Understanding VNF Structure and Deployment in Telecom

Virtual Network Functions (VNFs) marked a major step in the evolution of telecom networks, enabling operators to move away from costly hardware appliances and embrace software-driven flexibility. But VNFs are not just software packages — they are deployed and managed within a standardized framework defined by ETSI NFV architecture. Let’s break down the structure of a VNF and how it gets deployed.

VNF Standard Structure

A VNF is essentially a network function (like a firewall, EPC, or load balancer) running on virtualized infrastructure. Its structure usually includes:

• VNF Components (VNFCs): The building blocks of a VNF, often implemented as virtual machines that perform specific tasks.

• VNF Descriptor (VNFD): A template describing the VNF’s requirements (compute, storage, networking), deployment rules, and lifecycle management.

• Element Management System (EMS): Responsible for monitoring, configuration, and fault management of the VNF itself.

This modular structure allows operators to automate how VNFs are provisioned, scaled, and maintained.

VNF Deployment Flow

Deploying a VNF is not a single-step process — it requires coordination across several layers of the NFV architecture:

1. NFV Orchestrator (NFVO):
   The top-level brain of the system. The NFVO takes service requests (e.g., deploy a virtual EPC) and translates them into actions. It ensures resources are allocated, policies applied, and lifecycle operations managed.

2. VNF Manager (VNFM):
   Manages the lifecycle of individual VNFs, based on the VNFD. It handles tasks like instantiation, scaling, healing, and termination. The VNFM ensures that the VNF behaves as expected within the network.

3. Virtualized Infrastructure Manager (VIM):
   The VIM controls the cloud or virtualization layer (like OpenStack or VMware). It allocates compute, storage, and networking resources on demand for VNFs to run.

4. Element Management System (EMS):
   Once the VNF is running, the EMS provides day-to-day management, such as monitoring performance, configuring parameters, and troubleshooting alarms.

Advantages of Standardized Deployment

This layered approach ensures that VNFs can be:

• Automated: No need for manual provisioning of each component.

• Flexible: Easily scaled up or down based on traffic.

• Interoperable: Vendors follow the ETSI NFV framework, enabling multi-vendor environments.

Conclusion

The standard VNF structure — built on VNFCs, VNFD, and EMS — combined with orchestration through NFVO, VNFM, and VIM, makes telecom networks more agile and cost-effective. While it introduced complexity compared to traditional hardware, VNFs laid the foundation for today’s move toward fully cloud-native CNFs.