Under the Hood with SD-WAN, SDN, NFV, and VNF

By Steve Woo
Co-Founder and Vice President of Products, VeloCloud
August 3, 2017

It’s easy to be confused by the abundance of new terms and buzzwords crowding the industry on a daily basis, but no more so than when they are all in the form of an acronym: SD-WAN, SDN, NFV, and VNF.

They all sound similar, but we’re often asked to explain how they are the same or different from one another, and more importantly, can they work together in a single environment? Or do you have to choose one and stick to it? In this blog, we’ll take a look at SDN, NFV, and VNFs in relation to SD-WAN and our guidance on choosing the right recipe for your alphabet soup.

First, Let’s Deconstruct

Let’s start the discussion by defining each term.Image_AcronymsTogether

SDN (Software Defined Network) is an architecture where the key principle is the physical separation of the network control plane from the forwarding plane, which is an abstraction of all service and applications. The key tenets are to achieve central management, a global view of the network, to be agile, redundant, incorporate open standards, and allow widespread interoperability.

SD-WAN (Software Defined WAN) is a technology built on some of the key ideals of SDN as it also focuses on putting control into software, allowing abstracted business inputs and centralized management to support network agility. Decisions in an SD-WAN environment are made on context from centralized control policies and from local measurements of available links.

NFV (Network Functions Virtualization) is the infrastructure platform and orchestration of VNFs. NFV has been mostly used in the datacenters, but it is now being coupled with SD-WAN so that the benefits of NFV can be leveraged all the way down to the individual and remote branches.

VNF (Virtual Network Functions) is the virtualization of individual network services that are supported by NFV. Examples of VNFs are routers and firewalls.

At the Core: Goals are the Same

The introduction of these architectures and technologies signals the paradigm shift in the network to move away from dedicated and limiting hardware and instead to software and virtualization, which are flexible and scalable. At their core, all four share the same objectives and benefits.

  • Future proof
  • Complementary
  • Support the migration to the cloud
  • Software and cloud focused
  • Agile
  • Reduce enterprise costs
  • Widespread availability
  • Vendor agnostic
  • Highly interoperable

SD-WAN Leverages SDN Principles

SD-WAN marries the tenets of SDN with a distributed WAN, elevating the control and the transmission of information to the cloud. Because of this evolution, SD-WAN is highly scalable, based on internet routing so it is fully redundant, there is no single point of failure, and there is no need to wait for information from end devices in order to take action.

The primary difference between the tenets of the two platforms is where the actual decision making is made. For instance, as mentioned earlier, SDN is a central controller, dictating network behaviors from that controller. In contrast, SD-WAN is managed by central policy control, but decisions can be made locally while considering corporate policies.

NFV and VNF: A Closer Look

NFV and VNFs are similar to the relationship between SDN and SD-WAN, in that NFV is an architecture that performs the management and orchestration activities, whereas the VNF is the actual technology running over NFV.

NFV has been mostly used in the datacenters, but we’re now seeing that it is being coupled with SD-WAN so that the benefits of NFV can be leveraged all the way down to the individual and remote branches.

The advantages of NFV include:

  • Quick roll out of new services and locations, such as security in the form of a VNF
  • A cost effective method of distributing services enterprise-wide
  • Reduction of dependence on hardware (multiple VNFs can be deployed on the same hardware)
  • Flexibility scaling services, either up or down
  • Reduce maintenance windows
  • Allows VNFs can be upgraded independent of the hardware so the latest version is always in play

SD-WAN and NFV: Power Combinations

SD-WAN and NFV are complementary to each other and can be a powerful combination when used together. Both can easily be deployed in enterprise or cloud datacenters with SD-WAN service chaining, or distributed as virtual services (VNFs) all the way to branches. By leveraging NFV services with SD-WAN, service deployments can be made in batches across the enterprise and thereby simplify service insertion at the branches. Additionally, while NFV is typically used to deploy services in the cloud, it can be used with SD-WAN to deliver those cloud services across the entire organization and to each remote location.

VeloCloud Recommends

It is becoming increasingly important for vendors to offer existing services as VNFs, perpetuating a more open platform. Our recommendations for an open approach include either:

  • SD-WAN focused NFV platform that allows for third party VNF service choices in addition to core SD-WAN platform.
  • An open NFV service platform on a virtual CPE (vCPE) that includes SD-WAN as a VNF and allows for other third party VNFs to be loaded.

An example currently in the marketplace is AT&T’s vCPE that supports third party VNFs and hosts VeloCloud’s SD-WAN VNF solution.

Making It All Work Together

In conclusion, SD-WAN, SDN, NFV, and VNFs all share similar principles. While each of their implementations are different, they are very complementary and powerful when used in combination.  It is not a matter of having to choose one technology or architecture over another, but determining where to use each to maximize their benefits.

For the Enterprise and Service Provider alike, benefits include:

  • Agility
  • Reduced cost
  • Increase availability
  • Interoperability
  • Supports move to software base and cloud

To learn more about this subject, watch our on-demand webinar titled “Making It All Work Together with SD-WAN, SDN, NFV, and VNF.”

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