Over the next few months I’ll be diving into the technology from the perspective of a service provider selling hosted PBX services, to help you understand what all the hype is about, what the technology actually does, and in what circumstances it makes sense to use SD-WAN for your own customers.
To kick things off, this article will introduce the technology and help you understand why you should even care about any of this.
SD-WAN combines two IP networking acronyms:
- SDN stands for Software-Defined Networking, which (according to Wikipedia) “is a novel approach to cloud computing that facilitates network management and enables programmatically efficient network configuration in order to improve network performance and monitoring.” In other words, SDN allows the configuration of your routers to be remotely controlled by a central “brain” that understands the network as a whole.
- WAN stands for Wide Area Network (as opposed to LAN – Local Area Network), which is an IP network that spans a large geographic distance. In this context it usually refers to an internal corporate network that covers multiple geographic locations.
Therefore SD-WAN applies SDN to a WAN, allowing a central “brain” to improve the performance of a wide area network through control of the individual routers that make up the network. This is important for large enterprises because it can allow them to substantially reduce their use of expensive inter-site MPLS connections, and make much greater use of commercially available internet access.
And while that’s all true, it’s very misleading for our purposes. As a VoIP service provider we don’t really care about any of that – except perhaps the last line.
We can apply SD-WAN technology at Hosted PBX customers to make much more effective use of commercially available internet access to provide high quality VoIP service.
The world without SD-WAN
But before we look at how it works, let’s take a moment to remind ourselves of the problem it’s trying to solve.
If you’re selling hosted VoIP services to businesses then you’ll probably find yourself in one of the following situations:
- You own the transport network (including the parts of the customer LAN that carry voice), and are able to provide high quality VoIP service because you have great IP engineers and network architects. But you can only sell on-network.
- You own the transport network, so call quality is theoretically under your control, but to be honest you still see a lot of network issues that lead to customer complaints.
- You sell to businesses who “bring their own broadband” connection – a situation fraught with potential trouble. So you try to reduce the problems by (a) requiring a dedicated connection for voice, (b) installing an expensive MPLS connection between their site and your network, or (c) praying.
If you’re in the first category, and are happy doing all that work, then you can probably stop reading, but if you’ve ever had voice quality issues or outages caused by the IP network then SD-WAN could be a big help.
How does SD-WAN help with VoIP?
SD-WAN devices apply a variety of methods to voice traffic to significantly improve quality, even if we ignore all that stuff about multi-site, wide area networks. Here’s a very simple diagram (by a top quality artist) of a single-site business using hosted PBX services from a service provider over the public internet. We’ll refer to this as we talk through the ways SD-WAN can improve the quality of voice calls.
- SD-WAN products typically have a simple user-interface that makes it easy to prioritize VoIP traffic on the internet uplink from the business LAN to the ISP. Of course, this by itself isn’t groundbreaking – it’s been possible to do this through DSCP/QoS tags and prioritization rules in the router for many years – but anything that makes it easier to get this part right is a big help.
- Traditionally, while it was possible to control upload prioritization at the router, it was not possible to control traffic priority in the other direction – incoming traffic from the internet. Most SD-WAN products connect to a “cloud gateway” that can either be located in the SD-WAN providers data center or even in your own core network. Network traffic to and from the business routes through the cloud gateway which means that VoIP can be prioritized in both directions.
- Prioritization is a good start, but if there is congestion somewhere on the public internet between the two SD-WAN devices you could still see packet loss. However, through techniques like forward error correction and packet cloning, SD-WAN routers can increase the resilience of a VoIP audio stream to packet loss. (I’ll cover this in more detail in a future article.)
- All of the above benefits are true with a single internet uplink, but if you can make a second uplink available (even if both are consumer broadband connections, or even if one is a wireless gateway) the SD-WAN router can automatically shape the traffic between the two connections so that any outages or performance issues on the internet pipes don’t impact the experience for the end-user.
In future articles I’ll explore each of these areas in more detail, but for now suffice to say that SD-WAN can have a significant positive impact on voice quality even with a single uplink, but if you have two uplinks it can dramatically improve both quality and availability.
What next?
Hopefully this short introduction has convinced you that SD-WAN could be an important technology for anyone offering hosted PBX services. Over the coming weeks and months I’m planning to publish further articles (read the next one here) digging more deeply into the technical side of things, before trying to answer the core business question – is SD-WAN worth the investment?
Please join my mailing list to be notified when the next article is published. I’m also working on a guide to help you decide how best to deploy SD-WAN (if at all) for different types of businesses, which I’ll share with my email list once it’s ready.
