SD-WAN vs VPN: Which One Is Better & In Which Contexts

SD-WANs and VPNs securely connect remote workers and offices to the corporate network but in different ways. They have their strengths and weaknesses, none of which make either of them the better option in every setup. 

VPNs are the old guard, around for ages, and useful for creating secure, encrypted tunnels between offices or remote employees and the corporate network. On the other hand, SD-WAN is a newer technology that uses software to centralize control and extend the corporate network over vast geographical distances.

To design a robust enterprise network that protects the security and integrity of your data and enhances productivity for a dispersed workforce, it’s essential to understand the differences and similarities between SD-WAN and VPN networking solutions.

SD-WAN vs VPN - How do they compare?

Architecture and technology

A VPN, or Virtual Private Network, relies on a point-to-point architecture. This setup creates a secure "tunnel" between two points, typically a user’s device and a corporate server. Think of it like a direct, secure pathway that's established over the internet. 

Traditional VPNs often use protocols like IPsec or SSL to encrypt traffic and maintain security. However, because VPNs require traffic to route through a single, central point, they can sometimes be slower, especially if the central server is far from where the data originates or ends up.

In contrast, SD-WAN (Software-Defined Wide Area Network) technology, takes a more modern approach. Rather than creating a single tunnel, SD-WAN uses a distributed architecture. 

SD-WAN leverages multiple types of connections, such as MPLS, broadband, and LTE, adjusting dynamically based on current network conditions. Data can travel across multiple paths and take the most efficient route available. This flexibility can lead to better performance and more resilient connections.

For example, if you have offices in New York, London, and Tokyo, with a VPN each office would need to create a direct tunnel to the corporate server, which might be located in New York. Data packets traveling from Tokyo to London would first go to New York, then back out to London, which can be inefficient and slow. 

SD-WAN, however, would dynamically find the best path, perhaps sending data from Tokyo directly to London, bypassing New York altogether. This makes communications faster and more efficient.

So, while both SD-WAN and VPNs provide secure ways to connect remote locations and users to a corporate network, they do so in very different ways. SD-WAN offers a more flexible, efficient, and manageable solution compared to the often rigid and slower VPN architecture.

Traffic prioritization

VPNs typically route all traffic through the same tunnel without differentiating between types. If a user is video conferencing and also downloading large files, both types of data are treated equally, which can cause congestion and poor performance for time-sensitive applications like video calls. 

SD-WANs, however, can prioritize traffic based on the type of application. Video calls could be given higher priority over file downloads, ensuring smooth communication.

Configuration

Managing a VPN often involves complex configurations and a fair amount of manual intervention. Each new site or user needs to be configured and managed individually. 

SD-WAN simplifies this with central management and automation. Policies and configurations can be pushed out to all devices from a single dashboard, reducing administrative overhead and the potential for human error.

Underlying technologies

At their core, SD-WANs leverage software-defined networking (SDN) principles to manage and optimize a corporate network. One of the best features of SD-WAN is how it uses multiple types of connections like MPLS, broadband, and LTE simultaneously. 

SD-WANs also incorporate intelligent path control and application-aware routing. It can identify the best path for your data to travel, ensuring applications that need low latency, like video conferencing tools, always get the best possible service. 

SD-WANs also often come with built-in security features, such as end-to-end encryption and integrated firewalls, making them robust against cyber threats.

On the flip side, VPNs are based on well-established networking protocols. One of the most common protocols used here is IPsec (Internet Protocol Security). 

IPsec does a great job of encrypting your data, ensuring that it can't be read by anyone snooping around. For example, companies often use IPsec VPNs to allow remote workers to securely connect to the corporate network.

Another popular VPN protocol is SSL/TLS (Secure Sockets Layer/Transport Layer Security). SSL VPNs are particularly handy because they can be accessed through a web browser, making them incredibly user-friendly. Think of it as logging into a secure website; the same encryption that protects your online banking can protect your corporate data.

One thing to note, though, is that while VPNs do a fantastic job of providing secure remote access, they don't have the traffic optimization features that SD-WANs boast. 

VPN connections usually follow a single, static path, and if something goes wrong with that path, well, you may lose connectivity until the issue is resolved. This is where SD-WANs shine, with their dynamic rerouting capabilities and better overall performance management.

Network topology

With traditional VPNs, the architecture tends to be more static and centralized. Picture a corporate HQ with a massive server room. That's where all internet traffic from remote offices and workers funnels through. 

