It is very evident that Software-defined networking (SDN) and network functions virtualization (NFV) is on the rise. Not a day goes by, without some new statistic, survey or trend being announced that points to the rapid growth in SDN and NFV deployments. Service providers around the world, particularly in India, believe that SDN and NFV will help them to succeed as customer demand increases for more flexible networks and services.

In India, enterprises are showing growing interest in SDN and NFV. According to Gartner research, the Indian server, storage and networking market stands at approximately $2.3 billion of this market value, five to ten percent is SDN centric. According to IDC, the SDN market in the Asia Pacific region (excluding Japan), which consists of spending from the enterprise and cloud service provider segments, is set to grow from $6.2 million in 2013 to over $1 billion by 2018. With all this research and interest around to move to virtualized networks, it is important to understand not only the expected benefits of SDN and NFV, but the importance of service assurance in order to achieve these benefits.

SDN/NFV Benefits
One of the promises of SDN and NFV is the ability to lower ongoing Opex and Capex costs through the commoditization of hardware. By deploying networks that are simpler to configure and control, these architectures help to speed configuration and adaptation and, in turn, reduce the time it takes to rollout and assure new services. In addition, SDN and NFV networks will deliver improved network performance by centralizing and separating the control logic to make better traffic decisions. These new virtualized networks promise an increase in flexibility and agility for networks to make them more programmable, dynamic and more architecturally simplistic. Even with all these benefits, there are equally significant risks including the challenge of service assurance at a time where it is more necessary than it ever was with traditional networks.

The Need for Advanced Service Assurance for SDN/NFV
The current transition to virtual services has been primarily focused on network architecture and orchestration. The next area of focus will need to be on operationalizing the virtual networks and that of assuring the performance and availability of these virtual services. There is more to the transition than deployment, fulfillment and orchestration. Service assurance and performance management is an area of great importance that must be taken into consideration as SDN/NFV services are being deployed. Companies need to take into consideration how they are going to monitor and assure their networks as legacy and virtual networks co-exist in this new hybrid environment that will be the norm for the foreseeable future.

There are compelling challenges to assuring virtual services that will make the process much more difficult to address than previously with legacy networks. Due to legacy networks being more well-defined and static compared to virtualized networks, these end-to-end services can be defined in assurance systems and monitored for alarms, performance and SLA conformance. This becomes a much bigger challenge for SDN/ NFV networks primarily due to the increased complexity and dynamic nature of these new end-to-end services. Virtual service visualization and monitoring must go from application to logical network to physical network and the composition of the virtual service can change at any time. How will monitoring systems keep up with the changes to the services and also provide consistency to the data as the network evolves, adapts and self-heals?

With the dynamic nature of virtual services, orchestrators and controllers will have the ability to modify, reroute, re-configure virtual services on demand, in real-time. This places a requirement on a Service Assurance system to be able to adapt in real-time to these service changes to be able to accurately reflect the current state and path of both virtual and hybrid services. One of the biggest challenges to being able to support these network states will be the Service Assurance system's ability to maintain the consistency of performance metrics for the services as the virtual and physical elements of the service change over time.
Given the challenges associated with the transition to virtualized networks, some of the important questions a Service Assurance solution will need to answer include:

- How is my network configured right now?
- How is it performing?
- Where are the bottlenecks?
- How to plan for future capacity needs?
- How to guarantee service level agreements?
- How to integrate this with the legacy networking I already have?

To answer these questions and have the dynamic capabilities described, Service Assurance solutions will need to be integrated with OpenStack, OpenDaylight, SDN Controller(s) and Orchestration System(s). The solutions must also have the ability to adapt the virtual service in real-time yet maintain all health and performance historical records as the service evolves. In addition, the Service Assurance solution for virtual services must have the capacity to perform automated service optimization and remediation, closed loop feedback to assure service integrity, and dynamic SLA management to be able to monitor SLAs in real-time even as the service evolves and changes.

Also of critical importance will be the Service Assurance solutions analytics capabilities to provide performance roll-ups and trend analysis, as well as point-in-time snapshots. Point-in-time snapshots will allow for service providers to be able to look back in time at any particular point to see what the network or service looked like and what the performance of the service was at that time. This will be critical for diagnosing, troubleshooting and triaging problems in live, dynamic virtual networks.

All in all, Service Assurance is an overlooked, yet critical part of the requirements for a successful virtual service deployment. Service providers should start planning for what they will need as they plan for their deployment of SDN/NFV - a solution that is uniquely positioned to address the complex service assurance challenges of SDN and NFV environments.