💭Rethinking SD-WAN Path Determination: Avoiding the "SD-WAN Brainfart" 💨

💭Rethinking SD-WAN Path Determination: Avoiding the "SD-WAN Brainfart" 💨

🔥In a world where SD-WAN reliability is paramount, it's time to expose the pretenders!🚫


4 min read

In the world of Software-Defined Wide Area Networking (SD-WAN), the determination of active path status is of paramount importance. However, some SD-WAN solutions rely on what could be described as a "brainfart" in their path determination approach, using primitive network probes that might not serve the purpose effectively. In this article, we explore this issue and emphasize the need for a more reliable, sophisticated approach to path determination, like the one offered by Fusion's SD-WAN.

The Primitive Network Probe

One of the concerning practices in SD-WAN involves using a basic network probe, sometimes labeled as a "service level probe," to determine the status of network paths. Often, these probes are limited to performing a simple ping to, which, as it turns out, is Google's public DNS server. In essence, SD-WANs employing this method are entirely reliant on Google being operational. This over-reliance on a single service provider is a glaring flaw in SD-WAN architecture.

The Lack of Reliability

Relying on Google's availability as the primary path determinant is problematic on multiple levels. First and foremost, it places the reliability of the entire network in the hands of a third-party service, leaving the SD-WAN vulnerable to any issues Google may face. This approach is fundamentally flawed as it fails to provide a reliable network path status, especially when a robust, dedicated management plane should be in place.

The Correct Approach

The status of an Internet path should be determined by the actual status of the tunnel itself, not by relying on external services. By using a separate management plane, SD-WANs can ensure that path determination is based on the integrity of the network infrastructure itself, rather than third-party services. A well-implemented SD-WAN should not need to ping a public DNS server to determine path status.

The Pitfalls of PPPOE Reliance

Another common yet faulty approach is relying on the status of PPPOE connections as an indicator of Internet connectivity. This assumption, that a dialed-up PPPOE connection guarantees Internet access, can lead to poor performance and network drops. In reality, such a strategy is not suitable for robust SD-WAN solutions, as it does not accurately reflect the true status of the network.

Fusion's SD-WAN: A True Solution

Unlike some so-called SD-WAN solutions that rely on questionable path determinants, Fusion's SD-WAN offers a genuine, reliable alternative. Fusion's approach focuses on the actual status of the network tunnel and provides a superior level of path determination. This approach ensures that the network remains resilient and responsive, even when faced with challenges.

Beware of the Fakes

It's important to be discerning when selecting an SD-WAN solution. Some SD-WAN providers, such as Fortinet and Meraki, fall into the category of what we've termed "fake SD-WANs." These providers use primitive path determinants, lack automation, and often require extensive manual configuration, making them less effective in the real world.

Global Network Realities

The dependency on a single regional data center or service provider can have far-reaching consequences. Even in regions with reliable infrastructure, issues can arise, leading to network disruptions. The recent Cloudflare outage, caused by utility and backup generator failures, serves as a reminder that even in well-developed areas, network reliability is never guaranteed.

"Ah, but for those developers of less robust SD-WAN solutions in Europe and America, it's time to reconsider. The belief that Google never fails is a precarious assumption. In our particular region, Google's infrastructure is primarily housed in one regional co-location facility. When this hub experiences any issues, the consequences are significant - Google services go down.

To compound matters, we also have two other major regional data centers, and any disruptions in the national long-distance fiber backbone affect us too. Picture this: you might be in Cape Town, enjoying perfect internet connectivity and seamless data center access, but your SD-WAN comes crashing down. Why? It's all because Google's core infrastructure resides in Johannesburg, and any hiccups in the critical fiber connection between Cape Town and Johannesburg, such as a repeater station in Colesburg running out of diesel, can spell disaster.

The complexities of regional network dynamics often differ significantly from what many in Europe and America may experience, reminding us that SD-WAN design should consider the unique challenges that different geographical locations can pose. Eish!


In the rapidly evolving world of SD-WAN, it's crucial to distinguish between true solutions and those that rely on questionable practices. The "SD-WAN brainfart," or the reliance on primitive path determinants, can have significant consequences for network reliability. A genuine SD-WAN solution, such as Fusion's, offers a more sophisticated and dependable approach to path determination, safeguarding your network from unexpected disruptions and outages. In an increasingly interconnected world, the importance of reliable networking solutions cannot be overstated.

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