WAN vs SD-WAN Optimization: Which Is Better?

Illustration of a map of the world with location pointers above a handful of locations.
WAN in town, why not drop in!

Multi-site companies leverage wide area networks (WANs) for cross-site projects, collaboration, and business administration. These configurations need an efficient centralized data center to transfer data between branches. This can also be difficult if the data center has many business services like MS Exchange or CRM. To overcome this challenge, you need to optimize bandwidth. You also have to improve data redundancy and conserve TCP functionality. Finally, you should apply optimization. The traditional go-to solution was to use WAN optimization software. Now, a software-defined WAN (SD-WAN) is taking over. It has zero-touch provisioning (ZTP), making your life easier. 

In this article, we’ll take a look at both WAN and SD-WAN optimizations. We’ll also compare the benefits, limitations, and drawbacks of each. To this end, you’ll also learn when and where to use each technology effectively. In turn, you’ll save your company money. First, let’s take a look at what WAN optimization is. 

WAN Optimization: All You Need to Know

WAN optimization is a WAN software solution that optimizes the problems associated with transferring WAN data efficiently. In brief, its initial use case was for applications that weren’t optimized for data transfer over a WAN. 

Initially, these programs would run over a local area network (LAN) only. They weren’t written as a lightweight web application. That means they also didn’t have efficient communications over large distances.

WAN optimization software aims to improve bandwidth. To do that, it makes traffic lighter through packet and content optimization. Today, a business’s WAN optimization solution is only useful if physical locations will impact performance from latency, not bandwidth.

Additionally, you could also use WAN optimization to optimize TCP packets. However, this isn’t possible nowadays though due to data encryption. That’s also why you can’t check data redundancy anymore. 

That said, all software today is designed to work as a web application. As such, application optimization is no longer needed. Below, I’ll list the benefits, limitations, and drawbacks of WAN optimization.

Schematic of an example WAN.
Check this WAN configuration example.
Latency reduction through caching content locallyValue is added only where latency impacts business needs. (e.g., distance between sites causes latency)No centralized real-time monitoring. WAN health problematic to monitor and optimize
Hardware supportNo TCP, data redundancy, and software optimization thanks to modern programming standardsImplementation delay if the configuration isn’t applied on all hardware 
Monitoring capabilities limitedService costs make it  more costly than IP based WANs 
Hardware for each site needs provisioning before use
Transmission routes and bandwidth limited
Despite the benefits, WAN’s disadvantages are very limiting.

Clearly, WAN optimization is slowly losing its competitive edge. Let’s take a look at SD-WAN and see if it can beat the traditional WAN optimization in the following section.

What Is SD-WAN?

An SD-WAN is a web-based software that enables you to define the network’s intent after shipping the hardware to remote sites. This is called zero-touch provisioning (ZTP) and makes setup a lot easier. In effect, you only need to select some options on your terminal to get the WAN up and running. 

Apart from ZTP, SD-WAN is also a web-based WAN solution. This allows you to manage it centrally. Traditional WANs often use specific hardware to achieve a site connection. That also requires a dedicated WAN vendor with maintenance and support for provisioning. 

In contrast, SD-WAN uses a standard commercial internet service provider (ISP) for connectivity between sites. How does that benefit you? This means SD-WAN requires zero-touch provisioning. In turn, ZTP also streamlines the implementation process and eliminates the manual labor. However, you can’t optimize connection settings for long-distance latency with SD-WAN. Dedicated WAN service providers still win in this area.

Has zero-touch provisioning (ZTP); no need to configure each site’s hardware.Isn’t effective over large distances to handle the latency of non-web optimized applicationsMust rely on your ISP security measures with less configuration possible
Has low cost as it’s web-basedMust rely on the device firmware and its security measures. 
Provides you with granular traffic monitoringIsn’t dedicated bandwidth, you’re at the mercy of the ISP
Defines WAN intent through the software
Limits specific application speeds to improve network performance
Offers AI optimization of traffic and data types
Although it has some disadvantages, SD-WAN is still beneficial!

Next, let’s take a look at the top SD-WAN providers. 

Top 10 SD-WAN Providers

It’s important to use a larger provider as they often offer better services and support. Surely you’d want to get support immediately. Otherwise, you’ll extend your downtimes. As a result, consider the below top 10 SD-WAN providers:

  1. VMware
  2. Cisco
  3. Aryaka
  4. Silver Peak
  5. Nuage Networks
  6. Fortinet
  7. Huawei
  8. Citrix
  9. Versa Networks
  10.  InfoVista

Now that you know all about SD-WAN, I’ll discuss the differences and similarities between traditional WAN and SD-WAN. 

Traditional WAN vs SD-WAN—Differences & Similarities 

Traditional WAN needs hardware provisioning before you implement it. In this case, expect a long process. You also have to start again if you did something incorrectly. As a result, administrators want better solutions. 

SD-WAN abstracts software from each device’s hardware. This means you can ship your WAN devices, power them up, and then configure the software from anywhere. SD-WAN can also provide real-time granular traffic and packet monitoring, unlike traditional WAN. 

The following table highlights the key features of each solution.

