For the last few years, software-defined networking (SDN) has been the hottest topic in the industry. And over the past year, interest in network functions virtualization (NFV) has been growing, among service providers and enterprise IT organizations alike. But there is confusion about the relationship between SDN and NFV. Is there a tight bond between these two architectural approaches, or are they ships in the night?
Up until a year ago the general feeling was that SDN and NFV were complementary technologies and that neither one had a tight dependency on the other. That view began to change in March, 2014, when the Open Networking Foundation (ONF) and the European Telecommunications Standards Institute (ETSI) announced they signed of a Memorandum of Understanding (MOU). As part of the announcement, the ONF and ETSI said, "Together the organizations will explore the application of SDN configuration and control protocols as the base for the network infrastructure supporting NFV, and conversely the possibilities that NFV opens for virtualizing the forwarding plane functions."
In conjunction, the ONF released the OpenFlow-Enabled SDN and NFV Solution Brief. That document discussed how OpenFlow-enabled SDN can meet the need for automated, open, and programmable network connectivity to support some of the ETSI-defined use cases, such as network functions virtualization infrastructure as a service, and virtual network function forwarding graphs.
When interviewed for this article, Marc Cohn, chair of the Market Education Committee for ONF, said that it is very difficult to create a dynamic software environment such as NFV without the type of dynamic network environment that is enabled by SDN. In his words, "the traditional approach of over-provisioning the network will not work." Because of that, Cohn also believes that SDN will have to make significant progress before NFV will be broadly adopted.
In a recent white paper, ETSI expressed its belief that NFV and SDN are highly complementary efforts. The ETSI view is that both efforts are seeking to leverage virtualization and software-based architectures to make network infrastructures more cost-effective and agile, better accommodating the dynamic nature of workflows.
While ETSI states that NFV can be implemented using a non-SDN infrastructure, the ETSI vision is that NFV and SDN will increasingly be intertwined into a broad, unified, software-based networking paradigm based on the ability to abstract and programmatically control network resources.
Some of the ways that ETSI believes that NFV and SDN complement each other include:
My recently published report, The 2015 Guide to SDN & NFV, included the results of a survey taken by 135 IT professionals, most of whom work in enterprise IT organizations. One of the survey questions asked the respondents to indicate the relationship that their company sees between SDN and NFV. A large majority of survey respondents (61%) indicated that SDN and NFV are complementary activities in that each can proceed without the other, but the value of each activity may be enhanced by the other activity. A quarter of respondents said that, at least in some instances, NFV requires SDN. Only 6% said their company views SDN and NFV as totally independent activities.
The beginning of this article asked of whether there is a tight bond between SDN and NFV. Given the embryonic state of SDN and NFV development and implementation, it shouldn't be surprising that the answer to that question is a definite no. However, the ONF and ETSI, which are two of the key organizations driving the development of SDN and NFV, believe that there are NFV use cases whose value is significantly enhanced by SDN. The majority of IT organizations share that view.
Given the current trajectories of SDN and NFV, it is highly likely that over time the ETSI vision of NFV and SDN intertwining into a broad, unified, software-based networking paradigm based on the ability to abstract and programmatically control network resources will come true. At that time, we will no longer differentiate between SDN and NFV.
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