As companies seek to improve their IT to increase security and productivity, they consider various solutions for the purpose. Two solutions which are sometimes mentioned side by side in this discussion are VPN and SD-WAN.
Broadly speaking, both VPN and SD-WAN deal with communication over various networks, but their exact approach is very different.
This article explains the difference between VPN and SD-WAN and recommends which solution is best for which use cases.
Table of contents
VPN vs SD-WAN: What are they?
As mentioned above, both technologies connect users, apps, and networks, but there are fundamental technological differences between them.
What is a VPN?
A virtual private network (VPN) creates encrypted tunnels through the public internet to allow remote users to access company resources, whether on-site or cloud. The VPN is therefore a private network of devices and users with security and management controls.
VPNs were conceived to protect data from eavesdropping or interception and thus increase online privacy and security of individuals and businesses alike.
Both traditional hardware VPNs and modern cloud VPNs share the basic architectural principle, in which client connections are handled by a central VPN gateway. The individual connections are encapsulated in encrypted tunnels as per the configured VPN protocol.
Modern, cloud-based business VPNs provide much more than just encrypted connections, and offer additional functionalities like cloud and branch connectors, least-privilege access controls, user authentication mechanisms, or online threat protection.
What is an SD-WAN?
A software-defined wide area network (SD-WAN) is an evolved WAN that uses software defined networking to improve wide-area network and application performance. Modern SD-WANs use application-aware routing and load-balancing policies to maintain low latency of business applications (such as video calls and screen sharing) and preserve user experience.
The software-defined part of SD-WANs is in fact an overlay network, which is a logical networking structure that is added to an existing network infrastructure without major changes to hardware, and interconnects everything via the public internet, MPLS links (multiprotocol label switching), or VPN tunnels.
The beauty of an SD-WAN is that it decouples the control plane from the data plane, which offloads CPU-intensive tasks from the routers onto the SD-WAN controller. This improves the overall performance of the underlying network and frees it up to perform more advanced routing tasks at higher speed.
Software-defined networking (SDN) is an approach to network management that enables network administrators to manage network services more easily via an abstract mechanism superimposed on the physical infrastructure.
SDN separates the control plane (which determines how data is forwarded) from the data plane (which actually transports the data). This makes it possible for network services to be managed with software-based controllers, rather than relying on traditional hardware-based routers and switches.
In an SDN architecture, the network is a logical infrastructure and is managed through a software controller that communicates with the underlying network devices via a standardized protocol. This provides network administrators with a centralized view of the entire network, making it easier to automate and optimize network traffic, apply security policies, and manage resources.
SDN offers several benefits, including improved network performance, greater flexibility, easier management and maintenance, and enhanced security. By separating the control and data planes, SDN enables network administrators to configure and manage network services more easily, and to respond quickly to changing network traffic patterns and security threats.
Pros and cons of VPN
Below are the advantages and disadvantages of VPN. The list is not nearly extensive, but shows the most important points for the purposes of the comparison with SD-WAN.
Advantages of VPN
VPN is a broadly available solution that improves security and privacy on the internet.
- Security is the primary purpose of a VPN. VPNs use strong encryption to protect data during transit and to hide the identity of the communicating parties. Modern business VPNs also provide additional security features like identity-based authentication, access controls, and threat detection.
- Ease of management, especially in modern cloud VPNs like GoodAccess, makes them the go-to solution for smaller businesses that don’t have trained network specialists on staff.
Disadvantages of VPN
VPNs are built primarily for building secure connections, which means they often lack advanced networking features.
- Application performance can be reduced by the VPN due to its gateway-client architecture. User experience of latency-sensitive apps can degrade at high loads, especially in traditional hardware VPNs. However, modern cloud-based VPNs remedy this to an extent, as they generally provide better throughput and scale more easily thanks to their software-defined architecture.
- Traffic visibility can be reduced unless the VPN is designed to do so. This is due to the privacy-oriented pedigree of VPNs, where personal VPNs are designed to prevent observability. However, modern business VPNs provide a degree of application-level visibility and access logs.
DM-VPN (dynamic multipoint VPN) is a Cisco-developed variant of VPN technology that connects multiple branch offices or remote sites to a central node.
DM-VPNs combine point-to-site and site-to-site connections and allow traffic to be routed directly between the remote sites without having to pass the central hub, which improves network performance.
DM-VPN uses various encryption protocols, such as IPsec or SSL, to provide a secure tunnel for data transmission between sites. Additionally, it supports features such as Quality of Service (QoS) and multicast, which are essential for applications such as video conferencing and voice over IP (VoIP).
Overall, DM-VPN provides a scalable solution for connecting multiple remote sites to a central network hub, while also providing security and performance benefits. However, an in-house DM-VPN requires extensive networking knowledge and can be difficult to manage and scale.
Pros and cons of SD-WAN
Below are the advantages and disadvantages of SD-WAN. The list is not nearly extensive, but shows the most important points for the purposes of the comparison with VPN.
Advantages of SD-WAN
SD-WAN is a modern solution designed to maximize user experience and boost productivity.
- Application performance is arguably the key benefit of SD-WANs, especially for large enterprises. App-aware routing, supported by agent-based application performance monitoring, will automatically choose the fastest route for application delivery depending on the current load in different parts of the infrastructure.
- Network performance is also increased because an SD-WAN is not as strictly bound by physical infrastructure and will find ways to bypass network bottlenecks when traffic gets throttled.
Disadvantages of SD-WAN
SD-WAN was developed to ease network management and improve application performance, which means it generally doesn’t fit well with the needs of small companies in terms of both functionality and budget.
- Lack of security is a major disadvantage of SD-WAN, as it is primarily built as a networking solution, not a security measure, unless IPsec tunneling is added. Solutions called secure SD-WAN add security mechanisms to the concept, but they also come at an enterprise-grade cost.
- Cost can be high in SD-WANS. They require an additional controller (or more) to be deployed on the network to enable advanced routing policies. As mentioned above, additional features, like security, further increase the cost.
VPN and SD-WAN side-by-side comparison
Consumer VPNs for individuals serve a fundamentally different purpose than SD-WAN, and traditional hardware VPNs are on the way out. To make this comparison fair, the table below compares only the cloud VPN and SD-WAN.
Tab.1 – Cloud VPN and SD-WAN comparison
Verdict: Which should you choose?
Both VPN and SD-WAN are built differently to serve a different purpose. The choice of which is better depends closely on your organization and its needs.
- Large enterprises with thousands of employees across multiple branches will greatly benefit from the application-aware routing of SD-WAN. A secure SD-WAN will provide the in-transit data security and fit in well with other security solutions already in place.
- Small and medium businesses with fewer employees and smaller infrastructure do not need the advanced routing capabilities of an SD-WAN. For these companies a cloud VPN is the better choice, as it reduces their attack profile on the internet and secures communications between users and company systems.
- Fully remote companies without or with a minimal on-prem infrastructure can benefit greatly from mature cloud VPN solutions like GoodAccess, as it secures their data online and provides with robust security features, like MFA, access control, or threat detection, to reduce their attack surface and ensure regulatory compliance.