Each remote site or user has a VPN client that connects directly to this central hub. It's like having a spoke-and-wheel design; all communication routes through the center. This setup can work, but it often becomes a bottleneck, especially as the company grows. 

For instance, if you have offices in New York, Los Angeles, and Tokyo, all your data might need to be routed through HQ in Chicago. This can result in latency and reduced performance.

SD-WANs offer a more flexible and dynamic approach. They create a ‘mesh’ network where each branch office can connect directly to other branches, data centers, or cloud services without passing through a central hub. 

This means your New York office can connect directly to Tokyo for certain applications and directly to Los Angeles for others. It optimizes the path based on real-time conditions. If there's a faster route available due to lighter traffic, the SD-WAN can automatically switch to it.

Therefore, SD-WAN offers a modern, adaptable, and efficient network topology. VPNs, while still valuable, often feel like navigating an old highway system, whereas SD-WANs let you take advantage of new express lanes and direct routes for a smoother ride.

Performance and reliability

SD-WANs often provide better performance because they can choose from multiple connections. They can hop between different internet paths, like carrier links or broadband to maintain a smooth connection.

VPNs, on the other hand, usually stick to a single path. If that path gets congested, your performance can take a hit. Think of it like being stuck in traffic with no detour available. This makes VPNs less reliable in fluctuating network conditions. 

For instance, if there’s heavy traffic on the route your VPN is using, you might experience delays or timeouts. You don't want that to happen during a critical business meeting or when accessing cloud applications.

Monitoring and troubleshooting is also with SD-WANs. Many SD-WAN solutions come with built-in analytics. You can easily see which paths are performing well and which aren’t. This level of visibility isn’t typically available with VPNs. 

With VPNs, if something goes wrong, you might spend hours figuring out what happened. SD-WAN gives you real-time insights you can use to spot and solve issues quickly. Some SD-WANs even offer automated responses to network problems, ensuring minimal disruption.

So, overall, SD-WANs are more reliable than traditional VPNs. They’re designed to handle the complexities of modern corporate networks, making them a go-to for many businesses looking to optimize their network performance.

Latency, jitter, and packet loss

Latency is the time it takes for a packet of data to travel across your network to its destination. With a traditional VPN, you might experience higher latency because all traffic is routed through a centralized server, creating a bottleneck. This can be frustrating for real-time applications like video conferencing or VoIP calls.

SD-WAN, on the other hand, can significantly reduce latency. Most SD-WAN solutions sit outside of your data path. They won’t disrupt performance but can actually improve it. 

SD-WAN can detect the best possible paths for your data packets, steering them away from congested routes automatically. This means your traffic can avoid latency issues by leveraging multiple WAN links and choosing the optimal one in real time.

Packet loss happens when data packets fail to reach their destination, which can severely degrade application performance. With VPNs, you may face packet loss due to factors like network congestion or hardware failures. For instance, if you're sending large files or running a database application, packet loss can be catastrophic.

SD-WAN solutions can tackle packet loss much more effectively. Many SD-WANs offer Forward Error Correction (FEC), which reconstructs lost packets at the destination link. This means that even if packets get lost in transit, they can be recovered without significantly impacting performance. 

Jitter, which refers to the variability in packet arrival times, is another pain point. High jitter can cause disruptive performance issues, especially for real-time applications. In a VPN setup, jitter can occur due to network congestion or improper packet queuing.

SD-WAN offers better management of jitter by providing a clearer, real-time view of your network. This transparency helps you detect optimal traffic routes and steer your data accordingly. Additionally, Forward Error Correction can help mitigate jitter by avoiding TCP congestion and deduplication. So, if your team is working on a real-time collaboration tool, an SD-WAN can make the experience smoother and more reliable.

With these benefits, SD-WAN can offer a superior experience compared to traditional VPNs when managing latency, packet loss, and jitter. The improved visibility and control you get with SD-WAN can make all the difference for your corporate network.

Path optimization and redundancy

One of the standout features of SD-WAN is its ability to dynamically route traffic through the most efficient path. This ensures that critical applications always have the best possible performance. 

On the other hand, traditional VPNs don't offer the same level of path optimization. A VPN usually routes traffic through a single, predefined path. If that path becomes congested or fails, the traffic may get delayed or even drop until the issue is resolved. To mitigate this, businesses often rely on manual configuration and intervention, which can be time-consuming and error-prone.

Redundancy is another area where SD-WAN shines. Thanks to its ability to aggregate multiple types of connections, SD-WAN provides built-in redundancy. Whether it's a high-speed fiber link, a standard broadband line, or a 4G/5G connection, SD-WAN can combine these to ensure continuous connectivity. 

