SDN (Software Defined Networking) and NFV (Network Functions Virtualization) are currently the two hot topics in networking and vendors are climbing aboard with everything from badly defined marketing fluff to legitimate problem-solving solutions. While SDN and NFV are not interdependent, much more can be achieved when looking holistically at the networking challenges to see how NFV and SDN can work in concert.
SDN was born out of the need to better automate data center traffic by separating the control layer from the network switching layer. This separation allows traffic flows to be controlled programmatically by entities outside the switch infrastructure, allowing for faster time to service and lower Opex. While there have been many proprietary solutions to managing switching fabric within data centers, it really was not until the development of OpenFlow and its promotion by the Open Networking Foundation that SDN has evolved into a core strand of network vendor roadmaps. OpenFlow-enabled SDN Controllers allow external systems to interface with the switching fabric, which opens many opportunities for smarter and more flexible network management.
Orchestration systems and applications can interact with the SDN controller and dynamically adjust the network switches in response to application and network services requirements.
NFV, on the other hand, evolved from the service provider community’s desire to deploy network functions (i.e., firewalls) as virtual entities on commodity hardware. Historically, service provider networks have been subject to demanding processes and change controls to ensure service stability, integrity and quality when deploying new equipment and services. This resulted in significant delays to new product introduction and reduced agility to respond to the market and technical changes. NFV offers service providers a way to take a network service such as a firewall or load balancer that traditionally was on dedicated hardware and define that service as a Virtualized Network Function (VNF). Multiple VNFs can be chained together (network Service Chaining) to create more complex products and services which can be deployed quickly on a virtualized platform.
While both SDN and NFV can exist independently, much more can be achieved when they act in concert. One example is with load balancing and where load balancer services are implemented as VNF entities. If demand for load balancing capacity increases, a network orchestration layer can rapidly spin up new load balancing instances and also adjust the network switching infrastructure to accommodate the changed traffic patterns. In turn, the load balancing VNF entity can interact with the SDN controller to assess network performance and capacity and use this additional information to balance traffic better, or even to request provisioning of additional VNF resources.
So while SDN and NFV address very different network challenges, as these technologies mature they will inevitably become more integrated and deliver a new era in the design, delivery and orchestration of networking.