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How NFV architecture works
NFV enables organizations to virtualize operations and replace network equipment such as routers and switches. It's built on three components: VNFs, NFVI and the MANO framework.
NFV architecture delivers virtualized services for commercial off-the-shelf systems, which can replace costly proprietary devices and address many of their limitations.
In a traditional enterprise network, most network-related operations are carried out by proprietary, purpose-built hardware devices that each perform a specific task, such as routing network traffic or balancing data loads. Although this approach is widely implemented and the technology is mature, it can be costly, inefficient and inflexible, especially with today's dynamic workloads and massive sets of heterogeneous data.
In October 2012, members of the European Telecommunications Standards Institute proposed network functions virtualization (NFV) as a way to simplify and improve network management by transforming the underlying architecture. Since then, there has been slow and steady progress toward that vision for an NFV architecture: virtualizing network operations to replace proprietary network equipment such as routers, switches, gateways, firewalls, load balancers, intrusion detection systems and a variety of other hardware.
Cisco offers several NFV-related products, such as the Nexus 1000V Switch, which provides advanced switching and security features, including support for network access control lists, virtual extensible local area networks and Internet Group Management Protocol snooping.
Nokia also offers a variety of NFV-related products, including the Virtualized Service Router (VSR), a virtualized IP edge router designed for telecommunication cloud environments. Admins can scale up the VSR by adding more VMs, all while still supporting independent scaling of the control and data planes.
Even Microsoft has gotten in on the act with Windows Server. Since Windows Server 2016, the operating system has included NFV features, such as a software load balancer, a multi-tenant firewall and several types of gateways, including site to site, forwarding and Generic Routing Encapsulation.
The NFV architecture
NFV architecture relies on server virtualization technologies to provide the VMs necessary to host the network functions. Virtualization makes it possible to spin up resources as needed to meet the demands of fluctuating and evolving workloads, while also taking advantage of the cost savings that come with commercial off-the-shelf (COTS) hardware.
The vision for NFV also includes containers to host networking operations, but the focus has primarily been on VMs. NFV architecture is built on three components: virtual network functions (VNFs), the NFV infrastructure (NFVI) and an administrative framework that handles management, automation and network orchestration (MANO).
VNFs are software applications that run in VMs and carry out specific networking tasks, such as routing or load balancing. An individual VNF can span multiple VMs, and administrators can chain VNFs together to deliver broader network services.
The NFVI component provides the underlying structure to host the VMs and run the VNF applications. The infrastructure includes the physical compute, storage and network resources, as well as a hypervisor-based virtualization layer that abstracts the resources and makes them available to the VNFs. The NFVI can span multiple locations to support a distributed network.
The MANO framework handles all VNF-related tasks, such as chaining, connectivity and lifecycle management. It is also responsible for managing, monitoring and optimizing NFVI hardware and virtual resources.
NFV and software-defined networking
People sometimes confuse software-defined networking (SDN) and NFV architecture because the two technologies are similar, but they are distinct in several important ways.
With SDN, the control, data and management planes are separated into three different layers. The data plane is made up of the physical hardware components that carry out the data forwarding operations. The control plane is centrally located and interfaces with both the management plane and the data plane. The management plane communicates with the control plane, which in turn sends instructions to the data plane.
In a traditional network infrastructure, these three planes are tightly integrated on the same dedicated devices. With SDN, the control and management planes are abstracted into a software layer independent of the hardware components, which provides a more agile and efficient network to better accommodate today's dynamic workloads.
NFV architecture differs from both traditional and SDN architectures by virtualizing network operations and removing the dependency on proprietary hardware altogether, relying instead on COTS hardware and hypervisor technologies to deliver network services.
An NFV network does not present the network components as pooled and dynamic resources like SDN, but rather as flexible components that support VM-based agility and workload mobility. To make this possible, NFV architecture requires a central management infrastructure that orchestrates and automates administrative tasks and minimizes operational complexity.
In fact, it's the MANO framework that is most like SDN. For this reason, an NFV product might use SDN for MANO operations to help accelerate deployment, automate operations, reduce capital expenditure, and maximize scalability and performance. Indeed, NFV might prove to be one of SDN's most important use cases, and products that incorporate both technologies could become the norm.
Making the most of NFV architecture
An NFV-based network can offer a number of advantages over a traditional network, including increased flexibility, accelerated time-to-market, improved scalability and reduced costs. That said, NFV is still an emerging technology with a lack of well-defined standards. It also comes with its own level of complexities. Plus, the cost savings might not be as dramatic if IT teams are forced to upgrade equipment to meet the demands of NFV-based workloads. Even so, NFV shows a great deal of promise and is likely to be around for some time. The telecommunications industry in particular has taken a keen interest in NFV, especially with 5G networks on the horizon.