If one link goes down, the traffic automatically switches to another. This kind of redundancy is crucial for maintaining uptime and ensuring business continuity.

In contrast, achieving redundancy with VPNs usually involves setting up multiple VPN tunnels and manually configuring failover mechanisms. For instance, you might have a primary VPN tunnel over an MPLS link and a backup tunnel over a broadband connection. 

While  failover mechanisms can provide some level of redundancy, the failover process is typically slower and more complex compared to the automated, instantaneous switching that SD-WAN offers.

In essence, SD-WAN's capabilities for path optimization and redundancy make it far more adaptable and resilient than traditional VPNs. Whether you're dealing with network congestion, link failures, or simply aiming for the best performance, SD-WAN offers automated, dynamic solutions that are hard to match with a traditional VPN setup.

Security

VPNs rely heavily on encryption to secure data, typically using IPsec protocols which form a secure tunnel for data to travel through. On the other hand, SD-WANs offer a more sophisticated approach to security. 

SD-WANs often come integrated with a suite of security features like firewalls, intrusion detection systems, and even malware protection. This means you're not just encrypting data but also actively monitoring and defending against real-time threats. 

For instance, if an SD-WAN detects unusual traffic patterns that look like a potential attack, it can reroute or block that traffic immediately.

Another strength of SD-WANs is their ability to segment the network. This segmentation ensures that even if one part of the network is compromised, the threat doesn’t spread easily. 

If a hacker gains access to a segment of your network handling customer service, they wouldn’t automatically gain access to your financial data. This isolation adds a crucial layer of defense that VPNs typically lack.

SD-WANs are also designed to work seamlessly across various types of internet connections, from broadband to LTE. With this flexibility, they can enforce security policies consistently, regardless of how and where you're connecting. 

So, if you're in a remote office or on the go, the security protocols remain robust and uniform, unlike some VPNs which might struggle with varied connection qualities.

However, it's essential to mention that VPNs are still quite reliable for many standard use cases. For many organizations, especially smaller ones, a VPN might suffice for basic secure access needs. But as cyber threats become more sophisticated, the comprehensive security that SD-WANs provide provides more robust protection.

Centralized vs decentralized management

With a VPN, management is often decentralized. That means each site or office might have its own setup, and you’ll need to configure each location's firewall and security protocols individually. 

For instance, if your New York office and your London office both have VPNs, you’ll need to monitor and maintain each one separately.

SD-WAN offers a centralized management approach, like a command center for your entire network. You can control and monitor all your sites and connections from a single dashboard, which is a huge time-saver.

If you need to push a security update, for example, you can do it across all offices at once. No need to log into multiple systems. The centralized management also makes it easier to enforce company-wide policies and ensure compliance.

VPNs force you to juggle multiple independent setups whereas SD-WANs give you a unified control panel to manage everything efficiently. This simplicity and oversight make a world of difference when you’re managing a sprawling network.

When to use a VPN or an SD-WAN

Whether to use a VPN or SD-WAN often depends on specific needs and situations within the corporate network. If you are looking to connect remote employees or smaller branch offices back to the main office securely, a VPN usually makes sense. 

VPNs work well in situations where you don’t need constant, high-speed connections but just require secure access to the network.

On the other hand, SD-WAN is the way to go if you are dealing with multiple branch offices that need reliable, high-performance connections. It can dynamically route traffic to ensure each branch gets the best possible performance without hassles. It’s not just about speed but also about managing costs and improving the user experience.

SD-WAN also tends to be easier to manage and scale. If you have an expanding network with more applications, users, and data, SD-WAN provides the flexibility to handle all of these without significantly increasing complexity. 

Managing multiple locations through traditional VPN setups is highly demanding. SD-WAN streamlines the whole process, letting you easily add new sites and applications without a hitch.

Security is another angle where the choice might change. VPNs are typically sufficient if your primary goal is to ensure encrypted communications to keep data secure from point A to point B. But if you need comprehensive security features that include threat detection and response, SD-WAN solutions often come built-in with advanced security measures. 

For example, in a healthcare setting where protecting patient records is critical, SD-WAN can offer integrated security features like firewalls and intrusion prevention systems right out of the box, simplifying compliance with regulations.

Choosing between a VPN and SD-WAN boils down to the specific needs of the corporate network. If secure, point-to-point access for remote users is the goal, VPNs suffice. But for more complex, performance-driven, and scalable requirements, especially across multiple sites or regions, SD-WAN is the better choice.