Network Functions Virtualization Orchestrator

Description

The Network Functions Virtualization Orchestrator (NFVO) is the brain of the NFV Management and Orchestration (MANO) architecture. Its primary function is the orchestration of Network Services (NS) and the management of NFVI resources across multiple domains and locations. A Network Service is a complete, end-to-end service chain composed of one or more Virtualized Network Functions (VNFs) and the virtual links that interconnect them. The NFVO automates the entire lifecycle of these services—including instantiation, scaling, updating, healing, and termination—translating high-level service blueprints into actionable deployment and configuration commands.

Architecturally, the NFVO operates at a higher level than the Virtualized Infrastructure Manager (VIM). While the VIM manages the virtual resources within a single NFVI domain, the NFVO has a global view. It communicates with one or more VIMs to reserve and allocate resources from the underlying NFVI pools. It also interacts with one or more VNF Managers (VNFMs) to handle the lifecycle of individual VNF instances. The NFVO holds a network service catalog (storing NS blueprints) and a VNF catalog (storing VNF packages), which define the templates for deployment. Key interfaces include the Or-Vnfm reference point to VNFMs, the Or-Vi reference point to VIMs, and the Os-Ma-nfvo reference point for OSS/BSS integration.

The NFVO's workflow begins with receiving a service request, often from an Operations Support System (OSS). It validates the request against the catalog, performs resource feasibility checks across targeted NFVI points of presence (PoPs), and creates a deployment plan. It then coordinates the process: it instructs VIMs to prepare resource reservations, directs VNFMs to instantiate and configure the constituent VNFs, and finally establishes the virtual networking between them according to the service blueprint. Beyond instantiation, the NFVO continuously monitors the service's performance and state. It can trigger automated scaling actions (out/in, up/down) based on policies, coordinate software updates across VNFs, and initiate healing procedures (like re-instantiation) in case of VNF failure.

In the 3GPP context, the NFVO is integral to the management of 5G core network slices and services. It works in concert with other 3GPP management systems, such as the Network Slice Management Function (NSMF) and Communication Service Management Function (CSMF), to realize complex end-to-end network slices. By automating these processes, the NFVO drastically reduces service deployment time from months to minutes, optimizes resource utilization, and enables dynamic, policy-driven network operations that are essential for supporting diverse 5G use cases with varying latency, bandwidth, and reliability requirements.

Purpose & Motivation

The NFVO was created to solve the operational complexity and manual inefficiency inherent in deploying and managing composite network services built from virtualized functions. In early NFV deployments, instantiating and connecting VNFs required significant manual coordination between teams managing compute, network, and application layers, leading to slow service rollout and high error rates.

Its purpose is to provide automated, end-to-end service orchestration. Before NFVO, operators could virtualize individual functions (VNFs), but stitching them together into a working service remained a manual, error-prone process. The NFVO automates this stitching, treating the collection of VNFs and their connectivity as a single manageable entity—the Network Service. This addresses the critical need for agility, allowing operators to rapidly launch, modify, or retire services in response to market demands.

Furthermore, the NFVO enables efficient resource management at a global scale. It can make optimal placement decisions for VNFs across a distributed cloud infrastructure (central, regional, edge data centers), considering constraints like latency, resource availability, and cost. This is vital for cost-effective network operations and for fulfilling the stringent placement requirements of emerging services like mobile edge computing and ultra-reliable low-latency communications (URLLC).