reducing provisioning time to minutes. This agility is not just an operational improvement; it is a business enabler for new revenue streams like network slicing, where dedicated virtual networks must be created and modified rapidly for different customers or services. The VNFM is thus essential for transforming telecom networks into agile, software-driven platforms.