It is in vogue for industry pundits and various IT manufacturers and solution providers to proclaim that WAN optimization is dead, and dead at the hands of SD-WAN, or software-defined wide area networking. 

The market seems to reflect this. It's hot with at least 33 SD-WAN manufacturers and analysts predicting hyper growth. Riverbed first introduced modern WAN optimization 13 years ago in 2004, which is eons in the world of information technology. So naturally it's time to move on to the next big thing, right?

Let's start by examining why WAN optimization came to be in the first place. Steve McCanne, a legend in the world of internet protocol science, recognized that there were fundamental challenges inherent in the architecture of the data network. So, he and Jerry Kennelly, CEO of Riverbed, set out to address those challenges, co-founding Riverbed Technology. 

WAN optimization addressed three primary issues that bubbled up to the surface when it came to end users accessing data via applications over distance on the network. 

The network is governed at the base level by the speed of light. That is, as they would say in Boston, "wicked fast," but not fast enough as milliseconds of delay (latency) grow as distance between users and data increases.

Because the Transmission Control Protocol/Internet Protocol (TCP/IP) — the framework for how information is delivered over the network — uses packets with limited capacity to transmit data over the network, multiple packets are required to move information and files for applications.

When you have small distance-based delays (latency) on the network, and you have multiple packets that need to be delivered, this creates application performance problems. Applications themselves have various inefficiencies and can require multiple back and forth acknowledgements (chattiness) which exacerbates application delay. Thus, network delay, TCP/IP inefficiencies, and application inefficiencies are the three pillars of application performance problems.

While the cost of bandwidth has come down dramatically, there are still capacity constraints and more importantly, none of these elements have changed in the last 13 years in any measurable way:

• The speed of light is still 186,000 miles per second
• The internet protocol still uses the same inefficient packet-based architecture 
• Many key applications are still inefficient and poorly written

With these elements, it doesn't matter how much bandwidth you have if there is impactful latency. WAN optimization addresses all of these challenges and constraints. 

Beyond theory, there are real-world use cases. Consider one company that had installed WAN optimization around 2010. They decommissioned the solution in lieu of refreshing it in 2015, under a new regime, because it wasn't viewed as impactful.

This was done for cost savings without considering or measuring the impact to their application performance. They were looking to implement application performance monitoring to understand why their applications were slow. But, they actually didn't need performance monitoring tools to know why their application performance had degraded. Instead they are now re-installing WAN optimization to improve application performance.

Greenfield WAN optimization

The industry is also seeing net new greenfield WAN optimization installations, such as those deploying 100 or more sites of WAN optimization to drive increased capacity out of their existing network. This is to improve application performance, support cloud-based applications and facilitate additional new applications on the network.

This case is part of a new model, however, as it combines WAN optimization with SD-WAN, cloud and SaaS optimization, and network and application performance monitoring. 

So what are the key actions and considerations to ensure value is being derived from WAN optimization?

• Maintain current levels of code to ensure newer protocols are being optimized and that new encryption methods are being handled — commission a health check for existing WAN Optimization environments.
• Implement a network and application visibility solution to validate performance improvement and identify areas and sites to focus on. This also allows IT and lines of business to gain better alignment, enabling IT to become viewed as an enabling partner rather than a cost center.
• Review your data center backup and replication environment. This can be an easy win with WAN optimization, increasing circuit throughput 4-6X and substantially reducing backup and replication times. All of these elements lead to a rapid return on investment and help IT Executives meet the needs of the business.
• Address cloud and SaaS environments with optimization to drive holistic performance improvement. These are areas with high-level executive exposure and ensuring their successful adoption can be a major win for the IT group.
• Address mobile users with optimization as road warriors and home office workers tend to suffer the most on key business applications. 
• Maintain current support on your systems, preferably with a specialist in the space to ensure timely response to issues and an up to date environment.

The rise of a new world order

A new world model is arising where SD-WAN is the change agent and optimization and visibility are critical success factors as part of the overall solution.

But what are the drivers behind SD-WAN? And how can you ensure a successful SD-WAN implementation?

There are four general buckets in which we can place SD-WAN drivers and considerations, easily remembered as CAPS: cost, agility, performance and security.

• Cost: SD-WAN promises to deliver a much better cost model against several vectors. It uses lower cost internet circuits as opposed to expensive business-class circuits in either a hybrid or exclusive manner. With the ability to route traffic based on application type and circuit health, SD-WAN opens this to reality. SD-WAN solutions on the market now are also generally far less expensive compared to legacy routing solutions.
• Agility: SD-WAN, with a much more user-friendly deployment and management model, and various connectivity options, provides organizations with far more flexibility and agility in how they support the business both in current state and in growth modes.
• Performance: SD-WAN, with the ability to add additional low cost capacity and more affordable multiple circuits per site can certainly improve performance. However, it’s imperative to augment the SD-WAN environment with WAN optimization for the reasons outlined earlier. 
• Security: Some SD-WAN solutions provide more sophisticated security capabilities than others and this should be considered.

Now let's look at how you ensure a successful SD-WAN implementation to maximize the potential benefits.

• Due diligence: The market is crowded with SD-WAN. Understanding this landscape and making an informed decision based on your specific objectives is crucial.
• Consider decoupling (for added diversity): Carriers all offer SD-WAN solutions to go with their circuits. However, this eliminates diversity, which is one key benefit of SD-WAN. Diversity provides for resiliency in the case of a failure with a single provider. And, many times the provider is now also giving you their own performance measures in support of their SLA’s to the business. This is a case of the fox guarding the henhouse.
• WAN optimization: WAN optimization is critical for SD-WAN because you are now using potentially lower quality circuits.The application performance-inhibiting factors outlined above are still in play, and in many cases your data is getting farther from your end users.
• Visibility: This is critical in order to measure your network and application performance, respond quickly to issues and ensure your SLA’s are being met. Some SD-WAN solutions provide this as part of their offering.
• Sponsorship: As with any new undertaking, commitment from above and sponsorship is key to moving this into a fully-adopted state. This includes cultural and financial support.
• Ongoing maintenance and education: Keeping the environment up to date and orderly will ensure that you continue to derive maximum benefit from the investment. 

So, did SD-WAN kill WAN optimization? Perhaps the better question is, does SD-WAN replace the need for WAN optimization?

In the words of Mark Twain, "the report of my death has been grossly exaggerated" and the same can be perceived in context of the exposure SD-WAN is receiving today compared to WAN optimization.

Successful organizations will leverage the power of 1 + 1 = 3, where the usage of both technologies combined will be far greater than the performance benefits each could achieve individually.