The Convergence of SDN and NFV

June 13, 2016

I’ve been asked quite a bit recently about SDN (Software Defined Networking) and NFV (Network Functions Virtualization). There has been significant confusion in the market regarding these two terms –some say they compete, while others feel they are one and the same.

However, neither of those statements are true. SDN and NFV are complementary networking approaches, both residing within a common virtualization framework. One operates at a macro level, and the other at a more granular, functional level. And while many service providers are deploying SDN and NFV in conjunction, neither approach relies on the other.

I’ll define them both for you, and illustrate how they work together.

SDN is literally that – software-defined networking. It utilizes the same concepts as virtualization by abstracting all the physical components and connectivity of the network into a flexible, software-defined architecture. It is a centrally-controlled framework that resides on low cost, non-proprietary hardware.

The appeal of SDN is defined by the freedom it enables – freedom to centralize command and control, to create new network configurations on the fly, to reduce operational complexity, and to lower overall cost through the use of non-proprietary hardware.

The virtualization layer centrally manages the network, enabling changes to be made through a single console. This reduces the need to go onsite to rip and replace routers and switches, or to reconfigure physical network connections. With an investment in SDN, operational savings can be quickly realized.

Furthermore, by deploying these networks on low cost hardware, capital expenditures are reduced as well. An SDN-based infrastructure uses all physical resources at its disposal, delivering a more robust network in the process as the virtualization layer adds a high degree of intelligence and control. As a result, nothing is wasted, and every component is at full utilization and optimization.

In summary, by embracing SDN, the expensive legacy vendor models of the past will either need to adapt, or they will dissipate. This movement will only serve to benefit our friends in the operator community.

On the other hand, NFV is the virtualization of network applications and services (EPC, content filters, security monitors and sandboxes, load balancers, etc.) that reside and coexist within an SDN framework.

Formerly the provenance of specialized appliances or ATCA hardware, these applications are now deployed in a software-only configuration, also known as a VNF (virtualized network function) format. These VNFs are comprised of single or multiple VMs (virtual machines), and configured to execute their specific functionality optimally.

Like any VM or sequence of VMs, the VNF can be replicated like a file, and easily moved across the network as required for deployment or backup. In the case of the Affirmed Networks Mobile Content Cloud, the VNF can dynamically scale up and down based on traffic requirements, and can do so at a more granular level (per individual Mobile Content Cloud service requirements).

Software Defined Networking (SDN) Network Functions Virtualization (NFV)
Defined as virtualization of the network infrastructure. Centralizes command and control of the network. Allows rapid provisioning of new networks without the complexity of physical upgrades. Network functions that are fully virtualized, and free from dependencies on proprietary appliances and devices. Software-only in nature, and can be deployed on generic servers and SDN platforms.
Standards guided by the Open Networking Foundation (ONF). Initial standard is OpenFlow. Standards guided by the ETSI NFV Working Group. Basic NFV architecture/use case has been specified by ETSI.
Located in the Cloud data center, and extends to secondary server farms in support of network operations. Located in the service provider’s SDN network.
Initial uses are orchestration, Cloud infrastructure & networking. Initial uses are virtualized routers, firewalls, gateways, vEPC, etc.

SDN and NFV converge, meeting in the middle – the SDN layer abstracts the network itself, creating a virtualized environment for NFV applications to reside and thrive.

Even though SDN and NFV are different networking approaches, they can also be thought of as a dynamic duo. As SDN and NFV converge, they create a revolutionary architecture that’s drastically more robust, efficient, and profitable than legacy models of the past. The amalgamation of both these concepts is what truly constitutes the network of the future.

Affirmed - SDN + NFV Blog Post

However, just because the SDN layer is the macro approach, it does’t necessarily need to come first. Networks can be deployed without SDN while still taking advantage of NFV, and vice versa. Since the two network approaches are complementary, not interdependent, operators can decide the order in which their network transformation will take place. While ultimately, converging SDN and NFV allows operators to reach their full potential, the order in which they arrive at a fully virtualized network is not so important.