Traffic routingTraditional routing protocolsSoftware-defined traffic management
PerformanceGood performanceHigh performance
MonitoringDistributed; web-based. Limited practicality.Centralized; web-based
Bandwidth CostHigh; 3rd party supplierLow; web-based ISP solution
Provisioning ComplexityHighLow
SecurityGoodVery Good
Monitoring and AnalyticsNoYes
WAN and SD-WAN aren’t equally useful.
Schematic showing a traditional WAN connection compared to an SD-WAN with software abstraction above the hardware layer.
Who knew abstraction through adding another layer would make your life easier! (Source: TechTarget)

Feature Comparison: WAN Optimization vs SD-WAN

Below is a table comparing key features of WAN optimization and SD-WAN.

WAN optimizationSD-WAN
Problem AddressedLink quality, policy managementLatency congestion
WAN Segment FocusLast-mileMid-mile
Traffic SteeringYesNo
Link RemediationYesNo
Application ClassificationDeep Application Recognition5-tuple
Zero Touch DeploymentYesNo
Overlay VPNYesNo
TCP OptimizationNoYes
Application ProxiesNoYes
Data DeduplicationNoYes
WAN and SD-WAN are significantly different!

WAN Optimization and SD-WAN: Better Together?

If you have sites halfway around the world along with older software, you can use SD-WAN and WAN optimization simultaneously. You also need to reduce latency across large distances. To do this, you should strip bulky applications of duplicated content and conservative TCP packets. As such, put hardware using WAN optimization between the mainframe and your SD-WAN solution. 

Logically, you’ll likely have WAN optimization already in place before adding your SD-WAN solution, which is ZTP. In this setup, your WAN optimization configurations also require optimizing. However, the SD-WAN hardware will automatically configure to meet the network’s needs after initial setup.

Most businesses wouldn’t bother with older software. In fact, modern web-based enterprise solutions have been around for many years. If you write software, you’ll realize that any framework you use these days promotes web-based applications as a default format

Pro Tip

Older software is slower and incompatible with newer systems. It may also have known exploits that threaten your cybersecurity. As a result, you should:

  • Consider why you haven’t updated to leaner software
  • Think about avoiding WAN optimization altogether
  • Try to opt for a purely SD-WAN solution 

If you do that, your balance sheet will thank you. Remember, an SD-WAN solution would be better if you can slowly phase out your older software.

Final Thoughts

Many industry experts say that WAN optimization is dead. This isn’t true, and it’ll stay around even though you don’t need it. In effect, web-optimized applications and wider bandwidths also reduce WAN efficiency. However, if you have large distances to span, then you need to reduce latency using all the tricks in the book.

WAN optimization requires you to provision each connection device before use. It’s also more expensive than web-based SD-WAN. Evidently, monitoring traffic and packet data are also less effective for traditional WANs. 

To resolve this, use the web-based SD-WAN containing ZTP. In truth, you should also consider slowly phasing out traditional WAN optimization if you can. Eventually, SD-WAN will take over.

Looking for more information? Check out the FAQ and Resources sections below. 


What is a WAN branch?

A wide area network (WAN), unlike a local area network (LAN), spans multiple sites. To help relay WAN communications inside sites, you must use WAN branches. These are distributed frames placed within a company to logically silo communications and reduce latency. This also improves security between teams and divisions while simultaneously maximizing WAN performance at the main frame. The main frame is where the WAN connection enters each site. 

What is WAN Optimization?

Wide area network (WAN) optimization uses software to optimize traffic and data packets between WAN sites. These network tools optimize bandwidth, TCP, and software traffic. They also improve data redundancy

What is an SD-WAN?

A software defined wide area network (SD-WAN) uses software to define the network’s attributes. This means you simply need to ship and powerup SD-WAN hardware to your sites. Once online, you can then configure the SD-WAN centrally. SD-WAN also uses zero-touch provisioning (ZTP) to make using the setup much easier. 

What is encryption in relation to WAN?

Encryption is a security practice that takes data and ciphers it. That way, only the set receiver can decrypt and read it. This is only possible if the data’s recipient has a key to decrypt the data. All modern WANs also encrypt traffic. In turn, WAN optimization software doesn’t optimize TCP and data packets. 

Should I use WAN Optimization or SD-WAN?

In general, you should use WAN optimization if you have legacy software. Generally, it won’t be optimized as a web application. In turn, that impacts the company’s bandwidth between sites. You should also use WAN optimization if you need to reduce the site-to-site data latency. This is due to large distances being covered or dated connection hardware. For all other scenarios, use SD-WAN since you don’t need to provision hardware. You can also manage the system centrally. 


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About The Author

1 thought on “WAN vs SD-WAN Optimization: Which Is Better?”

  1. Christoph Jaggi

    A couple of remarks:
    – for WAN use, especially high bandwidth, Carrier Ethernet is often the better solution than MPLS, in terms of simplicity and cost.
    – SD-WAN isn’t limited to public Internet. The underlay network can be OTN, Carrier Ethernet, MPLS and IP or a combination thereof.
    – State-of-the-art encryption has more functionality than just encryption. AEAD ciphers provide additional functionality such as replay protection, integrity protection and authentication. These additional functionalities can provide a network layer firewall and intrusion detection/prevention at network layer.
    – ZTP is a double-edged sword. As the SD-WAN New Hope project has shown, many implementations come with their own security issues.

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