As the WAN quickly solidifies its role as the performance bottleneck for cloud services of all kinds, the SD-WAN market will continue to grow and evolve. This evolution will happen in lock step with the move to software-defined everything in data centers for both the enterprise and the service provider, with a focus on Virtual Network Functions (VNFs) and how they could be used to create specialized services based on custom WANs on demand. Although SD-WANs provide multiple benefits in terms of cost, ease-of-management, improved security, and improved telemetry, application performance and reliability remain paramount as the primary goals for the vast majority of SD-WAN deployments. When this is taken into consideration, the role of VNFs in extending and improving application performance becomes clear. Just as importantly, growing use of VNFs within SD-WANs extends an organization’s software-defined architecture throughout the broader network and sets the stage for the insertion of even more intelligence down the road.
What exactly do we mean by the term VNF?
Before we get started, let’s define what we mean by VNF, since similar to SD-WAN, this term can be used to describe multiple things. For some VNFs are primarily a means of replicating legacy capabilities on a local appliance (physical or virtual) by means of software defined architectures, such as firewall, DHCP, DNS etc. However, restricting one’s scope to legacy services alone limits the potential high-value benefits that can be realized from a software-defined approach for more advanced features. Our definition of a VNF therefore is a superset of localized VNF and is really about the creation of a software-defined functions of more advanced capabilities, such as application aware VPNs, flow-based load balancing, self-healing overlay tunnels etc. What’s more, many advanced SD-WAN vendors provide their customers with the ability to customize these VNF applications to apply exclusively to their own WAN and/or their specific network requirements to enable unique WAN services.
What do we need VNFs for?
SD-WAN’s enormous growth this year, as well as its predicted continued growth in the years to come follows the footsteps of the paradigm shift data centers are currently undergoing. That is, from a manually configured set of servers and storage appliances, to a software-defined architecture, where the servers and storage appliances (virtual or physical) can be managed and operated via a software-defined architecture. This means less manual errors, lower cost and more efficient way to operate the data center.
As an industry, as we implement some of the data-center approaches to the WAN (Wide Area Networks), one must note that there is a big difference between datacenter networks and WAN networks. Namely, datacenter LANs (Local Area Networks) have ample capacity and bandwidth and unless they are misconfigured, are never the bottleneck for performance. However, with WANs, whether done in-house by the enterprise or delivered as a service by a telecom or other MSP, the branch offices are connected to the Internet through WAN connections (MPLS, DSL, Cable, Fiber, T1, 3G/4G/LTE, etc.). As a result, the choking point of the performance is almost always the WAN. This is why SD-WANs became so popular so quickly, in that this provides immediate relief for this issue.
However, as WANs continue to grow in complexity, with enterprises operating multiple clouds and/or cloud models simultaneously, there is a growing need to add automation and programmability into the software-defined WAN in order to ensure performance and reliability. Therefore VNFs that can address this WAN performance bottleneck have the opportunity to transform how enterprises connect to their private, public and hybrid clouds. VNFs that extend beyond a single location, but can cover WAN networks, will have the ability to add programmability to the WAN. In a way, the “software defined” nature of the data center will be stretched out all the way to the branch office, including the WAN connectivity between them.
Defining SD-WAN VNFs
So what does a VNF that is programmable and addresses the WAN bottlenecks look like? These VNFs are overlay tunnels that can perform certain flow logic and therefore can work around network problems on a packet-by-packet basis per flow. These VNFs are so smart, they have the problem diagnosis, problem alerting and most importantly, resolution of the problem all baked into the VNF. In other words, unlike the days without SD-WAN where an IT manager would have an urgent support ticket whenever a network problem occurs. With VNF-based SD-WANs, the networks are becoming smart enough to solve the problem proactively, in most cases, before even it effects the applications, services and the user experience.
This increase in specific VNFs for the SD-WAN will start with the most immediate need, which is often latency and jitter sensitive applications such as voice, video, UC and other chatty applications. Even now, VNFs are being used to solve these issues. For example, a CIO can have a VNF that dynamically and automatically steers VOIP/SIP traffic around network problems caused by high latency, jitter and packet loss, and in parallel have another VNF to support cross-traffic and latency optimization for “chatty” applications.
In another example, a VNF can be built in minutes designed to steer non-real-time traffic away from a costly WAN link and apply header compression for real-time traffic only in situations where packet loss or latency crosses a specific threshold during certain times of the day, all the while updating syslog with telemetry data. With this level of flexibility and advanced capabilities, VNFs are poised to become the go-to solutions for issues related to the WAN.
A VNF load balancer is another such overlay that has the ability to load balance the traffic over the WAN links. Since the VNF load balancer is in essence a software code that can be deployed onto an SD-WAN appliance, it has the power of taking advantage of various types of intelligence and adaptability to optimize the WAN performance. VNF load balancers should also work with standard routing so that you can inject it in your network, say between the WAN modems and your firewall/router seamlessly.
Clearly, VNFs are part and parcel of SD-WAN next wave of evolution, bringing intelligence and agility to the enterprise WAN. As 2017 ramps up, we’ll see more and more innovation on this front, fully extending software-defined architecture from the data center throughout the network.
About the author
Dr. Cahit Jay Akin is the CEO and co-founder of Mushroom Networks, a long-time supplier of SD-WAN infrastructure for enterprises and service providers. Prior to Mushroom Networks, Dr. Akin spent many years as a successful venture capitalist. Dr. Akin received his Ph.D. and M.S.E. degree in Electrical Engineering and M.S. in Mathematics from the University of Michigan at Ann Arbor. He holds a B.S. degree in Electrical Engineering from Bilkent University, Turkey. Dr. Akin has worked on technical and research aspects of communications for over 15 years including authoring several patents and many publications. Dr. Akin was a nominee for the Most Admired CEO award by San Diego Business Journal.
