Virtualized Network Function Component

Description

A Virtualized Network Function Component (VNFC) is a core concept in the ETSI NFV architectural framework, adopted and specified by 3GPP for managing virtualized network functions. It represents an individual, deployable software module that encapsulates a specific subset of the functionality of a larger Virtualized Network Function (VNF). A VNF is typically composed of multiple interconnected VNFCs, each responsible for a distinct task, such as signal processing, session management, or packet forwarding. This decomposition is aligned with cloud-native principles, where applications are built as a suite of loosely coupled, independently deployable services.

VNFCs are instantiated as Virtual Machines (VMs) or Containers on virtualized infrastructure, specifically within a Network Functions Virtualization Infrastructure (NFVI). Each VNFC has its own resource requirements (CPU, memory, storage) and connects to other VNFCs via virtual links to form a complete VNF. The VNFC Descriptor (VNFC D) is a deployment template that defines these requirements, including software images, instantiation levels, and dependencies. This descriptor is part of the broader VNF Descriptor used by orchestration systems.

From an operational perspective, VNFCs are the primary units for scaling and healing actions. A VNF Manager (VNFM) can scale a VNF horizontally by adding or removing instances of a specific VNFC type, or vertically by adjusting the resources allocated to a VNFC instance. Similarly, if a VNFC fails, the VNFM can initiate a healing procedure to terminate the faulty instance and instantiate a new one. This fine-grained control allows for efficient resource utilization and high service availability, which are critical for telecom networks.

The role of VNFCs extends into service assurance and performance management. Since each component can be monitored independently, operators gain detailed visibility into the performance and health of their network services. Metrics such as throughput, latency, and error rates can be collected per VNFC, enabling precise root cause analysis and targeted optimization. This component-level management is a significant advancement over monolithic network appliances, paving the way for fully automated, intent-based network operations.

Purpose & Motivation

The VNFC concept was created to address the limitations of monolithic, hardware-based network appliances. Traditional network functions were implemented as integrated units of proprietary software and hardware, making them rigid, expensive to scale, and slow to upgrade. The shift towards Network Functions Virtualization (NFV) aimed to decouple software from hardware, but early virtualized functions often remained as large, monolithic software images, which limited the agility promised by virtualization.

The introduction of VNFCs enables a more granular and flexible architecture. By breaking down a VNF into smaller, functional components, operators can scale and update parts of a network function independently. For example, in a virtualized Evolved Packet Core (vEPC), the session management component (a VNFC) could be scaled out during peak hours without also scaling the packet gateway component, leading to more efficient resource use. This componentization is a stepping stone towards cloud-native network functions built using microservices, which offer even greater resilience and continuous delivery capabilities.

Ultimately, VNFCs are a foundational element for achieving the core NFV benefits: reduced capital and operational expenditure, accelerated service innovation, and improved operational agility. They allow network operators to manage their resources with the same efficiency and automation as cloud service providers, which is essential for competing in a market demanding rapid deployment of new services like 5G network slicing and edge computing.

Key Features

• Modular software component implementing a subset of VNF functionality
• Smallest independently deployable and manageable unit within a VNF
• Defined by a VNFC Descriptor specifying resource requirements and dependencies
• Instantiated as a Virtual Machine or Container on NFVI
• Primary unit for horizontal/vertical scaling and fault recovery actions
• Enables fine-grained performance monitoring and service assurance

Evolution Across Releases

Defining Specifications