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WHAT IS NFV - Overview

Network Function Virtualization (NFV) is the concept of replacing/virtualizing dedicated network appliances — such as routers, switches, firewalls etc. with software running on commercial/commodity servers.This blog helps you understand What is NFV and related concepts.

The aim of NFV is to separte network functions(control plane) from dedicated hardware devices(data plane) and allow network services that are now being hosted on routers, firewalls, load balancers and other dedicated hardware devices to be hosted on virtual machines (VMs). Once the network functions are under the control of a hypervisor(What is a Hypervisor?), the services that once require dedicated hardware can be performed on standard x86 servers.

Network Function Virtualization Advantages

  • Helps reduce capital expenditure (CAPEX) by lowering the need to purchase purpose-built hardware.
  • Helps reduce operational expenditure(OPEX) through reduced equipment running requirements (e.g. space to house, power to run etc.), and simplifying roll-out.
  • Helps accelerate time-to-market to new opportunities.
  • Helps minimizing the risk of rolling out new services by allowing providers to trial and evolve, or even roll back services as the customer needs them
  • Helps become more agile and on-demand, driving a better customer experience.


SDN and NFV are not dependent on each other, but they do have similarities. Both rely on virtualization and use network abstraction, but how they separate functions and abstract resources is different.

SDN separates network forwarding functions from network control functions with the goal of creating a network that is centrally manageable and programmable. NFV abstracts network functions from hardware. NFV supports SDN by providing the infrastructure on which SDN software can run.

NFV and SDN can be used together, depending on what you want to accomplish, and both use commodity hardware. With NFV and SDN, you can create a network architecture that is more flexible, programmable, and uses resources efficiently.


See the below points to understand the VNF and NFV and their related difference.
  1. First you create a VM on commodity hardware (x86 servers) to host a service (say Firewall). 
  2. Once the VM is created, required software firewall image is installed in that VM, network configuration is done, and other related config is done to make it ready for operation and start handling the customer traffic. This can also be said that a VNF (virtual firewall) is ready for operation. 
  3. While we connect this VNF (Noun - virtual firewall) to the network (say with other VNFs - a virtual switch, router, or a load balancer - also called service chaining) and the VNF starts handling the customer traffic/service the network function (intially that could be run using a dedicated Hardware firewall - say Cisco ASA) is virtualized and now running the service which is called NFV (verb).
In Summary or plain english VNF is a Noun and NFV is a verb.

NFV Architecture

NFV provides for an open architecture with many flexible options for deploying an NFV solution. The typical architecture of NFV consists of three distinct layers:

  • Network functions virtualization infrastructure (NFVi) – the hardware and infrastructure software platform required to run network applications.
  • Virtual network functions (VNFs) – software applications that deliver specific network functions, such as routing, security, mobile core, IP multi-media subsystems, video, etc.

  • Management, automation and network orchestration (MANO) – the framework for management and orchestration of NFVi and various VNFs.

NFV Use Cases

NFV is applicable across a wide range of network functions, including fixed and mobile networks.  Some leading NFV applications are listed below:
  • Software-Defined Branch and SD-WAN
  • IP Multi-Media Subsystem (IMS)
  • Session Border Control (SBC)
  • Video Servers
  • Voice Servers
  • Universal Customer Premises Equipment (uCPE)
  • Content Delivery Networks (CDN)
  • Network Monitoring
  • Network Slicing
  • Service Delivery
  • A variety of security functions such as firewalls, IDS, IPS, vRR, NAT etc.

Top NFV Suppliers


With help of NFV, network administrators have no need to purchase dedicated hardware devices (costing hundreds of dollars) in order to build a service chain. Because server capacity will be able to be added through software, there will be no need for network administrators to over-provision their data centers which will reduce both capital expenses (CAPex) and operating expenses (OPex). If an application running on a VM required more resources(CPU/RAM/HDD etc.), the administrator can dynamically do that or can move the VM to another physical server as per the requirement. He can also provision another virtual machine on the original server to balance the load earlier shared by single VM. Having this flexibility will allow an administrator to adapt to network requirements in a more agile manner and to changing business goals and network service demands.