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Software-defined WAN—An Overview

software-defined wide-area network (SD-WAN) is a virtual architecture that enables enterprises to securely connect users to their applications. It uses software to control connectivity, management, and services between cloud resources, data centers, and remote branches. 

An SD-WAN device deployment typically includes routers, switches, and virtualized customer premises equipment operating some form of software to handle networking functions, policies, and security. SD-WAN appliances use centralized control functions to intelligently and securely route traffic across the wide-area network (WAN), which enhances application performance and user experience.

Read this step-by-step guide to securing SD-WAN to increase the visibility of your network and guarantee availability and performance.

Virtual Private Network (VPN)—An Overview

virtual private network (VPN) enables internet users to keep their browsing history private and browse the web securely. VPNs are useful for remaining anonymous online, masking a device’s location, and securely accessing content from other countries. VPNs protect users from insecure Wi-Fi networks, which can expose login credentials and personal data to hackers. By connecting to a VPN, users can hide their location and retain their privacy.

VPNs encrypt user information and only use secure tunnels that mask users’ location and protect their data. This means users can evade geographical restrictions on streaming sites, gain online anonymity, and download or torrent files securely.

For more information, take a look at some of the common uses of VPNs.

SD-WAN vs. VPN: Pros and Cons

When comparing SD-WAN vs. VPN, it pays to remember that both aim to secure traffic and keep users safe while they browse the web or access internet-connected applications. Below are some SD-WAN pros and cons, the benefits and limitations of VPN, as well as the key differences between SD-WAN and VPN networking solutions:



SD-WAN pricing is generally lower than traditional WANs because they use the public internet, which removes the need for private connections. The SD-WAN pricing model also offers an inexpensive option to build a network, reducing operating expenses such as those associated with commodity lines like cable, digital subscriber line (DSL), or fiber.


There are free and paid-for VPN solutions available, but the more money organizations spend, the more reliable and secure the solution. VPN pricing for remote access packages begins at around $7 per user. Additional costs will include the time and human resources spent managing network connections.

Configuration and Maintenance


SD-WAN solutions are typically adaptable and easily updatable. The approach is centralized and software-driven, so it does not require specialized hardware coding or infrastructure changes. However, maintaining WAN connections gets more complex as organizations add more sites, resulting in performance issues and the infrastructure becoming disjointed. 


Managing and configuring a VPN service can require extensive work. For example, securely configuring Internet Key Exchange (IKE), Internet Protocol security (IPsec) tunneling, and Network Address Translation Traversal (NAT-T) requires networking expertise. VPNs are relatively simple to manage but offer less flexibility than SD-WAN, as each VPN connection is end to end rather than centralized. 



The SD-WAN approach establishes a dual-layer network formed of an underlay and overlay. The underlay connects to the public internet and an existing private WAN using public and private lines, such as dedicated internet access (DIA) circuits, multiprotocol label switching (MPLS), and point-to-point links. The overlay is a top software layer that enables organizations to monitor and fix connection issues. 

This approach ensures data is intelligently routed between public and private networks based on priority and simplifies the management of the network. However, SD-WAN can still be vulnerable to public internet issues like fluctuating bandwidth, latency, and packet loss.


A VPN provides encrypted tunnels that create secure, stable user connections. However, VPN connectivity speed often depends on the type of VPN service. It can also be impacted by the encryption process. Paid-for networking solutions typically offer more reliable, higher-speed connections than their free alternatives. 

Security Solutions


The advantages of migrating to SD-WAN include having high levels of security at a lower cost and reduced complexity than solutions like MPLS. SD-WAN security provides centralized controls that deliver end-to-end encryption across organizations’ entire networks rather than manually securing individual connections. It is compatible with advanced security features and solutions like antivirus, encryption, firewalls, sandboxing, and Uniform Resource Locator (URL) filtering.


Most leading VPN security services provide IPsec protocols and secure traffic through the Advanced Encryption Standard (AES) 256-bit encryption. Some also offer Layer 7 firewall protection, which enables organizations to filter application-specific traffic. However, VPNs can be vulnerable to threats from the public internet, so they need to be monitored carefully. 

For example, some remote-access VPNs have enabled malware and viruses to spread from users’ home devices onto corporate networks.



Using SD-WAN enables organizations to reap the benefits of networking features like application-aware routing, dynamic path selection, and quality of service (QoS). Cloud-based SD-WAN also eliminates latency issues. 


VPN solutions can be vulnerable to public internet performance issues. This includes spikes in traffic, which can lead to an internet connection slowing down, or latency issues caused by traffic traveling long distances.



SD-WAN technology provides stable connectivity, which drastically reduces the chances of downtime. It increases the reliability of WAN, the public internet, and mobile connections. The approach also simplifies network management through remote monitoring. Additionally, SD-WAN offers features like multiplexing and path conditioning, which protect networks from connection issues or dropped packets, and intelligent network resourcing, which guarantees the performance of business-critical applications.


Trusted VPN routers offer highly reliable services that should not suffer connection drops. However, if an encryption issue occurs, users’ actual Internet Protocol (IP) addresses will be exposed to the public internet.



The software-based nature of the technology means it can be implemented even without significant specialist knowledge, such as coding or making changes to the infrastructure. However, getting SD-WAN implementation right requires careful planning and deployment, especially if organizations are transitioning from old, legacy network hardware and topology. 

Furthermore, implementing SD-WAN can introduce loopholes or gaps in a secure network, so it is crucial to have vulnerability scans and robust quality assurance processes in place.


VPN software is relatively easy to implement, and most reliable providers offer how-to guides and troubleshooting assistance. However, implementing site-to-site VPNs can get complicated, requiring additional equipment or specialist resources. Also, the initial setup phase can create vast amounts of manual activity that is prone to human error.

Read more about VPN technology to understand the advantages and disadvantages of VPN.

Finding the Right Solution Best Suited for Your Organization

Choosing between VPN vs. SD-WAN will depend on the needs of your business. A small organization connecting just a few users or sites will likely only need an internet-based VPN to get going. Larger organizations that require agility, performance, reliability, and scalability from their networks will likely have to consider a cloud-based SD-WAN solution.
Managed SD-WAN Services

Driving Growth, Security, and Business Efficiency with Managed SD-WAN Services

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How Fortinet Can Help

The Fortinet Secure SD-WAN solution uses a security-driven networking approach that transforms organizations’ SD-WAN processes. The Fortinet FortiGate solution combines SD-WAN with Next-Generation Firewalls (NGFWs) and advanced routing. It simplifies WAN architecture, provides superior experiences at scale, accelerates network and security convergence, and guarantees consistent network and security policies.

Fortinet also helps organizations with VPN security through its high-performing FortiGate Crypto VPN solution. It allows organizations to securely transport and process vast volumes of data without impacting network security or performance.