Editor's note: As the software-defined WAN (SD-WAN) continues to expand its presence in networking, many enterprises compare SD-WAN benefits to those of traditional WANs. In this podcast, ZK Research founder and principal analyst Zeus Kerravala discusses how SD-WANs support better quality of experience than traditional WANs.
The majority of companies I've talked to that have switched to SD-WAN, or have at least been looking at deploying it, have done so for cost reasons. While I believe SD-WANs can invariably save companies money, that's not the primary reason companies should consider them. If deployed correctly, SD-WAN offers better quality of experience (QoE) for users than traditional WANs. Let me preface this by saying I am in no way suggesting a single internet connection will offer better quality than a single traditional WAN connection, like MPLS. However, if architected correctly, an SD-WAN that leverages multiple broadband connections will give you better quality of experience than a traditional network will.
To understand this, let's first take a look at the traditional WAN. Traditional WANs use bandwidth inefficiently because of active-passive technology. In an active-passive network, only the primary network can be active, while the backup network -- or passive network -- becomes active only when the primary fails. This results in enterprises buying twice as much bandwidth as needed to support traffic in both the primary mode and the backup mode. It's a little like building a road system where all traffic has to go down the same road. Alternative paths can be used only if the backup road becomes active due to primary road failure. The primary road would have to be built so wide that it wouldn't make sense.
The road to SD-WAN benefits
By comparison SD-WANs use multi-path technology that binds multiple broadband connections or even traditional network connections like MPLS together. Automation, of course, is a big SD-WAN benefit. You can set up policies that say, "Send all my mission-critical traffic down the primary WAN connection, or my high-cost WAN connection." Policies can ensure all traffic designated for the best link actually goes over the best link. Additionally, IT managers don't have to continually fiddle with the network. Another one of SD-WAN benefits is WAN optimization that is typically built into SD-WAN connections. So even traffic that isn't real time, like Windows replication, storage replication or email traffic, won't consume as much bandwidth as before.
So the question is how do SD-WANs support better QoE than traditional WANs? It all lies in the architecture. SD-WANs are being built for an era with different types of traffic -- both real time and non-real time, cloud and non-cloud, mobile, etc. -- moving over our networks, while traditional networks were not. That's why I think SD-WANs have better QoE than traditional WANs. But you need to analyze your traffic patterns ahead of time. You need to understand how to set up your policies and how to automate configuration. If you do those things, I think you'll have a successful SD-WAN deployment, better performance and happier users.
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