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Hybrid WAN — It’s Time To Do The Math

With more applications hosted by SaaS providers and businesses constantly looking at ways to drive down costs, without sacrificing performance, companies are looking at ways to augment or replace their costly MPLS WAN infrastructure with the Internet.

MPLS networks have long served the needs of the enterprise, however, more businesses are realizing that they are wasting money sending a variety of applications over expensive MPLS links that don’t benefit from what it has to offer. The questions many companies are now asking themselves is a simple one: What is the right ratio of traffic that belongs to my MPLS network vs. an Internet VPN?

One of the simplest ways to begin reducing costs, while adding more bandwidth, is to utilize a hybrid WAN setup. The hybrid WAN consists of a branch office using two or more WAN links to connect to the enterprise WAN infrastructure. Although many businesses may not realize it, there is a very good chance they may already have the infrastructure for a hybrid WAN deployed, typically with a primary MPLS link and a secondary Internet VPN in case the MPLS fails. Unfortunately for many, the secondary Internet WAN link simply sits idle, when in reality it could be brought online to help supplement the MPLS link. The reason for this is that it has traditionally been difficult to effectively utilize this link due to limitations in the way network technologies work today. This is where Software Defined WAN (SD-WAN) can help.

Before companies begin to utilize a hybrid WAN infrastructure they should perform an analysis to determine what the most critical applications are on their enterprise WAN. For this example let’s take a look at a sample branch WAN infrastructure and see what our key applications are.

Enterprise WAN pie chart
Enterprise WAN Applications [click to enlarge]

After performing our initial assessment we get a better idea of the type of applications our users are using, and what is immediately clear is that many of these applications are either already running across the Internet and/or don’t benefit from MPLS. For example, Email, SharePoint, Oracle, HTTP, HTTP/S, CIFS/SMB and ERP applications work perfectly fine across an Internet link, and in fact, as more users shift to services such as Office365 and more of these services will be located off-premise and accessed solely through an Internet connection. Many of these applications were designed to work across less than perfect connections and can function well across an Internet VPN. MPLS adds very little value to any of these services.

The only three applications we have left that have something to gain from MPLS are VoIP, Video Conferencing and Virtual Desktops (VDI). These services all rely heavily on reliable delivery of packets for a high-quality experience to the end user, this is something an MPLS networks were designed to do. Carriers will generally offer some high priority buckets for your most critical traffic, this is commonly known as Class of Service (COS) and/or Quality of Service (QoS). These buckets provide the reliability your critical applications need to always work well, but the buckets only support so much bandwidth, so you have to pick and choose what is really critical. Applications that don’t fit into these buckets simply leave with the same priority, very much like what happens on Internet links.

A hybrid WAN configuration is a great way for businesses to start augmenting their MPLS network to enable more bandwidth while also providing cost savings. As businesses look to further distance themselves from MPLS a full SD-WAN strategy can be put in place to move to all Internet. Silver Peak’s SD-WAN solution offers several tools that actually fix problems commonly associated with the Internet such as packet loss and out-of-order packets, one of the most important reasons critical applications such as VoIP, Video, and VDI commonly need an MPLS network to run. The ability to condition an Internet link to be carrier quality with Silver Peak allows your most critical traffic to run over any type of link.

In our example above only 30% of the applications our sample customer ran could benefit from an MPLS network, the other 70% work perfectly well across an Internet link, and these ratios are rapidly shifting towards more traffic running over the Internet. The move to SaaS and the advent of SD-WAN are forever changing the enterprise WAN landscape, it’s only a matter of time before more businesses make their own calculations and come to this realization.

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